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Патент USA US3096225

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areil@
3,®%,2l5
Patented July 2, Intel?»
2
FIG. 1 is a schematic elevational view in crosssection
of an embodiment of a battery according to the present
3,096,215
SEALED STORAGE BATTERY
Ernst Voss and Klaus Dehmelt, Frankfurt am Main, Ger
many, assignors to Varta Aktiengesellschaft, Hagen,
Wes halla, Germany
tp Filed Apr. 11, 1960, Ser, No. 21,229
. Claims priority, application Germany Apr. 9, 1959
1 0 Claims. (Cl. 136-6)
The present invention relates to a sealed storage bat
tery, and more particularly, to a sealed storage battery
including a free-?owing liquid electrolyte and auxiliary
electrode means for eliminating gases formed during
invention;
‘
"
FIGS. 2-4 are schematic illustrations of various switch»
ing arrangements for electrically connecting the auxiliary
electrode of the present invention with the positive or
negative electrode of the battery. FIGURES 5 and 6 il
lustrate schematic elevational views in cross section of
additional embodiments of the battery according to the
present invention.
According to the present invention, a permanently her
metically sealed storage battery with free ?owing liquid
electrolyte Will include, in addition to the regular active
operation of the battery.
mass-containing positive and negative electrodes, one or
Hermetically sealed storage batteries are known in 15 more auxiliarygas-consuming electrodes which consist of
which the electrolyte is substantially ?xed in the pores
electrically conductive material which is inert relatively
of the electrodes and separator. However, the quantity
to the electrolyte. The auxiliary electrode or electrodes
of electrolyte which can be incorporated in such a bat
tery is limited by the quantity' which can
absorbed
are partially immersed in the liquid electrolyte and ex
tend with their uppermost portion into the gas space above
by the porous electrodes and separators. ThlS quantity 20 the liquid electrolyte. According to the present invention,
frequently is relatively small and this is disadvantageous
the auxiliary electrode consists of a porous material, thus
with respect to the capacity of the cell or battery. Pri
increasing the surface area available for gas consumption,
and is formed with a cavity communicating with the gas
'space through an opening in the upper portion of the
such battery with ?xed electrolyte will cause a consider 25 electrode, while the greatest part of the outer surface
able loss of useful output. Furthermore, batteries with
of the auxiliary electrode is in contact withthe electro
lyte.
‘
?xed electrolyte could up to now only be built with rela
tively small capacity. The above disadvantages are par
Thus, the battery according to the present invention
ticularly marked in batteries with acidic electrolyte where
operates with a free ?owing liquid electrolyte so that all
in, for instance in the case of a lead acid battery, the 30 of the favorable conditions generally associated with open
electrolyte is directly involved in the electro-chemical 1 and not hermetically closed cell will prevail. The cavity
reactions occurring during charging and discharging of the
in the ‘auxiliary gas-consuming electrode may be of any
battery.
desired shape, however, it is essential that the interior of
It is therefore an object of the present invention to
the cavity communicates with the gas space and will be
provide a hermetically sealed storage battery which will 35 ?lled with gas. Consequently, the opening in the auxili
not be subject to the above-discussed disadvantages.
ary electrode which leads to the cavity must be located
It is a further object of the present invention to pro
in a portion of the auxiliary electrode which is located
vide a hermetically sealed storage battery including a
above the upper level of the free ?owing liquid electrolyte
relatively large quantity of free ?owing electrolyte, in
so that liquid electrolyte will not enter into the cavity.
which gases can be safely eliminated so that the build
In this manner, it is accomplished that the surface area
up of excessive overpressure will be prevented.
of the auxiliary electrode which is available for gas
marily upon discharge of the battery with high current
density, the necessarily relatively high inner resistance of
vide a hermetically sealed storage battery of large ca
consumption will be much larger than previously thought
possible, while simultaneously any reduction in the size
pacity and including a speci?c auxiliary gas-consuming
of the surface area of the auxiliary electrode which is in
It is a further object of the present invention to pro
electrode which will consume gases evolved during opera 45 contact with the liquid electrolyte is avoided. In other
tion of the battery with sufficient speed to prevent build
words, the structure according to the present invention
up of excessive overpressure.
Other objects and advantages of the present invention
will become apparent from a further reading of the de
scription and of the appended claims.
With the above and other objects in view, the present
invention contemplates in a storage battery,‘ in combina
tion, a casing, means for hermetically sealing the casing,
a free ?owing liquid‘ electrolyte in'the casing ?lling the
same but partly so as to de?ne a gas space within the
casing, positive and negative electrodes in the casing in
contact with the free ?owing liquid electrolyte, and an
auxiliary gas-consuming electrode located in the casing,
permits in an extremely simple and economical manner
to increase the contact areas of the auxiliary electrode
which on the one hand contact the gas‘ space and on the
other hand contact the liquid electrolyte. This is ac
complished in such a manner that the overall size of the
battery need not be markedly increased.
.
The auxiliary gas-consuming electrode according to the
present invention which possesses a gas-consuming sur
face area much larger than up to now available, is ex
tremely well suited to prevent pressure increase due to the
development of gases during deep discharge or super
charging of the battery. Depending on the type of gas
which is evolved, i.e. whether primarily oxygen or hydro
the auxiliary electrode having an exterior surface ex
tending at least partly into the liquid electrolyte and 60 gen gas is formed, the auxiliary electrode will be elec
trically connected either with the negative or with the
being formed with a cavity opening into the gas space
positive electrode. It has been found that during charg
so that the interior surface of the auxiliary electrode
ing and supercharging of the battery formation of oxygen
formed by the cavity communicates with the gas space.
at the positive electrode is nearly unavoidable, so that in
The novel features which are considered as character
istic for the invention are set forth in particular in the - consequence thereof the gas-consuming auxiliary electrode
is generally electrically connected with the negative elec
appended claims. The invention itself, however, both‘
trode of the battery, in order to be capable of consuming
as to its construction and its method of operation, to
gether with additional objects and advantages thereof,
will be best understood from the following description
oxygen gas.
According to a preferred embodiment of the present
invention, the conductor leading from the auxiliary elec
of speci?c embodiments when read in connection with 70 trode passes through the wall of the hermetically closed
the accompanying drawings, in which:
battery housing, insulated therefrom. Outside of the
smears
.
housing, the conductor leading from the auxiliary elec
trode can then be conductively connected either with the
positive or with the negative electrode. According to
this arrangement, it is possible to adjust the battery to the
charge and ‘discharge conditions by selectively electrical
ly connecting the auxiliary electrode with either the nega
tive or the positive electrode, depending on the type of
gas and the charging or discharging condition of the
battery.
d
3
Furthermore, it is possible to connect a cur
rent-measuring instrument to the conductor leading out 10
wardly ‘from the auxiliary electrode and to ascertain im
_mediately by reading such instrument whether an equili
brium between gas formation and gas consumption is
any such covering or application of a layer to the outer
surface of the auxiliary electrode is to cover only such
portion of the outer surface as will be below the surface
level of the liquid electrolyte, so that any surface portions
located above the surface level of the liquid electrolyte will
be available for gas consumption.
‘ Referring now to the drawing and particularly to FIG.
1, a hermetically sealed battery is shown comprising a
hermetically sealed casing 1 partially ?lled with liquid
electrolyte 2, positive electrode 3 and negative electrode
4, these electrodes containing active mass, e"d auxiliary
gas-consuming electrode 5. It can readily be seen that
auxiliary electrode 5 is formed with a cavity 6 which com
established.
_
municates with gas space 7. The portion of the outer
It is also within the scope of the present invention 15 surface of auxiliary electrode 5 which is below the upper
to insert a resistor, and preferably a variable resistor,
level of liquid electrolyte 2, is surrounded by a layer 8
between the auxiliary gas-consuming electrode and the
of’thickened electrolyte. The outer surface of thickened .
negative electrode of the battery in order to make the
electrolyte
8 is surrounded and thus held in place by a
auxiliary electrode relatively more positive and thus to
prevent with certainty that the potential of the auxiliary 20 covering 9 which may consist of an electrolytesassistant
synthetic fabric or of a suitable semi-permeable mem
electrode would be such as to permit hydrogen gas de
brane. Conductors 10, 11 and 12 lead outwardly from
velopment thereon. By means of an auxiliary voltage, -it
the positive, negative and auxiliary electrode, respectively.
is possible to adjust the potential of the gas-consuming
These conductors pass through the sealed casing elec
auxiliary electrode relative to the electrolyte in such a
manner that at all times optimum conditions for gas 25 trically insulated from the same and through a gas-tight
packing so that the hermetical seal of the battery is not
consumption are assured. For this reason, according to
broken by the conductors extending outwardly of‘ the
another embodiment of the present invention, it is in“
same.
’
tended to connect the gas-consuming electrode with the
When it is desired permanently to connect the auxiliary
positive or negative electrode by way of either a variable
resistor or a variable auxiliary voltage, so that during 30 electrode 5 to, for instance, negative electrode 4, a con
ductor 13 may be provided in the interior of the battery
supercharging as well as during deep discharge with re
versal of polarity, the potential of the gas-consuming
electrode can be adjusted to the value required for react
housing.
‘
FIGS. 2-4 illustrate some of the switching arrange
ments which may be used for selectively connecting the
ing the evolving gas at the auxiliary electrode.
In order to prevent liquid electrolyte from entering into 35 auxiliary electrode with either the positive or the-nega
tive electrode of the battery. These switching arrange
the cavity of the gas-consuming electrode, several measures
ments will be located outside of the hermetically sealed
can be taken.
battery housing.
'
The porous material of the auxiliary electrode can be
> According to FIG. 2, auxiliary electrode 5 is connected
impregnated with a hydrophobic agent, or the material of
the auxiliary electrode may be so ?nely porous that elec~ 40 with positive electrode 3 over a variable resistor 14.
According to FIG. 3, variable resistor 14 which is con,
trolyte will not be capable of penetrating through the
nected with auxiliary electrode 5 may be selectively con
entire thickness of the cavity-forming auxiliary electrode
nected with either the positive electrode 3 or the negative
wall. It is also possible to cover the outer surface of the
electrode It.
'
portion of the auxiliary electrode which is immersed in
FIG. 4 shows an arrangement wherein the auxiliary
the electrolyte with a semi-permeable membrane which 45
electrode 5 is connected with the negative electrode 4 by
allows passage of ions therethrough but will prevent
way of an auxiliary voltage 15.
entry of the electrolyte into the auxiliary electrode wall.
FIG. 5 and FIG. 6 show a cross section of two other
Preferably, the auxiliary electrode is made of sintered
materials which are to be such that no chemical reaction
arrangements where the auxiliary gas-consuming elec
trode 5 is inserted at other places of the casing.
will take place between the electrode material and the
liquid electrolyte. Such materials may be metals or non 50
FIG. 5 shows an arrangement where the auxiliary
gas-consuming electrode 5 is placed above that plate group
metallic materials such as carbon or silicon carbide, or
synthetic materials which have ‘been treated so as to be
which is composed of positive electrodes 3, negative elec
come current conducting, as well as metal oxides or sul
trodes 4 and inserted separators 16. The auxiliary gas
phides. It is essential that the material of the auxiliary 55 consuming electrode 5 is immersed for more than the
electrode will resist chemical attack by the electrolyte,
half of its length into the liquid electrolyte 2.
will be current conducting and preferably will be of porous
The cavity 6 of the auxiliary gas-consuming electrode
structure so that the contact area between the auxiliary
electrode and the gas to be consumed in contact with the
same, is increased.
5 communicates with gas space 7.
The auxiliary gas
consuming electrode 5 is connected with the negative
‘
plates 4 by means of a conductor 13. The conductors 10
According to another preferred embodiment of the 60 and 11 are passing through gasstight packing and pro
present invention, the outer wall of the gas~consuming
truding from the casing.
auxiliary electrode is covered in the area which will bev
FIG. 6 shows-an arrangement where the auxiliary gas
below the surface level of the liquid electrolyte, with a
consuming electrode 5 is placed aside the plate group and
layer of thickened electrolyte solution. Such layer of
immerses for most of its length into the electrolyte 2. In
thickened electrolyte solution may consist of the liquid
this case, it communicates electrically with the positive
plates 3.
electrolyte of the battery which has been thickened to
more or less paste-like consistency by treatment with con
The thickness of the‘auxiliary gas-consuming electrode
ventional swelling agents, which do not markedly in?uence
can be 1 to 5 mm., a thickness of 2 to 3 mm. is preferable.
or decrease the migration velocity of the ions. It has
The separators 16 can be porous or perforated, they are
been found to be particularly advantageous to cover the 70. frequently corrugated or ribbed; the electrodes 3 and 4
submerged outer surface portion of the auxiliary electrode
with such layer of thickened electrolyte and then to cover
the free surface of the layer of thickened electrolyte with
are spaced apart by them in a distance of 0.7 up to 2 mm.
When utilizing an acid electrolyte 2, as for - instance
sulphuric acid, separators 16 should be used which are
made of material resistant to and electrically inert to this
75
the stability of the thickened electrolyte layer. Of course,
medium, as for instance glass wool, hard-rubber or plastic
an inert and porous fabric or the like, in order to increase
3,096,216
material deriving from the polyvinyl, polystyrene and
polyole?n groups.
'
When utilizing an alkaline electrolyte, as for instance
potassium hydroxide, separators analogously made of
6
in connection with an acidic or alkaline electrolyte. Silver
and nickel depositions are suitable for auxiliary electrodes
which will ‘have to operate with an alkaline electrolyte.
Preferably, the metal is mixed with the pulverulent elec
trode material prior to the sintering or pressing of the
same, or, the conductive metal can be precipitated from
impregnating solutions onto the electrode surface after
the electrode has been formed. In the case of metal
oxides as electrode material, it is possible to achieve suf
alkaline-resistant material should be used, such as poly
amides, polyvinyl-alcohols and copolymers of such ma
terials.
Positive and negative electrodes 3 and 4 and separators
16 can ‘be employed according to the directives and in
structions as mentioned, for instance, in the book by G. M. 10 ?cient conductivity by the addition of graphite or other
Vinal, “Storage Batteries,” 4th edition 1955, John Wiley
carbon modi?cations. This last mentioned method is
and Sons, New York, pages 27 to 60.
particularly suitable in connection with titanium dioxide
When acid electrolyte is applied, the thickness of the
and aluminum oxide while when carbon is added to oxides
plate is l to 5 mm., preferably 1 to 2 mm.; also tubular
of tin, chromium or iron, reduction of the metal oxide
plates may be employed.
15 would take place.
When utilizing alkaline electrolyte, the arrangement is
, The following examples of methods of producing aux
iliary electrodes such as are incorporated in hermetically
the same as described above, with the exception of the ap
plication of other material for the active mass and for
sealed batteries in accordance with the present invention,
the separators 16; also sintered electrodes may be em
are given as illustratives only, the invention however not
ployed.
20 being limited to any of the speci?c details of the examples.
It is essential according to the present invention to'pro
Example 1
vide a gas-consuming electrode as illustrated in FIG. 1, in
other words an electrode which is formed with a cavity
Finely pulverulent titanium dioxide is introduced into
a mold cavity which corresponds to the con?guration of
having a relatively large surface area and communicat
ing with the gas space, so that the gas~consuming surface 25 the electrode. The pulverulent titanium dioxide is then
compressed and sintered for between about 7 and 12 min
of the auxiliary electrode is greatly increased without
utes, depending on the thickness of the electrode wall,
thereby having to decrease the surface area of the aux
at a temperature of between 1,660 and 1,710 degrees C.
iliary electrode which will be in contact with the electro
After cooling, the sintered titanium dioxide electrode is
lyte. Since it is desired to produce a porous gas-con
suming electrode, the auxiliary electrode may be either 30 then introduced into a 10%, ammonia-containing silver
a press electrode produced by compressing a pulverulent _ nitrate solution, whereby a partial vacuum may be em
ployed in order to speed up penetration of the pores of
material, or a sinter electrode which preferably is pro
the electrode by the silver nitrate solution. The thus
duced by ?rst compressing a pulverulent material and
thereafter sintering the same.
treated electrode is then dried and thereafter introduced
into a bath which contains a su?icient concentration of
In any event, the auxiliary electrode must possess the
following qualities:
_
'(l) The material of the auxiliary electrode must be
formaldehyde for precipitating silver from the silver salt
adhering to the inner surfaces of the electrodes. If de
sired, the impregnation and precipitation of silver may be
repeated.
(2) The material must be resistant against chemical
Example 2
attack by the electrolyte which is to be used in the re 40
spective hermetically sealed battery.
Silicon carbide possesses suf?cient electric conductivity
(3) The material and thus the electrode must com
for use as the material for the auxiliary electrode. Finely
bine sut?cient porosity with su?icient mechanical strength
pulverulent silicon carbide is sintered at temperatures
so that at the respective surface portions of the electrode
which may be as high as l,800° C. whereby the sintering
' electrically conductive.
which will be in contact with gas and which will be in 45 time will be about 10 minutes, or as low as 1,550° C.
whereby then the sintering time will be about 30 minutes.
tion of water will take place with the desired speed.
Due to the fact that the auxiliary electrode must possess
For this purpose, two characteristics of the structure
a certain degree of mechanical strength, it is generally
are of major importance, namely the formation of a
not advisable to prepare the auxiliary electrode by press-.
cavity as illustrated and described above which cavity 50 ing without sintering. However, there are certain excep
will communicate with the gas space above the liquid
tions to this rule, it is for instance possible to produce
electrolyte and will be ?lled with gas and, consequently,
press electrodes from pulverulent synthetic materials which
that at least a minor portion of the electrode structure
have been treated so as to become electrically conductive.
(namely the portion in which the opening leading to the
However, in most cases, the auxiliary electrodes will be
' contact with electrolyte, gas consumption and the forma
cavity is located) extends upwardly of the liquid electro 55 produced by sintering.
lyte.
The particle size of the pulverulent materials which are
In view of the fact that the vmaterial ofthe auxiliary
to be sintered (or compressed) to form the auxiliary elec
electrode must be current conducting, it is necessary in
trode, will preferably be within 1 and 100 microns.
cases to treat otherwise suitable material in conventional
manner so as to make the same current conducting. This
is not necessary in the case of graphite and other elec
If a pulverulent material of substantially even ‘particle
size, for instance a particle size of between 10 and 25
microns is used, electrodes are obtained which possess
trically conducting modi?cations of carbon, or in the case
pores of relatively even size, and which also possess a
of a sintered metal, or silicon carbide. However, it is
rather high total pore volume. In many cases, however,
necessary to make the material current conductive, when
it is advisable to reduce the total pore volume without
the auxiliary electrode is to be produced of synthetic ma 65 losing the average even size of the pore. For this pur
terials such as polyvinylchloride or polyvinylstyrene, or
pose, it is advisable to mix two pulverulent materials of
of metal oxides such as tin dioxide, titanium dioxide chro~
dilferent sizes each of which per so should be of even or
mium (III) oxide, iron (III) oxide or aluminum oxide,
as even as possible particle size. For instance, a ?rst pul
or of metal sul?des such as lead sul?de.
verulent material having a particle size of between x10 and
Non~conductive porous materials can be made con
25 microns may be mixed with a pulverulent material
ductive, for instance by vapor deposition of metals.
having a particle size of between 5 and 10 microns. The
Noble metals of the platinum group may be applied for
pore volume which in the ?rst described case, namely by
auxiliary gas-consuming electrodes which consist of a
using only one pulverulent material having a particle size
material which per se would not be conductive, regard
of between 10 and 25 microns, will be between about 50
less whether the auxiliary electrodes will have to operate 75 and 70% of the total volume of the electrode, can be
8,096,215
7’
0
.
reduced by mixing two materials of di?erent particle
sizes as described above, to a total pore volume of be
tween about 25 and 45% of the total volume of the
auxiliary electrode. Thereby, the further advantage is
achieved that, although the total pore volume is reduced,
the active surface of the electrode including the inner
surface thereof will be increased. By using equal quan
tities of identical material, such as 50% by weight of
the relatively larger particle size and 50% by weight of
the relatively smaller particle size, the total pore volume
completely preventing slight penetration of the electrolyte
into the outer portion of the submerged electrode wall.
For this purpose, it has been found to be particularly
suitable to use fatty acid aluminum salts such as alu~
minum stearate, or silicon oil emulsions. It is important
to watch that not too much of the hydrophobic agent will
be retained in the porous electrode.
For instance, if
paraffin is used as the hydrophobic agent, the same is
preferably applied to the electrode in vapor form. How
10 ever, it is also possible to admix the hydrophobic agents
will be between about 30 and 40%.
to the pulverulent mass prior to forming did sintering
While it is possible to sinter all of the starting materials
of the same. During the sintering, the major portion of
mentioned above under atmospheric conditions, it is advis
the hydrophobic agents will volatilize, however, 21 audi
able when producing auxiliary electrodes from carbon or
cient quantity will be retained in order to prevent elec
nickel, to operate in a reducing atmosphere. Nickel elec 15 trolyte from passing through the electrode wall into the
trodes have been found particularly suitable in connection
cavity in the interior of the auxiliary electrode.
_
with alkaline electrolytes. At the temperature of 1,000",
It is sometimes desired to surround the outer surface
su?iciently ?rm sintering is achieved within a period of
portion of the auxiliary electrode which is immersed in
between 2 and 4 minutes. However, it is also possible
the liquid electrolyte, with a layer of thickened elec
to sinter nickel powder at a temperature of only about
trolyte. For the purpose of thickening the electrolyte
600° C. whereby, however, the sintering time has to be 20 any suitable conventional gelatinizing agent can be used.
increased to between 50 and 75 minutes. Aluminum
Particularly good results have been obtained with a col
oxide sinter electrodes can be produced by sintering at
loidal silicon-dioxide which is known under the trade
800° C. for 30 minutes. Carbon electrodes can be pro
name “Aerosil” and which consists of very ?ne silicic
duced in two ways. Either electrically conductive car
acid dust having a particle size of between 15 and 35
25
bon is severely compressed and the thus-produced elec
millimicrons. This silicon dioxide can be used for alkaline
trode is heated to glowing temperature in order to adhere
as well as for acidic electrolytes. The thickness of the
the individual particles of carbon to each other whereby
layer of thickened electrolyte preferably will be between
a sufficiently strong electrode with relatively small total
about 0.5 and 2 millimeters. In the case of alkaline elec
pore volume and an average active surface is obtained, 80 trolytes, good results are also obtained with a thickened
or the electrically conductive carbon is ?rst mixed with
.electrolyte layer consisting of precipitated nickel hydrox
organic materials such as starch or sugar and the electrode
ide, in such cases where the auxiliary electrode is con~
is then pressed of such mixture with subsequent heating
nected to the cathode. In order to maintain the layer
to glowing temperature. Thereby, carbon electrodes with
of thickened electrolyte in place, in contact with the sub
a relatively larger pore volume are obtained, due to the
merged outer surface portion of the auxiliary electrode, a
decomposition of the organic material and the surface 35 covering
of electrolyte resistant synthetic fabric such as
area which is available for gas consumption will be greater
Perlon or polyvinylchloride may be used. It is also pos
in electrodes of the last-described type which were pro
sible, instead of the above-mentioned covering, to place
duced from a mixture of electrically conductive carbon
the ‘thickened electrolyte layer-covered portion of the‘
and such organic material. Somewhat similar electrodes 40 electrode into a semi-permeable membrane such as isin
can also be produced from a mixture of electrically con~
glass or into a membrane-filter paper having pore sizes
ductive carbon and ?nely pulverulent nickel powder. In
stead of nickel, it is also possible to admix silver, cad
mium or zinc‘ powder to the carbon powder. However,
electrodes containing the last-mentioned three metals
should be used only in connection with alkaline elec
trolyte. Good results are obtained with mixed carbon
of between 5 and 100 millimicrons.
These pores are
sut?ciently large to allow passage therethrough not only
of hydrogen ions, but also of hydroxyl ions and of water
molecules.
.
.
‘
Basically there will be no di?erence in the structure of
the hermetically sealed battery according to the present
metal electrodes containing 25% by weight of carbon
invention irrespective of Whether alkaline or acidic free
and 75% by weight of metal.
?owing electrolyte is used.
The following example relates to a gas-consuming elec 50 The following examples describe two batteries accord
trode made of polyvinylchloride powder.
ing to the present invention.
.
Example 3
Example 4
Synthetic material—-sinter electrodes may be produced
In a battery with acidic electrolyte, the positive elec
of polyvinylchloride powder having a particle size of be 55 trode may consist of a lead grid and conventional lead
tween 4 and 100 microns. Particularly good results are
oxide mass. The capacity may be about 14 ampere hours,
obtained with particle sizes between about 6 and 15
the negative electrode will also consist of a grid electrode
microns. Prior to sintering, carbon powder may be ad
with lead sponge as active mass and will have a capacity
mixed provided that sintering is then carried out in a
of about 20 ampere hours. The 'gasconsuming auxiliary
reducing atmosphere, or it is also possible to admix ?nely 60 electrode in the hermetically sealed battery may be made
divided metals such as silver. After forming an intimate
of silicon carbide in the manner described further above
mixture of the polyvinylchloride powder and the added . and may have a porosity of 70%. The square area of
electrically conductive material, auxiliary electrode bodies
the surface of the auxiliary electrode which de?nes the
are formed and pressed of these mixtures at a temperature
cavity therein will be between 200 and 300 square centi
65
of between 230 and 300° C., depending on the thickness
meters, prefer-ably between 240 and 260 square centi~
of the electrode wall. Sintering is carried out for a
period of between about 20 and 40 seconds.
In order to prevent penetration of the auxiliary elec
meters. By electrically connecting the auxiliary gas
consuming electrode with the cathode of the battery,
oxygen gas will be consumed in a quantity corresponding
trode by free ?owing liquid electrolyte, it is sometimes
to the quantity evolved by a current of between 1 and
desirable to impregnate the auxiliary electrode with hydro~ 70 2 amperes. On the other hand, by connecting the auxil
phobic agents. The purpose of such impregnation is of
course to prevent passage of electrolyte through the wall
of the electrode into the cavity in the interior of the
electrode which cavity communicates with the gas space
iary electrode with the anode, hydrogen gas can be con
surned in a quantity corresponding to the quantity evolved '
by a current of between 0.5 and 1.5 amperes. The inner
pressure in the sea-led battery will not exceed in either
above the surface level of the liquid electrolyte, without 7 case 1.5 atmospheres above atmospheric pressure. The
3,096,215
‘id
density of the sulphuric acid elutrolyte will be 1.285. A
thickened layer of electrolyte is for-med around the outer
of said auxiliary electrode formed by said cavity cont‘
municates with said gas space and said cavity will be sub»
submerged surface of the auxiliary electrode with the help
stantially free of liquid electrolyte.
of colloidal silicon dioxide of the type described further
2. In a storage battery, in combination, a casing; means
above. The hermetically sealed casing preferably will
consist of polystyrene.
Example 5
for hermetically sealing said casing; a free ?owing liquid
electrolyte in said casing ?lling the same but partly so
as to de?ne a gas space within said casing; positive and
negative electrodes in said casing substantially submerged
In the case of an alkaline electrolyte, the positive elec
in said free ?owing liquid electrolyte; and an auxiliary
trode will be a sintered plate made of nickel with nickel 10 gas-consuming electrode consisting of an electrically con~
oxide as active mass, having a capacity of 1 ampere hour,
ductive porous material which is inert with respect to said
and the negative electrode will be a sinter electrode with
liquid electrolyte located in said casing spaced from said
cadmium as active mass having a capacity of 1.5 ampere
positive and negative electrodes and electrically connected
hours. The auxiliary gas-consuming electrode may be a
to one of said electrodes, said porous auxiliary electrode
carbon electrode which has been impregnated with cobalt 15 having a major exterior surface portion in contact with
compounds and will have a porosity of 45%. Thereby
said liquid electrolyte and being formed with a cavity
the quantity of cobalt will approximate 1% of the total
opening into said gas space so that the interior surface of
weight of the electrode. The surface portion of the elec
trode which surrounds the cavity therein will be between
30 and 60 square centimeters, preferably between 45 and
50 square centimeters.
said auxiliary electrode formed by said cavity communi
cates with said gas space and the pores of said porous
auxiliary electrode being su?iciently ?ne to prevent access
of said free ?owing electrolyte to said cavity.
3. A storage battery as de?ned in claim 2, including‘
electric conduits extending from said positive, negative
Allowing for an inner pressure
of at most 1.5 atmospheres above atmospheric pressure,
and by connecting the auxiliary electrode with the cath
ode, oxygen corresponding to 100 milliam-peres, and by
and auxiliary electrodes, respectively, outwardly through
connecting the auxiliary electrode with the anode, hy 25 said casing; and conduit means located outwardly of said
drogen corresponding to 60 rnilliamperes can be con
sumed. The liquid electrolyte is an aqueous potassium~
hydroxide solution having a density of 1.20. The her
metioally sealed housing may consist for instance of nickel
plated sheet iron.
casing for selectively connecting the conduit extending
from said auxiliary electrode with one of said conduits
extending from said positive and negative electrodes,
respectively.
30'
In order to save space, and to reduce the inner resistance
between the positive and negative electrode, it is also
.
4. A storage battery as de?ned in claim 3 wherein said
conduit means include auxiliary voltage controlling means
for adjusting the potential of said auxiliary electrode to
possible to arrange the auxiliary electrode in a position
the potential required for consumption of ‘gas concur
relative to the positive and negative electrodes which
rently formed with said battery.
differs from what is illustrated in FIG. 1. For instance, 35
5.. In a storage battery, in combination, a casing; means
the auxiliary electrode can be arranged closer to one
for hermetically sealing said casing; a free ?owing liquid
side of the housing so as not to be interposed ‘between
electrolyte in said casing ?lling the same but partly so
the positive and negative electrode, or the auxiliary elec
as to de?ne a gas space within said casing; positive and
trode can also be of a ?attened con?guration and arranged
negative electrodes in said casing substantially submerged
above the positive and negative electrodes.
40
It will be understood that each of the elements de
scribed above, or two or more together, may also ?nd
in said free ?owing liquid electrolyte; and an auxiliary
gas-consuming electrode located in said casing spaced
from said positive and negative electrodes and electrically
a useful application in other types of batteries differing
connected to one of said electrodes, said gas-consuming
from the types described above.
electrode consisting of an electrically conductive porous
While the invention has been illustrated and described 45 material which is inert with respect to said liquid elec~
as embodied in a hermetically sealed storage battery op
trolyte and which is impregnated with a hydrophobic
erating with a free ?owing electrolyte, it is not intended
agent which is incapable of reacting with said electrolyte,
to be limited to the details shown, since various modi?ca
said auxiliary electrode having a major exterior ‘surface
tions and structural changes may be made without depart
portion in contact with said liquid electrolyte and being
50 formed with a cavity opening into said gas space so that
ing in any way from the spirit of the present invention.
Without further analysis, the foregoing will so fully
the interior surface of said auxiliary electrode formed by
reveal the gist of the present invention that others can
said cavity communicates with said gas spaceand the
by applying current knowledge readily adapt it for various
applications without omitting features that, from the
standpoint of prior art, fairly constitute essential char
acteristics of the generic or speci?c aspects of this in
vention and, therefore, such adaptations should and are
intended to be comprehended within the meaning and
range of equivalence of the following claims.
‘
What is claimed as new and desired to be secured by
Letters Patent is: ’
1. in a storage battery, in combination, a casing; means
for hermetically sealing said casing; a free ?owing liquid
electrolyte in said casing ?lling the same but partly so
as to define a gas space within said casing; positive and
negative electrodes in said casing substantially submerged
pores of said porous auxiliary electrode being su?iciently
?ne to prevent access of said free ?owing electrolyte to
said cavity.
6. In a storage battery, in combination, a casing; means
for vhermetically sealing said casing; a free ?owing liquid
electrolyte in said casing ?lling the same but partly so
as'to de?ne a gas space within said casing; positive and
negative electrodes in said casing substantially submerged
in said free ?owing liquid electrolyte; and an auxiliary
gas-consuming electrode consisting of a porous sintered
metal which is inert with respect to said liquid electrolyte
> located in, said casing spaced from said positive and nega
tive electrodes and electrically connected to one of said
electrodes, said auxiliary electrode having a major exterior
in said free ?owing liquid electrolyte; and an 'auxiliary
surface portion in contact with said liquid electrolyte and
gas-consuming electrode consisting essentially of an elec
being formed with a cavity opening into said gas space so
trically conductive material which is inert with respect to
that the interior surface of said auxiliary electrode formed
said liquid electrolyte located in said casing spaced from 70 by said cavity communicates with said ‘gas space, the
said positive and negative electrodes and electrically con~
pores of said sintered auxiliary electrode being su?iciently
nected to one of said electrodes, said auxiliary electrode
having a major exterior surface portion in contact'with
said liquid electrolyte and being formed with a cavity
opening into said gas space so that the interior surface
?ne to prevent said free ?owing electrolyte from passing
into said cavity.
'
7. In a storage battery, in combination, a casing; means
for hermetically sealing said casing; a free ?owing liquid
8,096,215
11
electrolyte in said casing ?lling the same but partly so
liquid electrolyte located in said casing spaced from said
positive and negative electrodes and electrically connected
as to de?ne a gas space within said casing; positive and
negative electrodes in said casing substantially submerged
in said free ?owing liquid electrolyte; and an auxiliary
to one of said electrodes, said gas-consuming electrode
having a major exterior surface portion in contact with
gas-consuming electrode consisting of a porous material
which is inert with respect to said liquid electrolyte and
which is selected from the group consisting of carbon
and silicon carbide, and of metal oxides, metal sul?des,
said liquid electrolyte, said auxiliary electrode being
formed with a cavity opening into said gas space so that
the interior surface of said auxiliary electrode formed by
said cavity communicates with said gas space and said
and synthetic materials which have been treated so as to
cavity will be substantially free of liquid electrolyte; and
be capable of conducting electric current located in said 10 an electrolyte-impermeable, ion'pcrmeable membrane
casing spaced from said positive and negative electrodes
covering said exterior surface portion of srid auxiliary
and electrically connected to one of said electrodes, said
electrode and the pores of said porous auxiliary electrode
auxiliary electrode having a major exterior surface por
‘being sut?ciently ?ne to prevent access of said free ?ow
tion in vcontact with said liquid electrolyte and being
ing electrolyte to said cavity.
’ formed with a cavity opening into said gas space so that 15
10. In a storage battery, in combination, a casing;
the interior surface of said auxiliary electrode formed
means for hermetically sealing said casing; a free ?owing
by said cavity communicates with said gas space and the
liquid electrolyte in said casing ?lling the same but partly
pores of said porous auxiliary electrode being sut?ciently
so as to de?ne a gas space within said casing; positive
?ne to prevent access of said free ?owing electrolyte to
and negative electrodes in said casing substantially sub
said cavity.‘
20
8. In a storage battery, in combination, a casing; means
merged in said free ?owing liquid electrolyte; an‘auxiliary
gas-consuming porous electrode consisting of an elec
trically conductive material which is inert with respect
to said liquid electrolyte located in said casing spaced
from said positive and negative electrodes and electrically
for hermetically sealing said casing; a free ?owing liquid
electrolyte in said casing ?lling the same but partly so as
to de?ne a gas space within said casing; positive and
negative electrodes in said casing substantially submerged 25 connected to one of said electrodes, said gas-consuming
in said free ?owing liquid electrolyte; and auxiliary gas
electrode having a major exterior surface portion in con
consuming electrode consisting of an electrically con
tact with said liquid electrolyte, said auxiliary electrode
ductive material which is inert with respect to said liquid
being formed with a cavity opening into said gas space
electrolyte located in said casing spaced from said positive
so that the interior surface of said auxiliary electrode
and negative electrodes and electrically connected to one 30 formed by said cavity communicates with said gas space
of said electrodes, said gas-consuming electrode having a
and said cavity will be substantially free of liquid elec
major exterior surface portion in contact with said liquid
trolyte; and a layer of thickened electrolyte adhering to
electrolyte, said auxiliary electrode ‘being formed with a
and covering said exterior surface portion of said auxil
iary electrode ‘and the pores of ‘said porous auxiliary elec
surface of said auxiliary electrode formed by said cavity 35 trode being sul?ciently ?ne to prevent access of said free
communicates with said gas space and said cavity will
?owing electrolyte to said cavity.
‘ 7
be substantially free of liquid electrolyte; and a semi
permeable membrane surrounding said exterior surface
References Cited in the ?le of this patent
cavity opening into said gas space so that the interior
portion of said auxiliary electrode.
'
UNITED‘ STATES‘ PATENTS
9. In a storage battery, in combination, a casing; means 40
for hermetically sealing said casing; a free ?owing liquid
electrolyte in said casing ?lling the same but partly so as
to de?ne a gas space within said casing; positive and
negative electrodes in said casing substantially submerged
in said free ?owing liquid electrolyte; an auxiliary gas
consuming porous electrode consisting of an electrically
conductive material which is inert with respect to said
45
2,131,592
2,842,607
Lange et al ___________ -.. Sept. 27, 1938
Germershausen et al _____ __ July 8, 1958
2,857,447
2,934,580
3,005,943
Lindstrorn ___________ __ Oct. 21, 1958
Neumann ___________ __ Apr. 26, 1960
‘Ja?ee _______________ .._ Oct. 24, 1961
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