Note: Descriptions are shown in the official language in which they were submitted.
CA 02426379 2003-04-17
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RECHARGEABLE BATTER7~'
The present invention relates to a rechargeable battery, and in pauticular to
a
rechargeable battery incorporating a solid state material having
longitudinally-
S extending holes into which longitudinally extending conductors are formed or
placed.
The present application is cross-referenced with a simultaneously-filed U'K
application entitled "Rechargeable Battez-y" and having the agents' reference
CTV/P4S202.1 (please insert applicationlpublication number), the full
disclosure of
1 U which is hereby incorporated into the present application by reFerence.
Various rechargeable batteries are known in the az-t. These include chemical
accumulators based, for example, on nickel-cadmium or nickel-metal hydride
systems. These battez'ies have a limited operational life due to izxeversible
chemical
1S changes that gradually take place within the battery upon charging and
discharging,
and they are environmentally unfriendly in that they contain toxic chemicals.
An accumulator comprising a capacitoz~ having a pair of electrode plates, one
on
either side of a solid electrolyte is known From R~J 2070756. The battery is
charged
20 by way of current flow through the electrolyte,
An accumulator comprising a capacitor having a pair of electrode plates
immersed in
a liquid electrolyte is known from RL.~ 2132S8S. The battery is changed by way
of
cun-ent flow through the electrolyte.
A rechargeable battery comprising a piezoceramic component having a pair of
attached electrodes is known from RU 2087066. '7°he battery is charged
by heating
the piezoceramic compo~~ent.
There is also known, from RU 207~~75, an accumulator comprising a capacitor
bank
which is charged by way of a dynamo.
CONFIRMATION COPY
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All of these devices have an inadequate operational liFe and tend to be
environmentally unfriendly,
According to a first aspect of the present invention, there is provided a
rechargeable
battery including an energy storage member in the form of a solid state
dielectric or
semiconductor material having formed therein a plurality of holes with
elongate
conductors located within the holes and contacting the energy storage member
at
least at one point along their lengths, a first pair of electrodes adapted to
apply a DG
voltage therebetween and formed or located on generally opposed sides of the
energy
storage member in a first spatial orientation and a second pair of electrodes
formed or
located on generally opposed sides of the enez-gy storage member in a second
spatial
orientation diCfez°ent front the first,
In operation, the application of a DC voltage across the first pair of
electrodes Forms
an electric weld across the solid state material which induces electrostatic
charges in
the elongate conductors, thereby generating a voltage across the second pair
of
electrodes.
Advantageously, at least some of the elongate conductors have substantially
the same
or similar spatial orientation to each other. 1n a particularly preferred
embodiment,
enough of tha conductors extend in substantially the same or similar direction
so as
to give the solid state material isotropic properties; that is to say, more
conductors
extend substantially in one given, predominant direction than in any other.
The
conduclors and electrodes are preferably conFgured such chat an imaginary line
drawl between the first pair of electrodes extends substantially perpendicular
to the
predominant conducfor direction and such that an imaginary line drawn between
the
second pair of electrodes extends substantially parallel to the predominant
conductor
dII'eGtloll.
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According to a second aspect of the present invention, there is provided a
rechargeable battery comprising an energy storage positioned between two pairs
of
electrodes. The energy storage is made From solid-state dielectric or
semiconductor
material containing holes with elongate conductors located within the holes.
The
elongate conductors are Founed so that they are attached to the solid state
body at
least at one point along their length. At least some of these conductors have
substantially the same or similar spatial orientation to each other. A first
pair of
electrodes is located on generally opposed sides of energy storage in a first
spatial
orientation and is adapted to apply DC voltage there between. A second pair of
7 0 electrodes, being the output electrodes, is formed or located on generally
opposed
sides of the energy storage in a second spatial orientation different from the
First one.
The conductors and electrodes are preferably conTigured such that an imaginary
line
drawn between the first pair of electrodes extends substantially pependicular
to the
predominant conductor direction and such that an imaginary line drawn between
the
second pair of electrodes extends substantially parallel to the predominant
conductor
direction.
The elongate conductors are formed so that they contact the solid state
material at
least at some point along their lengths.
Preferably, the first pair of electrodes is formed or located tightly against
the solid
state material.
Preferably, the second pair of electrodes is formed or located Tightly against
The solid
state material.
The electrodes may be electroFormed, electrodepositeci or sputtered onto the
solid
state material. Alternatively, the electrodes may be formed separately and
clamped,
3U adhered or otherwise located on the solid state material.
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The electrodes may be founed Pram metals such as gold, silver, platinum or
copper or
combinations thereof: Other metals may be used where appropriate.
The solid state material is a dielectric or semiconductor material, for
example as
described in the present applicant's copending International patent
application WO
00/40506, the full disclosure of which is hereby incorporated into the present
application by reference.
The solid state material may be a dielectric ceramic material such as a solid
state
crystalline ceramic material, including piezoceramic materials and solid
eomposife
mixtures of different ceramic materials. The solid state material may also be
a
semiconductor, such as silicon or gallium arsenide, among others. The solid
state
material may be a composite mixture of dielectric and semiconductor materials.
The solid state material may be manufactured in accordance with the
manufacturing
processes described in WO 00/4DSD6; that is to say, the holes may be formed by
an
electrical erosion process and the conductors may be formed by local ion
precipitation within the holes.
The holes may be in the form o~f pores, and preferably have a diameter of up
to
2pOnm, more preferably from l0nm to 200nm.
'fhe conductors may be formed from metals such as gold, silver, platinum or
copper
or combinations thereof Other metals may be used where appropriate. The
conductors are preferably in the form of elongate Filaments or fibres, and one
or more
Olaments or fibres may be located within a given elongate hole.
The conductors preferably have a diameter of up to 200nm, more preferably from
1 Dnm to 200nm.
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The holes and the canductors advantageously have a longitudinal length of
100nm to
1000nm, although lengths outside this range may be appropriate in particular
circumstances.
When a DC voltage is applied across first pair of electrodes, a DC electric
field is
generated across the solid state material. 'this electric f eld causes
electrostatic
charges to be induced in the elongate conductors, and these charges will Then
move
under the influence oC the electric field so as to induce a potential
difference across
the second pair of electrodes. By applying a potential difference across the
first pair
of electrodes and connecting a load or other circuitry across the second pair,
cuu-ent
can be caused to flow through the load or other circuitry.
The rechargeable cell of the present invention does not include any chemically
active
components, and is thus environmentally friendly. Furthermore, because there
is
I ~ little or no mechanical or thermal degradation during recharging, the cell
of the
present invention has an improved operational life as compared to existing
accumulators. In some embodiments, the present invention provides a
20°~Q
improvement in operational lime over existing rechargeable batteries.
~'or a better understanding of the present invention and to show how it rnay
be carried
into efFect, reference shall now be made by way of example to the accompanying
drawing, in which:
FIGURI3 1 shows a solid state material provided with two pairs of electrodes.
Figure 1 shows a solid state ceramic block I having a plurality of elongate
pores in
which era formed a plurality of elongate conductive filaments 2 made out of
silver.
'hl~e pores and the filaments 2 have a predominant longitudinal direction
indicated by
arrow 'A'. A Crst pair of silver electrodes 3 is electroformed, one on either
side of
the solid state material 1, such that an imaginary line drawn between the
electrodes 3
is substantially perpendicular to the predominant direction ~A'. A second pair
of
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WO 02/35637 PCT/GBO1/04765
silver electrodes 4 is electrofonned, one on either side of the solid state
material 1,
such that an imaginary line drawn between the electrodes 4 is substantially
parallel to
the predominant direction 'A'. A DC voltage applied across the electrodes 3
causes
an electric field to be generated across the solid state material 1, The
electric field
induces electrostatic charges in the filaments 2, the charges then being
caused to
move along the filaments 2 under the influence of the electric field so as to
generate a
DC voltage across the electrodes 4, this voltage then being available to cause
an
electric current to pass through a load (not shown) connected across the
electrodes 4.
Example 1. Piezoceramic material with metal filaments laid in pores.
I~Fanapores are formed on one of the end faces of a piezoceramic blank
produced by
standard technology (a pressed pieaoceramic charge with a binder is fired at a
temperature of 1450°C and gradually cooled) by an electrical erosion
method using a
first probe of point diameter 20nm, made of antimony sulfoiodide (SSbI), by
supplying pulses of negative polarity (pitch ol~ treatment - 600nm, moth tying
voltage
4V; treatment time for each pare - 400nsee). A second probe, made of silver
(point
diameter l0nm) is then used, with pulses of positive polarity supplied, to
form silver
nanofilaments in the formed nanopores by a method of local ion precipitation
(pitch
of treatment - 600nm; modifying voltage 2V; treatment time for each pore
600nsec).
The positioning of the first and second probes is carried out with the aid of
a
scanning tunnel microscope, The concentration of pores averaged 3 pores per
lam'.
A piezoceramic plate treated by the above method was subjected to study for
strength
(breaking strain). 'this was 3100I~llmm~. whereas the strength of an analogous
plate
which had not been subjected to this treatment was 2200N1mm~.
The electromechanical coupling coefficient, which is inversely proportional to
the
value of the acoustic lasses in the material, increased from 0.71 to 0.85.
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