Note: Descriptions are shown in the official language in which they were submitted.
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ADVANCED ELECTROLYTE SYSTEMS AND THEIR USE IN
ENERGY STORAGE DEVICES
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority from U.S.
Provisional Patent
Application No. 61/602,713, filed February 24, 2012, entitled "Electrolytes
for
Ultracapacitors," International Application No. PCT/US2012/045994, filed, July
9, 2012,
entitled "High Temperature Energy Storage Device," U.S. Application Serial No.
13/553,716,
filed July 19, 2012, entitled "Power Supply for Downhole Instruments," and and
U.S.
Provisional Patent Application No. 61/724,775, filed November 9, 2012,
entitled
"Electrolytes for Ultracapacitors". The entirety of each of these disclosures
is hereby
incorporated herein by reference thereto.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The invention disclosed herein relates to energy storage cells,
and in particular
to advanced electrolyte systems for use in these energy storage cells, and
related techniques
for providing an electric double-layer capacitor that is operable at high
temperatures.
2. Description of the Related Art
[0003] Energy storage cells are ubiquitous in our society. While most
people
recognize an energy storage cell simply as a "battery," other types of cells
should also be
included within this context. For example, recently, ultracapacitors have
garnered much
attention as a result of their favorable characteristics. In short, many types
of energy storage
cells are known and in use today.
[0004] An electric double-layer capacitor, also known as a
"supercapacitor,"
"supercondenser," "pseudocapacitor," "electrochemical double layer capacitor,"
or
"ultracapacitor," is a capacitor that exhibits substantially improved
performance over
common capacitors. One such parameter is energy density. Generally, an
ultracapacitor has
an energy density that is on the order of thousands of times greater than a
high capacity
electrolytic capacitor.
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[0005] Capacitors are one of the key components in any electronic device
and system.
Traditional functions include power supply voltage smoothing, supporting the
energy source,
and filtering. A variety of industries present demanding environments for
implementation of
electronics and capacitors.
[0006] Consider, for example, that industries such as oil-drilling,
aerospace, aviation,
military and automotive have some applications that require electrical
components to work
continuously at high temperatures (for example, at temperatures in excess of
eighty degrees
Celsius). This heat exposure, along with a variety of factors, work to degrade
performance of
energy storage systems at elevated temperatures, and lead to premature
degradation of the
energy storage cell. Durability and safety are key requirements in typical
aerospace and
defense applications. Applications such as those where engines, turbo fans,
and control and
sensing electronics are placed near outer shells of a rocket engine.
Automotive applications,
such as small gearboxes or embedded alternators/starters, also require
durability and long life
at elevated temperatures.
[0007] Electronic components used in industrial environments must be
physically
robust while meeting demands for performance. For designers and producers of
ultracapacitors, one of the attendant challenges is obtaining an electrolyte
that will function
well and reliably at high temperatures, as well as one that will function well
and reliably at
both high temperatures and low temperatures. Unfortunately, the desirable
properties of
some electrolytes are not exhibited or sustained at higher temperatures, and
even those that
have achieved durability at high temperatures have not been able to serve as
reliably at lower
temperatures. Thus, what are needed are electrolytes for ultracapacitors that
perform well in
demanding situations. Preferably, the electrolytes provide stable conductivity
and low
internal resistance as well as stable and high capacitance, and stable and low
leakage current
over a wide range of temperatures.
SUMMARY OF THE INVENTION
[0008] In one embodiment, an ultracapacitor is disclosed. The
ultracapacitor includes
an energy storage cell and an advanced electrolyte system (AES) within an
hermetically
sealed housing, the cell electrically coupled to a positive contact and a
negative contact,
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wherein the ultracapacitor is configured to operate at a temperature within a
temperature
range between about -40 degrees Celsius to about 210 degrees Celsius.
[0009] In another embodiment, a method for fabricating an ultracapacitor
is provided.
The method includes the steps of: disposing an energy storage cell comprising
energy storage
media within a housing; and filling the housing with an advanced electrolyte
system (AES),
such that an ultracapacitor is fabricated to operate within a temperature
range between about -
40 degrees Celsius to about 210 degrees Celsius.
[0010] In yet another embodiment, a method of using a high temperature
rechargeable
energy storage device (HTRESD) is provided. The method includes the steps of:
obtaining
an HTRESD comprising an advanced electrolyte system (AES); and cycling the
HTRESD by
alternatively charging and discharging the HTRESD at least twice, while
maintaining a
voltage across the HTRESD, such that the HTRESD exhibits an initial peak power
density
between 0.01 W/liter and 150 kW/liter, such that the HTRESD is operated at an
ambient
temperature that is in a temperature range of between about -40 degrees
Celsius to about 210
degrees Celsius.
[0011] In yet another embodiment, a method of using an ultracapacitor is
provided.
The method includes the steps of: obtaining an ultracapacitor as described
herein, wherein the
ultracapacitor exhibits a volumetric leakage current (mA/cc) that is less than
about 10mA/cc
while held at a substantially constant temperature within a range of between
about 100
degrees Celsius and about 150 degrees Celsius; and cycling the ultracapacitor
by alternatively
charging and discharging the ultracapacitor at least twice, while maintaining
a voltage across
the ultracapacitor, such that the ultracapacitor exhibits an ESR increase less
than about 1,000
percent after at least 1 hour of use while held at a substantially constant
temperature within a
range of between about -40 degrees Celsius to about 210 degrees Celsius.
[0012] In another embodiment, a method of providing a high temperature
rechargeable energy storage device to a user is provided. The method includes
the steps of
selecting a high temperature rechargeable energy storage device (HTRESD)
comprising an
advanced electrolyte system (AES) that exhibits an initial peak power density
between 0.01
W/liter and 100 kW/liter and a durability period of at least 1 hour when
exposed to an
ambient temperature in a temperature range from about -40 degrees Celsius to
about 210
degrees Celsius; and delivering the storage device, such that the HTRESD is
provided to the
user.
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[0013] In yet another embodiment, a method of providing a high
temperature
rechargeable energy storage device to a user is provided. The method includes
the steps of
obtaining any ultracapacitor as described herein that exhibits a volumetric
leakage current
(mA/cc) that is less than about 10mA/cc while held at a substantially constant
temperature
within a range of between about -40 degrees Celsius and about 210 degrees
Celsius; and
delivering the storage device, such that the HTRESD is provided to the user.
[0014] In yet another embodiment, an advanced electrolyte system (AES) is
disclosed. The AES comprises an ionic liquid comprising at least one anion and
at least one
cation and exhibits a halide content less than 1,000 ppm and a water content
less than 100
PPm=
[0015] In yet another embodiment, an advanced electrolyte system (AES) is
disclosed. The AES comprises an ionic liquid comprising at least one anion and
at least one
cation and at least one solvent and exhibits a halide content less than 1,000
ppm and a water
content less than 1.000 ppm.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The foregoing and other features and advantages of the invention
are apparent
from the following detailed description taken in conjunction with the
accompanying
drawings, which should not be considered as limiting:
[0017] FIG. 1 illustrates aspects of an exemplary ultracapacitor;
[0018] FIG. 2 is a block diagram depicting a plurality of carbon
nanotubes (CNT)
grown onto a substrate;
[0019] FIG. 3 is a block diagram depicting deposition of a current
collector onto the
CNT of FIG. 3 to provide an electrode element;
[0020] FIG. 4 is a block diagram depicting addition of transfer tape to
the electrode
element of FIG. 3;
[0021] FIG. 5 is a block diagram depicting the electrode element during a
transfer
process;
[0022] FIG. 6 is a block diagram depicting the electrode element
subsequent to
transfer;
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[0023] FIG. 7 is a block diagram depicting an exemplary electrode
fabricated from a
plurality of the electrode elements;
[0024] FIG. 8 depicts embodiments of primary structures for cations that
may be
included in the exemplary ultracapacitor;
[0025] FIGS. 9 and 10 provide comparative data for the exemplary
ultracapacitor
making use of raw electrolyte and purified electrolyte, respectively;
[0026] FIG. 11 depicts an embodiment of a housing for an exemplary
ultracapacitor;
[0027] FIG. 12 illustrates an embodiment of a storage cell for an
exemplary capacitor;
[0028] FIG. 13 depicts a barrier disposed on an interior portion of a
body of the
housing;
[0029] FIGS. 14A and 14B, collectively referred to herein as FIG. 14,
depict aspects
of a cap for the housing;
[0030] FIG. 15 depicts assembly of the ultracapacitor according to the
teachings
herein;
[0031] FIGS. 16A and 16B, collectively referred to herein as FIG. 16, are
graphs
depicting performance for the ultracapacitor for an embodiment without a
barrier and a
similar embodiment that includes the barrier, respectively;
[0032] FIG. 17 depicts the barrier disposed about the storage cell as a
wrapper;
[0033] FIGS. 18A, 18B and 18C, collectively referred to herein as FIG.
18, depict
embodiments of the cap that include multi-layered materials;
[0034] FIG. 19 is a cross-sectional view of an electrode assembly that
includes a
glass-to-metal seal;
[0035] FIG. 20 is a cross-sectional view of the electrode assembly of
FIG. 19
installed in the cap of FIG. 18B;
[0036] FIG. 21 depicts an arrangement of the energy storage cell in
assembly;
[0037] FIGS. 22A, 22B and 22C, collectively referred to herein as FIG.
22, depict
embodiments of an assembled energy storage cell;
[0038] FIG. 23 depicts incorporation of polymeric insulation into the
ultracapacitor;
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[0039] FIGS. 24A, 24B and 24C, collectively referred to herein as FIG.
24, depict
aspects of a template for another embodiment of the cap for the energy
storage;
[0040] FIG. 25 is a perspective view of an electrode assembly that
includes
hemispherically shaped material;
[0041] FIG. 26 is a perspective view of a cap including the electrode
assembly of
FIG. 25 installed in the template of FIG. 24;
[0042] FIG. 27 is a cross-sectional view of the cap of FIG. 26;
[0043] FIG. 28 depicts coupling of the electrode assembly with a terminal
of a storage
cell;
[0044] FIG. 29 is a transparent isometric view of the energy storage cell
disposed in a
cylindrical housing;
[0045] FIG. 30 is a side view of the storage cell, showing the various
layers of one
embodiment;
[0046] FIG. 31 is an isometric view of a rolled up storage cell which
includes a
reference mark for placing a plurality of leads;
[0047] FIG. 32 is an isometric view of the storage cell of FIG. 31 once
unrolled;
[0048] FIG. 33 depicts the rolled up storage cell with the plurality of
leads included;
[0049] FIG. 34 depicts a Z-fold imparted into aligned leads (i.e., a
terminal) coupled
to the storage cell;
[0050] FIGS. 35 - 38 are graphs depicting performance of exemplary
ultracapacitors;
and
[0051] FIGS. 39 - 43 are graphs depicting performance of exemplary
ultracapacitors
at 210 degrees Celsius.
[0052] FIGS. 44A and 44B are capacitance and ESR graphs, respectively,
depicting
performance for an ultracapacitor with the novel electrolyte entity: 1-buty1-1-
methylpiperidinium bis(trifluoromethylsulfonyl)imide at 150 degrees Celsius
and 1.5V.
[0053] FIGS. 45A and 45B are capacitance and ESR graphs, respectively,
depicting
performance for an ultracapacitor with the novel electrolyte entity,
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trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide at 150 degrees
Celsius and
1.5V.
[0054] FIGS. 46A and 46B are capacitance and ESR graphs, respectively,
depicting
performance for an ultracapacitor with the novel electrolyte entity,
butyltrimethylammonium
bis(trifluoromethylsulfonyl)imide at 150 degrees Celsius and 1.5V.
[0055] FIGS. 47A and 47B are capacitance and ESR graphs, respectively,
depicting
performance for an ultracapacitor with an ionic liquid selected from the ionic
liquids used in
preparing the enhanced electrolyte combinations, at 125 degrees Celsius and
1.5V.
[0056] FIGS. 48A and 48B are capacitance and ESR graphs, respectively,
depicting
performance for an ultracapacitor with a 37.5% organic solvent-ionic liquid
(same as in FIG.
47) v/v, at 125 degrees Celsius and 1.5V
[0057] FIG. 49 is an ESR graph depicting performance for an
ultracapacitor with a
37.5% organic solvent-ionic liquid (same as in FIG. 47) v/v, at -40 degrees
Celsius and 1.5V.
DETAILED DESCRIPTION OF THE INVENTION
[0058] In the present application a variety of variables are described,
including but
not limited to components (e.g. electrode materials, electrolytes, etc.),
conditions (e.g.,
temperature, freedom from various impurities at various levels), and
performance
characteristics (e.g., post-cycling capacity as compared with initial
capacity, low leakage
current, etc.). It is to be understood that any combination of any of these
variables can define
an embodiment of the invention. For example, a combination of a particular
electrode
material, with a particular electrolyte, under a particular temperature range
and with impurity
less than a particular amount, operating with post-cycling capacity and
leakage current of
particular values, where those variables are included as possibilities but the
specific
combination might not be expressly stated, is an embodiment of the invention.
Other
combinations of articles, components, conditions, and/or methods can also be
specifically
selected from among variables listed herein to define other embodiments, as
would be
apparent to those of ordinary skill in the art.
[0059] The present invention, including advanced electrolyte systems and
uses
thereof will be described with reference to the following definitions that,
for convenience, are
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set forth below. Unless otherwise specified, the below terms used herein are
defined as
follows:
I. Definitions
[0060] When introducing elements of the present invention or the
embodiment(s)
thereof, the articles "a," "an," and "the" are intended to mean that there are
one or more of
the elements. Similarly, the adjective "another," when used to introduce an
element, is
intended to mean one or more elements. The terms "including," "has" and
"having" are
intended to be inclusive such that there may be additional elements other than
the listed
elements.
[0061] The terms "alkenyl" and "alkynyl" are recognized in the art and
refer to
unsaturated aliphatic groups analogous in length and possible substitution to
the alkyls
described below, but that contain at least one double or triple bond
respectively.
[0062] The term "alkyl" is recognized in the art and may include
saturated aliphatic
groups, including straight-chain alkyl groups, branched-chain alkyl groups,
cycloalkyl
(alicyclic) groups, alkyl substituted cycloalkyl groups, and cycloalkyl
substituted alkyl
groups. In certain embodiments, a straight chain or branched chain alkyl has
about 20 or
fewer carbon atoms in its backbone (e.g., C1-C20 for straight chain, C1-C20
for branched
chain). Likewise, cycloalkyls have from about 3 to about 10 carbon atoms in
their ring
structure, and alternatively about 5, 6 or 7 carbons in the ring structure.
Examples of alkyl
groups include, but are not limited to, methyl, ethyl, propyl, butyl, pentyl,
hexyl, ethyl hexyl,
cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like.
[0063] As used herein, the terms "clad," "cladding" and the like refer to
the bonding
together of dissimilar metals. Cladding is often achieved by extruding two
metals through a
die as well as pressing or rolling sheets together under high pressure. Other
processes, such
as laser cladding, may be used. A result is a sheet of material composed of
multiple layers,
where the multiple layers of material are bonded together such that the
material may be
worked with as a single sheet (e.g., formed as a single sheet of homogeneous
material would
be formed).
[0064] As a matter of convention, it may be considered that a
"contaminant" may be
defined as any unwanted material that may negatively affect performance of the
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ultracapacitor 10 if introduced. Also note, that generally herein,
contaminants may be
assessed as a concentration, such as in parts-per-million (ppm). The
concentration may be
taken as by weight, volume, sample weight, or in any other manner as
determined
appropriate.
[0065] The term "cyano" is given its ordinary meaning in the art and
refers to the
group, CN. The term "sulfate" is given its ordinary meaning in the art and
refers to the
group, S02. The term "sulfonate" is given its ordinary meaning in the art and
refers to the
group, SO3X, where X may be an electron pair, hydrogen, alkyl or cycloalkyl.
The term
"carbonyl" is recognized in the art and refers to the group, C=O.
[0066] In general, the term "electrode" refers to an electrical conductor
that is used to
make contact to another material which is often non-metallic, in a device that
may be
incorporated into an electrical circuit. Generally, the term "electrode," as
used herein, is with
reference to the current collector 2 and the additional components as may
accompany the
current collector 2 (such as the energy storage media 1) to provide for
desired functionality
(for example, the energy storage media 1 which is mated to the current
collector 2 to provide
for energy storage and energy transmission).
[0067] "Energy density" is one half times the square of a peak device
voltage times a
device capacitance divided by a mass or volume of said device
[0068] As discussed herein, "hermetic" refers to a seal whose quality
(i.e., leak rate)
is defined in units of "atm-cc/second," which means one cubic centimeter of
gas (e.g., He)
per second at ambient atmospheric pressure and temperature. This is equivalent
to an
expression in units of "standard He-cc/sec." Further, it is recognized that 1
atm-cc/sec is
equal to 1.01325 mbar-liter/sec.
[0069] The terms "heteroalkenyl" and "heteroalkynyl" are recognized in
the art and
refer to alkenyl and alkynyl alkyl groups as described herein in which one or
more atoms is a
heteroatom (e.g., oxygen, nitrogen, sulfur, and the like).
[0070] The term "heteroalkyl" is recognized in the art and refers to
alkyl groups as
described herein in which one or more atoms is a heteroatom (e.g., oxygen,
nitrogen, sulfur,
and the like). For example, alkoxy group (e.g., -OR) is a heteroalkyl group.
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[0071] As
a matter of convention, the terms "internal resistance" and "effective series
resistance" and "ESR", terms that are known in the art to indicate a resistive
aspect of a
device, are used interchangeably herein.
[0072] As
a matter of convention, the term "leakage current" generally refers to
current drawn by the capacitor which is measured after a given period of time.
This
measurement is performed when the capacitor terminals are held at a
substantially fixed
potential difference (terminal voltage). When assessing leakage current, a
typical period of
time is seventy two (72) hours, although different periods may be used. It is
noted that
leakage current for prior art capacitors generally increases with increasing
volume and
surface area of the energy storage media and the attendant increase in the
inner surface area
of the housing. In general, an increasing leakage current is considered to be
indicative of
progressively increasing reaction rates within the ultracapacitor 10.
Performance
requirements for leakage current are generally defined by the environmental
conditions
prevalent in a particular application. For example, with regard to an
ultracapacitor 10 having
a volume of 20 mL, a practical limit on leakage current may fall below 200 mA.
[0073] A
"lifetime" for the capacitor is also generally defined by a particular
application and is typically indicated by a certain percentage increase in
leakage current or
degradation of another parameter such as capacitance or internal resistance
(as appropriate or
determinative for the given application). For instance, in one embodiment, the
lifetime of a
capacitor in an automotive application may be defined as the time at which the
leakage
current increases to 200% of its initial (beginning of life or "BOL") value.
In another
example, the lifetime of a capacitor in an oil and gas application may be
defined as the time
at which any of the following occurs: the capacitance falls to 50% of its BOL
value, the
internal resistance increases to 200% of its BOL value, the leakage increases
to 200% of its
BOL value. As a matter of convention, the terms "durability" and "reliability"
of a device
when used herein generally relate to a lifetime of said device as defined
above.
[0074] An
"operating temperature range" of a device generally relates to a range of
temperatures within which certain levels of performance are maintained and is
generally
determined for a given application. For instance, in one embodiment, the
operating
temperature range for an oil and gas application may be defined as the
temperature range in
which the resistance of a device is less than about 1,000% of the resistance
of said device at
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30 degrees Celsius, and the capacitance is more than about 10% of the
capacitance at 30
degrees Celsius.
[0075] In some instances, an operating temperature range specification
provides for a lower
bound of useful temperatures whereas a lifetime specification provides for an
upper bound of
useful temperatures.
[0076] "Peak power density" is one fourth times the square of a peak
device voltage
divided by an effective series resistance of said device divided by a mass or
volume of said
device.
[0077] As referred to herein, a "volumetric leakage current" of the
ultracapacitor 10
generally refers to leakage current divided by a volume of the ultracapacitor
10, and may be
expressed, for example in units of mA/cc. Similarly, a "volumetric
capacitance" of the
ultracapacitor 10 generally refers to capacitance of the ultracapacitor 10
divided by the
volume of the ultracapacitor 10, and may be expressed, for example in units of
F/cc.
Additionally, "volumetric ESR" of the ultracapacitor 10 generally refers to
ESR of the
ultracapacitor 10 multiplied by the volume of the ultracapacitor 10, and may
be expressed, for
example in units of Ohms=cc.
[0078] As a matter of convention, it should be considered that the term
"may" as used
herein is to be construed as optional; "includes" is to be construed as not
excluding other
options (i.e., steps, materials, components, compositions, etc,); "should"
does not imply a
requirement, rather merely an occasional or situational preference. Other
similar terminology
is likewise used in a generally conventional manner.
[0079] As discussed herein, terms such as "adapting," "configuring,"
"constructing"
and the like may be considered to involve application of any of the techniques
disclosed
herein, as well as other analogous techniques (as may be presently known or
later devised) to
provide an intended result.
H. Capacitors of the Invention
[0080] Disclosed herein are capacitors that provide users with improved
performance
in a wide range of temperatures. For example, the capacitor of the present
invention
comprising advanced electrolyte systems described herein may be operable at
temperatures
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ranging from about as low as minus 40 degrees Celsius to as high as about 210
degrees
Celsius.
[0081] In general, the capacitor of the present invention includes energy
storage
media that is adapted for providing a combination of high reliability, wide
operating
temperature range, high power density and high energy density when compared to
prior art
devices. The capacitor includes components that are configured to ensure
operation over the
temperature range, and includes electrolytes 6 that are selected solely from
the advanced
electrolyte systems described herein. The combination of construction, energy
storage media
and advanced electrolyte systems provide the robust capacitors of the present
invention that
afford operation under extreme conditions with enhanced properties over
existing capacitors,
and with greater performance and durability.
[0082] Accordingly, the present invention provides an ultracapacitor
comprising: an
energy storage cell and an advanced electrolyte system (AES) within an
hermetically sealed
housing, the cell electrically coupled to a positive contact and a negative
contact, wherein the
ultracapacitor is configured to operate at a temperature within a temperature
range
("operating temperature") between about -40 degrees Celsius to about 210
degrees Celsius;
about -35 degrees Celsius to about 210 degrees Celsius; about -40 degrees
Celsius to about
205 degrees Celsius; about -30 degrees Celsius to about 210 degrees Celsius;
about -40
degrees Celsius to about 200 degrees Celsius; about -25 degrees Celsius to
about 210 degrees
Celsius; about -40 degrees Celsius to about 195 degrees Celsius; about -20
degrees Celsius to
about 210 degrees Celsius; about -40 degrees Celsius to about 190 degrees
Celsius; about -15
degrees Celsius to about 210 degrees Celsius; about -40 degrees Celsius to
about 185 degrees
Celsius; about -10 degrees Celsius to about 210 degrees Celsius; about -40
degrees Celsius to
about 180 degrees Celsius; about -5 degrees Celsius to about 210 degrees
Celsius; about -40
degrees Celsius to about 175 degrees Celsius; about 0 degrees Celsius to about
210 degrees
Celsius; about -40 degrees Celsius to about 170 degrees Celsius; about 5
degrees Celsius to
about 210 degrees Celsius; about -40 degrees Celsius to about 165 degrees
Celsius; about 10
degrees Celsius to about 210 degrees Celsius; about -40 degrees Celsius to
about 160 degrees
Celsius; about 15 degrees Celsius to about 210 degrees Celsius; about -40
degrees Celsius to
about 155 degrees Celsius; about 20 degrees Celsius to about 210 degrees
Celsius; about -40
degrees Celsius to about 150 degrees Celsius.
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[0083] In one particular embodiment, the AES comprises a novel
electrolyte entity
(NEE), e.g., wherein the NEE is adapted for use in high temperature
ultracapacitors. In
certain embodiments, the ultracapacitor is configured to operate at a
temperature within a
temperature range between about 80 degrees Celsius to about 210 degrees
Celsius, e.g., a
temperature range between about 80 degrees Celsius to about 150 degrees
Celsius.
[0084] In one particular embodiment, the AES comprises a highly purified
electrolyte, e.g., wherein the highly purified electrolyte is adapted for use
in high temperature
ultracapacitors. In certain embodiments, the ultracapacitor is configured to
operate at a
temperature within a temperature range between about 80 degrees Celsius to
about 210
degrees Celsius.
[0085] In one particular embodiment, the AES comprises AES comprises an
enhanced electrolyte combination, e.g., wherein the enhanced electrolyte
combination is
adapted for use in both high and low temperature ultracapacitors. In certain
embodiments,
the ultracapacitor is configured to operate at a temperature within a
temperature range
between about -40 degrees Celsius to about 150 degrees Celsius.
[0086] As such, and as noted above, the advantages over the existing
electrolytes of
known energy storage devices are selected from one or more of the following
improvements:
decreased total resistance, increased long-term stability of resistance,
increased total
capacitance, increased long-term stability of capacitance, increased energy
density, increased
voltage stability, reduced vapor pressure, wider temperature range performance
for an
individual capacitor, increased temperature durability for an individual
capacitor, increased
ease of manufacturability, and improved cost effectiveness.
[0087] In certain embodiments of the ultracapacitor, the energy storage
cell comprises
a positive electrode and a negative electrode.
[0088] In certain embodiments of the ultracapacitor, at least one of the
electrodes
comprises a carbonaceous energy storage media, e.g., wherein the carbonaceous
energy
storage media comprises carbon nanotubes. In particular embodiments, the
carbonaceous
energy storage media may comprise at least one of activated carbon, carbon
fibers, rayon,
graphene, aerogel, carbon cloth, and carbon nanotubes.
[0089] In certain embodiments of the ultracapacitor, each electrode
comprises a
current collector.
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[0090] In certain embodiments of the ultracapacitor, the AES is purified
to reduce
impurity content. In certain embodiments of the ultracapacitor, the content of
halide ions in
the electrolyte is less than about 1,000 parts per million, e.g., less than
about 500 parts per
million, e.g., less than about 100 parts per million, e.g., less than about 50
parts per million.
In a particular embodiment, the halide ion in the electrolyte is selected from
one or more of
the halide ions selected from the group consisting of chloride, bromide,
fluoride and iodide.
In particular embodiments, the total concentration of impurities in the
electrolyte is less than
about 1,000 parts per million. In certain embodiments, the impurities are
selected from one
or more of the group consisting of bromoethane, chloroethane, 1-bromobutane, 1-
chlorobutane, 1-methylimidazole, ethyl acetate and methylene chloride.
[0091] In certain embodiments of the ultracapacitor, the total
concentration of
metallic species in the electrolyte is less than about 1,000 parts per
million. In a particular
embodiment, the metallic species is selected from one or more metals selected
from the group
consisting of Cd, Co, Cr, Cu, Fe, K, Li, Mo, Na, Ni, Pb, and Zn. In another
particular
embodiment, the metallic species is selected from one or more alloys of metals
selected from
the group consisting of Cd, Co, Cr, Cu, Fe, K, Li, Mo, Na, Ni, Pb, and Zn. In
yet another
particular embodiment, the metallic species is selected from one or more
oxides of metals
selected from the group consisting of Cd, Co, Cr, Cu, Fe, K, Li, Mo, Na, Ni,
Pb, and Zn.
[0092] In certain embodiments of the ultracapacitor, the total water
content in the
electrolyte is less than about 500 parts per million, e.g., less than about
100 parts per million,
e.g., less than about 50 parts per million, e.g., about 20 parts per million.
[0093] In certain embodiments of the ultracapacitor, the housing
comprises a barrier
disposed over a substantial portion of interior surfaces thereof. In
particular embodiments,
the barrier comprises at least one of polytetrafluoroethylene (PTFE),
perfluoroalkoxy (PFA),
fluorinated ethylene propylene (FEP), ethylene tetrafluoroethylene (ETFE). In
particular
embodiments, the barrier comprises a ceramic material. The barrier may also
comprise a
material that exhibits corrosion resistance, a desired dielectric property,
and a low
electrochemical reactivity. In a specific embodiment of the barrier, the
barrier comprises
multiple layers of materials.
[0094] In certain embodiments of the ultracapacitor, the housing
comprises a
multilayer material, e.g., wherein the multilayer material comprises a first
material clad onto
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a second material. In a particular embodiment, the multilayer material
comprises at least one
of steel, tantalum and aluminum.
[0095] In certain embodiments of the ultracapacitor, the housing
comprises at least
one hemispheric seal.
[0096] In certain embodiments of the ultracapacitor, the housing
comprises at least
one glass-to-metal seal, e.g., wherein a pin of the glass-to-metal seal
provides one of the
contacts. In a particular embodiment, the glass-to-metal seal comprises a feed-
through that is
comprised of a material selected from the group consisting of an iron-nickel-
cobalt alloy, a
nickel iron alloy, tantalum, molybdenum, niobium, tungsten, and a form of
stainless and
titanium. In another particular embodiment, the glass-to-metal seal comprises
a body that is
comprised of at least one material selected from the group consisting of
nickel, molybdenum,
chromium, cobalt, iron, copper, manganese, titanium, zirconium, aluminum,
carbon, and
tungsten and an alloy thereof.
[0097] In certain embodiments of the ultracapacitor, the energy storage
cell comprises
a separator to provide electrical separation between a positive electrode and
a negative
electrode, e.g., wherein the separator comprises a material selected from the
group consisting
of polyamide, polytetrafluoroethylene (PTFE), polyether ether ketone (PEEK),
aluminum
oxide (A1203), fiberglass, fiberglass reinforced plastic, or any combination
thereof. In a
particular embodiment, the separator is substantially free of moisture. In
another particular
embodiment, the separator is substantially hydrophobic.
[0098] In certain embodiments of the ultracapacitor, the hermetic seal
exhibits a leak
rate that is no greater than about 5.0x10-6 atm-cc/sec, e.g., no greater than
about 5.0x10-7 atm-
cc/sec, e.g., no greater than about 5.0x10-8 atm-cc/sec, e.g., no greater than
about 5.0x10-9
atm-cc/sec, e.g, no greater than about 5.0x10-1 atm-cc/sec.
[0099] In certain embodiments of the ultracapacitor, at least one contact
is configured
for mating with another contact of another ultracapacitor.
[00100] In certain embodiments of the ultracapacitor, the storage cell
comprises a
wrapper disposed over an exterior thereof, e.g., wherein the wrapper comprises
one of PTFE
and polyimide.
[00101] In certain embodiments of the ultracapacitor, a volumetric leakage
current is
less than about 10 Amperes per Liter within the temperature range.
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[00102] In certain embodiments of the ultracapacitor, a volumetric leakage
current is
less than about 10 Amperes per Liter over a specified voltage range between
about 0 Volts
and about 4 Volts, e.g. between about 0 Volts and about 3 Volts, e.g. between
about 0 Volts
and about 2 Volts, e.g. between about 0 Volts and about 1 Volt. .In certain
embodiments of
the ultracapacitor, the level of moisture within the housing is less than
about 1,000 parts per
million (ppm), e.g., less than about 500 parts per million (ppm), e.g., less
than about 350 parts
per million (ppm).
[00103] In certain embodiments of the ultracapacitor, the moisture content
in an
electrode of the ultracapacitor that is less than about 1,000 ppm, e.g., less
than about 500
ppm, e.g., less than about 350 parts per million (ppm).
[00104] In certain embodiments of the ultracapacitor, the moisture content
in a
separator of the ultracapacitor that is less than about 1,000 ppm, e.g., less
than about 500
ppm, e.g., less than about 160 parts per million (ppm).
[00105] In certain embodiments of the ultracapacitor, the chloride content
is less than
about 300 ppm for one of the components selected from the group consisting of
an electrode,
electrolyte and a separator.
[00106] In certain embodiments of the ultracapacitor, the volumetric
leakage current
(mA/cc) of the ultracapacitor is less than about 10mA/cc while held at the
substantially
constant temperature, e.g., less than about 1 mA/cc while held at the
substantially constant
temperature. In a particular embodiment,
[00107] In certain embodiments of the ultracapacitor, the volumetric
leakage current of
the ultracapacitor is greater than about 0.0001mA/cc while held at the
substantially constant
temperature.
[00108] In certain embodiments of the ultracapacitor, volumetric
capacitance of the
ultracapacitor is between about 6 F/cc and about 1 mF/cc; between about 10
F/cc and about 5
F/cc; or between about 50 F/cc and about 8 F/cc.
[00109] In certain embodiments of the ultracapacitor, the volumetric ESR
of the
ultracapacitor is between about 20 mOhms=cc and 200 mOhms=cc; between about
150
mOhms=cc and 2 Ohms=cc; between about 1.5 Ohms=cc and 200 Ohms=cc; or between
about
150 Ohms=cc and 2000 Ohms=cc.
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[00110] In
certain embodiments of the ultracapacitor, the ultracapacitor exhibits a
capacitance decrease less than about 90 percent while held at a substantially
constant voltage
and operating temperature. In a particular embodiment, the ultracapacitor
exhibits a
capacitance decrease less than about 90 percent while held at a substantially
constant voltage
and operating temperature for at least 1 hour, e.g. for at least 10 hours,
e.g. for at least 50
hours, e.g. for at least 100 hours, e.g. for at least 200 hours, e.g. for at
least 300 hours, e.g. for
at least 400 hours, e.g. for at least 500 hours, e.g. for at least 1,000
hours.
[00111] In
certain embodiments of the ultracapacitor, the ultracapacitor exhibits an
ESR increase less than about 1,000 percent while held at a substantially
constant voltage and
operating temperature for at least 1 hour, e.g. for at least 10 hours, e.g.
for at least 50 hours,
e.g. for at least 100 hours, e.g. for at least 200 hours, e.g. for at least
300 hours, e.g. for at
least 400 hours, e.g. for at least 500 hours, e.g. for at least 1,000 hours.
[00112] For
example, as shown in FIG. 1, an exemplary embodiment of a capacitor is
shown. In this case, the capacitor is an "ultracapacitor 10." The exemplary
ultracapacitor 10
is an electric double-layer capacitor (EDLC). The ultracapacitor 10 may be
embodied in
several different form factors (i.e., exhibit a certain appearance). Examples
of potentially
useful form factors include a cylindrical cell, an annular or ring-shaped
cell, a flat prismatic
cell or a stack of flat prismatic cells comprising a box-like cell, and a flat
prismatic cell that is
shaped to accommodate a particular geometry such as a curved space. A
cylindrical form
factor may be most useful in conjunction with a cylindrical system or a system
mounted in a
cylindrical form factor or having a cylindrical cavity. An annular or ring-
shaped form factor
may be most useful in conjunction with a system that is ring-shaped or mounted
in a ring-
shaped form factor or having a ring-shaped cavity. A
flat prismatic form factor may be
most useful in conjunction with a system that is rectangularly-shaped, or
mounted in a
rectangularly-shaped form factor or having a rectangularly-shaped cavity.
[00113]
While generally disclosed herein in terms of a "jelly roll" application (i.e.,
a
storage cell 12 that is configured for a cylindrically shaped housing 7), the
rolled storage cell
23 may take any form desired. For example, as opposed to rolling the storage
cell 12, folding
of the storage cell 12 may be performed to provide for the rolled storage cell
23. Other types
of assembly may be used. As one example, the storage cell 12 may be a flat
cell, referred to
as a coin type, pouch type, or prismatic type of cell. Accordingly, rolling is
merely one
option for assembly of the rolled storage cell 23. Therefore, although
discussed herein in
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terms of being a "rolled storage cell 23", this is not limiting. It may be
considered that the
term "rolled storage cell 23" generally includes any appropriate form of
packaging or packing
the storage cell 12 to fit well within a given design of the housing 7.
[00114] Various forms of the ultracapacitor 10 may be joined together. The
various
forms may be joined using known techniques, such as welding contacts together,
by use of at
least one mechanical connector, by placing contacts in electrical contact with
each other and
the like. A plurality of the ultracapacitors 10 may be electrically connected
in at least one of
a parallel and a series fashion.
[00115] For the purposes of this invention, an ultracapacitor 10 may have
a volume in
the range from about 0.05 cc to about 7.5 liters.
[00116] A variety of environments may exist where the ultracapacitor 10 is
particularly useful. For example, in automotive applications, ambient
temperatures of 105
degrees Celsius may be realized (where a practical lifetime of the capacitor
will range from
about 1 year to 20 years). In some downhole applications, such as for
geothermal well
drilling, ambient temperatures of 300 degrees Celsius or more may be reached
(where a
practical lifetime of the capacitor will range from about 1 hour to about
10,000 hours).
[00117] The components of the ultracapacitors of the present invention
will now be
discussed, in turn.
A. Advanced Electrolyte Systems of the Invention
[00118] The advanced electrolyte systems of the present invention provide
the
electrolyte component of the ultracapacitors of the present invention, and are
noted as
"electrolyte 6" in FIG. 1. The electrolyte 6 fills void spaces in and between
the electrodes 3
and the separator 5. In general, the advanced electrolyte systems of the
invention comprise
unique electrolytes, purified enhanced electrolytes, or combinations thereof,
wherein the
electrolyte 6 is a substance, e.g., comprised of one or more salts or ionic
liquids, which
disassociate into electrically charged ions (i.e., positively charged cations
and negatively
charged anions) and may include a solvent. In the advanced electrolyte systems
of the
present invention, such electrolyte components are selected based on the
enhancement of
certain performance and durability characteristics, and may be combined with
one or more
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solvents, which dissolve the substance to generate compositions with novel and
useful
electrochemical stability and performance.
[00119] The advanced electrolyte systems of the present invention afford
unique and
distinct advantages to the ultracapacitors of the present invention over
existing energy storage
devices (e.g., energy storage devices containing electrolytes not disclosed
herein, or energy
storage devices containing electrolytes having insufficient purity). These
advantages include
improvements in both performance and durability characteristics, such as one
or more of the
following: decreased total resistance, increased long-term stability of
resistance (e.g.,
reduction in increased resistance of material over time at a given
temperature), increased total
capacitance, increased long-term stability of capacitance (e.g. reduction in
decreased
capacitance of a capacitor over time at a given temperature), increased energy
density (e.g. by
supporting a higher voltage and/or by leading to a higher capacitance),
increased voltage
stability, reduced vapor pressure, wider temperature range performance for an
individual
capacitor (e.g. without a significant drop in capacitance and/or increase in
ESR when
transitioning between two temperatures, e.g. without more than a 90% decrease
in
capacitance and/or a 1000% increase in ESR when transitioning from about +30 C
to about -
40 C), increased temperature durability for an individual capacitor (e.g.,
less than a 50%
decrease in capacitance at a given temperature after a given time and/or less
than a 100%
increase in ESR at a given temperature after a given time, and/or less than 10
A/L of leakage
current at a given temperature after a given time, e.g., less than a 40%
decrease in capacitance
and/or a 75% increase in ESR, and/or less than 5 A/L of leakage current, e.g.,
less than a 30%
decrease in capacitance and/or a 50% increase in ESR, and/or less than 1 A/L
of leakage
current); increased ease of manufacturability (e.g. by having a reduced vapor
pressure, and
therefore better yield and/or more efficient methods of filling a capacitor
with electrolyte),
and improved cost effectiveness (e.g. by filling void space with material that
is less costly
than another material). For clarity, performance characteristics relate to the
properties
directed to utility of the device at a given point of use suitable for
comparison among
materials at a similar given point of use, while durability characteristics
relate to properties
directed to ability to maintain such properties over time. The performance and
durability
examples above should serve to provide context for what are considered
"significant changes
in performance or durability" herein.
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[00120] For clarity, and in general, reference to "electrolyte 6" as used
herein for
inclusion in the energy storage devices of the present invention refers to the
advanced
electrolyte systems of the present invention.
[00121] The properties of the AES, or Electrolyte 6, may be the result of
improvements in properties selected from increases in capacitance, reductions
in equivalent-
series-resistance (ESR), high thermal stability, a low glass transition
temperature (Tg), an
improved viscosity, a particular rhoepectic or thixotropic property (e.g., one
that is dependent
upon temperature), as well as high conductivity and exhibited good electric
performance over
a wide range of temperatures. As examples, the electrolyte 6 may have a high
degree of
fluidicity, or, in contrast, be substantially solid, such that separation of
electrodes 3 is
assured.
[00122] The advanced electrolyte systems of the present invention include,
novel
electrolytes described herein for use in high temperature ultracapacitors,
highly purified
electrolytes for use in high temperature ultracapacitors, and enhanced
electrolyte
combinations suitable for use in temperature ranges from -40 degrees Celsius
to 210 degrees
Celsius, without a significant drop in performance or durability across all
temperatures.
[00123] Although the disclosure presented herein shall focus on the
applicability of the
advanced electrolyte systems described herein to the ultracapacitors, these
advanced
electrolyte system are applicable to any energy storage device.
i. Novel Electrolyte Entities (NEE)
[00124] The advanced electrolyte systems (AES) of the present invention
comprise, in
one embodiment, certain novel electrolytes for use in high temperature
ultracapacitors. In this
respect, it has been found that maintaining purity and low moisture relates to
a degree of
performance of the energy storage 10; and that the use of electrolytes that
contain
hydrophobic materials and which have been found to demonstrate greater purity
and lower
moisture content are advantageous for obtaining improved performance. These
electrolytes
exhibit good performance characteristics in a temperature range of about 80
degrees Celsius
to about 210 degrees Celsius, e.g., about 80 degrees Celsius to about 200
degrees Celsius,
e.g., about 80 degrees Celsius to about 190 degrees Celsius e.g., about 80
degrees Celsius to
about 180 degrees Celsius e.g., about 80 degrees Celsius to about 170 degrees
Celsius e.g.,
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about 80 degrees Celsius to about 160 degrees Celsius e.g., about 80 degrees
Celsius to about
150 degrees Celsius e.g., about 85 degrees Celsius to about 145 degrees
Celsius e.g., about 90
degrees Celsius to about 140 degrees Celsius e.g., about 95 degrees Celsius to
about 135
degrees Celsius e.g., about 100 degrees Celsius to about 130 degrees Celsius
e.g., about 105
degrees Celsius to about 125 degrees Celsius e.g., about 110 degrees Celsius
to about 120
degrees Celsius.
[00125]
Accordingly, novel electrolyte entities useful as the advanced electrolyte
system (AES) include species comprising a cation (e.g., cations shown in FIG.
8 and
described herein) and an anion, or combinations of such species. In some
embodiments, the
species comprises a nitrogen-containing , oxygen-containing, phosphorus-
containing, and/or
sulfur-containing cation, including heteroaryl and heterocyclic cations. In
one set of
embodiments, the advanced electrolyte system (AES) include species comprising
a cation
selected from the group consisting of ammonium, imidazolium, oxazolium,
phosphonium,
piperidinium, pyrazinium, pyrazolium, pyridazinium, pyridinium, pyrimidinium,
sulfonium,
thiazolium, triazolium, guanidium, isoquinolinium, benzotriazolium, and
viologen-type
cations, any of which may be substituted with substituents as described
herein. In one
embodiment, the novel electrolyte entities useful for the advanced electrolyte
system (AES)
of the present invention include any combination of cations presented in FIG.
8, selected
from the group consisting of phosphonium, piperidinium, and ammonium, wherein
the
various branch groups Rx (e.g., R1, R2, R3,...Rx) may be selected from the
group consisting of
alkyl, heteroalkyl, alkenyl, heteroalkenyl, alkynyl, heteroalkynyl, halo,
amino, nitro, cyano,
hydroxyl, sulfate, sulfonate, and carbonyl, any of which is optionally
substituted, and wherein
at least two Rx are not H (i.e., such that the selection and orientation of
the R groups produce
the cationic species shown in FIG. 8); and the anion selected from the group
consisting of
[00126] For
example, given the combinations of cations and anions above, in a
particular embodiment, the AES may be selected from the group consisting of
trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide, 1-
buty1-1-
methylpiperidinium bis(trifluoromethylsulfonyl)imide, and
butyltrimethylammonium
bis(trifluoromethylsulfonyl)imide. Data supporting the enhanced performance
characteristics
in a temperature range as demonstrated through Capacitance and ESR
measurements over
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time, indicating high temperature utility and long term durability is provided
in FIG. 44A and
B, FIG. 45A and B, and FIG. 46A and B.
[00127] In
certain embodiments, the AES is trihexyltetradecylphosphonium
bis(trifluoromethylsulfonyl)imide.
[00128] In
certain embodiments, the AES is 1-butyl-1-methylpiperidinium
bis(trifluoromethylsulfonyl)imide.
[00129] In
certain embodiments, the AES is butyltrimethylammonium
bis(trifluoromethylsulfonyl)imide.
[00130] In
another embodiment, the novel electrolyte entities useful for the advanced
electrolyte system (AES) of the present invention include any combination of
cations
presented in FIG. 8, selected from the group consisting of imidazolium and
pyrrolidinium,
wherein the various branch groups Rx (e.g., R1, R2, R3,...Rx) may be selected
from the group
consisting of alkyl, heteroalkyl, alkenyl, heteroalkenyl, alkynyl,
heteroalkynyl, halo, amino,
nitro, cyano, hydroxyl, sulfate, sulfonate, and carbonyl, any of which is
optionally
substituted, and wherein at least two Rx are not H (i.e., such that the
selection and orientation
of the R groups produce the cationic species shown in FIG. 8); and the anion
selected from
the group consisting of tetrafluoroborate, bis(trifluoromethylsulfonyl)imide,
tetracyanoborate,
and trifluoromethanesulfonate. In one particular embodiment, the two Rx that
are not H, are
alkyl. Moreover, the noted cations exhibit high thermal stability, as well as
high conductivity
and exhibit good electrochemical performance over a wide range of
temperatures.
[00131] For
example, given the combinations of cations and anions above, in a
particular embodiment, the AES may be selected from the group consisting of 1
¨ butyl ¨ 3 ¨
methylimidazolium tetrafluoroborate;
1¨butyl-3¨methylimidazolium
bis(trifluoromethylsulfonyl)imide, 1 ¨ ethyl ¨ 3 ¨ methylimidazolium
tetrafluoroborate; 1 ¨
ethyl ¨ 3 ¨ methylimidazolium tetracyanoborate; 1 ¨ hexyl ¨ 3 ¨
methylimidazolium
tetracyanoborate; 1¨buty1-1¨methylpyrrolidinium
bis(trifluoromethylsulfonyl)imide; 1 ¨
butyl ¨ 1 ¨ methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate;
1¨butyl ¨ 1 ¨
methylp yrrolidinium tetracyanoborate, and
1¨butyl-3¨methylimidazolium
trifluoromethanesulfonate.
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[00132] In one embodiment, the AES is 1 ¨ butyl ¨ 3 ¨ methylimidazolium
tetrafluorob orate .
[00133] In one embodiment, the AES is 1 ¨ butyl ¨ 3 ¨ methylimidazolium
bis(trifluoromethylsulfonyl)imide.
[00134] In one embodiment, the AES is 1 ¨ ethyl ¨ 3 ¨ methylimidazolium
tetrafluorob orate .
[00135] In one embodiment, the AES is 1 ¨ ethyl ¨ 3 ¨ methylimidazolium
tetracyanob orate .
[00136] In one embodiment, the AES is 1 ¨ hexyl ¨ 3 ¨ methylimidazolium
tetracyanob orate .
[00137] In one embodiment, the AES is 1 ¨ butyl ¨ 1 ¨ methylpyrrolidinium
bis(trifluoromethylsulfonyl)imide.
[00138] In one embodiment, the AES is 1 ¨ butyl ¨ 1 ¨ methylpyrrolidinium
tris(pentafluoroethyl)trifluoropho sphate.
[00139] In one embodiment, the AES is 1 ¨ butyl ¨ 1 ¨ methylpyrrolidinium
tetracyanob orate .
[00140] In one embodiment, the AES is 1 ¨ butyl ¨ 3 ¨ methylimidazolium
trifluoromethanesulfonate.
[00141] In another particular embodiment, one of the two Rx that are not
H, is alkyl,
e.g., methyl, and the other is an alkyl substituted with an alkoxy. Moreover,
it has been
found that cations having an N,0-acetal skeleton structure of the formula (1)
in the molecule
have high electrical conductivity, and that an ammonium cation included among
these cations
and having a pyrrolidine skeleton and an N,0-acetal group is especially high
in electrical
conductivity and solubility in organic solvents and supports relatively high
voltage. As such,
in one embodiment, the advanced electrolyte system comprises a salt of the
following
formula:
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( ) X -
N +
/ \______õ0
Ri -...'"- R2 (1)
wherein R1 and R2 can be the same or different and are each alkyl, and X- is
an anion. In
some embodiments, R1 is straight-chain or branched alkyl having 1 to 4 carbon
atoms, R2 is
methyl or ethyl, and X- is a cyanoborate-containing anion 11. In a specific
embodiment, )(-
comprises [B(CN)]4 and R2 is one of a methyl and an ethyl group. In another
specific
embodiment, R1 and R2 are both methyl. In addition, in one embodiment,
cyanoborate
anions 11, X- suited for the advanced electrolyte system of the present
invention include,
[B(CN)4]- or [BFn(CN)4-n]-, where n = 0, 1, 2 or 3.
[00142]
Examples of cations of the AES of the present invention comprising a Novel
Electrolyte Entity of formula (1), and which are composed of a quaternary
ammonium cation
shown in formula (I) and a cyanoborate anion are selected from N-methyl-N-
methoxymethylpyrrolidinium (N-methoxymethyl-N-methylpyrrolidinium), N-ethyl-N-
methoxymethylpyrrolidinium, N-methoxymethyl-N-n-propylpyrrolidinium, N-
methoxymethyl-N-iso-propylpyrrolidinium, N-n-butyl-N-
methoxymethylpyrrolidinium, N-
iso-butyl-N-methoxymethylpyrrolidinium, N-tert-butyl-N-
methoxymethylpyrrolidinium, N-
ethoxymethyl-N-methylpyrrolidinium, N-ethyl-N-ethoxymethylpyrrolidinium
(N-
ethoxymethyl-N-ethylpyrrolidinium), N-
ethoxymethyl-N-n-propylpyrrolidinium, N-
ethoxymethyl-N-iso-propylpyrrolidinium, N-n-butyl-N-ethoxymethylpyrrolidinium,
N-iso-
butyl-N-ethoxymethylpyrrolidinium and N-tert-butyl-N-
ethoxymethylpyrrolidinium. Other
examples include N-methyl-N-methoxymethylpyrrolidinium (N-methoxymethyl-N-
methylpyrrolidinium), N-ethyl-N-methoxymethylpyrrolidinium and N-ethoxymethyl-
N-
methylpyrrolidinium.
[00143]
Additional examples of the cation of formula (1) in combination with
additional anions may be selected from N-methyl-N-methoxymethylpyrrolidinium
tetracyanoborate (N-methoxymethy-N-methylpyrrolidinium tetracyanoborate), N-
ethyl-N-
methoxymethylpyrrolidinium tetracyanoborate, N-ethoxymethyl-N-
methylpyrrolidinium
tetracyanoborate, N-
methyl-N-methoxymethylpyrrolidinium
bistrifluoromethanesulfonylimide, (N-
methoxymethy-N-methylpyrrolidinium
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bistrifluoromethanesulfonylimide), N-
ethyl-N-methoxymethylpyrrolidinium
bistrifluoromethanesulfonylimide, N-
ethoxymethyl-N-methylpyrrolidinium
bistrifluoromethanesulfonylimide, N-
methyl-N-methoxymethylpyrrolidinium
trifluoromethanesulfolate (N-methoxymethyl-N-methyltrifluoromethanesulfolate).
[00144]
When to be used as an electrolyte, the quaternary ammonium salt may be used
as admixed with a suitable organic solvent. Useful solvents include cyclic
carbonic acid
esters, chain carbonic acid esters, phosphoric acid esters, cyclic ethers,
chain ethers, lactone
compounds, chain esters, nitrile compounds, amide compounds and sulfone
compounds.
Examples of such compounds are given below although the solvents to be used
are not
limited to these compounds.
[00145]
Examples of cyclic carbonic acid esters are ethylene carbonate, propylene
carbonate, butylene carbonate and the like, among which propylene carbonate is
preferable.
[00146]
Examples of chain carbonic acid esters are dimethyl carbonate, ethylmethyl
carbonate, diethyl carbonate and the like, among which dimethyl carbonate and
ethylmethyl
carbonate are preferred.
[00147]
Examples of phosphoric acid esters are trimethyl phosphate, triethyl
phosphate, ethyldimethyl phosphate, diethylmethyl phosphate and the like.
Examples of
cyclic ethers are tetrahydrofuran, 2-methyltetrahydrofuran and the like.
Examples of chain
ethers are dimethoxyethane and the like. Examples of lactone compounds are y-
butyrolactone and the like. Examples of chain esters are methyl propionate,
methyl acetate,
ethyl acetate, methyl formate and the like. Examples of nitrile compounds are
acetonitrile
and the like. Examples of amide compounds are dimethylformamide and the like.
Examples
of sulfone compounds are sulfolane, methyl sulfolane and the like. Cyclic
carbonic acid
esters, chain carbonic acid esters, nitrile compounds and sulfone compounds
may be
particularly desirable, in some embodiments.
[00148]
These solvents may be used singly, or at least two kinds of solvents may be
used in admixture. Examples of preferred organic solvent mixtures are mixtures
of cyclic
carbonic acid ester and chain carbonic acid ester such as those of ethylene
carbonate and
dimethyl carbonate, ethylene carbonate and ethylmethyl carbonate, ethylene
carbonate and
diethyl carbonate, propylene carbonate and dimethyl carbonate, propylene
carbonate and
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ethylmethyl carbonate and propylene carbonate and diethyl carbonate, mixtures
of chain
carbonic acid esters such as dimethyl carbonate and ethylmethyl carbonate, and
mixtures of
sulfolane compounds such as sulfolane and methylsulfolane. More preferable are
mixtures of
ethylene carbonate and ethylmethyl carbonate, propylene carbonate and
ethylmethyl
carbonate, and dimethyl carbonate and ethylmethyl carbonate.
[00149] In
some embodiments, when the quaternary ammonium salt of the invention is
to be used as an electrolyte, the electrolyte concentration is at least 0.1 M,
in some cases at
least 0.5 M and may be at least 1 M. If the concentration is less than 0.1 M,
low electrical
conductivity will result, producing electrochemical devices of impaired
performance. The
upper limit concentration is a separation concentration when the electrolyte
is a liquid salt at
room temperature. When the solution does not separate, the limit concentration
is 100%.
When the salt is solid at room temperature, the limit concentration is the
concentration at
which the solution is saturated with the salt.
[00150] In
certain embodiments, the advanced electrolyte system (AES) may be
admixed with electrolytes other than those disclosed herein provided that such
combination
does not significantly affect the advantages achieved by utilization of the
advanced
electrolyte system, e.g., by altering the performance or durability
characteristics by greater
than 10%. Examples of electrolytes that may be suited to be admixed with the
AES are alkali
metal salts, quaternary ammonium salts, quaternary phosphonium salts, etc.
These
electrolytes may be used singly, or at least two kinds of them are usable in
combination, as
admixed with the AES disclosed herein. Useful alkali metal salts include
lithium salts,
sodium salts and potassium salts.
Examples of such lithium salts are lithium
hexafluorophosphate, lithium borofluoride, lithium
perchlorate, lithium
trifluoromethanesulfonate, sulfonylimide lithium, sulfonylmethide lithium and
the like, which
nevertheless are not limitative.
Examples of useful sodium salts are sodium
hexafluorophosphate, sodium borofluoride, sodium
perchlorate, sodium
trifluoromethanesulfonate, sulfonylimide sodium, sulfonylmethide sodium and
the like.
Examples of useful potassium salts are potassium hexafluorophosphate,
potassium
borofluoride, potassium perchlorate, potassium trifluoromethanesulfonate,
sulfonylimide
potassium, sulfonylmethide potassium and the like although these are not
limitative.
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[00151]
Useful quaternary ammonium salts that may be used in the combinations
described above (i.e., which do not significantly affect the advantages
achieved by utilization
of the advanced electrolyte system) include tetraalkylammonium salts,
imidazolium salts,
pyrazolium salts, pyridinium salts, triazolium salts, pyridazinium salts,
etc., which are not
limitative. Examples of useful tetraalkylammonium salts are tetraethylammonium
tetracyanoborate, tetramethylammonium
tetracyanoborate, tetraprop yl ammonium
tetracyanoborate, tetrabutylammonium tetracyanoborate, triethylmethylammonium
tetracyanoborate, trimethylethylammonium tetracyanoborate,
dimethyldiethylammonium
tetracyanoborate, trimethylpropylammonium tetracyanoborate,
trimethylbutylammonium
tetracyanoborate, dimethylethylpropylammonium
tetracyanoborate,
methylethylprop ylbutyl ammonium tetracyanoborate, N,N-
dimethylpyrrolidinium
tetracyanoborate, N-ethyl-N-methylpyrrolidinium
tetracyanoborate, N-methyl-N-
prop ylp yrrolidinium tetracyanoborate, N-ethyl-N-propylpyrrolidinium
tetracyanoborate,
N,N-dimethylpiperidinium tetracyanoborate, N-
methyl-N-ethylpiperidinium
tetracyanoborate, N-methyl-N-propylpiperidinium
tetracyanoborate, N-ethyl-N-
propylpiperidinium tetracyanoborate, N,N-dimethylmorpholinium
tetracyanoborate, N-
methyl-N-ethylmorpholinium tetracyanoborate, N-
methyl-N-propylmorpholinium
tetracyanoborate, N-ethyl-N-propylmorpholinium tetracyanoborate and the like,
whereas
these examples are not limitative.
[00152]
Examples of imidazolium salts that may be used in the combinations described
above (i.e., which do not significantly affect the advantages achieved by
utilization of the
advanced electrolyte system) include 1,3-dimethylimidazolium tetracyanoborate,
1-ethy1-3-
methylimidazolium tetracyanoborate, 1,3-diethylimidazolium tetracyanoborate,
1,2-dimethy1-
3-ethylimidazolium tetracyanoborate and 1,2-
dimethy1-3-propylimidazolium
tetracyanoborate, but are not limited to these. Examples of pyrazolium salts
are 1,2-
dimethylpyrazolium tetracyanoborate, 1-methy1-2-ethylpyrazolium
tetracyanoborate, 1-
prop y1-2 -methylp yrazolium tetracyanoborate and
1 -methyl-2-butylp yrazolium
tetracyanoborate, but are not limited to these. Examples of pyridinium salts
are N-
methylp yridinium tetracyanoborate, N-ethylpyridinium
tetracyanoborate, N-
propylpyridinium tetracyanoborate and N-butylpyridinium tetracyanoborate, but
are not
limited to these. Examples of triazolium salts are 1-methyltriazolium
tetracyanoborate, 1-
ethyltriazolium tetracyanoborate, 1-propyltriazolium tetracyanoborate and 1-
butyltriazolium
tetracyanoborate, but are not limited to these. Examples of pyridazinium salts
are 1-
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methylpyridazinium tetracyanoborate, 1-ethylpyridazinium tetracyanoborate, 1-
propylpyridazinium tetracyanoborate and 1-butylpyridazinium tetracyanoborate,
but are not
limited to these. Examples of quaternary phosphonium salts are
tetraethylphosphonium
tetracyanoborate, tetramethylphosphonium tetracyanoborate,
tetrapropylphosphonium
tetracyanoborate, tetrabutylphosphonium tetracyanoborate,
triethylmethylphosphonium
tetrafluoroborate, trimethylethylphosphonium tetracyanoborate,
dimethyldiethylphosphonium
tetracyanoborate, trimethylpropylphosphonium tetracyanoborate,
trimethylbutylphosphonium
tetracyanoborate, dimethylethylpropylphosphonium
tetracyanoborate,
methylethylpropylbutylphosphonium tetracyanoborate, but are not limited to
these.
[00153] In
certain embodiments, the novel electrolytes selected herein for use the
advanced electrolyte systems may also be purified. Such purification may be
performed
using art-recognized techniques or the techniques provided herein. This
purification may
further improve the characteristics of the Novel Electrolyte Entities
described herein.
ii. Highly Purified Electrolytes
[00154] The
advanced electrolyte systems of the present comprise, in one embodiment,
certain highly purified electrolytes for use in high temperature
ultracapacitors. In certain
embodiments. The highly purified electrolytes that comprise the AES of the
present invention
are those electrolytes described below as well as those novel electrolytes
described above
purified by the purification process described herein. The purification
methods provided
herein produce impurity levels that afford an advanced electrolyte system with
enhanced
properties for use in high temperature applications, e.g., high temperature
ultracapacitors, for
example in a temperature range of about 80 degrees Celsius to about 210
degrees Celsius,
e.g., about 80 degrees Celsius to about 200 degrees Celsius, e.g., about 80
degrees Celsius to
about 190 degrees Celsius e.g., about 80 degrees Celsius to about 180 degrees
Celsius e.g.,
about 80 degrees Celsius to about 170 degrees Celsius e.g., about 80 degrees
Celsius to about
160 degrees Celsius e.g., about 80 degrees Celsius to about 150 degrees
Celsius e.g., about 85
degrees Celsius to about 145 degrees Celsius e.g., about 90 degrees Celsius to
about 140
degrees Celsius e.g., about 95 degrees Celsius to about 135 degrees Celsius
e.g., about 100
degrees Celsius to about 130 degrees Celsius e.g., about 105 degrees Celsius
to about 125
degrees Celsius e.g., about 110 degrees Celsius to about 120 degrees Celsius.
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[00155] Obtaining improved properties of the ultracapacitor 10 results in
a requirement
for better electrolyte systems than presently available. For example, it has
been found that
increasing the operational temperature range may be achieved by the
significant
reduction/removal of impurities from certain forms of known electrolytes.
Impurities of
particular concern include water, halide ions (chloride, bromide, fluoride,
iodide), free amines
(ammonia), sulfate, and metal cations (Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K,
Li, Mg, Mn,
Mo, Na, Ni, Pb, Sr, Ti, Zn). The highly purified electrolyte product of such
purification
provides electrolytes that are surprisingly far superior to the unpurified
electrolyte, and as
such, fall with the advanced electrolyte systems of the present invention.
[00156] In a particular embodiment, the present invention provides a
purified mixture
of cation 9 and anion 11 and, in some instances a solvent, which may serve as
the AES of the
present invention which comprises less than about 5000 parts per million (ppm)
of chloride
ions; less than about 1000 ppm of fluoride ions; and/or less than about 1000
ppm of water
(e.g. less than about 2000 ppm of chloride ions; less than about less than
about 200 ppm of
fluoride ions; and/or less than about 200 ppm of water, e.g. less than about
1000 ppm of
chloride ions; less than about less than about 100 ppm of fluoride ions;
and/or less than about
100 ppm of water, e.g. less than about 500 ppm of chloride ions; less than
about less than
about 50 ppm of fluoride ions; and/or less than about 50 ppm of water, e.g.
less than about
780 parts per million of chloride ions; less than about 11 parts per million
of fluoride ions;
and less than about 20 parts per million of water.)
[00157] Generally, impurities in the purified electrolyte are removed
using the
methods of purification described herein. For example, in some embodiments, a
total
concentration of halide ions (chloride, bromide, fluoride, iodide), may be
reduced to below
about 1,000 ppm. A total concentration of metallic species (e.g., Cd, Co, Cr,
Cu, Fe, K, Li,
Mo, Na, Ni, Pb, Zn, including an at least one of an alloy and an oxide
thereof), may be
reduced to below about 1,000 ppm. Further, impurities from solvents and
precursors used in
the synthesis process may be reduced to below about 1,000 ppm and can include,
for
example, bromoethane, chloroethane, 1-bromobutane, 1-chlorobutane, 1-
methylimidazole,
ethyl acetate, methylene chloride and so forth.
[00158] In some embodiments, the impurity content of the ultracapacitor 10
has been
measured using ion selective electrodes and the Karl Fischer titration
procedure, which has
been applied to electrolyte 6 of the ultracapacitor 10. In certain
embodiments, it has been
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found that the total halide content in the ultracapacitor 10 according to the
teachings herein
has been found to be less than about 200 ppm of halides (a- and F) and water
content is less
than about 100 ppm.
[00159] Impurities can be measured using a variety of techniques, such as,
for
example, Atomic Absorption Spectrometry (AAS), Inductively Coupled Plasma-Mass
Spectrometry (ICPMS), or simplified solubilizing and electrochemical sensing
of trace heavy
metal oxide particulates. AAS is a spectro-analytical procedure for the
qualitative and
quantitative determination of chemical elements employing the absorption of
optical radiation
(light) by free atoms in the gaseous state. The technique is used for
determining the
concentration of a particular element (the analyte) in a sample to be
analyzed. AAS can be
used to determine over seventy different elements in solution or directly in
solid samples.
ICPMS is a type of mass spectrometry that is highly sensitive and capable of
the
determination of a range of metals and several non-metals at concentrations
below one part in
1012 (part per trillion). This technique is based on coupling together an
inductively coupled
plasma as a method of producing ions (ionization) with a mass spectrometer as
a method of
separating and detecting the ions. ICPMS is also capable of monitoring
isotopic speciation
for the ions of choice.
[00160] Additional techniques may be used for analysis of impurities. Some
of these
techniques are particularly advantageous for analyzing impurities in solid
samples. Ion
Chromatography (IC) may be used for determination of trace levels of halide
impurities in the
electrolyte 6 (e.g., an ionic liquid). One advantage of Ion Chromatography is
that relevant
halide species can be measured in a single chromatographic analysis. A Dionex
A59-HC
column using an eluent consisting 20 mM NaOH and 10% (v/v) acetonitrile is one
example
of an apparatus that may be used for the quantification of halides from the
ionic liquids. A
further technique is that of X-ray fluorescence.
[00161] X-ray fluorescence (XRF) instruments may be used to measure
halogen
content in solid samples. In this technique, the sample to be analyzed is
placed in a sample
cup and the sample cup is then placed in the analyzer where it is irradiated
with X-rays of a
specific wavelength. Any halogen atoms in the sample absorb a portion of the X-
rays and
then reflect radiation at a wavelength that is characteristic for a given
halogen. A detector in
the instrument then quantifies the amount of radiation coming back from the
halogen atoms
and measures the intensity of radiation. By knowing the surface area that is
exposed,
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concentration of halogens in the sample can be determined. A further technique
for assessing
impurities in a solid sample is that of pyrolysis.
[00162] Adsorption of impurities may be effectively measured through use
of pyrolysis
and microcoulometers. Microcoulometers are capable of testing almost any type
of material
for total chlorine content. As an example, a small amount of sample (less than
10 milligrams)
is either injected or placed into a quartz combustion tube where the
temperature ranges from
about 600 degrees Celsius to about 1,000 degrees Celsius. Pure oxygen is
passed through the
quartz tube and any chlorine containing components are combusted completely.
The resulting
combustion products are swept into a titration cell where the chloride ions
are trapped in an
electrolyte solution. The electrolyte solution contains silver ions that
immediately combine
with any chloride ions and drop out of solution as insoluble silver chloride.
A silver electrode
in the titration cell electrically replaces the used up silver ions until the
concentration of silver
ions is back to where it was before the titration began. By keeping track of
the amount of
current needed to generate the required amount of silver, the instrument is
capable of
determining how much chlorine was present in the original sample. Dividing the
total
amount of chlorine present by the weight of the sample gives the concentration
of chlorine
that is actually in the sample. Other techniques for assessing impurities may
be used.
[00163] Surface characterization and water content in the electrode 3 may
be
examined, for example, by infrared spectroscopy techniques. The four major
absorption
bands at around 1130, 1560, 3250 and 2300 cm-1, correspond to vC = 0 in , vC =
C in aryl,
v0 - H and vC - N, respectively. By measuring the intensity and peak position,
it is possible
to quantitatively identify the surface impurities within the electrode 3.
[00164] Another technique for identifying impurities in the electrolyte 6
and the
ultracapacitor 10 is Raman spectroscopy. This spectroscopic technique relies
on inelastic
scattering, or Raman scattering, of monochromatic light, usually from a laser
in the visible,
near infrared, or near ultraviolet range. The laser light interacts with
molecular vibrations,
phonons or other excitations in the system, resulting in the energy of the
laser photons being
shifted up or down. Thus, this technique may be used to characterize atoms and
molecules
within the ultracapacitor 10. A number of variations of Raman spectroscopy are
used, and
may prove useful in characterizing contents the ultracapacitor 10.
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iii. Enhanced Electrolyte Combinations
[00165] The advanced electrolyte systems of the present comprise, in one
embodiment,
include certain enhanced electrolyte combinations suitable for use in
temperature ranges from
-40 degrees Celsius to 210 degrees Celsius, e.g., -40 degrees Celsius to 150
degrees Celsius,
e.g., -30 degrees Celsius to 150 degrees Celsius, e.g., -30 degrees Celsius to
140 degrees
Celsius, e.g., -20 degrees Celsius to 140 degrees Celsius, e.g., -20 degrees
Celsius to 130
degrees Celsius, e.g., -10 degrees Celsius to 130 degrees Celsius, e.g., -10
degrees Celsius to
120 degrees Celsius, e.g., 0 degrees Celsius to 120 degrees Celsius, e.g., 0
degrees Celsius to
110 degrees Celsius, e.g., 0 degrees Celsius to 100 degrees Celsius, e.g., 0
degrees Celsius to
90 degrees Celsius, e.g., 0 degrees Celsius to 80 degrees Celsius, e.g., 0
degrees Celsius to 70
degrees Celsius, without a significant drop in performance or durability.
[00166] Generally, a higher degree of durability at a given temperature
may be
coincident with a higher degree of voltage stability at a lower temperature.
Accordingly, the
development of a high temperature durability AES, with enhanced electrolyte
combinations,
generally leads to simultaneous development of high voltage, but lower
temperature AES,
such that these enhanced electrolyte combinations described herein may also be
useful at
higher voltages, and thus higher energy densities, but at lower temperatures.
[00167] In one embodiment, the present invention provides an enhanced
electrolyte
combination suitable for use in an energy storage cell, e.g., an
ultracapacitor, comprising a
novel mixture of electrolytes selected from the group consisting of an ionic
liquid mixed with
a second ionic liquid, an ionic liquid mixed with an organic solvent, and an
ionic liquid
mixed with a second ionic liquid and an organic solvent:
wherein each ionic liquid is selected from the salt of any combination of the
following
cations and anions, wherein the cations are selected from the group consisting
of 1 ¨ butyl ¨ 3
¨ methylimidazolium, 1-ethyl ¨ 3 ¨ methylimidazolium, 1 ¨ hexyl ¨ 3 ¨
methylimidazolium,
1-buty1-1-methylpiperidinium, butyltrimethylammonium, 1¨ butyl
¨1¨methylpyrrolidinium,
trihexyltetradecylphosphonium, and 1¨butyl-3¨methylimidaxolium; and the anions
are
selected from the group consisting of tetrafluoroborate,
bis(trifluoromethylsulfonyl)imide,
tetracyanoborate, and trifluoromethanesulfonate; and
wherein the organic solvent is selected from the group consisting of linear
sulfones
(e.g., ethyl isopropyl sulfone, ethyl isobutyl sulfone, ethyl methyl sulfone,
methyl isopropyl
sulfone, isopropyl isobutyl sulfone, isopropyl s-butyl sulfone, butyl isobutyl
sulfone, and
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dimethyl sulfone), linear carbonates (e.g., ethylene carbonate, propylene
carbonate, and
dimethyl carbonate), and acetonitrile.
[00168] For
example, given the combinations of cations and anions above, each ionic
liquid may be selected from the group consisting of 1 ¨ butyl ¨ 3 ¨
methylimidazolium
tetrafluoroborate; 1 ¨ butyl ¨ 3 ¨ methylimidazolium
bis(trifluoromethylsulfonyl)imide; 1 ¨
ethyl ¨ 3 ¨ methylimidazolium tetrafluoroborate; 1 ¨ ethyl ¨ 3 ¨
methylimidazolium
tetracyanoborate; 1 ¨ hexyl ¨ 3 ¨ methylimidazolium tetracyanoborate; 1¨butyl-
1¨
methylpyrrolidinium bis(trifluoromethylsulfonyl)imide; 1 ¨ butyl ¨ 1 ¨
methylpyrrolidinium
tris(pentafluoroethyl)trifluorophosphate; 1¨butyl ¨ 1 ¨ methylpyrrolidinium
tetracyanoborate;
trihexyltetradecylpho sphonium bis(trifluoromethylsulfonyl)imide, 1-
buty1-1-
methylpiperidinium bis(trifluoromethylsulfonyl)imide,
butyltrimethylammonium
bis(trifluoromethylsulfonyl)imide, and
1¨butyl-3¨methylimidazolium
trifluoromethanesulfonate.
[00169] In
certain embodiments, the ionic liquid is 1 ¨ butyl ¨ 3 ¨ methylimidazolium
tetrafluoroborate.
[00170] In
certain embodiments, the ionic liquid is 1 ¨ butyl ¨ 3 ¨ methylimidazolium
bis(trifluoromethylsulfonyl)imide.
[00171] In
certain embodiments, the ionic liquid is 1 ¨ ethyl ¨ 3 ¨ methylimidazolium
tetrafluoroborate.
[00172] In
certain embodiments, the ionic liquid is 1 ¨ ethyl ¨ 3 ¨ methylimidazolium
tetracyanoborate.
[00173] In
certain embodiments, the ionic liquid is 1 ¨ hexyl ¨ 3 ¨ methylimidazolium
tetracyanoborate.
[00174] In
certain embodiments, the ionic liquid is 1 ¨ butyl ¨ 1 ¨ methylpyrrolidinium
bis(trifluoromethylsulfonyl)imide.
[00175] In
one embodiment, the ionic liquid is 1 ¨ butyl ¨ 1 ¨ methylpyrrolidinium
tris(pentafluoroethyl)trifluoropho sphate.
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[00176] In certain embodiments, the ionic liquid is 1 ¨ butyl ¨ 1 ¨
methylpyrrolidinium
tetracyanoborate.
[00177] In certain embodiments, the ionic liquid is
trihexyltetradecylphosphonium
bis(trifluoromethylsulfonyl)imide.
[00178] In certain embodiments, the ionic liquid is 1-buty1-1-
methylpiperidinium
bis(trifluoromethylsulfonyl)imide.
[00179] In certain embodiments, the ionic liquid is butyltrimethylammonium
bis(trifluoromethylsulfonyl)imide
[00180] In certain embodiments, the ionic liquid is 1 ¨ butyl ¨ 3 ¨
methylimidazolium
trifluoromethanesulfonate.
[00181] In certain embodiments, the organic solvent is selected from ethyl
isopropyl
sulfone, ethyl isobutyl sulfone, ethyl methyl sulfone, methyl isopropyl
sulfone, isopropyl
isobutyl sulfone, isopropyl s-butyl sulfone, butyl isobutyl sulfone, or
bimethyl sulfone, linear
sulfones.
[00182] In certain embodiments, the organic solvent is selected from
polypropylene
carbonate, propylene carbonate, dimethyl carbonate, ethylene carbonate.
[00183] In certain embodiments, the organic solvent is acetonitrile.
[00184] In certain embodiments, the enhanced electrolyte composition is an
ionic
liquid with an organic solvent, wherein the organic solvent is 55%-90%, e.g.,
37.5%, by
volume of the composition.
[00185] In certain embodiments, the enhanced electrolyte composition is an
ionic
liquid with a second ionic liquid, wherein one ionic liquid is 5%-90%, e.g.,
60%, by volume
of the composition.
[00186] The enhanced electrolyte combinations of the present invention
provide a
wider temperature range performance for an individual capacitor (e.g. without
a significant
drop in capacitance and/or increase in ESR when transitioning between two
temperatures,
e.g. without more than a 90% decrease in capacitance and/or a 1000% increase
in ESR when
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transitioning from about +30 C to about -40 C), and increased temperature
durability for an
individual capacitor (e.g., less than a 50% decrease in capacitance at a given
temperature
after a given time and/or less than a 100% increase in ESR at a given
temperature after a
given time, and/or less than 10 A/L of leakage current at a given temperature
after a given
time, e.g., less than a 40% decrease in capacitance and/or a 75% increase in
ESR, and/or less
than 5 A/L of leakage current, e.g., less than a 30% decrease in capacitance
and/or a 50%
increase in ESR, and/or less than 1 A/L of leakage current). Figures 47A&B,
Figures
48A&B and Figure 49 depicts the behavior of an ionic liquid from the above
listing at 125
degrees Celsius, a 37.5% organic solvent-ionic liquid (same) v/v at 125
degrees Celsius, and
the same composition at -40 degrees Celsius, respectively.
[00187] Without wishing to be bound by theory, the combinations described
above
provide enhanced eutectic properties that affect the freezing point of the
advanced electrolyte
system to afford ultracapacitors that operate within performance and
durability standards at
temperatures of down to -40 degrees Celsius.
[00188] As described above for the novel electrolytes of the present
invention, in
certain embodiments, the advanced electrolyte system (AES) may be admixed with
electrolytes provided that such combination does not significantly affect the
advantages
achieved by utilization of the advanced electrolyte system.
[00189] In certain embodiments, the enhanced electrolyte combinations are
selected
herein for use the advanced electrolyte systems may also be purified. Such
purification may
be performed using art-recognized techniques or techniques provided herein.
B. Electrodes
[00190] The EDLC includes at least one pair of electrodes 3 (where the
electrodes 3
may be referred to as a negative electrode 3 and a positive electrode 3,
merely for purposes of
referencing herein). When assembled into the ultracapacitor 10, each of the
electrodes 3
presents a double layer of charge at an electrolyte interface. In some
embodiments, a
plurality of electrodes 3 is included (for example, in some embodiments, at
least two pairs of
electrodes 3 are included). However, for purposes of discussion, only one pair
of electrodes 3
are shown. As a matter of convention herein, at least one of the electrodes 3
uses a carbon-
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based energy storage media 1 (as discussed further herein) to provide energy
storage.
However, for purposes of discussion herein, it is generally assumed that each
of the
electrodes includes the carbon-based energy storage media 1.
i. Current Collector
[00191] Each of the electrodes 3 includes a respective current collector 2
(also referred
to as a "charge collector"). In some embodiments, the electrodes 3 are
separated by a
separator 5. In general, the separator 5 is a thin structural material
(usually a sheet) used to
separate the negative electrode 3 from the positive electrode 3. The separator
5 may also
serve to separate pairs of the electrodes 3. Note that, in some embodiments,
the carbon-based
energy storage media 1 may not be included on one or both of the electrodes 3.
That is, in
some embodiments, a respective electrode 3 might consist of only the current
collector 2.
The material used to provide the current collector 2 could be roughened,
anodized or the like
to increase a surface area thereof. In these embodiments, the current
collector 2 alone may
serve as the electrode 3. With this in mind, however, as used herein, the term
"electrode 3"
generally refers to a combination of the energy storage media 1 and the
current collector 2
(but this is not limiting, for at least the foregoing reason).
ii. Energy Storage Media
[00192] In the exemplary ultracapacitor 10, the energy storage media 1 is
formed of
carbon nanotubes. The energy storage media 1 may include other carbonaceous
materials
including, for example, activated carbon, carbon fibers, rayon, graphene,
aerogel, carbon
cloth, and a plurality of forms of carbon nanotubes. Activated carbon
electrodes can be
manufactured, for example, by producing a carbon base material by carrying out
a first
activation treatment to a carbon material obtained by carbonization of a
carbon compound,
producing a formed body by adding a binder to the carbon base material,
carbonizing the
formed body, and finally producing an active carbon electrode by carrying out
a second
activation treatment to the carbonized formed body. Carbon fiber electrodes
can be
produced, for example, by using paper or cloth pre-form with high surface area
carbon fibers.
[00193] In an exemplary method for fabricating carbon nanotubes, an
apparatus for
producing an aligned carbon-nanotube aggregate includes apparatus for
synthesizing the
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aligned carbon-nanotube aggregate on a base material having a catalyst on a
surface thereof.
The apparatus includes a formation unit that processes a formation step of
causing an
environment surrounding the catalyst to be an environment of a reducing gas
and heating at
least either the catalyst or the reducing gas; a growth unit that processes a
growth step of
synthesizing the aligned carbon-nanotube aggregate by causing the environment
surrounding
the catalyst to be an environment of a raw material gas and by heating at
least either the
catalyst or the raw material gas; and a transfer unit that transfers the base
material at least
from the formation unit to the growth unit. A variety of other methods and
apparatus may be
employed to provide the aligned carbon-nanotube aggregate.
[00194] In some embodiments, material used to form the energy storage
media 1 may
include material other than pure carbon (and the various forms of carbon as
may presently
exist or be later devised). That is, various formulations of other materials
may be included in
the energy storage media 1. More specifically, and as a non-limiting example,
at least one
binder material may be used in the energy storage media 1, however, this is
not to suggest or
require addition of other materials (such as the binder material). In general,
however, the
energy storage media 1 is substantially formed of carbon, and may therefore
referred to
herein as a "carbonaceous material," as a "carbonaceous layer" and by other
similar terms. In
short, although formed predominantly of carbon, the energy storage media 1 may
include any
form of carbon (as well as any additives or impurities as deemed appropriate
or acceptable) to
provide for desired functionality as energy storage media 1.
[00195] In one set of embodiments, the carbonaceous material includes at
least about
60% elemental carbon by mass, and in other embodiments at least about 75%,
85%, 90%,
95% or 98% by mass elemental carbon.
[00196] Carbonaceous material can include carbon in a variety forms,
including carbon
black, graphite, and others. The carbonaceous material can include carbon
particles,
including nanoparticles, such as nanotubes, nanorods, graphene sheets in sheet
form, and/or
formed into cones, rods, spheres (buckyballs) and the like.
[00197] Some embodiments of various forms of carbonaceous material suited
for use
in energy storage media 1 are provided herein as examples. These embodiments
provide
robust energy storage and are well suited for use in the electrode 3. It
should be noted that
these examples are illustrative and are not limiting of embodiments of
carbonaceous material
suited for use in energy storage media 1.
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[00198] In certain embodiments, the porosity of the energy storage media 1
of each
electrode may be selected based on the size of the respective electrolyte to
improve the
performance of the capacitor.
[00199] An exemplary process for complimenting the energy storage media 1
with the
current collector 2 to provide the electrode 3 is now provided. Referring now
to FIG. 2, a
substrate 14 that is host to carbonaceous material in the form of carbon
nanotube aggregate
(CNT) is shown. In the embodiment shown, the substrate 14 includes a base
material 17 with
a thin layer of a catalyst 18 disposed thereon.
[00200] In general, the substrate 14 is at least somewhat flexible (i.e.,
the substrate 14
is not brittle), and is fabricated from components that can withstand
environments for
deposition of the energy storage media 1 (e.g., CNT). For example, the
substrate 14 may
withstand a high-temperature environment of between about 400 degrees Celsius
to about
1,100 degrees Celsius. A variety of materials may be used for the substrate
14, as determined
appropriate.
[00201] Refer now to FIG. 3. Once the energy storage media 1 (e.g., CNT)
has been
fabricated on the substrate 14, the current collector 2 may be disposed
thereon. In some
embodiments, the current collector 2 is between about 0.5 micrometers ( m) to
about 25
micrometers ( m) thick. In some embodiments, the the current collector 2 is
between about
20 micrometers ( m) to about 40 micrometers ( m) thick. The current collector
2 may
appear as a thin layer, such as layer that is applied by chemical vapor
deposition (CVD),
sputtering, e-beam, thermal evaporation or through another suitable technique.
Generally, the
current collector 2 is selected for its properties such as conductivity, being
electrochemically
inert and compatible with the energy storage media 1 (e.g., CNT). Some
exemplary materials
include aluminum, platinum, gold, tantalum, titanium, and may include other
materials as
well as various alloys.
[00202] Once the current collector 2 is disposed onto the energy storage
media 1 (e.g.,
CNT), an electrode element 15 is realized. Each electrode element 15 may be
used
individually as the electrode 3, or may be coupled to at least another
electrode element 15 to
provide for the electrode 3.
[00203] Once the current collector 2 has been fabricated according to a
desired
standard, post-fabrication treatment may be undertaken. Exemplary post-
treatment includes
heating and cooling of the energy storage media 1 (e.g., CNT) in a slightly
oxidizing
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environment. Subsequent to fabrication (and optional post-treatment), a
transfer tool may be
applied to the current collector 2. Reference may be had to FIG. 4.
[00204] FIG. 4 illustrates application of transfer tool 13 to the current
collector 2. In
this example, the transfer tool 13 is a thermal release tape, used in a "dry"
transfer method.
Exemplary thermal release tape is manufactured by NITTO DENKO CORPORATION of
Fremont, California and Osaka, Japan. One suitable transfer tape is marketed
as
REVALPHA. This release tape may be characterized as an adhesive tape that
adheres tightly
at room temperature and can be peeled off by heating. This tape, and other
suitable
embodiments of thermal release tape, will release at a predetermined
temperature.
Advantageously, the release tape does not leave a chemically active residue on
the electrode
element 15.
[00205] In another process, referred to as a "wet" transfer method, tape
designed for
chemical release may be used. Once applied, the tape is then removed by
immersion in a
solvent. The solvent is designed to dissolve the adhesive.
[00206] In other embodiments, the transfer tool 13 uses a "pneumatic"
method, such as
by application of suction to the current collector 2. The suction may be
applied, for example,
through a slightly oversized paddle having a plurality of perforations for
distributing the
suction. In another example, the suction is applied through a roller having a
plurality of
perforations for distributing the suction. Suction driven embodiments offer
advantages of
being electrically controlled and economic as consumable materials are not
used as a part of
the transfer process. Other embodiments of the transfer tool 13 may be used.
[00207] Once the transfer tool 13 has been temporarily coupled to the
current collector
2, the electrode element 15 is gently removed from the substrate 14 (see FIGS.
4 and 5). The
removal generally involves peeling the energy storage media 1 (e.g., CNT) from
the substrate
14, beginning at one edge of the substrate 14 and energy storage media 1
(e.g., CNT).
[00208] Subsequently, the transfer tool 13 may be separated from the
electrode
element 15 (see FIG. 6). In some embodiments, the transfer tool 13 is used to
install the
electrode element 15. For example, the transfer tool 13 may be used to place
the electrode
element 15 onto the separator 5. In general, once removed from the substrate
14, the
electrode element 15 is available for use.
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[00209] In instances where a large electrode 3 is desired, a plurality of
the electrode
elements 15 may be mated. Reference may be had to FIG. 7. As shown in FIG. 7,
a plurality
of the electrode elements 15 may be mated by, for example, coupling a coupling
52 to each
electrode element 15 of the plurality of electrode elements 15. The mated
electrode elements
15 provide for an embodiment of the electrode 3.
[00210] In some embodiments, the coupling 22 is coupled to each of the
electrode
elements 15 at a weld 21. Each of the welds 21 may be provided as an
ultrasonic weld 21. It
has been found that ultrasonic welding techniques are particularly well suited
to providing
each weld 21. That is, in general, the aggregate of energy storage media 1
(e.g., CNT) is not
compatible with welding, where only a nominal current collector, such as
disclosed herein is
employed. As a result, many techniques for joining electrode elements 15 are
disruptive, and
damage the element 15. However, in other embodiments, other forms of coupling
are used,
and the coupling 22 is not a weld 21.
[00211] The coupling 22 may be a foil, a mesh, a plurality of wires or in
other forms.
Generally, the coupling 22 is selected for properties such as conductivity and
being
electrochemically inert. In some embodiments, the coupling 22 is fabricated
from the same
material(s) as are present in the current collector 2.
[00212] In some embodiments, the coupling 22 is prepared by removing an
oxide layer
thereon. The oxide may be removed by, for example, etching the coupling 22
before
providing the weld 21. The etching may be accomplished, for example, with
potassium
hydroxide (KOH). The electrode 3 may be used in a variety of embodiments of
the
ultracapacitor 10. For example, the electrode 3 may be rolled up into a "jelly
roll" type of
energy storage.
C. Separator
[00213] The separator 5 may be fabricated from various materials. In some
embodiments, the separator 5 is non-woven glass. The separator 5 may also be
fabricated
from fiberglass, ceramics and flouro-polymers, such as polytetrafluoroethylene
(PTFE),
commonly marketed as TEFLON Tm by DuPont Chemicals of Wilmington, DE. For
example,
using non-woven glass, the separator 5 can include main fibers and binder
fibers each having
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a fiber diameter smaller than that of each of the main fibers and allowing the
main fibers to
be bonded together.
[00214] For longevity of the ultracapacitor 10 and to assure performance
at high
temperature, the separator 5 should have a reduced amount of impurities and in
particular, a
very limited amount of moisture contained therein. In particular, it has been
found that a
limitation of about 200 ppm of moisture is desired to reduce chemical
reactions and improve
the lifetime of the ultracapacitor 10, and to provide for good performance in
high temperature
applications. Some embodiments of materials for use in the separator 5 include
polyamide,
polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK), aluminum oxide
(A1203),
fiberglass, and glass-reinforced plastic (GRP).
[00215] In general, materials used for the separator 5 are chosen
according to moisture
content, porosity, melting point, impurity content, resulting electrical
performance, thickness,
cost, availability and the like. In some embodiments, the separator 5 is
formed of
hydrophobic materials.
[00216] Accordingly, procedures may be employed to ensure excess moisture
is
eliminated from each separator 5. Among other techniques, a vacuum drying
procedure may
be used. A selection of materials for use in the separator 5 is provided in
Table 1. Some
related performance data is provided in Table 2.
Table 1
Separator Materials
Melting PPM H20 PPM H20 Vacuum dry
Material point unbaked baked procedure
Polyamide 256 C 2052 20 180 C for 24h
Polytetrafluoroethylene,
PTFE 327 C 286 135 150 C for 24h
Polyether ether ketone,
PEEK 256 C 130 50 215 C for 12h
Aluminum Oxide,
A1203 330 C 1600 100 215 C for 24h
Fiberglass (GRP) 320 C 2000 167 215 C for 12h
Table 2
Separator Performance Data
ESR 1 st ESR 2nd After 10
Material lam Porosity test (SI) test (SI) CV
Polyamide 42 Nonwoven 1.069 1.069 1.213
PEEK 45 Mesh 1.665 1.675 2.160
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PEEK 60% 25 60% 0.829 0.840 0.883
Fiberglass (GRP) 160 Nonwoven 0.828 0.828 0.824
Aluminum
Oxide, A1203 25 2.400 2.400 2.400
[00217] In order to collect data for Table 2, two electrodes 3, based on
carbonaceous
material, were provided. The electrodes 3 were disposed opposite to and facing
each other.
Each of the separators 5 were placed between the electrodes 3 to prevent a
short circuit. The
three components were then wetted with electrolyte 6 and compressed together.
Two
aluminum bars and PTFE material was used as an external structure to enclose
the resulting
ultracapacitor 10.
[00218] The ESR 1 st test and ESR 2nd test were performed with the same
configuration
one after the other. The second test was run five minutes after the first
test, leaving time for
the electrolyte 6 to further soak into the components.
[00219] In certain embodiments, the ultracapacitor 10 does not include the
separator 5.
For example, in particular embodiments, such as where the electrodes 3 are
assured of
physical separation by a geometry of construction, it suffices to have
electrolyte 6 alone
between the electrodes 3. More specifically, and as an example of physical
separation, one
such ultracapacitor 10 may include electrodes 3 that are disposed within a
housing such that
separation is assured on a continuous basis. A bench-top example would include
an
ultracapacitor 10 provided in a beaker.
D. Storage Cell
[00220] Once assembled, the electrodes 3 and the separator 5 provide a
storage cell 12.
Generally, the storage cell 12 is formed into one of a wound form or prismatic
form which is
then packaged into a cylindrical or prismatic housing 7. Once the electrolyte
6 has been
included, the housing 7 may be hermetically sealed. In various examples, the
package is
hermetically sealed by techniques making use of laser, ultrasonic, and/or
welding
technologies. In addition to providing robust physical protection of the
storage cell 12, the
housing 7 is configured with external contacts to provide electrical
communication with
respective terminals 8 within the housing 7. Each of the terminals 8, in turn,
provides
electrical access to energy stored in the energy storage media 1, generally
through electrical
leads which are coupled to the energy storage media 1.
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[00221] Generally, the ultracapacitor 10 disclosed herein is capable of
providing a
hermetic seal that has a leak rate no greater than about 5.0x10-6 atm-cc/sec,
and may exhibit a
leak rate no higher than about 5.0x10-1 atm-cc/sec. It is also considered
that performance of
a successfully hermetic seal is to be judged by the user, designer or
manufacturer as
appropriate, and that "hermetic" ultimately implies a standard that is to be
defined by a user,
designer, manufacturer or other interested party.
[00222] Leak detection may be accomplished, for example, by use of a
tracer gas.
Using tracer gas such as helium for leak testing is advantageous as it is a
dry, fast, accurate
and non destructive method. In one example of this technique, the
ultracapacitor 10 is placed
into an environment of helium. The ultracapacitor 10 is subjected to
pressurized helium. The
ultracapacitor 10 is then placed into a vacuum chamber that is connected to a
detector capable
of monitoring helium presence (such as an atomic absorption unit). With
knowledge of
pressurization time, pressure and internal volume, the leak rate of the
ultracapacitor 10 may
be determined.
[00223] In some embodiments, at least one lead (which may also be referred
to herein
as a "tab") is electrically coupled to a respective one of the current
collectors 2. A plurality
of the leads (accordingly to a polarity of the ultracapacitor 10) may be
grouped together and
coupled to into a respective terminal 8. In turn, the terminal 8 may be
coupled to an electrical
access, referred to as a "contact" (e.g., one of the housing 7 and an external
electrode (also
referred to herein for convention as a "feed-through" or "pin")). Reference
may be had to
FIGS. 28 and 32-34.
E. Housing
[00224] FIG. 11 depicts aspects of an exemplary housing 7. Among other
things, the
housing 7 provides structure and physical protection for the ultracapacitor
10. In this
example, the housing 7 includes an annular cylindrically shaped body 20 and a
complimentary cap 24. In this embodiment, the cap 24 includes a central
portion that has
been removed and filled with an electrical insulator 26. A cap feed-through 19
penetrates
through the electrical insulator 26 to provide users with access to the stored
energy.
Moreover, the housing may also include an inner barrier 30.
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[00225] Although this example depicts only one feed-through 19 on the cap
24, it
should be recognized that the construction of the housing 7 is not limited by
the embodiments
discussed herein. For example, the cap 24 may include a plurality of feed-
throughs 19. In
some embodiments, the body 20 includes a second, similar cap 24 at the
opposing end of the
annular cylinder. Further, it should be recognized that the housing 7 is not
limited to
embodiments having an annular cylindrically shaped body 20. For example, the
housing 7
may be a clamshell design, a prismatic design, a pouch, or of any other design
that is
appropriate for the needs of the designer, manufacturer or user.
[00226] Referring now to FIG. 12, there is shown an exemplary energy
storage cell 12.
In this example, the energy storage cell 12 is a "jelly roll" type of energy
storage. In these
embodiments, the energy storage materials are rolled up into a tight package.
A plurality of
leads generally form each terminal 8 and provide electrical access to the
appropriate layer of
the energy storage cell 12. Generally, when assembled, each terminal 8 is
electrically
coupled to the housing 7 (such as to a respective feed-through 19 and/or
directly to the
housing 7). The energy storage cell 12 may assume a variety of forms. There
are generally
at least two plurality of leads (e.g., terminals 8), one for each current
collector 2. For
simplicity, only one of terminal 8 is shown in FIGS. 12, 15 and 17.
[00227] A highly efficient seal of the housing 7 is desired. That is,
preventing
intrusion of the external environment (such as air, humidity, etc,) helps to
maintain purity of
the components of the energy storage cell 12. Further, this prevents leakage
of electrolyte 6
from the energy storage cell 12.
[00228] In this example, the cap 24 is fabricated with an outer diameter
that is
designed for fitting snugly within an inner diameter of the body 20. When
assembled, the cap
24 may be welded into the body 20, thus providing users with a hermetic seal.
Exemplary
welding techniques include laser welding and TIG welding, and may include
other forms of
welding as deemed appropriate.
[00229] Common materials for the housing 7 include stainless steel,
aluminum,
tantalum, titanium, nickel, copper, tin, various alloys, laminates, and the
like. Structural
materials, such as some polymer-based materials may be used in the housing 7
(generally in
combination with at least some metallic components).
[00230] In some embodiments, a material used for construction of the body
20
includes aluminum, which may include any type of aluminum or aluminum alloy
deemed
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appropriate by a designer or fabricator (all of which are broadly referred to
herein simply as
"aluminum"). Various alloys, laminates, and the like may be disposed over
(e.g., clad to) the
aluminum (the aluminum being exposed to an interior of the body 20).
Additional materials
(such as structural materials or electrically insulative materials, such as
some polymer-based
materials) may be used to compliment the body and/or the housing 7. The
materials disposed
over the aluminum may likewise be chosen by what is deemed appropriate by a
designer or
fabricator.
[00231] In some embodiments, the multi-layer material is used for internal
components. For example, aluminum may be clad with stainless steel to provide
for a multi-
layer material in at least one of the terminals 8. In some of these
embodiments, a portion of
the aluminum may be removed to expose the stainless steel. The exposed
stainless steel may
then be used to attach the terminal 8 to the feed-through 19 by use of simple
welding
procedures.
[00232] Using the clad material for internal components may call for
particular
embodiments of the clad material. For example, it may be beneficial to use
clad material that
include aluminum (bottom layer), stainless steel and/or tantalum (intermediate
layer) and
aluminum (top layer), which thus limits exposure of stainless steel to the
internal
environment of the ultracapacitor 10. These embodiments may be augmented by,
for
example, additional coating with polymeric materials, such as PTFE.
[00233] Accordingly, providing a housing 7 that takes advantage of multi-
layered
material provides for an energy storage that exhibits leakage current with
comparatively low
initial values and substantially slower increases in leakage current over time
in view of the
prior art. Significantly, the leakage current of the energy storage remains at
practical (i.e.,
desirably low) levels when the ultracapacitor 10 is exposed to ambient
temperatures for
which prior art capacitors would exhibit prohibitively large initial values of
leakage current
and / or prohibitively rapid increases in leakage current over time.
[00234] Additionally, the ultracapacitor 10 may exhibit other benefits as
a result of
reduced reaction between the housing 7 and the energy storage cell 12. For
example, an
effective series resistance (ESR) of the energy storage may exhibit
comparatively lower
values over time. Further, the unwanted chemical reactions that take place in
a prior art
capacitor often create unwanted effects such as out-gassing, or in the case of
a hermetically
sealed housing, bulging of the housing 7. In both cases, this leads to a
compromise of the
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structural integrity of the housing 7 and/or hermetic seal of the energy
storage. Ultimately,
this may lead to leaks or catastrophic failure of the prior art capacitor.
These effects may be
substantially reduced or eliminated by the application of a disclosed barrier.
[00235] By use of a multi-layer material (e.g., a clad material),
stainless steel may be
incorporated into the housing 7, and thus components with glass-to-metal seals
may be used.
The components may be welded to the stainless steel side of the clad material
using
techniques such as laser or resistance welding, while the aluminum side of the
clad material
may be welded to other aluminum parts (e.g., the body 20).
[00236] In some embodiments, an insulative polymer may be used to coat
parts of the
housing 7. In this manner, it is possible to insure that the components of the
energy storage
are only exposed to acceptable types of metal (such as the aluminum).
Exemplary insulative
polymer includes PFA, FEP, TFE, and PTFE. Suitable polymers (or other
materials) are
limited only by the needs of a system designer or fabricator and the
properties of the
respective materials. Reference may be had to FIG. 23, where a small amount of
insulative
material 39 is included to limit exposure of electrolyte 6 to the stainless
steel of the sleeve 51
and the feed-through 19. In this example, the terminal 8 is coupled to the
feed-through 19,
such as by welding, and then coated with the insulative material 39.
i. Housing Cap
[00237] Although this example depicts only one feed-through 19 on the cap
24, it
should be recognized that the construction of the housing 7 is not limited by
the embodiments
discussed herein. For example, the cap 24 may include a plurality of feed-
throughs 19. In
some embodiments, the body 20 includes a second, similar cap 24 at an opposing
end of the
annular cylinder. Further, it should be recognized that the housing 7 is not
limited to
embodiments having an annular cylindrically shaped body 20. For example, the
housing 7
may be a clamshell design, a prismatic design, a pouch, or of any other design
that is
appropriate for the needs of the designer, manufacturer or user.
[00238] Referring now to FIG. 18, aspects of embodiments of a blank 34 for
the cap 24
are shown. In FIG. 18A, the blank 34 includes a multi-layer material. A layer
of a first
material 41 may be aluminum. A layer of a second material 42 may be stainless
steel. In the
embodiments of FIG. 18, the stainless steel is clad onto the aluminum, thus
providing for a
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material that exhibits a desired combination of metallurgical properties. That
is, in the
embodiments provided herein, the aluminum is exposed to an interior of the
energy storage
cell (i.e., the housing), while the stainless steel is exposed to exterior. In
this manner,
advantageous electrical properties of the aluminum are enjoyed, while
structural properties
(and metallurgical properties, i.e., weldability) of the stainless steel are
relied upon for
construction. The multi-layer material may include additional layers as deemed
appropriate.
[00239] As mentioned above, the layer of first material 41 is clad onto
(or with) the
layer of second material 42. Referring still to FIG. 18A, in one embodiment, a
sheet of flat
stock (as shown) is used to provide the blank 34 to create a flat cap 24. A
portion of the layer
of second material 42 may be removed (such as around a circumference of the
cap 24) in
order to facilitate attachment of the cap 24 to the body 20. In FIG. 18B,
another embodiment
of the blank 34 is shown. In this example, the blank 34 is provided as a sheet
of clad material
that is formed into a concave configuration. In FIG. 18C, the blank 34 is
provided as a sheet
of clad material that is formed into a convex configuration. The cap 24 that
is fabricated
from the various embodiments of the blank 34 (such as those shown in FIG. 18),
are
configured to support welding to the body 20 of the housing 7. More
specifically, the
embodiment of FIG. 18B is adapted for fitting within an inner diameter of the
body 20, while
the embodiment of FIG. 18C is adapted for fitting over an outer diameter of
the body 20. In
various alternative embodiments, the layers of clad material within the sheet
may be reversed.
[00240] Referring now to FIG. 19, there is shown an embodiment of an
electrode
assembly 50. The electrode assembly 50 is designed to be installed into the
blank 34 and to
provide electrical communication from the energy storage media to a user.
Generally, the
electrode assembly 50 includes a sleeve 51. The sleeve 51 surrounds the
insulator 26, which
in turn surrounds the feed-through 19. In this example, the sleeve 51 is an
annular cylinder
with a flanged top portion.
[00241] In order to assemble the cap 24, a perforation (not shown) is made
in the blank
34. The perforation has a geometry that is sized to match the electrode
assembly 50.
Accordingly, the electrode assembly 50 is inserted into perforation of the
blank 34. Once the
electrode assembly 50 is inserted, the electrode assembly 50 may be affixed to
the blank 34
through a technique such as welding. The welding may be laser welding which
welds about a
circumference of the flange of sleeve 51. Referring to FIG. 20, points 61
where welding is
performed are shown. In this embodiment, the points 61 provide suitable
locations for
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welding of stainless steel to stainless steel, a relatively simple welding
procedure.
Accordingly, the teachings herein provide for welding the electrode assembly
50 securely
into place on the blank 34.
[00242] Material for constructing the sleeve 51 may include various types
of metals or
metal alloys. Generally, materials for the sleeve 51 are selected according
to, for example,
structural integrity and bondability (to the blank 34). Exemplary materials
for the sleeve 51
include 304 stainless steel or 316 stainless steel. Material for constructing
the feed-through
19 may include various types of metals or metal alloys. Generally, materials
for the feed-
through 19 are selected according to, for example, structural integrity and
electrical
conductance. Exemplary materials for the electrode include 446 stainless steel
or 52 alloy.
[00243] Generally, the insulator 26 is bonded to the sleeve 51 and the
feed-through 19
through known techniques (i.e., glass-to-metal bonding). Material for
constructing the
insulator 26 may include, without limitation, various types of glass,
including high
temperature glass, ceramic glass or ceramic materials. Generally, materials
for the insulator
are selected according to, for example, structural integrity and electrical
resistance (i.e.,
electrical insulation properties).
[00244] Use of components (such as the foregoing embodiment of the
electrode
assembly 50) that rely on glass-to-metal bonding as well as use of various
welding techniques
provides for hermetic sealing of the energy storage. Other components may be
used to
provide hermetic sealing as well. As used herein, the term "hermetic seal"
generally refers to
a seal that exhibits a leak rate no greater than that which is defined herein.
However, it is
considered that the actual seal efficacy may perform better than this
standard.
[00245] Additional or other techniques for coupling the electrode assembly
50 to the
blank 34 include use of a bonding agent under the flange of the sleeve 51
(between the flange
and the layer of second material 42), when such techniques are considered
appropriate.
[00246] Referring now to FIG. 21, the energy storage cell 12 is disposed
within the
body 20. The at least one terminal 8 is coupled appropriately (such as to the
feed-through
19), and the cap 24 is mated with the body 20 to provide for the
ultracapacitor10.
[00247] Once assembled, the cap 24 and the body 20 may be sealed. FIG. 22
depicts
various embodiments of the assembled energy storage (in this case, the
ultracapacitor 10). In
FIG. 22A, a flat blank 34 (see FIG. 18A) is used to create a flat cap 24. Once
the cap 24 is
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set on the body 20, the cap 24 and the body 20 are welded to create a seal 62.
In this case, as
the body 20 is an annular cylinder, the weld proceeds circumferentially about
the body 20 and
cap 24 to provide the seal 62. In a second embodiment, shown in FIG. 22B, the
concave
blank 34 (see FIG. 18B) is used to create a concave cap 24. Once the cap 24 is
set on the
body 20, the cap 24 and the body 20 are welded to create the seal 62. In a
third embodiment,
shown in FIG. 22C, the convex blank 34 (see FIG. 18C) is used to create a
convex cap 24.
Once the cap 24 is set on the body 20, the cap 24 and the body 20 may be
welded to create
the seal 62.
[00248] As appropriate, clad material may be removed (by techniques such
as, for
example, machining or etching, etc,) to expose other metal in the multi-layer
material.
Accordingly, in some embodiments, the seal 62 may include an aluminum-to-
aluminum
weld. The aluminum-to-aluminum weld may be supplemented with other fasteners,
as
appropriate.
[00249] Other techniques may be used to seal the housing 7. For example,
laser
welding, TIG welding, resistance welding, ultrasonic welding, and other forms
of mechanical
sealing may be used. It should be noted, however, that in general, traditional
forms of
mechanical sealing alone are not adequate for providing the robust hermetic
seal offered in
the ultracapacitor 10.
[00250] Refer now to FIG. 24 in which aspects of assembly another
embodiment of the
cap 24 are depicted. FIG. 24A depicts a template (i.e., the blank 34) that is
used to provide a
body of the cap 24. The template is generally sized to mate with the housing 7
of an
appropriate type of energy storage cell (such as the ultracapacitor 10). The
cap 24 may be
formed by initially providing the template forming the template, including a
dome 37 within
the template (shown in FIG. 24B) and by then perforating the dome 37 to
provide a through-
way 32 (shown in FIG. 24C). Of course, the blank 34 (e.g., a circular piece of
stock) may be
pressed or otherwise fabricated such that the foregoing features are
simultaneously provided.
[00251] In general, and with regard to these embodiments, the cap may be
formed of
aluminum, or an alloy thereof. However, the cap may be formed of any material
that is
deemed suitable by a manufacturer, user, designer and the like. For example,
the cap 24 may
be fabricated from steel and passivated (i.e., coated with an inert coating)
or otherwise
prepared for use in the housing 7.
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[00252]
Referring now also to FIG. 25, there is shown another embodiment of the
electrode assembly 50. In these embodiments, the electrode assembly 50
includes the feed-
through 19 and a hemispherically shaped material disposed about the feed-
through 19. The
hemispherically shaped material serves as the insulator 26, and is generally
shaped to
conform to the dome 37. The hemispheric insulator 26 may be fabricated of any
suitable
material for providing a hermetic seal while withstanding the chemical
influence of the
electrolyte 6. Exemplary materials include PFA (perfluoroalkoxy polymer), FEP
(fluorinated
ethylene-propylene), PVF (polyvinylfluoride), TFE (tetrafluoroethylene), CTFE
(chlorotrifluoroethylene), PCTFE (polychlorotrifluoroethylene),
ETFE
(polyethylenetetrafluoroethylene), ECTFE
(polyethylenechlorotrifluoroethylene), PTFE
(polytetrafluoroethylene), another fluoropolymer based material as well as any
other material
that may exhibit similar properties (in varying degrees) and provide for
satisfactory
performance (such as by exhibiting, among other things, a high resistance to
solvents, acids,
and bases at high temperatures, low cost and the like).
[00253] The
feed-through 19 may be formed of aluminum, or an alloy thereof.
However, the feed-through 19 may be formed of any material that is deemed
suitable by a
manufacturer, user, designer and the like. For example, the feed-through 19
may be
fabricated from steel and passivated (i.e., coated with an inert coating, such
as silicon) or
otherwise prepared for use in the electrode assembly 50. An exemplary
technique for
passivation includes depositing a coating of hydrogenated amorphous silicon on
the surface
of the substrate and functionalizing the coated substrate by exposing the
substrate to a
binding reagent having at least one unsaturated hydrocarbon group under
pressure and
elevated temperature for an effective length of time. The hydrogenated
amorphous silicon
coating is deposited by exposing the substrate to silicon hydride gas under
pressure and
elevated temperature for an effective length of time.
[00254] The
hemispheric insulator 26 may be sized relative to the dome 37 such that a
snug fit (i.e., hermetic seal) is achieved when assembled into the cap 24. The
hemispheric
insulator 26 need not be perfectly symmetric or of classic hemispheric
proportions. That is,
the hemispheric insulator 26 is substantially hemispheric, and may include,
for example,
slight adjustments in proportions, a modest flange (such as at the base) and
other features as
deemed appropriate. The hemispheric insulator 26 is generally formed of
homogeneous
material, however, this is not a requirement. For example, the hemispheric
insulator 26 may
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include an air or gas filled torus (not shown) therein to provide for desired
expansion or
compressibility.
[00255] As shown in FIG. 26, the electrode assembly 50 may be inserted
into the
template (i.e., the formed blank 34) to provide for an embodiment of the cap
24 that includes
a hemispheric hermetic seal.
[00256] As shown in FIG. 27, in various embodiments, a retainer 43 may be
bonded or
otherwise mated to a bottom of the cap 24 (i.e., a portion of the cap 24 that
faces to an
interior of the housing 7 and faces the energy storage cell 12). The retainer
43 may be
bonded to the cap 24 through various techniques, such as aluminum welding
(such as laser,
ultrasonic and the like). Other techniques may be used for the bonding,
including for
example, stamping (i.e., mechanical bonding) and brazing. The bonding may
occur, for
example, along a perimeter of the retainer 43. Generally, the bonding is
provided for in at
least one bonding point to create a desired seal 71. At least one fastener,
such as a plurality
of rivets may be used to seal the insulator 26 within the retainer 43.
[00257] In the example of FIG. 27, the cap 24 is of a concave design (see
FIG. 18B).
However, other designs may be used. For example, a convex cap 24 may be
provided (FIG.
18C), and an over-cap 24 may also be used (a variation of the embodiment of
FIG. 18C,
which is configured to mount as depicted in FIG. 22C).
[00258] The material used for the cap as well as the feed-through 19 may
be selected
with regard for thermal expansion of the hemispheric insulator 26. Further,
manufacturing
techniques may also be devised to account for thermal expansion. For example,
when
assembling the cap 24, a manufacturer may apply pressure to the hemispheric
insulator 26,
thus at least somewhat compressing the hemispheric insulator 26. In this
manner, there at
least some thermal expansion of the cap 24 is provided for without
jeopardizing efficacy of
the hermetic seal.
[00259] For further clarification of the assembled ultracapacitor, refer
to FIG. 28,
where a cut-away view of the ultracapacitor 10 is provided. In this example,
the storage cell
12 is inserted into and contained within the body 20. Each plurality of leads
are bundled
together and coupled to the housing 7 as one of the terminals 8. In some
embodiments, the
plurality of leads are coupled to a bottom of the body 20 (on the interior),
thus turning the
body 20 into a negative contact 55. Likewise, another plurality of leads are
bundled and
coupled to the feed-through 19, to provide a positive contact 56. Electrical
isolation of the
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negative contact 55 and the positive contact 56 is preserved by the electrical
insulator 26.
Generally, coupling of the leads is accomplished through welding, such as at
least one of
laser and ultrasonic welding. Of course, other techniques may be used as
deemed
appropriate.
ii. Inner Barrier
[00260] Referring now to FIG. 13, the housing 7 may include an inner
barrier 30. In
some embodiments, the barrier 30 is a coating. In this example, the barrier 30
is formed of
polytetrafluoroethylene (PTFE). Polytetrafluoroethylene (PTFE) exhibits
various properties
that make this composition well suited for the barrier 30. PTFE has a melting
point of about
327 degrees Celsius, has excellent dielectric properties, has a coefficient of
friction of
between about 0.05 to 0.10, which is the third-lowest of any known solid
material, has a high
corrosion resistance and other beneficial properties. Generally, an interior
portion of the cap
24 may include the barrier 30 disposed thereon.
[00261] Other materials may be used for the barrier 30. Among these other
materials
are forms of ceramics (any type of ceramic that may be suitably applied and
meet
performance criteria), other polymers (preferably, a high temperature polymer)
and the like.
Exemplary other polymers include perfluoroalkoxy (PFA) and fluorinated
ethylene propylene
(FEP) as well as ethylene tetrafluoroethylene (ETFE).
[00262] The barrier 30 may include any material or combinations of
materials that
provide for reductions in electrochemical or other types of reactions between
the energy
storage cell 12 and the housing 7 or components of the housing 7. In some
embodiments, the
combinations are manifested as homogeneous dispersions of differing materials
within a
single layer. In other embodiments, the combinations are manifested as
differing materials
within a plurality of layers. Other combinations may be used. In short, the
barrier 30 may be
considered as at least one of an electrical insulator and chemically inert
(i.e., exhibiting low
reactivity) and therefore substantially resists or impedes at least one of
electrical and
chemical interactions between the storage cell 12 and the housing 7. In some
embodiments,
the term "low reactivity" and "low chemical reactivity" generally refer to a
rate of chemical
interaction that is below a level of concern for an interested party.
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[00263] In general, the interior of the housing 7 may be host to the
barrier 30 such that
all surfaces of the housing 7 which are exposed to the interior are covered.
At least one
untreated area 31 may be included within the body 20 and on an outer surface
36 of the cap
24 (see FIG. 14A). In some embodiments, untreated areas 31 (see FIG. 14B) may
be
included to account for assembly requirements, such as areas which will be
sealed or
connected (such as by welding).
[00264] The barrier 30 may be applied to the interior portions using
conventional
techniques. For example, in the case of PTFE, the barrier 30 may be applied by
painting or
spraying the barrier 30 onto the interior surface as a coating. A mask may be
used as a part
of the process to ensure untreated areas 31 retain desired integrity. In
short, a variety of
techniques may be used to provide the barrier 30.
[00265] In an exemplary embodiment, the barrier 30 is about 3 mil to about
5 mil
thick, while material used for the barrier 30 is a PFA based material. In this
example,
surfaces for receiving the material that make up the barrier 30 are prepared
with grit blasting,
such as with aluminum oxide. Once the surfaces are cleaned, the material is
applied, first as a
liquid then as a powder. The material is cured by a heat treating process. In
some
embodiments, the heating cycle is about 10 minutes to about 15 minutes in
duration, at
temperatures of about 370 degrees Celsius. This results in a continuous finish
to the barrier
30 that is substantially free of pin-hole sized or smaller defects. FIG. 15
depicts assembly of
an embodiment of the ultracapacitor 10 according to the teachings herein. In
this
embodiment, the ultracapacitor 10 includes the body 20 that includes the
barrier 30 disposed
therein, a cap 24 with the barrier 30 disposed therein, and the energy storage
cell 12. During
assembly, the cap 24 is set over the body 20. A first one of the terminals 8
is electrically
coupled to the cap feed-through 19, while a second one of the terminals 8 is
electrically
coupled to the housing 7, typically at the bottom, on the side or on the cap
24. In some
embodiments, the second one of the terminals 8 is coupled to another feed-
through 19 (such
as of an opposing cap 24).
[00266] With the barrier 30 disposed on the interior surface(s) of the
housing 7,
electrochemical and other reactions between the housing 7 and the electrolyte
are greatly
reduced or substantially eliminated. This is particularly significant at
higher temperatures
where a rate of chemical and other reactions is generally increased.
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[00267] Referring now to FIG. 16, there is shown relative performance of
the
ultracapacitor 10 in comparison to an otherwise equivalent ultracapacitor. In
FIG. 16A,
leakage current is shown for a prior art embodiment of the ultracapacitor 10.
In FIG. 16B,
leakage current is shown for an equivalent ultracapacitor 10 that includes the
barrier 30. In
FIG. 16B, the ultracapacitor 10 is electrically equivalent to the
ultracapacitor whose leakage
current is shown in FIG. 16A. In both cases, the housing 7 was stainless
steel, and the
voltage supplied to the cell was 1.75 Volts, and electrolyte was not purified.
Temperature
was held a constant 150 degrees Celsius. Notably, the leakage current in FIG.
16B indicates
a comparably lower initial value and no substantial increase over time while
the leakage
current in FIG. 16A indicates a comparably higher initial value as well as a
substantial
increase over time.
[00268] Generally, the barrier 30 provides a suitable thickness of
suitable materials
between the energy storage cell 12 and the housing 7. The barrier 30 may
include a
homogeneous mixture, a heterogeneous mixture and/or at least one layer of
materials. The
barrier 30 may provide complete coverage (i.e., provide coverage over the
interior surface
area of the housing with the exception of electrode contacts) or partial
coverage. In some
embodiments, the barrier 30 is formed of multiple components. Consider, for
example, the
embodiment presented below and illustrated in FIG. 8.
[00269] Referring to FIG. 17, aspects of an additional embodiment are
shown. In
some embodiments, the energy storage cell 12 is deposited within an envelope
73. That is,
the energy storage cell 12 has the barrier 30 disposed thereon, wrapped
thereover, or
otherwise applied to separate the energy storage cell 12 from the housing 7
once assembled.
The envelope 73 may be applied well ahead of packaging the energy storage cell
12 into the
housing 7. Therefore, use of an envelope 73 may present certain advantages,
such as to
manufacturers. (Note that the envelope 73 is shown as loosely disposed over
the energy
storage cell 12 for purposes of illustration).
[00270] In some embodiments, the envelope 73 is used in conjunction with
the coating,
wherein the coating is disposed over at least a portion of the interior
surfaces. For example,
in one embodiment, the coating is disposed within the interior of the housing
7 only in areas
where the envelope 73 may be at least partially compromised (such as be a
protruding
terminal 8). Together, the envelope 73 and the coating form an efficient
barrier 30.
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[00271] Accordingly, incorporation of the barrier 30 may provide for an
ultracapacitor
that exhibits leakage current with comparatively low initial values and
substantially slower
increases in leakage current over time in view of the prior art.
Significantly, the leakage
current of the ultracapacitor remains at practical (i.e., desirably low)
levels when the
ultracapacitor is exposed to ambient temperatures for which prior art
capacitors would exhibit
prohibitively large initial values of leakage current and / or prohibitively
rapid increases in
leakage current over time.
[00272] Having thus described embodiments of the barrier 30, and various
aspects
thereof, it should be recognized the ultracapacitor 10 may exhibit other
benefits as a result of
reduced reaction between the housing 7 and the energy storage media 1. For
example, an
effective series resistance (ESR) of the ultracapacitor 10 may exhibit
comparatively lower
values over time. Further, unwanted chemical reactions that take place in a
prior art capacitor
often create unwanted effects such as out-gassing, or in the case of a
hermetically sealed
housing, bulging of the housing. In both cases, this leads to a compromise of
the structural
integrity of the housing and/or hermetic seal of the capacitor. Ultimately,
this may lead to
leaks or catastrophic failure of the prior art capacitor. In some embodiments,
these effects
may be substantially reduced or eliminated by the application of a disclosed
barrier 30.
[00273] It should be recognized that the terms "barrier" and "coating" are
not limiting
of the teachings herein. That is, any technique for applying the appropriate
material to the
interior of the housing 7, body 20 and/or cap 24 may be used. For example, in
other
embodiments, the barrier 30 is actually fabricated into or onto material
making up the
housing body 20, the material then being worked or shaped as appropriate to
form the various
components of the housing 7. When considering some of the many possible
techniques for
applying the barrier 30, it may be equally appropriate to roll on, sputter,
sinter, laminate,
print, or otherwise apply the material(s). In short, the barrier 30 may be
applied using any
technique deemed appropriate by a manufacturer, designer and/or user.
[00274] Materials used in the barrier 30 may be selected according to
properties such
as reactivity, dielectric value, melting point, adhesion to materials of the
housing 7,
coefficient of friction, cost, and other such factors. Combinations of
materials (such as
layered, mixed, or otherwise combined) may be used to provide for desired
properties.
[00275] Using an enhanced housing 7, such as one with the barrier 30, may,
in some
embodiments, limit degradation of the advanced electrolyte system. While the
barrier 30
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presents one technique for providing an enhanced housing 7, other techniques
may be used.
For example, use of a housing 7 fabricated from aluminum would be
advantageous, due to
the electrochemical properties of aluminum in the presence of electrolyte 6.
However, given
the difficulties in fabrication of aluminum, it has not been possible (until
now) to construct
embodiments of the housing 7 that take advantage of aluminum.
[00276] Additional embodiments of the housing 7 include those that present
aluminum
to all interior surfaces, which may be exposed to electrolyte, while providing
users with an
ability to weld and hermetically seal the housing. Improved performance of the
ultracapacitor 10 may be realized through reduced internal corrosion,
elimination of problems
associated with use of dissimilar metals in a conductive media and for other
reasons.
Advantageously, the housing 7 makes use of existing technology, such available
electrode
inserts that include glass-to-metal seals (and may include those fabricated
from stainless
steel, tantalum or other advantageous materials and components), and therefore
is economic
to fabricate.
[00277] Although disclosed herein as embodiments of the housing 7 that are
suited for
the ultracapacitor 10, these embodiments (as is the case with the barrier 30)
may be used with
any type of energy storage deemed appropriate, and may include any type of
technology
practicable. For example, other forms of energy storage may be used, including
electrochemical batteries, in particular, lithium based batteries.
[00278] In general, the material(s) exposed to an interior of the housing
7 exhibit
adequately low reactivity when exposed to the electrolyte 6, i.e., the
advanced electrolyte
system of the present invention, and therefore are merely illustrative of some
of the
embodiments and are not limiting of the teachings herein.
F. Factors for General Construction of Capacitors
[00279] An important aspect for consideration in construction of the
ultracapacitor 10
is maintaining good chemical hygiene. In order to assure purity of the
components, in
various embodiments, the activated carbon, carbon fibers, rayon, carbon cloth,
and/or
nanotubes making up the energy storage media 1 for the two electrodes 3, are
dried at
elevated temperature in a vacuum environment. The separator 5 is also dried at
elevated
temperature in a vacuum environment. Once the electrodes 3 and the separator 5
are dried
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under vacuum, they are packaged in the housing 7 without a final seal or cap
in an
atmosphere with less than 50 parts per million (ppm) of water. The uncapped
ultracapacitor
may be dried, for example, under vacuum over a temperature range of about 100
degrees
Celsius to about 300 degrees Celsius. Once this final drying is complete, the
electrolyte 6
may be added and the housing 7 is sealed in a relatively dry atmosphere (such
as an
atmosphere with less than about 50 ppm of moisture). Of course, other methods
of assembly
may be used, and the foregoing provides merely a few exemplary aspects of
assembly of the
ultracapacitor 10.
M. Methods of the Invention
Certain methods of the invention useful for reducing impurities or fabricating
devices
of the present invention are described herein below. Such methods of
purification are also
additionally applicable to any advanced electrolyte system of the present
invention
A. Methods of Reduction of Impurities
i. AES Contaminants
[00280] In certain embodiments, the advanced electrolyte system (AES) of
the present
invention is purified remove contaminants and to provide desired enhanced
performance
characteristics described herein. As such, the present disclosure provides a
method for
purifying an AES, the method comprising: mixing water into an advanced
electrolyte system
to provide a first mixture; partitioning the first mixture; collecting the
advanced electrolyte
system from the first mixture; adding a solvent to the collected liquid to
provide a second
mixture; mixing carbon into the second mixture to provide a third mixture;
separating the
advanced electrolyte system from the third mixture to obtain the purified
advanced electrolyte
system. Generally, the process calls for selecting an electrolyte, adding de-
ionized water as
well as activated carbon under controlled conditions. The de-ionized water and
activated
carbon are subsequently removed, resulting in an electrolyte that is
substantially purified.
The purified electrolyte is suited for use in, among other things, an
ultracapacitor.
[00281] This method may be used to ensure a high degree of purity of the
advanced
electrolyte system (AES) of the present invention. It should be noted that
although the
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process is presented in terms of specific parameters (such as quantities,
formulations, times
and the like), that the presentation is merely exemplary and illustrative of
the process for
purifying electrolyte and is not limiting thereof.
[00282] For example, the method may further comprise one or more of the
following
steps or characterizations: heating the first mixture; wherein partitioning
comprises letting the
first mixture sit undisturbed until the water and the AES are substantially
partitioned; wherein
adding a solvent comprises adding at least one of diethylether, pentone,
cyclopentone,
hexane, cyclohexane, benzene, toluene, 1-4 dioxane, and chloroform; wherein
mixing carbon
comprises mixing carbon powder; wherein mixing carbon comprises stirring the
third mixture
substantially constantly; wherein separating the AES comprises at least one of
filtering
carbon from the third mixture and evaporating the solvent from the third
mixture.
[00283] In a first step of the process for purifying electrolyte, the
electrolyte 6 (in some
embodiments, the ionic liquid) is mixed with deionized water, and then raised
to a moderate
temperature for some period of time. In a proof of concept, fifty (50)
milliliters (ml) of ionic
liquid was mixed with eight hundred and fifty (850) milliliters (ml) of the
deionized water.
The mixture was raised to a constant temperature of sixty (60) degrees Celsius
for about
twelve (12) hours and subjected to constant stirring (of about one hundred and
twenty (120)
revolutions per minute (rpm)).
[00284] In a second step, the mixture of ionic liquid and deionized water
is permitted
to partition. In this example, the mixture was transferred via a funnel, and
allowed to sit for
about four (4) hours.
[00285] In a third step, the ionic liquid is collected. In this example, a
water phase of
the mixture resided on the bottom, with an ionic liquid phase on the top. The
ionic liquid
phase was transferred into another beaker.
[00286] In a fourth step, a solvent was mixed with the ionic liquid. In
this example, a
volume of about twenty five (25) milliliters (ml) of ethyl acetate was mixed
with the ionic
liquid. This mixture was again raised to a moderate temperature and stirred
for some time.
[00287] Although ethyl acetate was used as the solvent, the solvent can be
at least one
of diethylether, pentone, cyclopentone, hexane, cyclohexane, benzene, toluene,
1-4 dioxane,
chloroform or any combination thereof as well as other material(s) that
exhibit appropriate
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performance characteristics. Some of the desired performance characteristics
include those
of a non-polar solvent as well as a high degree of volatility.
[00288] In a fifth step, carbon powder is added to the mixture of the
ionic liquid and
solvent. In this example, about twenty (20) weight percent (wt%) of carbon (of
about a 0.45
micrometer diameter) was added to the mixture.
[00289] In a sixth step, the ionic liquid is again mixed. In this example,
the mixture
with the carbon powder was then subjected to constant stirring (120 rpm)
overnight at about
seventy (70) degrees Celsius.
[00290] In a seventh step, the carbon and the ethyl acetate are separated
from the ionic
liquid. In this example, the carbon was separated using Buchner filtration
with a glass
microfiber filter. Multiple filtrations (three) were performed. The ionic
liquid collected was
then passed through a 0.2 micrometer syringe filter in order to remove
substantially all of the
carbon particles. In this example, the solvent was then subsequently separated
from the ionic
liquid by employing rotary evaporation. Specifically, the sample of ionic
liquid was stirred
while increasing temperature from seventy (70) degrees Celsius to eighty (80)
degrees
Celsius, and finished at one hundred (100) degrees Celsius. Evaporation was
performed for
about fifteen (15) minutes at each of the respective temperatures.
[00291] The process for purifying electrolyte has proven to be very
effective. For the
sample ionic liquid, water content was measured by titration, with a titration
instrument
provided by Mettler-Toledo Inc., of Columbus, Ohio (model No: AQC22). Halide
content
was measured with an ISE instrument provided by Hanna Instruments of
Woonsocket, Rhode
Island (model no. AQC22). The standards solution for the ISE instrument was
obtained from
Hanna, and included HI 4007-03 (1,000 ppm chloride standard), HI 4010-03
(1,000 ppm
fluoride standard) HI 4000-00 (ISA for halide electrodes), and HI 4010-00
(TISAB solution
for fluoride electrode only). Prior to performing measurements, the ISE
instrument was
calibrated with the standards solutions using 0.1, 10, 100 and 1,000 parts per
million (ppm) of
the standards, mixed in with deionized water. ISA buffer was added to the
standard in a 1:50
ratio for measurement of a- ions. Results are shown in Table 3.
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Table 3
Purification Data for Electrolyte Containing
1-buty1-1-methylpyrolidinium and tetracyanoborate
Before After DI Water
Impurity
(1)Pm) (1)Pm) (1)Pm)
Cl- 5,300.90 769 9.23E-1
F- 75.61 10.61 1.10E-1
H20 1080 20
[00293] A four step process was used to measure the halide ions. First, Cl-
and F ions
were measured in the deionized water. Next, a 0.01 M solution of ionic liquid
was prepared
with deionized water. Subsequently, a- and F ions were measured in the
solution.
Estimation of the halide content was then determined by subtracting the
quantity of ions in
the water from the quantity of ions in the solution.
[00294] Purification standards were also examined with respect to the
electrolyte
contaminant compositions through the analysis of leakage current. FIG. 9
depicts leakage
current for unpurified electrolyte in the ultracapacitor 10. FIG. 10 depicts
leakage current for
purified electrolyte in a similarly structured ultracapacitor 10. As one can
see, there is a
substantial decrease in initial leakage current, as well as a modest decrease
in leakage current
over the later portion of the measurement interval. More information is
provided on the
construction of each embodiment in Table 4.
Table 4
Test Ultracapacitor Configuration
Parameter Fig. 9 Fig. 10
Cell Size: Open Sub C Open Sub C
Casing: Coated P870 Coated P870
Electrode Double Sided Activated Double Sided Activated
Material: Carbon(150/40) Carbon(150/40)
Separator: Fiberglass Fiberglass
Size of IE: 233x34 mm OE: IE: 233x34 mm OE: 256x34
256x34 mm mm
Electrodes:
Tabs: 0.005" Aluminum (3 0.005" Aluminum (3 Tabs)
Tabs)
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Temperature 150 C 150 C
Electrolyte: Unpurified AES Purified AES
[00295] Other benefits are also realized, including improvements in
stability of
resistance and capacitance of the ultracapacitor 10.
[00296] Leakage current may be determined in a number of ways.
Qualitatively,
leakage current may be considered as current drawn into a device, once the
device has
reached a state of equilibrium. In practice, it is always or almost always
necessary to
estimate the actual leakage current as a state of equilibrium that may
generally only be
asymptotically approached. Thus, the leakage current in a given measurement
may be
approximated by measuring the current drawn into the ultracapacitor 10, while
the
ultracapacitor 10 is held at a substantially fixed voltage and exposed to a
substantially fixed
ambient temperature for a relatively long period of time. In some instances, a
relatively long
period of time may be determined by approximating the current time function as
an
exponential function, then allowing for several (e.g., about 3 to 5)
characteristic time
constants to pass. Often, such a duration ranges from about 50 hours to about
100 hours for
many ultracapacitor technologies. Alternatively, if such a long period of time
is impractical
for any reason, the leakage current may simply be extrapolated, again,
perhaps, by
approximating the current time function as an exponential or any approximating
function
deemed appropriate. Notably, leakage current will generally depend on ambient
temperature.
So, in order to characterize performance of a device at a temperature or in a
temperature
range, it is generally important to expose the device to the ambient
temperature of interest
when measuring leakage current.
[00297] Note that one approach to reduce the volumetric leakage current at
a specific
temperature is to reduce the operating voltage at that temperature. Another
approach to
reduce the volumetric leakage current at a specific temperature is to increase
the void volume
of the ultracapacitor. Yet another approach to reduce the leakage current is
to reduce loading
of the energy storage media 1 on the electrode 3.
[00298] Having disclosed aspects of embodiments for purification of
electrolyte and
ionic liquid, it should be recognized that a variety of embodiments may be
realized. Further a
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variety of techniques may be practiced. For example, steps may be adjusted,
the order of
steps and the like.
ii. Water/Moisture Content and Removal
[00299] The housing 7 of a sealed ultracapacitor 10 may be opened, and the
storage
cell 12 sampled for impurities. Water content may be measured using the Karl
Fischer
method for the electrodes, separator and electrolyte from the cell 12. Three
measurements
may be taken and averaged.
[00300] In general, a method for characterizing a contaminant within the
ultracapacitor
includes breaching the housing 7 to access contents thereof, sampling the
contents and
analyzing the sample. Techniques disclosed elsewhere herein may be used in
support of the
characterizing.
[00301] Note that to ensure accurate measurement of impurities in the
ultracapacitor
and components thereof, including the electrode, the electrolyte and the
separator, assembly
and disassembly may be performed in an appropriate environment, such as in an
inert
environment within a glove box.
[00302] By reducing the moisture content in the ultracapacitor 10 (e.g.,
to less than 500
part per million (ppm) over the weight and volume of the electrolyte and the
impurities to less
than 1,000 ppm), the ultracapacitor 10 can more efficiently operate over the
temperature
range, with a leakage current (I/L) that is less than 10 Amperes per Liter
within that
temperature range and voltage range.
[00303] In one embodiment, leakage current (I/L) at a specific temperature
is measured
by holding the voltage of the ultracapacitor 10 constant at the rated voltage
(i.e., the
maximum rated operating voltage) for seventy two (72) hours. During this
period, the
temperature remains relatively constant at the specified temperature. At the
end of the
measurement interval, the leakage current of the ultracapacitor 10 is
measured.
[00304] In some embodiments, a maximum voltage rating of the
ultracapacitor 10 is
about 4 V at room temperature. An approach to ensure performance of the
ultracapacitor 10
at elevated temperatures (for example, over 210 degrees Celsius), is to derate
(i.e., to reduce)
the voltage rating of the ultracapacitor 10. For example, the voltage rating
may be adjusted
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down to about 0.5 V, such that extended durations of operation at higher
temperature are
achievable.
B. Methods of Fabrication of Ultracapacitors
[00305] In another embodiment, the present invention provides a method for
fabricating an ultracapacitor comprising the steps of: disposing an energy
storage cell
comprising energy storage media within a housing; and filling the housing with
an advanced
electrolyte system (AES), such that an ultracapacitor is fabricated to operate
within a
temperature range between about -40 degrees Celsius to about 210 degrees
Celsius.
[00306] In one particular embodiment, the AES comprises a novel
electrolyte entity
(NEE), e.g., wherein the NEE is adapted for use in high temperature
ultracapacitors. In
certain embodiments, the ultracapacitor is configured to operate at a
temperature within a
temperature range between about 80 degrees Celsius to about 210 degrees
Celsius, e.g., a
temperature range between about 80 degrees Celsius to about 150 degrees
Celsius.
[00307] In one particular embodiment, the AES comprises a highly purified
electrolyte, e.g., wherein the highly purified electrolyte is adapted for use
in high temperature
ultracapacitors. In certain embodiments, the ultracapacitor is configured to
operate at a
temperature within a temperature range between about 80 degrees Celsius to
about 210
degrees Celsius, e.g., a temperature range between about 80 degrees Celsius to
about 150
degrees Celsius.
[00308] In one particular embodiment, the AES comprises an enhanced
electrolyte
combination, e.g., wherein the enhanced electrolyte combination is adapted for
use in both
high and low temperature ultracapacitors. In certain embodiments, the
ultracapacitor is
configured to operate at a temperature within a temperature range between
about -40 degrees
Celsius to about 150 degrees Celsius, e.g., a temperature range between about -
30 degrees
Celsius to about 125 degrees Celsius.
[00309] In one embodiment, the ultracapacitor fabricated is an
ultracapacitor described
in Section II, herein above. As such, and as noted above, the advantages over
the existing
electrolytes of known energy storage devices are selected from one or more of
the following
improvements: decreased total resistance, increased long-term stability of
resistance,
increased total capacitance, increased long-term stability of capacitance,
increased energy
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density, increased voltage stability, reduced vapor pressure, wider
temperature range
performance for an individual capacitor, increased temperature durability for
an individual
capacitor,; increased ease of manufacturability, and improved cost
effectiveness.
[00310] In certain embodiments, the disposing further comprises pre-
treating
components of the ultracapacitor comprising at least one of: an electrode, a
separator, a lead,
an assembled energy storage cell and the housing to reduce moisture therein.
In particular
embodiments, the pre-treating comprises heating the selected components
substantially under
vacuum over a temperature range of about 100 degrees Celsius to about 150
degrees Celsius.
The pre-treating may comprise heating the selected components substantially
under vacuum
over a temperature range of about 150 degrees Celsius to about 300 degrees
Celsius.
[00311] In certain embodiments, the disposing is performed in a
substantially inert
environment.
[00312] In certain embodiments, the constructing comprises selecting an
interior facing
material for the housing that exhibits low chemical reactivity with an
electrolyte, which may
further comprise including the interior facing material in substantial
portions of the interior of
the housing. The interior facing material may be selected from at least one of
aluminum,
polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA), fluorinated ethylene
propylene
(FEP), ethylene tetrafluoroethylene (ETFE), and a ceramic material as the
interior facing
material.
[00313] In certain embodiments, the constructing comprises forming the
housing from
a multilayer material, e.g., wherein forming the housing from a multilayer
material comprises
disposing a weldable material on an exterior of the housing.
[00314] In certain embodiments, the constructing comprises fabricating at
least one of
a cap and a body for the housing. The fabricating may comprise disposing a
seal comprising
an insulator and an electrode insulated from the housing into the housing.
Furthermore,
disposing the seal may comprise disposing a glass-to-metal seal, e.g., welding
the glass-to-
metal seal to an outer surface of the housing In particular embodiments,
disposing the seal
comprises disposing a hemispheric seal.
[00315] In certain embodiments, the constructing comprises disposing a
fill port in the
housing to provide for the filling.
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[00316] In certain embodiments, the method of fabricating may further
comprise
fabricating the energy storage cell, e.g., obtaining an electrode by joining
energy storage
media with a current collector, e.g., joining at least one lead to an
electrode. In certain
embodiments, the joining at least one lead to the electrode comprises placing
at least one
reference mark onto the electrode. In certain embodiments, the joining at
least one lead to the
electrode comprises locating each lead at a respective reference mark. In
certain
embodiments, the joining at least one lead comprises clearing energy storage
media from the
current collector. In certain embodiments, the joining at least one lead
comprises ultrasonic
welding the lead to the current collector.
[00317] The electrode may also be obtained by joining a plurality of
electrode
elements fabricated from joining energy storage media with a current
collector. The plurality
of electrode elements may be joined by ultrasonically welding a joining
element to the
current collector of one electrode element and to the current collector of
another electrode
element.
[00318] In certain embodiments, fabricating the energy storage cell
comprises
disposing a separator between at least two electrodes. And may further
comprise aligning
each of the electrodes with the separator.
[00319] In certain embodiments, fabricating the energy storage cell
comprises packing
at least two electrodes with a separator disposed therebetween, e.g., wherein
the packing
comprises rolling the storage cell into a rolled storage cell.
[00320] In certain embodiments, fabricating the energy storage cell
comprises
disposing a wrapper over the storage cell.
[00321] In certain embodiments, disposing the energy storage cell
comprises grouping
a plurality of leads together to provide a terminal, e.g., wherein grouping
the plurality of
leads together comprises aligning the leads together into a set of aligned
leads to form a
terminal. In a particular embodiment, the method further comprises, placing a
wrapper about
the set of aligned leads, placing a fold in the set of aligned leads, or
coupling the set of
aligned leads to a contact of the housing. Moreover, the coupling may comprise
welding the
set of aligned leads to the contact, or welding the set of aligned leads to
one of a jumper and a
bridge for coupling to a contact of the housing.
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[00322] In certain embodiments, the method of fabricating may further
comprise
electrically coupling at least one of a jumper and a bridge to a contact of
the housing. In a
particular embodiment, this may further comprise substantially disposing an
insulative
material over the contact on the interior of the housing.
[00323] In certain embodiments, the method of fabricating may further
comprise
hermitically sealing the energy storage cell within the housing, e.g., wherein
hermitically
sealing comprises at least one of pulse welding, laser welding, resistance
welding and TIG
welding components of the housing together.
[00324] In certain embodiments, the method of fabricating may further
comprise
mating at least one cap with a body to provide the housing, e.g., wherein the
cap comprises
one of a concave cap, a convex cap and a flat cap. In a particular embodiment,
the method
may further comprise removing at least a portion of a multilayer material in
the housing to
provide for the mating.
[00325] In certain embodiments, the method of fabricating may further
comprise
purifying the AES.
[00326] In certain embodiments, the method of fabricating further
comprising
disposing a fill port in the housing to provide for the filling, e.g., wherein
the filling
comprises disposing the AES over a fill port in the housing. In particular
embodiments, the
method further comprises sealing the fill port upon completion of the filling,
e.g., fitting a
compatible material into the fill port. Such material may then, in another
step, be welded to
the housing.
[00327] In certain embodiments, the step of filling comprises drawing a
vacuum on the
fill port in the housing, e.g., wherein the vacuum is below about 150 mTorr,
e.g., .wherein the
vacuum is below about 40 mTorr.
[00328] In certain embodiments, the step of filling is performed in a
substantially inert
environment.
i. Fabrication Techniques
[00329] Moreover, it should be recognized that certain robust assembly
techniques
may be required to provide highly efficient energy storage. Accordingly, some
of the
techniques for assembly are now discussed.
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[00330] Once the ultracapacitor 10 is fabricated, it may be used in high
temperature
applications with little or no leakage current and little increase in
resistance. The
ultracapacitor 10 described herein can operate efficiently at temperatures
from about minus
40 degrees Celsius to about 210 degrees Celsius with leakage currents
normalized over the
volume of the device less than 10 amperes per liter (A/L) of volume of the
device within the
entire operating voltage and temperature range. In certain embodiments, the
capacitor is
operable across temperatures from minus 40 degrees Celsius to 210 degrees
Celsius.
[00331] As an overview, a method of assembly of a cylindrically shaped
ultracapacitor
is provided. Beginning with the electrodes 3, each electrode 3 is fabricated
once the
energy storage media 1 has been associated with the current collector 2. A
plurality of leads
are then coupled to each electrode 3 at appropriate locations. A plurality of
electrodes 3 are
then oriented and assembled with an appropriate number of separators 5
therebetween to
form the storage cell 12. The storage cell 12 may then be rolled into a
cylinder, and may be
secured with a wrapper. Generally, respective ones of the leads are then
bundled to form
each of the terminals 8.
[00332] Prior to incorporation of the electrolyte 6, i.e., the advanced
electrolyte
systems of the present invention, into the ultracapacitor 10 (such as prior to
assembly of the
storage cell 12, or thereafter) each component of the ultracapacitor 10 may be
dried to
remove moisture. This may be performed with unassembled components (i.e., an
empty
housing 7, as well as each of the electrodes 3 and each of the separators 5),
and subsequently
with assembled components (such as the storage cell 12).
[00333] Drying may be performed, for example, at an elevated temperature
in a
vacuum environment. Once drying has been performed, the storage cell 12 may
then be
packaged in the housing 7 without a final seal or cap. In some embodiments,
the packaging
is performed in an atmosphere with less than 50 parts per million (ppm) of
water. The
uncapped ultracapacitor 10 may then be dried again. For example, the
ultracapacitor 10 may
be dried under vacuum over a temperature range of about 100 degrees Celsius to
about 300
degrees Celsius. Once this final drying is complete, the housing 7 may then be
sealed in, for
example, an atmosphere with less than 50 ppm of moisture.
[00334] In some embodiments, once the drying process (which may also be
referred to
a "baking" process) has been completed, the environment surrounding the
components may
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be filled with an inert gas. Exemplary gasses include argon, nitrogen, helium,
and other
gasses exhibiting similar properties (as well as combinations thereof).
[00335] Generally, a fill port (a perforation in a surface of the housing
7) is included in
the housing 7, or may be later added. Once the ultracapacitor 10 has been
filled with
electrolyte 6, i.e., the advanced electrolyte systems of the present
invention, the fill port may
then be closed. Closing the fill port may be completed, for example, by
welding material
(e.g., a metal that is compatible with the housing 7) into or over the fill
port. In some
embodiments, the fill port may be temporarily closed prior to filling, such
that the
ultracapacitor 10 may be moved to another environment, for subsequent re-
opening, filling
and closure. However, as discussed herein, it is considered that the
ultracapacitor 10 is dried
and filled in the same environment.
[00336] A number of methods may be used to fill the housing 7 with a
desired quantity
of the advanced electrolyte system. Generally, controlling the fill process
may provide for,
among other things, increases in capacitance, reductions in equivalent-series-
resistance
(ESR), and limiting waste of electrolyte. A vacuum filling method is provided
as a non-
limiting example of a technique for filling the housing 7 and wetting the
storage cell 12 with
the electrolyte 6.
[00337] First, however, note that measures may be taken to ensure that any
material
that has a potential to contaminate components of the ultracapacitor 10 is
clean, compatible
and dry. As a matter of convention, it may be considered that "good hygiene"
is practiced to
ensure assembly processes and components do not introduce contaminants into
the
ultracapacitor 10.
[00338] In the "vacuum method" a container is placed onto the housing 7
around the
fill port. A quantity of electrolyte 6, i.e., the advanced electrolyte systems
of the present
invention, is then placed into the container in an environment that is
substantially free of
oxygen and water (i.e., moisture). A vacuum is then drawn in the environment,
thus pulling
any air out of the housing and thus simultaneously drawing the electrolyte 6
into the housing
7. The surrounding environment may then be refilled with inert gas (such as
argon, nitrogen,
or the like, or some combination of inert gases), if desired. The
ultracapacitor 10 may be
checked to see if the desired amount of electrolyte 6 has been drawn in. The
process may be
repeated as necessary until the desired amount of electrolyte 6 is in the
ultracapacitor 10.
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[00339] After filling with electrolyte 6, i.e., the advanced electrolyte
systems of the
present invention, in certain embodiments, material may be fit into the fill
port to seal the
ultracapacitor 10. The material may be, for example, a metal that is
compatible with the
housing 7 and the electrolyte 6. In one example, material is force fit into
the fill port,
essentially performing a "cold weld" of a plug in the fill port. In particular
embodiments, the
force fit may be complimented with other welding techniques as discussed
further herein.
[00340] In general, assembly of the housing often involves placing the
storage cell 12
within the body 20 and filling the body 20 with the advanced electrolyte
system. Another
drying process may be performed. Exemplary drying includes heating the body 20
with the
storage cell 12 and advanced electrolyte system therein, often under a reduced
pressure (e.g.,
a vacuum). Once adequate (optional) drying has been performed, final steps of
assembly
may be performed. In the final steps, internal electrical connections are
made, the cap 24 is
installed, and the cap 24 is hermetically sealed to the body 20, by, for
example, welding the
cap 24 to the body 20.
[00341] In some embodiments, at least one of the housing 7 and the cap 24
is
fabricated to include materials that include a plurality of layers. For
example, a first layer of
material may include aluminum, with a second layer of material being stainless
steel. In this
example, the stainless steel is clad onto the aluminum, thus providing for a
material that
exhibits a desired combination of metallurgical properties. That is, in the
embodiments
provided herein, the aluminum is exposed to an interior of the energy storage
cell (i.e., the
housing), while the stainless steel is exposed to exterior. In this manner,
advantageous
electrical properties of the aluminum are enjoyed, while structural properties
(and
metallurgical properties, i.e., weldability) of the stainless steel are relied
upon for
construction. The multi-layer material may include additional layers as deemed
appropriate.
Advantageously, this provides for welding of stainless steel to stainless
steel, a relatively
simple welding procedure.
[00342] While material used for construction of the body 20 includes
aluminum, any
type of aluminum or aluminum alloy deemed appropriate by a designer or
fabricator (all of
which are broadly referred to herein simply as "aluminum"). Various alloys,
laminates, and
the like may be disposed over (e.g., clad to) the aluminum (the aluminum being
exposed to an
interior of the body 20. Additional materials (such as structural materials or
electrically
insulative materials, such as some polymer-based materials) may be used to
compliment the
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body and/or the housing 7. The materials disposed over the aluminum may
likewise be
chosen by what is deemed appropriate by a designer or fabricator.
[00343] Use of aluminum is not necessary or required. In short, material
selection may
provide for use of any material deemed appropriate by a designer, fabricator,
or user and the
like. Considerations may be given to various factors, such as, for example,
reduction of
electrochemical interaction with the electrolyte 6, structural properties,
cost and the like.
[00344] Embodiments of the ultracapacitor 10 that exhibit a relatively
small volume
may be fabricated in a prismatic form factor such that the electrodes 3 of the
ultracapacitor 10
oppose one another, at least one electrode 3 having an internal contact to a
glass to metal seal,
the other having an internal contact to a housing or to a glass to metal seal.
[00345] A volume of a particular ultracapacitor 10 may be extended by
combining
several storage cells (e.g., welding together several jelly rolls) within one
housing 7 such that
they are electrically in parallel or in series.
[00346] In a variety of embodiments, it is useful to use a plurality of
the ultracapacitors
together to provide a power supply. In order to provide for reliable
operation, individual
ultracapacitors 10 may be tested in advance of use. In order to perform
various types of
testing, each of the ultracapacitors 10 may be tested as a singular cell, in
series or in parallel
with multiple ultracapacitors 10 attached. Using different metals joined by
various
techniques (such as by welding) can reduce the ESR of the connection as well
as increase the
strength of the connections. Some aspects of connections between
ultracapacitors 10 are now
introduced.
[00347] In some embodiments, the ultracapacitor 10 includes two contacts.
The two
contacts are the glass-to-metal seal pin (i.e., the feed-through 19) and the
entire rest of the
housing 7. When connecting a plurality of the ultracapacitors 10 in series, it
is often desired
to couple an interconnection between a bottom of the housing 7 (in the case of
the cylindrical
form housing 7), such that distance to the internal leads is minimized, and
therefore of a
minimal resistance. In these embodiments, an opposing end of the
interconnection is usually
coupled to the pin of the glass-to-metal seal.
[00348] With regard to interconnections, a common type of weld involves
use of a
parallel tip electric resistance welder. The weld may be made by aligning an
end of the
interconnection above the pin and welding the interconnection directly to the
pin. Using a
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number of welds will increase the strength and connection between the
interconnection and
the pin. Generally, when welding to the pin, configuring a shape of the end of
the
interconnection to mate well with the pin serves to ensure there is
substantially no excess
material overlapping the pin that would cause a short circuit.
[00349] An opposed tip electric resistance welder may be used to weld the
interconnection to the pin, while an ultrasonic welder may used to weld the
interconnection to
the bottom of the housing 7. Soldering techniques may used when metals
involved are
compatible.
[00350] With regard to materials used in interconnections, a common type
of material
used for the interconnection is nickel. Nickel may be used as it welds well
with stainless
steel and has a strong interface. Other metals and alloys may be used in place
of nickel, for
example, to reduce resistance in the interconnection.
[00351] Generally, material selected for the interconnection is chosen for
compatibility
with materials in the pin as well as materials in the housing 7. Exemplary
materials include
copper, nickel, tantalum, aluminum, and nickel copper clad. Further metals
that may be used
include silver, gold, brass, platinum, and tin.
[00352] In some embodiments, such as where the pin (i.e., the feed-through
19) is
made of tantalum, the interconnection may make use of intermediate metals,
such as by
employing a short bridge connection. An exemplary bridge connection includes a
strip of
tantalum, which has been modified by use of the opposed tip resistance welder
to weld a strip
of aluminum/copper/nickel to the bridge. A parallel resistance welder is then
used to weld
the tantalum strip to the tantalum pin.
[00353] The bridge may also be used on the contact that is the housing 7.
For
example, a piece of nickel may be resistance welded to the bottom of the
housing 7. A strip
of copper may then be ultrasonic welded to the nickel bridge. This technique
helps to
decrease resistance of cell interconnections. Using different metals for each
connection can
reduce the ESR of the interconnections between cells in series.
[00354] Having thus described aspects of a robust ultracapacitor 10 that
is useful for
high temperature environments (i.e., up to about 210 degrees Celsius), some
additional
aspects are now provided and / or defined.
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[00355] A variety of materials may be used in construction of the
ultracapacitor 10.
Integrity of the ultracapacitor 10 is essential if oxygen and moisture are to
be excluded and
the electrolyte 6 is to be prevented from escaping. To accomplish this, seam
welds and any
other sealing points should meet standards for hermiticity over the intended
temperature
range for operation. Also, materials selected should be compatible with other
materials, such
as ionic liquids and solvents that may be used in the formulation of the
advanced electrolyte
system.
[00356] In some embodiments, the feed-through 19 is formed of metal such
as at least
one of KOVARTm (a trademark of Carpenter Technology Corporation of Reading,
Pennsylvania, where KOVAR is a vacuum melted, iron-nickel-cobalt, low
expansion alloy
whose chemical composition is controlled within narrow limits to assure
precise uniform
thermal expansion properties), Alloy 52 (a nickel iron alloy suitable for
glass and ceramic
sealing to metal), tantalum, molybdenum, niobium, tungsten, Stainless Steel
446 (a ferritic,
non-heat treatable stainless steel that offers good resistance to high
temperature corrosion and
oxidation) and titanium.
[00357] The body of glass-to-metal seals that take advantage of the
foregoing may be
fabricated from 300 series stainless steels, such as 304, 304L, 316, and 316L
alloys. The
bodies may also be made from metal such as at least one of various nickel
alloys, such as
Inconel (a family of austenitic nickel-chromium-based superalloys that are
oxidation and
corrosion resistant materials well suited for service in extreme environments
subjected to
pressure and heat) and Hastelloy (a highly corrosion resistant metal alloy
that includes nickel
and varying percentages of molybdenum, chromium, cobalt, iron, copper,
manganese,
titanium, zirconium, aluminum, carbon, and tungsten).
[00358] The insulating material between the feed-through 19 and the
surrounding body
in the glass-to-metal seal is typically a glass, the composition of which is
proprietary to each
manufacturer of seals and depends on whether the seal is under compression or
is matched.
Other insulative materials may be used in the glass-to-metal seal. For
example, various
polymers may be used in the seal. As such, the term "glass-to-metal" seal is
merely
descriptive of a type of seal, and is not meant to imply that the seal must
include glass.
[00359] The housing 7 for the ultracapacitor 10 may be made from, for
example, types
304, 304L, 316, and 316L stainless steels. They may also be constructed from,
but not limited
to, some of the aluminum alloys, such as 1100, 3003, 5052, 4043 and 6061.
Various multi-
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layer materials may be used, and may include, for example, aluminum clad to
stainless steel.
Other non-limiting compatible metals that may be used include platinum, gold,
rhodium,
ruthenium and silver.
[00360] Specific examples of glass-to-metal seals that have been used in
the
ultracapacitor 10 include two different types of glass-to-metal seals. A first
one is from
SCHOTT with a US location in Elmsford, NY. This embodiment uses a stainless
steel pin,
glass insulator, and a stainless steel body. A second glass-to-metal seal is
from HERMETIC
SEAL TECHNOLOGY of Cincinnatti, OH. This second embodiment uses a tantalum
pin,
glass insulator and a stainless steel body. Varying sizes of the various
embodiments may be
provided.
[00361] An additional embodiment of the glass-to-metal seal includes an
embodiment
that uses an aluminum seal and an aluminum body. Yet another embodiment of the
glass-to-
metal seal includes an aluminum seal using epoxy or other insulating materials
(such as
ceramics or silicon).
[00362] A number of aspects of the glass-to-metal seal may be configured
as desired.
For example, dimensions of housing and pin, and the material of the pin and
housing may be
modified as appropriate. The pin can also be a tube or solid pin, as well as
have multiple pins
in one cover. While the most common types of material used for the pin are
stainless steel
alloys, copper cored stainless steel, molybdenum, platinum-iridium, various
nickel-iron
alloys, tantalum and other metals, some non-traditional materials may be used
(such as
aluminum). The housing is usually formed of stainless steel, titanium and / or
various other
materials.
[00363] A variety of fastening techniques may be used in assembly of the
ultracapacitor 10. For example, and with regards to welding, a variety of
welding techniques
may be used. The following is an illustrative listing of types of welding and
various purposes
for which each type of welding may be used.
[00364] Ultrasonic welding may be used for, among other things: welding
aluminum
tabs to the current collector; welding tabs to the bottom clad cover; welding
a jumper tab to
the clad bridge connected to the glass-to-metal seal pin; and welding jelly
roll tabs together.
Pulse or resistance welding may be used for, among other things: welding leads
onto the
bottom of the can or to the pin; welding leads to the current collector;
welding a jumper to a
clad bridge; welding a clad bridge to the terminal 8; welding leads to a
bottom cover. Laser
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welding may be used for, among other things: welding a stainless steel cover
to a stainless
steel can; welding a stainless steel bridge to a stainless steel glass-to-
metal seal pin; and
welding a plug into the fill port. TIG welding may be used for, among other
things: sealing
aluminum covers to an aluminum can; and welding aluminum seal into place. Cold
welding
(compressing metals together with high force) may be used for, among other
things: sealing
the fillport by force fitting an aluminum ball/tack into the fill port.
ii. Certain Advantageous Embodiments of the Fabrication
[00365] Certain advantageous embodiments, which are not intended to be
limiting are
provided herein below.
[00366] In one particular embodiment, and referring to FIG. 29, components
of an
exemplary electrode 3 are shown. In this example, the electrode 3 will be used
as the
negative electrode 3 (however, this designation is arbitrary and merely for
referencing).
[00367] As may be noted from the illustration, at least in this
embodiment, the
separator 5 is generally of a longer length and wider width than the energy
storage media 1
(and the current collector 2). By using a larger separator 5, protection is
provided against
short circuiting of the negative electrode 3 with the positive electrode 3.
Use of additional
material in the separator 5 also provides for better electrical protection of
the leads and the
terminal 8.
[00368] Refer now to FIG. 30 which provides a side view of an embodiment
of the
storage cell 12. In this example, a layered stack of energy storage media 1
includes a first
separator 5 and a second separator 5, such that the electrodes 3 are
electrically separated
when the storage cell 12 is assembled into a rolled storage cell 23. Note that
the term
"positive" and "negative" with regard to the electrode 3 and assembly of the
ultracapacitor 10
is merely arbitrary, and makes reference to functionality when configured in
the
ultracapacitor 10 and charge is stored therein. This convention, which has
been commonly
adopted in the art, is not meant to apply that charge is stored prior to
assembly, or connote
any other aspect other than to provide for physical identification of
different electrodes.
[00369] Prior to winding the storage cell 12, the negative electrode 3 and
the positive
electrode 3 are aligned with respect to each other. Alignment of the
electrodes 3 gives better
performance of the ultracapacitor 10 as a path length for ionic transport is
generally
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minimized when there is a highest degree of alignment. Further, by providing a
high degree
of alignment, excess separator 5 is not included and efficiency of the
ultracapacitor 10 does
not suffer as a result.
[00370] Referring now also to FIG. 31, there is shown an embodiment of the
storage
cell 12 wherein the electrodes 3 have been rolled into the rolled storage cell
23. One of the
separators 5 is present as an outermost layer of the storage cell 12 and
separates energy
storage media 1 from an interior of the housing 7.
[00371] "Polarity matching" may be employed to match a polarity of the
outermost
electrode in the rolled storage cell 23 with a polarity of the body 20. For
example, in some
embodiments, the negative electrode 3 is on the outermost side of the tightly
packed package
that provides the rolled storage cell 23. In these embodiments, another degree
of assurance
against short circuiting is provided. That is, where the negative electrode 3
is coupled to the
body 20, the negative electrode 3 is the placed as the outermost electrode in
the rolled storage
cell 23. Accordingly, should the separator 5 fail, such as by mechanical wear
induced by
vibration of the ultracapacitor 10 during usage, the ultracapacitor 10 will
not fail as a result of
a short circuit between the outermost electrode in the rolled storage cell 23
and the body 20.
[00372] For each embodiment of the rolled storage cell 23, a reference
mark 72 may be
in at least the separator 5. The reference mark 72 will be used to provide for
locating the
leads on each of the electrodes 3. In some embodiments, locating of the leads
is provided for
by calculation. For example, by taking into account an inner diameter of the
jelly roll and an
overall thickness for the combined separators 5 and electrodes 3, a location
for placement of
each of the leads may be estimated. However, practice has shown that it is
more efficient and
effective to use a reference mark 72. The reference mark 72 may include, for
example, a slit
in an edge of the separator(s) 5.
[00373] Generally, the reference mark 72 is employed for each new
specification of
the storage cell 12. That is, as a new specification of the storage cell 12
may call for differing
thickness of at least one layer therein (over a prior embodiment), use of
prior reference marks
may be at least somewhat inaccurate.
[00374] In general, the reference mark 72 is manifested as a single radial
line that
traverses the roll from a center thereof to a periphery thereof. Accordingly,
when the leads
are installed along the reference mark 72, each lead will align with the
remaining leads (as
shown in FIG. 10). However, when the storage cell 12 is unrolled (for
embodiments where
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the storage cell 12 is or will become a roll), the reference mark 72 may be
considered to be a
plurality of markings (as shown in FIG. 32). As a matter of convention,
regardless of the
embodiment or appearance of marking of the storage cell 12, identification of
a location for
incorporation of the lead is considered to involve determination of a
"reference mark 72" or a
"set of reference marks 72."
[00375] Referring now to FIG. 32, once the reference mark 72 has been
established
(such as by marking a rolled up storage cell 12), an installation site for
installation each of the
leads is provided (i.e., described by the reference mark 72). Once each
installation site has
been identified, for any given build specification of the storage cell 12, the
relative location
of each installation site may be repeated for additional instances of the
particular build of
storage cell 12.
[00376] Generally, each lead is coupled to a respective current collector
2 in the
storage cell 12. In some embodiments, both the current collector 2 and the
lead are fabricated
from aluminum. Generally, the lead is coupled to the current collector 2
across the width, W,
however, the lead may be coupled for only a portion of the width, W. The
coupling may be
accomplished by, for example, ultrasonic welding of the lead to the current
collector 2. In
order to accomplish the coupling, at least some of the energy storage media 1
may be
removed (as appropriate) such that each lead may be appropriately joined with
the current
collector 2. Other preparations and accommodations may be made, as deemed
appropriate, to
provide for the coupling.
[00377] In certain embodiments, opposing reference marks 73 may be
included. That
is, in the same manner as the reference marks 72 are provided, a set of
opposing reference
marks 73 may be made to account for installation of leads for the opposing
polarity. That is,
the reference marks 72 may be used for installing leads to a first electrode
3, such as the
negative electrode 3, while the opposing reference marks 73 may be used for
installing leads
to the positive electrode 3. In the embodiment where the rolled storage cell
23 is cylindrical,
the opposing reference marks 73 are disposed on an opposite side of the energy
storage media
1, and offset lengthwise from the reference marks 72 (as depicted).
[00378] Note that in FIG. 32, the reference marks 72 and the opposing
reference marks
73 are both shown as being disposed on a single electrode 3. That is, FIG. 29
depicts an
embodiment that is merely for illustration of spatial (i.e., linear) relation
of the reference
marks 72 and the opposing reference marks 73. This is not meant to imply that
the positive
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electrode 3 and the negative electrode 3 share energy storage media 1.
However, it should be
noted that in instances where the reference marks 72 and the opposing
reference marks 73 are
placed by rolling up the storage cell 12 and then marking the separator 5,
that the reference
marks 72 and the opposing reference marks 73 may indeed by provided on a
single separator
5. However, in practice, only one set of the reference marks 72 and the
opposing reference
marks 73 would be used to install the leads for any given electrode 3. That
is, it should be
recognized that the embodiment depicted in FIG. 32 is to be complimented with
another layer
of energy storage media 1 for another electrode 3 which will be of an opposing
polarity.
[00379] As shown in FIG. 33, the foregoing assembly technique results in a
storage
cell 12 that includes at least one set of aligned leads. A first set of
aligned leads 91 are
particularly useful when coupling the rolled storage cell 23 to one of the
negative contact 55
and the positive contact 56, while a set of opposing aligned leads 92 provide
for coupling the
energy storage media 1 to an opposite contact (55, 56).
[00380] The rolled storage cell 23 may be surrounded by a wrapper 93. The
wrapper
93 may be realized in a variety of embodiments. For example, the wrapper 93
may be
provided as KAPTONTm tape (which is a polyimide film developed by DuPont of
Wilmington DE), or PTFE tape. In this example, the KAPTONTm tape surrounds and
is
adhered to the rolled storage cell 23. The wrapper 93 may be provided without
adhesive,
such as a tightly fitting wrapper 93 that is slid onto the rolled storage cell
23. The wrapper 93
may be manifested more as a bag, such as one that generally engulfs the rolled
storage cell 23
(e.g., such as the envelope 73 discussed above). In some of these embodiments,
the wrapper
93 may include a material that functions as a shrink-wrap would, and thereby
provides an
efficient physical (and in some embodiments, chemical) enclosure of the rolled
storage cell
23. Generally, the wrapper 93 is formed of a material that does not interfere
with
electrochemical functions of the ultracapacitor 10. The wrapper 93 may also
provide partial
coverage as needed, for example, to aid insertion of the rolled storage cell
23.
[00381] In some embodiments, the negative leads and the positive leads are
located on
opposite sides of the rolled storage cell 23 (in the case of a jelly-roll type
rolled storage cell
23, the leads for the negative polarity and the leads for the positive
polarity may be
diametrically opposed). Generally, placing the leads for the negative polarity
and the leads
for the positive polarity on opposite sides of the rolled storage cell 23 is
performed to
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facilitate construction of the rolled storage cell 23 as well as to provide
improved electrical
separation.
[00382] In some embodiments, once the aligned leads 91, 92 are assembled,
each of
the plurality of aligned leads 91, 92 are bundled together (in place) such
that a shrink-wrap
(not shown) may be disposed around the plurality of aligned leads 91, 92.
Generally, the
shrink-wrap is formed of PTFE, however, any compatible material may be used.
[00383] In some embodiments, once shrink-wrap material has been placed
about the
aligned leads 91, the aligned leads 91 are folded into a shape to be assumed
when the
ultracapacitor 10 has been assembled. That is, with reference to FIG. 34, it
may be seen that
the aligned leads assume a "Z" shape. After imparting a "Z-fold" into the
aligned leads 91,
92 and applying the shrink-wrap, the shrink-wrap may be heated or otherwise
activated such
that the shrink-wrap shrinks into place about the aligned leads 91, 92.
Accordingly, in some
embodiments, the aligned leads 91, 92 may be strengthened and protected by a
wrapper. Use
of the Z-fold is particularly useful when coupling the energy storage media 1
to the feed-
through 19 disposed within the cap 24.
[00384] Additionally, other embodiments for coupling each set of aligned
leads 91, 92
(i.e., each terminal 8) to a respective contact 55, 56 may be practiced. For
example, in one
embodiment, an intermediate lead is coupled to the one of the feed-through 19
and the
housing 7, such that coupling with a respective set of aligned leads 91, 92 is
facilitated.
[00385] Furthermore, materials used may be selected according to
properties such as
reactivity, dielectric value, melting point, adhesion to other materials,
weldability, coefficient
of friction, cost, and other such factors. Combinations of materials (such as
layered, mixed,
or otherwise combined) may be used to provide for desired properties.
iii. Particular Ultracapacitor Embodiments
[00386] Physical aspects of an exemplary ultracapacitor 10 of the present
invention are
shown below. Note that in the following tables, the terminology "tab"
generally refers to the
"lead" as discussed above; the terms "bridge" and "jumper" also making
reference to aspects
of the lead (for example, the bridge may be coupled to the feed-through, or
"pin," while the
jumper is useful for connecting the bridge to the tabs, or leads). Use of
various connections
may facilitate the assembly process, and take advantage of certain assembly
techniques. For
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example, the bridge may be laser welded or resistance welded to the pin, and
coupled with an
ultrasonic weld to the jumper.
Table 5
Weights of Complete Cell With Electrolyte
Weight Percent
Component (grams) of total
SS Can (body of the housing) 14.451 20.87%
SS Top cover (cap) 5.085 7.34%
Tantalum glass-metal Seal 12.523 18.09%
SS/A1 Clad Bottom 10.150 14.66%
Tack (seal for fill hole) 0.200 0.29%
Inner Electrode (cleared, no tabs) 3.727 5.38%
Inner Electrode Aluminum 1.713 2.47%
Inner Electrode Carbon 2.014 2.91%
Outer Electrode (cleared, no tabs) 4.034 5.83%
Outer Electrode Aluminum 1.810 2.61%
Outer Electrode Carbon 2.224 3.21%
Separator 1.487 2.15%
Alum. Jelly roll Tabs (all 8) 0.407 0.59%
Ta/A1 clad bridge 0.216 0.31%
Alum. Jumper (bridge-JR tabs) 0.055 0.08%
Teflon heat shrink 0.201 0.29%
AES 16.700 24.12%
Total Weight 69.236 100.00%
Table 6
Weights of Complete Cell Without Electrolyte
Weight Percent
Component (grams) of total
SS Can 14.451 27.51%
SS Top cover 5.085 9.68%
Tantalum glass-metal Seal 12.523 23.84%
SS/A1 Clad Bottom 10.150 19.32%
Tack 0.200 0.38%
Inner Electrode (cleared, no
tabs) 3.727 7.09%
Outer Electrode (cleared, no
tabs) 4.034 7.68%
Separator 1.487 2.83%
Alum. Jelly roll Tabs (all 8) 0.407 0.77%
Ta/A1 clad bridge 0.216 0.41%
Alum. Jumper (bridge-JR tabs) 0.055 0.10%
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Teflon heat shrink 0.201 0.38% 1
Total Weight 52.536 100.00%
Table 7
Weights of Cell Components in Full Cell with Electrolyte
Weight Percent
Component (grams) of total
Can, covers, seal, bridge,
42.881 61.93%
jumper, heat shrink, tack
Jelly Roll with Electrodes,
tabs, separator 9.655 13.95%
Electrolyte 16.700 24.12%
Total Weight 69.236 100.00%
Table 8
Weights of Electrode
Weight Percent of
Component (grams) total
Inner electrode carbon 2.014 25.95%
Inner electrode aluminum 1.713 22.07%
Outer electrode carbon 2.224 28.66%
Outer electrode aluminum 1.810 23.32%
Total Weight 7.761 100.00%
[00387] FIGS. 35 - 38 are graphs depicting performance of these exemplary
ultracapacitors 10. FIGS. 35 and 36 depict performance of the ultracapacitor
10 at 1.75 volts
and 125 degrees Celsius. FIGS. 37 and 38 depict performance of the
ultracapacitor 10 at 1.5
volts and 150 degrees Celsius.
[00388] Generally, the ultracapacitor 10 may be used under a variety of
environmental
conditions and demands. For example, terminal voltage may range from about 100
mV to 10
V. Ambient temperatures may range from about minus 40 degrees Celsius to plus
210
degrees Celsius. Typical high temperature ambient temperatures range from plus
60 degrees
Celsius to plus 210 degrees Celsius.
[00389] FIGS. 39 - 43 are additional graphs depicting performance of
exemplary
ultracapacitors 10. In these examples, the ultracapacitor 10 was a closed cell
(i.e., housing).
The ultracapacitor was cycled 10 times, with a charge and discharge of 100mA,
charged to
0.5 Volts, resistance measurement, discharged to 10mV, 10 second rest then
cycled again.
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[00390] Tables 11 and 12 provide comparative performance data for these
embodiments of the ultracapacitor 10. The performance data was collected for a
variety of
operating conditions as shown.
Table 9
Comparative Performance Data
73
co,
c71
Q)
1.) 1.)
A,4
)?-= 71' C.) C.) cS1
= tf) r\
d C.) (1-) = ,17;
(1)
F44 c9
D2011-09 150 1.25 1500 30 0 93 5 - 0.5
C1041-02 150 1.5 1150 45 60 32 - 28.35 0.5
C2021-01 150 1.5 1465 33 100 32 70 26.61 0.8
D5311-01 150 1.6 150 9 10 87 4 - 5
C6221-05 150 1.75 340 15 50 - - 38.31 1
C6221-05 150 1.75 500 15 100 - - 38.31 2
C6221-05 150 1.75 600 15 200 - - 38.31 2
C6221-05 150 1.75 650 15 300 - - 38.31 2
D1043-02 150 1.75 615 43 50 100 - - 3
D1043-02 150 1.75 700 43 100 100 - - 3
C5071-01 150 1.75 600 26 100 27 32 - 2
C5071-01 150 1.75 690 26 200 27 35 - 2
C5071-01 150 1.75 725 26 300 27 50 - 2
C8091-06 125 1.75 500 38 5 63 11 37.9 0.5
C9021-02 125 1.75 1250 37 10 61 - 39.19 0.3
D5011-02 125 1.9 150 13 0 105 0 - 1.4
C8091-06 125 2 745 41 22 56 37.9 1.2
D2011-08 175 1 650 33 12 89 30 - 4
D1043-10 175 1.3 480 30 100 93 50 - 6.5
C2021-04 175 1.4 150 35 100 27 - 27.17 3.5
C4041-04 210 0.5 10 28 0 32 - 28.68 1
C4041-04 210 0.5 20 28 0 32 - 28.68 7
C4041-04 210 0.5 50 28 100 32 - 28.68 18
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Table 10
Comparative Performance Data
cAL1
(-)
0 c9 Aa' P4 a 9,
a) 8 L3
7c3 c9 El 8 E `) 8
a-) At) Ar.) cc.l
4 c%1'
Ass' r \c/
F44 :i (-)
E. E. =Ez,' w 4
D2011-09 150 1.25 1500 30 93 0.5 0.75 3.72 0.02 0 5 25
C2021-01 150 1.5 1465 33 32 0.75 0.396 2.67 0.06 100 5 12
C5071-01 150 1.75 600 26 27 2 0.338 2.08 0.15 100 32 13
C5071-01 150 1.75 690 26 27 2 0.338 2.08 0.15 200 35 13
C5071-01 150 1.75 725 26 27 2 0.338 2.08 0.15 300 50 13
C8091-06 125 1.75 500 38 63 0.5 0.494 4.85 0.04 5 11 13
C9021-02 125 1.75 1250 37 61 0.25 0.481 4.69 0.02 10 11 13
D2011-08 175 1 650 33 89 4 0.825 3.56 0.16 12
30 25
D1043-10 175 1.3 480 30 93 6.5 0.75 3.72 0.26 100 50 25
C4041-04 210 0.5 50 28 32 18
0.336 2.67 1.50 100 50 12
[00391] Thus, data provided in Tables 9 and 10 demonstrate that the
teachings herein
enable performance of ultracapacitors in extreme conditions. Ultracapacitors
fabricated
accordingly may, for example, exhibit leakage currents of less than about 1 mA
per milliliter
of cell volume, and an ESR increase of less than about 100 percent in 500
hours (while held
at voltages of less than about 2 V and temperatures less than about 150
degrees Celsius). As
trade-offs may be made among various demands of the ultracapacitor (for
example, voltage
and temperature) performance ratings for the ultracapacitor may be managed
(for example, a
rate of increase for ESR, capacitance, etc) may be adjusted to accommodate a
particular need.
Note that in reference to the foregoing, "performance ratings" is given a
generally
conventional definition, which is with regard to values for parameters
describing conditions
of operation.
[00392] Figures 35 through 43 depict performance of an exemplary
ultracapacitor
having AES comprising 1-buty1-1-methylpyrrolidinium and tetracyanoborate for
temperatures in the range from 125 degrees Celsius to 210 degrees Celsius.
[00393] Figures 44A and 44B depict performance data of an exemplary
ultracapacitor
having AES comprising 1-buty1-1-methylpiperdinium
bis(trifluoromethylsulfonyl)imide.
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[00394] Figures 45A and 45B depict performance data of an exemplary
ultracapacitor
having AES comprising trihexyltetradecylphosphonium
bis(trifluoromethylsulfonyl)imide.
[00395] Figures 46A and 46B depict performance data of an exemplary
ultracapacitor
having AES comprising butyltrimethylammonium
bis(trifluoromethylsulfonyl)imide.
[00396] Figures 47A and 47B depict performance data of an exemplary
ultracapacitor
having AES comprising 1-buty1-1-methylpyrrolidinium and tetracyanoborate at
125 degrees
Celsius.
[00397] Figures 48A and 48B and 49 depict performance data of an exemplary
ultracapacitor having AES comprising a mixture of propylene carbonate and 1-
buty1-1-
methylpyrrolidinium and tetracyanoborate, the mixture being about 37.5%
propylene
carbonate by volume; the capacitor operating at 125 degrees Celsius (Figures
48A and 48B)
and at -40 degrees Celsius (Figure 49).Another exemplary ultracapacitor tested
included an
AES comprising 1 -butyl-3-methylimidaz olium tetrafluorob orate .
[00398] Another exemplary ultracapacitor tested included an AES comprising
1-butyl-
3-methylimidazolium bis(trifluoromethylsulfonyl)imide.
[00399] Another exemplary ultracapacitor tested included an AES comprising
1-ethyl-
3-methylimidazolium tetrafluoroborate.
[00400] Another exemplary ultracapacitor tested included an AES comprising
1-ethyl-
3-methylimidazolium tetracyanoborate.
[00401] Another exemplary ultracapacitor tested included an AES comprising
1-hexy1-
3-methylimidazolium tetracyanoborate.
[00402] Another exemplary ultracapacitor tested included an AES comprising
1-butyl-
1 -methylp yrrolidinium bis(trifluoromethylsulfonyl)imide
[00403] Another exemplary ultracapacitor tested included an AES comprising
1-butyl-
1 -methylp yrrolidinium tris(pentafluoroethyl)trifluoropho sphate.
[00404] Another exemplary ultracapacitor tested included an AES comprising
1-butyl-
1 -methylp yrrolidinium tetracyanoborate.
[00405] Another exemplary ultracapacitor tested included an AES comprising
1-butyl-
3-methylimidazolium trifluoromethanesulfonate.
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[00406] Another exemplary ultracapacitor tested included an AES comprising
1-ethyl-
3-methylimidazolium tetracyanoborate.
[00407] Another exemplary ultracapacitor tested included an AES comprising
1-ethyl-
3-methylimidazolium and 1-buty1-1-methylpyrrolidinium and tetracyanoborate.
[00408] Another exemplary ultracapacitor tested included an AES comprising
1-butyl-
1-methylpyrrolidinium and tetracyanoborate and ethyl isopropyl sulfone.
[00409] Note that measures of capacitance as well as ESR, as presented in
Table 9 and
elsewhere herein, followed generally known methods. Consider first, techniques
for
measuring capacitance.
[00410] Capacitance may be measured in a number of ways. One method
involves
monitoring the voltage presented at the capacitor terminals while a known
current is drawn
from (during a "discharge") or supplied to (during a "charge") of the
ultracapacitor. More
specifically, we may use the fact that an ideal capacitor is governed by the
equation:
I = C*dVidt,
where / represents charging current, C represents capacitance and dV/dt
represents the time-
derivative of the ideal capacitor voltage, V. An ideal capacitor is one whose
internal
resistance is zero and whose capacitance is voltage-independent, among other
things. When
the charging current, /, is constant, the voltage V is linear with time, so
dVIdt may be
computed as the slope of that line, or as DeltaVIDeltaT. However, this method
is generally
an approximation and the voltage difference provided by the effective series
resistance (the
ESR drop) of the capacitor should be considered in the computation or
measurement of a
capacitance. The effective series resistance (ESR) may generally be a lumped
element
approximation of dissipative or other effects within a capacitor. Capacitor
behavior is often
derived from a circuit model comprising an ideal capacitor in series with a
resistor having a
resistance value equal to the ESR. Generally, this yields good approximations
to actual
capacitor behavior.
[00411] In one method of measuring capacitance, one may largely neglect
the effect of
the ESR drop in the case that the internal resistance is substantially voltage-
independent, and
the charging or discharging current is substantially fixed. In that case, the
ESR drop may be
approximated as a constant and is naturally subtracted out of the computation
of the change
in voltage during said constant-current charge or discharge. Then, the change
in voltage is
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substantially a reflection of the change in stored charge on the capacitor.
Thus, that change in
voltage may be taken as an indicator, through computation, of the capacitance.
[00412] For example, during a constant-current discharge, the constant
current, I, is
known. Measuring the voltage change during the discharge, DeltaV, during a
measured time
interval DeltaT, and dividing the current value I by the ratio DeltaV/DeltaT,
yields an
approximation of the capacitance. When I is measured in amperes, DeltaV in
volts, and
DeltaT in seconds, the capacitance result will be in units of Farads.
[00413] Turning to estimation of ESR, the effective series resistance
(ESR) of the
ultracapacitor may also be measured in a number of ways. One method involves
monitoring
the voltage presented at the capacitor terminals while a known current is
drawn from (during
a "discharge") or supplied to (during a "charge") the ultracapacitor. More
specifically, one
may use the fact that ESR is governed by the equation:
V = I*R,
where I represents the current effectively passing through the ESR, R
represents the
resistance value of the ESR, and V represents the voltage difference provided
by the ESR (the
ESR drop). ESR may generally be a lumped element approximation of dissipative
or other
effects within the ulracapacitor. Behavior of the ultracapacitor is often
derived from a circuit
model comprising an ideal capacitor in series with a resistor having a
resistance value equal
to the ESR. Generally, this yields good approximations of actual capacitor
behavior.
[00414] In one method of measuring ESR, one may begin drawing a discharge
current
from a capacitor that had been at rest (one that had not been charging or
discharging with a
substantial current). During a time interval in which the change in voltage
presented by the
capacitor due to the change in stored charge on the capacitor is small
compared to the
measured change in voltage, that measured change in voltage is substantially a
reflection of
the ESR of the capacitor. Under these conditions, the immediate voltage change
presented by
the capacitor may be taken as an indicator, through computation, of the ESR.
[00415] For example, upon initiating a discharge current draw from a
capacitor, one
may be presented with an immediate voltage change DeltaV over a measurement
interval
DeltaT. So long as the capacitance of the capacitor, C, discharged by the
known current, I,
during the measurement interval, DeltaT, would yield a voltage change that is
small
compared to the measured voltage change, DeltaV, one may divide DeltaV during
the time
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interval DeltaT by the discharge current, /, to yield an approximation to the
ESR. When / is
measured in amperes and DeltaV in volts, the ESR result will have units of
Ohms.
[00416] Both ESR and capacitance may depend on ambient temperature.
Therefore, a
relevant measurement may require the user to subject the ultracapacitor 10 to
a specific
ambient temperature of interest during the measurement.
[00417] Performance requirements for leakage current are generally defined
by the
environmental conditions prevalent in a particular application. For example,
with regard to a
capacitor having a volume of 20 mL, a practical limit on leakage current may
fall below 100
mA.
[00418] Nominal values of normalized parameters may be obtained by
multiplying or
dividing the normalized parameters (e.g. volumetric leakage current) by a
normalizing
characteristic (e.g. volume). For instance, the nominal leakage current of an
ultracapacitor
having a volumetric leakage current of 10 mA/cc and a volume of 50 cc is the
product of the
volumetric leakage current and the volume, 500 mA. Meanwhile the nominal ESR
of an
ultracapacitor having a volumetric ESR of 20 mOhm=cc and a volume of 50 cc is
the quotient
of the volumetric ESR and the volume, 0.4 mOhm.
iv. Examination of Fill Effects on Ultracapacitors Comprising an
AES
[00419] Moreover, in order to show how the fill process effects the
ultracapacitor 10,
two similar embodiments of the ultracapacitor 10 were built. One was filled
without a
vacuum, the other was filled under vacuum. Electrical performance of the two
embodiments
is provided in Table 11. By repeated performance of such measurements, it has
been noted
that increased performance is realized with by filling the ultracapacitor 10
through applying a
vacuum. It has been determined that, in general, is desired that pressure
within the housing 7
is reduced to below about 150 mTorr, and more particularly to below about 40
mTorr.
Table 11
Comparative Performance for Fill Methods
Parameter Without With
(at 0.1 V) vacuum vacuum Deviation
ESR @ 450 (I) 3.569 Ohms 2.568 Ohms (-28%)
Capacitance @ 12 mHz 155.87 mF 182.3 mF
(+14.49%)
Phase @ 12 mHz 79.19 degrees
83 degrees (+4.59%)
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[00420] In order to evaluate efficacy of vacuum filling techniques, two
different pouch
cells were tested. The pouch cells included two electrodes 3, each electrode 3
being based on
carbonaceous material. Each of the electrodes 3 were placed opposite and
facing each other.
The separator 5 was disposed between them to prevent short circuit and
everything was
soaked in electrolyte 6. Two external tabs were used to provide for four
measurement points.
The separator 5 used was a polyethylene separator 5, and the cell had a total
volume of about
0.468 ml.
C. Methods of Use of the Ultracapacitors
[00421] The present invention is also intended to include any and all uses
of the energy
storage devices, e.g., ultracapacitors, described herein. This would include
the direct use of
the ultracapacitor, or the use of the ultracapacitor in another other device
for any application.
Such use is intended to include the manufacture, the offering for sale, or
providing of said
ultracapacitors to a user.
[00422] For example, in one embodiment, the invention provides a method of
using a
high temperature rechargeable energy storage device (HTRESD) e.g., an
ultracapacitor,
comprising the steps of obtaining an HTRESD comprising an advanced electrolyte
system
(AES); and cycling the HTRESD by alternatively charging and discharging the
HTRESD at
least twice, while maintaining a voltage across the HTRESD, such that the
HTRESD exhibits
an initial peak power density between 0.01 W/liter and 150 kW/liter, such that
the HTRESD
is operated at an ambient temperature that is in a temperature range of
between about -40
degrees Celsius to about 210 degrees Celsius. In certain embodiments the
temperature range
is between about -40 degrees Celsius and about 150 degrees Celsius; between
about -40
degrees Celsius and about 125 degrees Celsius; between about 80 degrees
Celsius and about
210 degrees Celsius; between about 80 degrees Celsius and about 175 degrees
Celsius;
between about 80 degrees Celsius and about 150 degrees Celsius; or between
about -40
degrees Celsius to about 80 degrees Celsius. In certain embodiments, the
HTRESD exhibits
an initial peak power density that is between about 0.01 W/liter and about 10
kW/liter, e.g.,
between about 0.01 W/liter and about 5 kW/liter, e.g., between about 0.01
W/liter and about
2 kW/liter.
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In another embodiment, the invention provides a method of using an
ultracapacitor,
the method comprising: obtaining an ultracapacitor of any one of claims 1 to
85, wherein the
ultracapacitor exhibits a volumetric leakage current (mA/cc) that is less than
about 10mA/cc
while held at a substantially constant temperature within a range of between
about 100
degrees Celsius and about 150 degrees Celsius; and cycling the
ultracapacitor by
alternatively charging and discharging the ultracapacitor at least twice,
while maintaining a
voltage across the ultracapacitor, such that the ultracapacitor exhibits an
ESR increase less
than about 300 percent after 20 hours of use while held at a substantially
constant
temperature within a range of between about -40 degrees Celsius to about 210
degrees
Celsius. In certain embodiments the temperature range is between about -40
degrees Celsius
and about 150 degrees Celsius; between about -40 degrees Celsius and about 125
degrees
Celsius; between about 80 degrees Celsius and about 210 degrees Celsius;
between about 80
degrees Celsius and about 175 degrees Celsius; between about 80 degrees
Celsius and about
150 degrees Celsius; or between about -40 degrees Celsius to about 80 degrees
Celsius.
[00423] In
another embodiment, the invention provides a method of providing a high
emperature rechargeable energy storage device to a user, the method
comprising: selecting a
high temperature rechargeable energy storage device (HTRESD) comprising an
advanced
electrolyte system (AES) that exhibits an initial peak power density between
0.01 W/liter and
100 kW/liter and a durability period of at least 1 hour, e.g. for at least 10
hours, e.g. for at
least 50 hours, e.g. for at least 100 hours, e.g. for at least 200 hours, e.g.
for at least 300
hours, e.g. for at least 400 hours, e.g. for at least 500 hours, e.g. for at
least 1,000 hourswhen
exposed to an ambient temperature in a temperature range from about -40
degrees Celsius to
about 210 degrees Celsius; and delivering the storage device, such that the
HTRESD is
provided to the user.
[00424] In
another embodiment, the invention provides a method of providing a high
temperature rechargeable energy storage device to a user, the method
comprising: obtaining
an ultracapacitor of any one of claims 1 to 85 that exhibits a volumetric
leakage current
(mA/cc) that is less than about 10mA/cc while held at a substantially constant
temperature
within a range of between about -40 degrees Celsius and about 210 degrees
Celsius; and
delivering the storage device, such that the HTRESD is provided to the user.
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Incorporation By Reference
[00425] The
entire contents of all patents, published patent applications and other
references cited herein are hereby expressly incorporated herein in their
entireties by
reference.
Equivalents
[00426]
Those skilled in the art will recognize, or be able to ascertain using no more
than routine experimentation, numerous equivalents to the specific procedures
described
herein. Such equivalents were considered to be within the scope of this
invention and are
covered by the following claims. Moreover, any numerical or alphabetical
ranges provided
herein are intended to include both the upper and lower value of those ranges.
In addition,
any listing or grouping is intended, at least in one embodiment, to represent
a shorthand or
convenient manner of listing independent embodiments; as such, each member of
the list
should be considered a separate embodiment.
[00427] It
should be recognized that the teachings herein are merely illustrative and are
not limiting of the invention. Further, one skilled in the art will recognize
that additional
components, configurations, arrangements and the like may be realized while
remaining
within the scope of this invention. For example, configurations of layers,
electrodes, leads,
terminals, contacts, feed-throughs, caps and the like may be varied from
embodiments
disclosed herein. Generally, design and/or application of components of the
ultracapacitor
and ultracapacitors making use of the electrodes are limited only by the needs
of a system
designer, manufacturer, operator and/or user and demands presented in any
particular
situation.
[00428]
Further, various other components may be included and called upon for
providing for aspects of the teachings herein. For
example, additional materials,
combinations of materials and/or omission of materials may be used to provide
for added
embodiments that are within the scope of the teachings herein.
[00429]
While the invention has been described with reference to exemplary
embodiments, it will be understood that various changes may be made and
equivalents may
be substituted for elements thereof without departing from the scope of the
invention. In
addition, many modifications will be appreciated to adapt a particular
instrument, situation or
material to the teachings of the invention without departing from the
essential scope thereof.
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Therefore, it is intended that the invention not be limited to the particular
embodiment
disclosed as the best mode contemplated for carrying out this invention but to
be construed
by the claims appended herein.
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