Note: Descriptions are shown in the official language in which they were submitted.
87~1
Field of Invention:
This invention relates yenerally to improved storage
cells and to devices, including storage batteries, which incorpor-
ate such cells in their construction. More specifically, the pre-
sent invention is concerned with the active mass used in making
the electrodes of such cells, wherein said active mass is a mix-
ture of crystalline and polycrystalline lead superoxide, and to
themethods of making the active mass.
The Prior Art:
. The construction and operation of a cell is generally
well known. A cell, whether primary or secondary, is an electro-
chemical device which consists of two plates of conducting material
immersed in an electrolyte. A primary cell is designed to develop
an electric potential and to convert chemical energy into electri-
cal energy irreversibly. A secondary cell, however, is reversible
in its function and can transform chemical energy into electrical
energy, or vice versa. Secondary cells are more commonly called
"storage cells".
When a storage cell is supplying electric energy, the
cell is said to be "discharging" and chemical energy is being con-
verted to electrical energy~ and when the storage cell is supplied
with electrical energy, the process is reversed and the cell is
said to be "charging".
- 2 -
B ~
7~
, I
,1 .
1 I ~o or more cells connected together, in series or in ¦
parallel, constitute a battery and a battery made from connectirg I
several storage cells is known as a storage battery. There are
. Itwo common types of storage bat-teries; the lead-acid type battery,¦
¦or as it is simply called, the lead battery, and the nickel- ¦
alkaline or Edison type battery, popularly called the alkaline
¦battery. It is with the former type battery that the present in-
¦vention is concerned.
¦ The cells in the lead-acid battery consist of a posi-
¦tive plate of lead oxide and a negative plate of spongy lead whlch
i
are immersed in a diluted solution of sulfuric acid (electrolyte).
~The active mass or material of bach plate is that part which un-- ¦
¦dergoes a chemical change when electricity flows through the ba}-
¦tery. This active mass is supported by a frame or grid of pure
¦lead or lead alloy, e.g., an alloy of lead and antimony, which
serves the dual function of carrying the active mass and conductin~
the electric current. It is with a novel, unique and improved ac-¦
tive mass that the present invention is more specifically con- ¦
¦cerned.
¦ The charging and discharging cycles of a typical l~ad-
i
¦acid type battery may be represented by the following reversible
Ireaction:
¦ Charge Discharge
PbO2+2H2s04~pb c ---- ~ 2PbS04+2H20
+ plate - plate
i Tne active material of the positive plate is brown,
!Porous lead oxide, while the active mass on the neyative plate 1s
yray r spongy and porous lead, in pure form.
_3_
30~7~
1 I The lead-acid batteries which are currently available
on the mar~etplace exhibit limited performance capabilities, and
numerous attempts and suggestions have here-tofore been made to
~improve them. Thus, improvemen~s in charging and discharying
Icharacteristics of these batteries, increasing their current dis-
Icharye rate and reduction in the in-ternal resistance of the bat-
Itery cells are but few of the numerous properties which have re-
¦ceived considerable attention of the prior art workers in this
¦field. Some have focused their attention on the electrodes while
¦others have suggested a variety of electrolytes in order to im-
Iprove the overall performance of the cells, and the devices which
¦incorporate such cells.
Thus, U.S. 2,933,547 describes a battery made fro~. ~
plurallty of solid state electric cells consisting of silver and
~inc electrodes and a solid, so~vated cation-exchange resin meM-
brane which is sandwiched between the electrodes.
U.S. 3,468,719 discloses a solid state ionic conductor
made of a polycrystalline material in which the structural lat~ce¦
is composed of ions of aluminum and oxygen in combination, and
: sodium ions whiah migrate in relation to the crystal lattice under
the influence of an electric field. This material is employed 39
a half-cell separator in the construction of batteries as more
fully described in example 3 of said patent.
I U.S. 3j499,796 discloses a ceramic sandwich between a
¦pair of elec-trochemically and cationically-conductive crystalline
objects which are in cation exchanye relationship and separated by
a cationicelly-conductive, electrcnically nnn-conductive cryLtdl- ¦
-4-
I
l I
3~ 7~3 ~
I
1 , line object, and to storage devices comprising the same.
¦~ U.S. 3,709,820 discloses an organic solid electrolyte ,
which is a crystalline electron donor-acceptor complex comprising
¦ ionic crystals of 7,7,8,8-tetracyanoquinodimethane, an aromatic
lamine, and a liquid impregnated in the ionic crystal lattice. The¦
electrolyte described in this patent is employed in eapacitors to ¦
¦lower their resistivity.
U S 3,765,915 describes the uses of Beta-alu~ina
Ipolycrystalline ceramics for use as electrolyte in the construction
of cells or batteries of the sodium~sulfur type.
The foregoing patents are but a few of the plethora f¦
Ipatents which represent the research and activities which have
¦been expended in this art. Nevertheless, however, the basic con- ¦
struction of the lead-acid battery and its constituent cells re-
main essentially unchanged. Today, as it was made several decades
ago, lead-acid batteries are made by serial connection of a plu-
rality of cells (usually 3 or 6) wherein porous lead o~ide is the
lactive mass on the positive plate and spongy, porous lead is the
Inegative plate, and dilute sulfuric acid is the electrolyte oF
Ichoice.
¦ Accordingly, it is an object of the present invention !
to provide improved storage cells and devices which are made from ¦
Isuch cells.
I It is a further object of this invention to provide a I
storage battery in which the active mass on the positive electrode !
is a unique material made from crystalline and polycrystalline
--5--
37~3
1 llead oxide. Such batteries will hereinafter be referred ~o as
"lead-crystal" batteries to distinguish them from the conventional
lead-acid batteries.
' It is another object of this invention to provide
novel and unique lead-crystal batteries which have superior per-
formance characteristics as compared with the conventional lead
I batteries .
It is also an object of this invention to provide such
llead-crystal batteries which exhibit lower internal resistance and
¦higher potential difference (electromotive force) than the con-
ventional lead batteries.
It is still another object of this invention to pro-
vide lead-crystal batteries which exhibit higher current charge
land discharge capacity and which can be charged at a considerah'y ¦
Ifaster rate than the conventional lead battery.
It is a further object of this invention to provide
~lead-crystal batte~ies which exhibit considerably lower:sulphati-
zation as compared with the lead-acid battery.
¦ It is also an object of this invention to provide a
¦method of making crystalline and polycrystalline lead oxide as the
active mass.
It is yet another object of this invention to provlde ¦
~a unique positive plate for the construction of storage cells and ¦
batteries made from such cells.
¦ I~ is also an ob~ect of this invention to provide such
I
~positive plates which comprise a carrier plate such as lead, an
alloy of lead with antimony, or a non-conductive carrier material
with a conductive coating, and lead oxide in crystalline and
-6-
I
I
7B
polycrystalline form applied to the surface of the carrier plate.
The foregoing and other objects of this invention will
be more readily comprehended from the following detailed
description of the invention taken in conjunction with the
accompanying drawings which form a part of this application.
SUMMARY OF THE INVENTION
Thus the present invention provides a solid state
conductor for use in storage cells comprised of a carrier
plate made from a material selected from the group consisting of
lead, an alloy of lead with antimony and an inert, non-
conductive substance coated with lead or an alloy of lead with
antimony, and a uniform, adherent and durable layer of an
active mass on said carrier plate, said active mass consisting
essentially of crystalline and polycrystalline lead superoxide
in which lead is at its maximum valence of four.
In another embodiment the present invention provides
a storage cell comprised of a dilute solution of sulfuric acid,
at least one negative electrode and at least one positive
electrode, each made from a material selected from the group
consisting of lead, an alloy of lead with antimony and an inert,
non-conductive substance coated with lead or an alloy of lead
with antimony, and wherein said positive electrode is coated
with a uniform, adherent and durable layer of polycrystalline
and crystalline lead superoxide in which lead is at its
maximum valence of four. A preferred embodiment of such a
storage cell is provided wherein said electrodes are an inert,
non-conductive material coated with lead, or an alloy of lead
with antimony.
In another embodiment the present invention provides
a method of making a solid state conductor for use in storage
cells which comprises: (a) forming a uniform and adherent layer
-- 7 --
7~3
of lead and cadmium on a carrier plate made from lead, an
alloy of lead with antimony or an inert, non-conductive
material coated with lead or an alloy of lead with antimonyi
(b) immersing the resulting carrier plate in a container
containing a dilute solution of sulfuric acid and a lead plate;
(c) connecting said carrier plate to the positive terminal
of an emf source and connecting lead plate to the negative
terminal of said emf source, thereby causing electric current
to flow through said plates; and (d) causing said cadmium in
said lead~cadmium layer to react with sulfuric acid to form
cadmium sulfate which is deposited on said lead plate, and
simultaneously oxidizing said lead in said lead-cadmium layer
thereby forming a mixture of crystalline and polycrystalline
lead superoxide, in which lead is at its maximum valence of
four. In one embodiment there is disclosed a method of
making such a solid state conductor wherein, in step (a)
said uniform and adherent layer of lead and cadmium is formed
by making a relatively thin paste of lead and cadmium mixture
in a reducing organic liquid, depositing said paste on said
carrier plate and evaporating said solvent from the paste.
In a further embodiment the present invention
provides a method of making a solid state conductor wherein,
in step (a), said uniform and adherent layer of lead and
cadmium is formed on the surface of said carrier plate by an
electroplating process which comprises immersing, in an
electrolytic bath, two conductors, a cathode made from an
alloy of lead and antimony and an anode made from lead and
cadmium, wherein said electrolytic bath comprises lead
fluoroborate, metallic lead, fluoroboric acid, boric acid,
cadmium fluoroborate, metallic cadmium, ammonium fluoroborate
and water, connecting said cathode and said anode, respectively,
- 7(a) -
.~
7i~3
to the negative and positive terminals of an emf source, andcausing an electric current to flow through said electrodes.
In accordance with this invention, a storage cell i5
provided in which the active mass OII the positive electrode
of the cell is a mixture of crystal:Line and polycrystalline
lead superoxide (PbO2). Thus, a mixture of lead and cadmium
is first deposited, or otherwise conveniently applied, as a
uniform, adherent layer, on a carrier plate made of lead, an
alloy of lead with antimony, or a suitable inert and non-
conductive material which is coated with lead or an alloy oflead with antimony. The lead-cadmium mixture may be deposited
on the carrier plate by hot-spraying, so-called "powdered
metallurgy" technique or by electroplating, all as hereinafter
described in the ensuing detailed description of the invention.
The carrier plate which has been coated with lead
and cadmium as aforesaid is then immersed in a container
containing a dilute solution of sulfuric acid (electrolyte)
and a lead plate or sheet which serves as the cathode. The
carrier plate is then connected to the positive terminal of
an emf source and the lead sheet is connected to the negative
terminal of said source. The passage of electric current
through the plates causes the oxidation
- 7(b) -
j,
1 I,of lead (in the lead-cadmium layer) to lead superoxide, in the
Eorm of crystalline and polycrystalline mass, while the cadmium
reacts with sulfuric acid to form cadmium sulfate which is de-
Iposited on the lead sheet as a spongy material. The carrier plate
lis then removed from the solution, rin.sed clean with water and
dried.
Three carrier plates made as aforesaid are thereafter
immersed in a second container containing a dilute solution of
Isulfuric acid. The middle carrier plate is connected to the posi-
Itive terminal of an emf source while the other two carrier plates
lare jointly connected to the negative terminal of said emf source.
¦Upon the passage of electric current, the middle carrier plate
¦will be positively charged and the lead superoxide will remain
lunchanged while the lead oxide on the other two carrier plates is
¦reduc~d to lead and becomes negatively charged.
After a few minutes the emf source is removed and
the emf within the cell drops from 2.9 volts to approximately 2.4 !
¦volts and remains essentially constant at this level. The cell is
Inow charged and is storing energy for subsequent release.
¦ Three or more such cells may be connected in series to
¦form the lead-crystal battery of this invention.
! ~RIEF DESCRIPTION OF THE DRAWINGS
i Figure 1 is a schematic representation illustrating
the method of formation oE the active mass, i~e., the crystalline
and polycrystalline lead oxide, in accordance with this invention;l
, . I
I
I -8~
~I.vsslt37a
1 ~I E'igure 2 is anot~ier schematic diagram illustrating
the formation of the positive and negative plates and the cell
¦icomprising such plates; and
¦I Figure 3 shows two curves which compare the discharge
¦Icharacteristics of a lead-crystal cell made in accordance with
¦Ithis invention with a conventional lead-acid type cell.
DETAILED DESCRIPTION OF THE INVENTION
1 It has now been unexpectedly discovered that the per-
Iformance of storage cells can be xemarkably improved by providing
¦the cells with a unique positive plate comprising crystalline and
polycrystalline lead oxide in the form of Pb02 as the active mass.
Conse~uently, lead-cr~stal batteries made from such cells exhibit
superior performance characteristics as compared with the con-
¦ventibnal lead-acid batteries.
In the ensuing description, the present invention will
~be described in detail with particular reference to the construc~
tion of a storage cell, and a battery made from such cells. Such
description, however, is not to be taken as limitin~ the scope of
this invention as there are other storage devices which can be
constructed on the basis of the principles set forth herein and
which are, therefore, comprehended, contemplated and included
Iwithin this disclosuxe.
~ It has been discovered that a storage cell constructed
lin accordance ~ith this invention exhibits properties which have
. Iheretofore been unattainable in the prior art type storage cells,
and conse~uently, devlces, e.g , storaqe batteries, made by the
7~
.
1 ' serial connection of such cells, also exhibit superior perform~
i ance characteristics as compared with the conventional lead bat-
teries. Such improved properties include, althoughthey are not
I limited to, lower internal resistance, higher activity, lower sul-
I phatization, better char~ing and discharging characteristics,
greater storage capacity, faster charging rates and higher em~
per cell.
The unique active mass which is formed in accordance
I with the method of this invention is composed essentially of
¦ crystalline and polycrystalline lead oxide (PbO2) in which lead
has its maximum electron valence of four, and which is sometimes
¦ referred to as lead superoxide to distinguish it from PbO in
¦ which lead has its lower electron valence of two.
The term "polycrystalline" as used herein denotes an
aggregation of single crystalline masses of lead superoxide,
wherein such crystals are at varying stages of growth and develop-
ment. Thus, the active mass of this invention is a mixture of
¦ single crystalline masses of PbO2 together with such polycrystal-
¦ line aggregates.
¦ In accordance with one embodiment of this invention,
and with particular reference first to Fig. 1, a carrier plate 1
¦ which is typically made of pure lead (Pb) or an alloy of lead
I with antimony (Pb-Sb), coated with a layer of Pb-Cd as hereinafter
described, is immersed in a dilute solution of sulfuric acid
(electrolyte~ in a container 3. The carrier plate used herein is ¦
conveniently a foil of approximately 0.2mm thickness and is made
... l
.
1.
l I
~0~:3~i7E~
of an alloy of lead and antimony. The thickness of the carrier
plate, however, may vary somewhat depending on the particular
construction and intended use of the storage device.
Prior to immersing the carrier plate 1 in the sul-
furic acid solutlon, a hot melt of lead and cadmium is sprayed
on the surface of the foil by means of a conventional spray
gun, or some other suitable spraying device, to deposit a
uniform and adherent layer of lead and cadmium on both sur-
faces of the foil. A reducing gas such as, for example,
hydrogen is used in conjunction with the spraying of the hot
melt on the foil's surface, and spraying is discontinued
when the thickness of the deposited layer reaches approxi-
mately 0.5mm on each surface. Again, this thickness may
vary somewhat depending on the particular construction, the
required resistivity and the intended use of the device.
Generally, the thickness of Pb-Cd layer on each surface may
vary from about 0.1 to 2mm, preferably from about 0.5 to
about 1.2mm and is most preferably about lmm.
The Pb-Cd melt is prepared by coating a cadmium
wire of approximately lmm thickness electroyltically or by
plating to obtain an approximately 1:1 ratio by weight of
lead to cadmium, and the resulting wire is then melted,
sprayed onto the surface of the foil as hereinbefore des-
cribed at a temperature which is higher than the melting
points of lead and cadmium, but lower than the temperature
which will~cause significant melting of the particular
alloy of lead and antimony from which the carrier plate is
made,
78
.' .
ll
1 , thus causing sinterization of the Pb-Cd on the surface of the
I carrier plate.
¦ In order to improve the adhesion of the Pb-Cd layer to
~ I the surface o~ the carrier pl~te 1, the carrier plate (foil) may
¦ first be sandblasted for several minutes to create a roughened
surEace so that the sinterized Pb-Cd mixture will be better
bonded to the foil's surface. It must be understood that the
terms "foil", "carrier plate" and "collector plate" are used in-
terchangeably throughout this application to refer to the Pb-Sb
carrier plate.
Referring again to,Fig. 1, there is shown the con-
tainer 3 made from a non-conductive material (e.g., glass, plas-
tic, etc.) and containing a dilute solution of sulfuric acid
, (electrolyte) having approximately the same specific gravity as
the sulfuric acid solutions employed in ordinary lead-acid type
¦~ storage batteries. The container 3 is also provided with a lead
plate or lead sheet 5 which serves as -the negative electrode (ca-
thode). The collector or carrier plate 1 which has been made as
aforesaid is immersed in the electrolyte as shown in Fig. 1 and
is connected to the positive terminal of a 3 volt emf source 7
(e.g., a battery) while the lead sheet 5 is connected to the nega-
tive terminal of said 3 volt emf source. ~lthough more than one
carrier plate may be immersed in the electrolyte and suitably
connected to the emf source, the invention will be describe~ and
I illustrated with reference to the preparation of one positive
plate only for the sake of simplicity of illustration.
. i
, l I
lU'~ 7~
1 When the circuit is closed as hereinbefore described,
the cadmium from the Pb-Cd layer on the carrier plate will react
j with sulfuric acid to form cadmium sulEate which is deposited as
I a porous; s~on~y mass on the lead sheet 5. Water is dissociated
I into hydrogen (H2) and oxygen ~2) Hydrogen appears as gas bub-
! bles on the surface on the negative elec-trode while oxy~en com-
¦ bines with lead, rapidly and continuously, to form lead Super-
¦ oxide (PbO2) in the form of crystalline and polycrystalline mass.
¦ The formation of the active mass is thus completed within minutes
~ and the carrier plate is removed, rinsed clean and dried. It is
now ready to be used in the construction of the lead-crystal hat-
tery or cell of this invention.
¦ The lead superoxide crystalline and polycrystalline
I active mass is a dark brown to black material. It is hard, homo-
¦ geno~s, highly porous and has remarkably low internal resistance.
In preparing a carrier plate having crystalline and
polycrystalline lead superoxide as the active mass, it is cri~ica~
to the formation of such mass that the Pb-Sb plate be coated with
- Pb-Cd that is sinterized. Thus, care must be taken to avoid the
formation of Pb-Cd alloy during sinterization or hot spraying on
the carrier plate in this embodiment of the invention. The pre-
sence of Cd in the sinterized mass is also critical since it aids
¦ or promotes the formation of PbO2 crystals and polycrystals. Ad-
ditionally, it must be noted that even though cadmium reacts with
the sulfuric acid in container 3 to form cadmium sulfate and it
is removed from this container, trace amounts of cadmium
. l I
Il .
I ` -13- ~
l
1 lnever~lleless remain in the active mass.
In order to construct a lead crystal cell in a~cord- !
ance with this invention, three identical carrier plates la, lb
¦and lc whiah have been made by the aforedescribed procedure are
limmersed in a container 9 as shown in Fig. 2. Container 9 is
5 Isimilar in structure to the cell of a lead-acid battery and con-
tains a dilute solution of sulfuric acid which is conventionally
employed in such batteries. Carrier plates la and lc are joined
together by conductor 11 and connected by conductor 13 to the
'negative terminal of a 3 volt emf source 15 (e.g., a battery, a
Ibattery charger, etc.) while carrier plate lb is connected to
,the positive terminal of the emf source 15 via conductor 17.
,~Jhen the circuit is thus closed, the PbO2 on -the carrier plates
la and lc is reducea to Pb and the plates become negatively
!charged, whereas the PbO2 on the carrier plate lb remains chemi-
¦cally unchanged and will become positively charged. Thus, thelead plates will serve as the negative electrodes (cathode) and
Ithe lead superoxide plate will serve as the positive electrode
¦(anode).
j After a few minutes when the cell has been fully
charged, the emf source 15 is removed and the emf within the cell
thus drops from 2.9 volts to approximately 2.4 volts, and re-
mains essentially constant at this level. The cell is now
charged and is storing energy for later release.
, When a cell made as hereinbefore described is con-
Inected in series with other cells (e.g., 3 cells in all), each
icontaining several plates (usually 17 or 19) connected in parallel,
. 1.
.
-14-
0~7~
1 la lead-crystal battery is formed which may contain 51 or 57
~plates depen~ing on the number of cells and the number of plates ir
I each cell. It is obvious, however, that more than 3 cells (e.g., i
6 cells, etc.) may be connectecl in series, if desired.
Lead crystal batteries incorporating the unique fea-
~tures of this invention exh~bit superior performance character-
istics as compared with lead-acid batteries. Thus, because of
lits lower internal resistance, a lead crystal battery comprising
¦,51 or 57 plates can accept about 10 to about 15 times as much
~electric current as the lead-acid battery. Consequently, the
llead-crystal ~attery can be charged at much faster rates than the
lead-acid battery. Similarly, the discharge rate of the lead-
crystal battery is considerably improved since i-t can supply
electric current at a considerably more accelerated rate than the
llead-acid battery.
I The discharge curve of a lead-crystal cell made in
¦accordance with this invention is compared in Fig. 3 with the
¦discharge curve for a typical lead-acid cell. The solid curve i~
¦this figure represents the discharge curve for the lead-crystai
Icell and the dotted curve represents the discharge curve for khe
lead-acid cell. A comparison of these two curves indicates that
¦during the first 16 minutes (i.e., during approximately 80~ of
¦the discharge cycle), the emf oE the lead-crystal cell remains con~
stant, then dropping very slightly from 2.32 to approximately
~2.3 volts, whereas the emf of the lead-acid cell decreases
Isteadily and constantly during the same period, dropping from 2.1 ¦
Ito approximately 2.0 volts. This difference is particularly sig- ¦
i
. I . I
-15- ~
78
nificant in batteries made from such cells, and indicates
that the lead-crystal battery can maintain a higher emf level
than the lead acid battery, and, therefore, exhibits superior
performance characteristics.
Additionally, the lead-crystal batteries of this
invention exhibit from about 25 to about 30 per cen-t higher
capacity than the conventional lead-acid batteries. Moreover,
the lead-crystal cell is capable of a far more complete charge
and discharge, with no after-reaction or self-charge, as
compared with a lead-acid cell; consequently, the lead-crystal
battery exhibits far greater storage capacity than a lead-acid
battery of comparable weight and volume. Cells made in
accordance with the principles set forth herein are capable
of developing from about O.l to about 0.2 volt higher emf
than conventional storage cells from which the lead~acid
batteries are made.
In the foregoing description, sinterized lead and
cadmium was applied to the surface of the collector plates
by hot spraying to deposit a homogenous, uniform and adherent
layer of Pb-Cd thereon. Two additional methods will now be
- described for depositing such layer of Pd-Cd on the surface
of the Pb-Sb carrier plate.
In another embodiment of this invention, a soft,
granular, 1:1 mixture of lead and cadmium, wherein the size
of the granules is from about 100 to a-lmost 500 microns, is
dissolved in a suitable organic liquid such as, for example,
methanol (or ethanol) to prepare a paste which is then
deposited on the surface of the carrier plate by a suitable
sieve. The methanol
- 16 -
`7~
1 is thereater evaporated; the plate is dried, and the Pb-Cd is
sinkerized in a press at a témperature of Erom about 300C. to
about 400C. for approximately 3 seconds. Once again, the ternp-
I erature and pressure during sinteriza-tion must be carefully con-
~ trolled so as to prevent the formation of the Pb-Cd 'alloy.
i The thickness of the Pb-Cd layer on the carrier plate¦
¦ may be controlled by the selection of the proper sieve and by de-¦
positing the appropriate amount of paste ~iformly on the surface
I of the plate. Thus, a Pb-Cd layer of approximately 0.5~m thick-
I ness may be deposited on both sides of the carrier plates.
I After depositing the desired coatin~ thickness, th~
¦ carrier plate is immersed in a container comprising a dilute
solutlon of sulfuric acid and a lead plate as hereinbefore de-
I scribed in connection with Fig. 1 and crystalline and polycrystal
line lead superoxide (Pb02) is once a~ain formed on the surface o~
the carrier plate in the same manner. The cadmium from the Pb~Cd
¦ layer reacts with sulfuric acid and is deposited in the form Gf
¦ CdS04 from which the cadmium can be recovered and reused, and the
¦ carrier plate or plates then used to construct a lead-crystal
cell as heretofore described in connection with Fig. 2.
In another embodiment of the invention a hard; com-
~ pact alloy of lead and cadmium was deposited on the carr1er plate
~ by electroplating in a fluoroboratebath. Thus, two electrodes,
¦ one made from an alloy of lead with antimony (cathode) and the
! other ~rom a 1:1 alloy o~ lead and cadmium (anode) were immersed
., ~ I
. I
I
I -17-
l l
l I
~v9~7
1~ l
Il I
1 1 in a rluorborate bath havin~J the following composition: l
¦' !
Lead Fluoroborate, Pb (BF4)2 119 oz.
Metallic Lead, Pb 65 oz.
Fluoroboric Acid HBF41.0 oz. I
Boric Acid 8.0 oz.
Cadmium Fluoroborate Cd(BF ) 32.5 oz.
j Cadmium Metal, Cd 412.0 oz.
5 ~ ~mmonium Fluoroborate8.0 oz.
WateE 1 gallon
The electrodes were then connected to the positive
¦and negative terminals of a 5 volt emf source for 1 hour until a
¦uniform layer of cadmium and lead of approximately O.lmm thick- I
Iness was deposited on each surface of the cathode. The emf sourcel
was then disconnected, the cathode removed from the bath, rinsed
clean with water and dried. I
I In order to produce three carrier plates with cry~
,talline and polycrystalline lead superoxide on their surfaces,
,three cathodic carrier plates made by this procedure were immersedl
in a dilute sulfuric acid electrolyte and subjected to the same
operation as hereinabove described in connection with Fig. 1.
¦The resulting carrier plates were then used to construct a lead-
Icrystal cell as hereinbefore described in connection with Fig. 2. 1
¦ It is evident from the foregoing detailed descrip~ion¦
that the lead-crystal battery of this invention is remarkably
superior to the lead-acid battery. In addition to the several
uni~ue features which were described supra, the lead-crystal bat- ¦
tery is usually from about 15% to about 30% lighter in weight than !
~5 a lead-acid battery of comparable size and capacity, and exhibits
from about 25~ to about 30% greater capacity as compared to a
lead-acid battery of comparable size and weight. The ability to
~draw substantially larger anounts of power in a considerably
shorter period of time due to its significalltly lower internal
_J~ I
~' I
D~7~
resistance and higher activity makes it particularly useful
in vehicles which require fast acceleration, e.g., electric
vehicles and cars, and other electrically motivated power
sources.
Also, the lead-crystal batteries which are made in
accordance with this invention exhibit little or no sulphatiz-
ation. This means that, as a practical matter, these bat-
teries can discharge to a point approaching zero emf. In
contrast, sulphatization is a rather common phenomenon in the
lead-acid batteries, and consequently, the lead-acid batteries
cannot discharge beyond about 1.5 to 1.8 volts emf, or almost
irreversible sulphatization will take place in the lead grids
which hold the paste of the active mass.
It must also be noted that while the invention has
heretofore been described and illustrated with certain
degrees of particularity, several changes and/or modifica-
tions may be made which are obvious from the foregoing des-
cription and which are, therefore, encompassed within the
spirit and scope of this invention.
For example, instead of using Pb-Sb carrier plates,
it is possible to use inert, non-co~ductive carrier plates
(è.g., made from a suitable plastic such as polypropylene
or cellulosic material) on which lead, or a mixture of lead
with antimony, may be deposited as hereinbefore described.
Such carrier plates are considerably lighter in weight than
Pb-Sb carrier plates, and consequently, the resulting batteries
will be considerably lighter as well.
-- 19 --
~)~3~
i
li
l I ~lso, while the inven-tion was heretofore illustrated
¦with reference to a l:l ratio by weight of Pb:Cd, this ratio
1Imay vary from about 30 to about 70 weight per cent and preferably
¦Ifrom about 45 to about 55 weight per cent; however, optimum re-
1sults are obtained when an approximately equal weight ratio of
5 ¦I the two components are used. If the mixture is predominantly
¦1lead, say, 70 weight per cent, the Pb-Cd layer will be softer and
less porous, whereas if the cadmium component predominates, say,
1it constitutes 70 weight per cent of the mixture, the resultiny
¦Pb-Cd layer will be harder and more porous. Optimum hardness and
¦porosity of the Pb-Cd layer are attained when the mixture is ap-
proxi~ate1y ~ 1:1 ratio by weight.
l I
!
.. I ,
-20-
I
