Note: Descriptions are shown in the official language in which they were submitted.
;2979
In the packaged power industry7 there is an ever increasing emphasis
upon the development of high capacity, small volume electric cellsO The follo-
wing is a comparison of the capacity and voltage for some active materials
currently used in commercially available cells:
Active E~ vs. Zn in Capacity
MaterialAlkaline Electrolyte ~ amp-hr./cc
HgO 1-35v- 248 2.76
Ag20 1.60v. 232 1.67
Ag~ 1.82v. 432 3.22
Divalent silver oxide (AgO) is an excellent high capacity battery
active material, but it has two properties which have limited its use as a
battery active material. During the discharge of a battery employing a diva-
lent silver oxide positive active material, the initial voltage is at the
higher divalent voltage level (1082v. vs. Zn in alkaline electrolyte) Until
substantially all of the AgO is converted to Ag20, and thereafter, the dischar-
ge continues at the lower monovalent voltage level (1060v. vsO~n in alkaline
electrolyte). This two plateau voltage level during discharge cannot be
tolerated b~ many types of battery operated equipment.
Another problem encountered when using divalent silver oxide as a
depolarizer (positive active material) is its lack of stability when in con-
tact with aqueous alkaline solutions. It is well known that divalent silver
oxide evolves oxygen when in contact with aqueous alkaline solutions, and
this gassing phenomenon causes self-discharge of the divalent silver oxide~
converting it to monovalent silver oxide or metallic silverO Divalent silver
oxide cannot be used as the positive active material in hermetically sealed
cells because of this instability in alkaline solutions and the consequent
hazard of pressure build-up and possible cell rupture.
The problem of the two plateau voltage level during the electrical
discharge of divalent silver oxide has previously been overcome by the
2979
in~entions disclosed in United States Patent Numbers 3,615,858 and 3,655,450
issued to Luis Soto-Krebs. These patents disclose a battery having a positive
electrode comprising a principal active material (e.g. divalent silver oxide)
and a secondary active material (e.g. monovalent silver oxide) whose discharge
product is readily oxidized by the principal active material in the presence
of alkaline electrolyte, and wherein khe sole electronic path for discharge
of the principal active material is through the secondary active material.
The battery invented by Soto-Krebs ischaracterizedthroughout discharge by the
potential of the secondary active material (Ag20) vs. the negative electrode
in the alkaline electrolyte. The battery has the advantage of a single voltage
level during electrical discharge and also the increased capacity provided by
the divalent silver oxide positive acti~e materialO
The problem of the divalent silver oxide instability has been over-
come by the inventions disclosed in United States Patent Numbers 3,476,610
and 3~484~295 issued to Luis Soto-Krebs and Robert Dawson. These patents
disclose a battery having a positive electrode comprising a principal active
material (e.g. divalent silver oxide) and a secondary active material (e.g.
monovalent silver oxide) employed as a substantially electolyte-impermeable
layer interposed between the principal active material and the battery compo-
nents containing the electrolyte. This construction isolates the principalactive material from contact with the electrolyte until the secondary active
material is discharged, thereby providing improved stand or shelf lifeO
It is the general object of this invention to provide a high drain
rate~ primary alkaline cell having a divalent silver oxide/monovalent silver
oxide depolarizer blend which is stable in the potassium hydroxide alkaline
electrolyte and which cell is characterized by a single voltage plateau during
discharge. Another object of the invention is to provide a high drain rate~
primary alkaline cell, particularly of the "button cell" construction, which
has increased capacity per unit weight and volume compared to a cell employing
-- 2 --
~4Z979
only monovalent silver oxide as the positive active material. A further
; object is to provide a high drain rate, primary alkaline cell having a posi-
tive electrode comprising a blend of divalent silver oxide and monovalent
silver oxide which will utilize the capacity of both of these active materials
and having a maximum open circuit voltage ~vs. Zn in alkaline electrolyte) of
about 1.75 volts. A still further object is to provide a novel method of
manufacturing a divalent silver oxide/momovalent silver oxide depolarizer
blend coated with a layer of silver.
According to one aspect of the present invention, there is provided
a high drain rate, primary alkaline cell comprising a negative electrode, a
divalent silver oxide/monovalent silver oxide depolarizer blend, a separator
between said negative electrode and the depolarizer blend, and an aqueous
potassium hydroxide electrolyte, said depolarizer blend containing up to
about 70% by weight of divalent silver oxide, and a substantially continuous
and electrolyte permeable layer of silver on the surface of the depolarizer
blend adjacent to the separator, whereby the cell is characterized by the
stability of the depolarizer blend in the potassium hydroxide electrolyte,
a maximum open circuit voltage of about 1.75 volts, a single voltage plateau
during discharge and is capable of providing a flash current greater than
an average of 0.2 amps per square centimeter of cell cross-sectional area.
Quite unexpectedly, it has been found that the depolarizer blend
can be discharged at a single voltage plateau without restricting the elec-
tronic path to monovalent silver oxide; however, it is essential that the
silver layer on the surface of the depolarizer blend be present. The layer
of silver on the depolarizer blend is essential to achieve a single voltage
plateau during discharge of the cell, and it also provides improved stability
of the depolarizer blend in the potassium hydroxide electrolyte.
The layer of silver may be formed by treating the surface of the
depolarizer blend with a strong reducing agent such as hydrazine or formalde-
hyde.
The surface of the depolarizer blend can be reduced either priorto being placed in the cell container, or preferably, after the blend is
~Yl ~3~
~
., . ' ~ b
~ . ,'" ', ' ' ' ~ ~ ,
- /
4Z979
consolidated in the container.
Thus, according to one aspect of the method of ~he present
invention, there is provided a method for manufacturing the depolarizer blend
used in the primary alkaline cell of the invention comprising forming the
depolarizer blend comprising divalent silver oxide and monovalent silver
oxide, compressing the blend to form a pellet, placing the pellet in a
cathode container, consolidating the pellet in the container by compression,
and treating the consolidated pellet/cathode container component with a
strong reducing agent for a period of time sufficient to reduce the surface
of the depolarizer blend to metallic silver.
According to another aspect of the method of the present invention,
there is provided a method for manufacturing the depolarizer blend used in
the primary alkaline cell of the invention comprising forming the depolarizer
blend comprising divalent silver oxide and monovalent silver oxide, compress-
ing the blend to form a pellet, treating the pellet with a strong reducing
agent for a period of time sufficient to reduce the surface of the depolarizer
blend to metallic silver, placing the pellet with the reduced surface in a
cathode container, and consolidating the pellet with the reduced surface in
the cathode container by compression.
-3a-
297~
:,
The high drain rate, primary alkaline cells of this invention are
particularly useful as power sources for elec~ronic watches, and they are
manufactured in the "button cell" construction for use in small electric
; devices such as watches and hearing aids. The cells have the required single
voltage plateau discharge characteristics and also stability of the depolari-
zer blend in potassium hydroxide electrolyte without incorporating special
additives, such as those disclosed in United States patent Number 3,650,832.
The primary alkaline cells have substantially increased electrochemical capa-
city over that supplied by cells using a monovalent silver oxide depolarizer.
These cells also have improved high drain rate capability required for pulsing
to activate a light emitting diode.
The above and other objects and advantages of this invention will
be more fully described in the description of the preferred embodiment, parti-
cularly when read in conjunction with the accompanying drawing.
Pigure 1 is a cross-sectional view of the high drain rate, primary
alkaline cell of this invention, in completely assembled condition.
This invention comprises a highdrain rate, primary alkaline cell
having a divalent silver oxide (AgO)/monovalent silver oxide (Ag20) depolarizer
blend (cathode) coated with a layer of silver, a negative electrode (anode),
2~ a separator between the depolarizer blend and the negative electrode, and an
aqueous potassium hydroxide solution as the electrolyte. It is essential
that the surface of the depolarizer blend adjacent to the separator be coated
with a layer of silver which provides improved stability of the depolarizer
blend in the potassium hydroxide electrolyte and provides the cell with a
single voltage plateau during discharge. The silver layer may be formed by
treating the surface of the depolarizer blend with a strong reducing agent,
such as hydrazine, which provides a substantially continuous and electrolyte
permeable silver layer. The maximum open circuit voltage of the cell is about
~4Z979
1.75 volts, and it is preferred that the open circuit voltage be approximately
1.6 volts which is characteristic of monovalent silver oxide. The open cir-
cuit voltage is measured by discharging the cell through a very high load, on
the order of one to one hundred megaohms. If a cell has an open circuit vol-
tage of less than about 1.75 volts, it should provide a single voltage plateau
during closed circuit discharge, even at low drains, for example discharges
through loads of about 100,000 to about 500,000 ohms.
In addition to the silver layer on the depolarizer blend, the amount
of divalent silver oxide present in the depolarizer blend is criticalO It is
preferred to have the maximum amount of divalent silver oxide and still achieve
a single voltage plateau during discharge and a stable depolarizer blend. It
has been determined that the amount of divalent silver oxide should not be
greater than about 70% by weight of the silver oxide blend. In addition to
the divalent and monovalent silver oxides, the depolarizer may also contain
minor amounts of a lubricant and/or binder such as polytetrafluoroethylene or
other suitable plastic binder. Ingredients may also be incorporated in the
depolarizer for the purpose of providing voltage stability such as silver powder,
and to insure the stability of the divalent silver oxide in the alkaline elec-
trolyte~ such as gold hydroxide as disclosed in United States patent Number
3,853,623.
The negative electrode may be zinc, cadmium, indium, magnesium,
aluminum, titani~ or manganese. It is preferred to use zinc active material
which may be in the form of finely divided zinc particles, gelled or semi-
gelled zinc particles, or a zinc foil. It is generally preferred that the zinc
active material should be amalgamated regardless of the form which is usedO
Between the depolarizer blend and the negative electrode, there is
placed a separator which generally comprises both an absorbent component and a
barrier material. The absorbent component may be made from a cellulosic mate-
rial such as matted cotton fibers or from a non-cellulosic material such as
-- 5 --
l~Z97~
microporous polyethylene. The absorbent material holds the electrolyte (gene-
rally in contact with the negative active material), and a plurality of layers
may be used. The barrier material may also comprise one or more layers for
preventing the passage of metallic ions or dendrite growth from one electrode
to the other. The barrier material may be any suitable semi-permeable material
such as the regenerated cellulose material commercially available under the
trademark "Cellophane", either alone or in combination with a synthetic bar-
rier such as polyethylene grafted with methacrylic acid. It is preferred to
use a laminated barrier material which comprises a layer of polyethylene
grafted with methacrylic acid be~ween layers of Cellophane, ~trademark).
The cells of this invention utilize an alkaline electrolyte consis-
ting essentially of an aqueous solution of potassium hydroxide. The electrolyte
is preferably limited to an amount sufficient only to provide wetting of the
cell components without establishing a liquid level of free electrolyte in
the cell. The alkaline electrolyte preferably has a potassium hydroxide con-
centration of at least about 3% by weight ranging up to about 50% by weight.
It may contain minor amounts of additives such as zinc oxide to inhibit dis-
solution of the zinc negative active material, and other alkali metal hydro-
xides, e.g. cesium, rubidium or sodium, may be substituted for minor portions
of the potassium hydroxide.
A critical feature of this invention is the formation of the layer
of silver on the surface of the depolarizer blend adjacent to the separator.
A substantially continuous and electrolyte permeable layer of silver may be
fo~med by treating the surface of the depolarizer blend with a strong reducing
agent such as hydrazine or formaldehyde solutions. Other relatively strong
reducing agents such as hydrogen, metals ~zinc and iron), tin chloride, iron
sulfate, sulfurous acid, oxalic acid, formic acid and hydroxylamine can also
be used, provided that they are strong enough to reduce the depolarizer blend
to silver within a reasonable time. When using hydrazine or formaldehyde,
methanol solutions of the reducing agent are preferred and the surface of the -
97g
depolarizer blend is treated for several minutes, generally from about 2-6
minutes is su-fficient. A high proportions o-f AgO may require a longer reducingagent treatment. The treatment with the reducing agent is usually performed
at room temperature, however~ elevated temperatures may be used especially
if it is desired to accelerate the reduction. Aqueous solutions of the reducing
agent can be used as well as an organic so]vent solution.
The depolarizer blend can be physically mixed, incorporating additi-
ves for special purposes, and then compressed into a pellet. The entire
surface of the pellet can be reduced to silver by soaking the pellet or tumblingit in the reducing agent solution. This is not a preferred method, for it was
found that pieces of the compressed depolarizer pellet broke off during the
reduction treatment, and in some cases there was non-uniform pellet reduction~
In addition to physical mixing, the depolarizer blend may be prepared by (1)
oxidizing silver powder, ~2) reducing a portion of a divalent silver oxide
active material, or (3) reducing the AgO in situ by mixing it with a reducing
metal such as zinc or cadmium.
The preferred method for manufacturing the depolarizer blend com-
prises (1) forming the depolarizer blend comprising divalent silver oxide
and monovalent silver oxide9 (2) compressing the blend in a press to form a
pellet using a pressure ranging from about 40,000 to 60,000 psi, (3) placing
the pellet in the cathode container, (4) consolidating the pellet in the con-
tainer by compression using a consolidation pressure ranging from about 50,000
to 70,000 psi, and (5) treating the consolidated pellet/cathode container
component with the reducing agent solution. In this preferred method, the
bottom and sides of the depolarizer blend pellet remain non-reduced, however,
treatment with the reducing agent may be carried out prior to consolidation~
It is preferred to place a sleeve around the upper edge of the depolarizer
blend, and this may be done prior to consolidating the pellet in the cathode
containerO The sleeve functions as a supporting surface to protect ~he
-- 7 --
1~)429~9
depolari~er pellet during consolidation and when the cell is sealed by crimping
the upper edge of the cathode container upon the grommet molded on the edge
of the anode container.
One of the principal objectives of this invention is to increase
the energy density per unit weight or volume of the depolarizerO Maximum
energy density would be achieved by using only divalent silver oxide depolarizer
materialg but the resultant cell has two vol~age plateaus during discharge
and the divalent silver oxide is very unstable in the potassium hydroxide
electrolyte. It has been found that the depolarizer blend can contain a maxi-
mum of about 70% by weight of divalent silver oxide and still provide a highdrain rate alkaline cell having a single voltage plateau and a stable depola-
rizer. When mass producing the high drain rate, primary alkaline cells, it is
generally preferred to use a depolarizer blend comprising at least about 50%
divalent silver oxide in order to insure that the cell has a single voltage
plateau, satisfactory elevated temperature stability, and improved electro-
chemical capacity.
; Referring now to Figure 1~ a button cell construction (10) is illus-
trated~ for the high drain rate, primary alkaline cells of this invention are
particularly adapted for use in this construction, and button cells were used
to evaluate the divalent silver oxide/monovalent silver oxide depolari~er
blendsO These button cells are of the type currently used as a power source
for electronic watches, an application for which the high drain rate, primary
alkaline cells having a divalent silver oxide/monovalent silver oxide depola-
rizer blend coated with a layer of silver are particularly effective.
The negative electrode (anode) container (11) comprises what is
commonly referred to as a "double top". Two cans are placed in physical,
electrical contact with each other, with the inner can (12) being nested in
the outer can (13) to form a tight friction fit. It is generally preferred
to spot weld the cans together as indicated at (14) to maintain permanent
-- 8 --
~)42~9
electrical contactc The cans may be made from nickel-plated stcel which has
good corrosion resistance, however, other materials may be used and the sur-
faces of the cans can be given special coatings. The "double top" anode con-
tainer is pref7erred for its superior leakage prevention properties~ however~
a single top container can be used. A collar orgrommet (15) of nylon or poly-
ethylene is molded onto the edge of the anode container (11) to electrically
insula~e it from the depolarizer (cathode) container (16)o. The negatiue elec-
trode or anode ¦17) is a zinc active material in the form of a gel or semi-gel
comprising finel~ divided zinc particles, a small amount of gelling agent such
as guar gum or carboxymethyl cellulose (e.gO 0.2% by weight) and a portion of
the aqueous potassium hydroxide electrolyte solution.
The separator comprises an abs~rbent component (18) and a barrier
material (19). It is preferred to use matted cotton fibers (commercially
available under the trademark "~ebril") as the absorbent component which also
contains a portion of the alkaline electrolyteO The semi-permeable barrier
material comprises a layer (20) of polyethylene grafted with methacrylic acid
(commercially available under the trademark "Permion") sandwiched between layers
A ~ ~ ~ I/dp~
(21) of ~e~10~h~n~. The absorbent component (18) is placed in contact with
the ~inc active material, and the barrier material is in contact with the
silver layer (22) on the surface of the depolarizer blend (23)o
The depolarizer blend or cathode (23) comprises a mixture of diva-
lent silver oxide ~AgO) and monovalent silver oxide (Ag20) and additives for
special effects. The depolarizer blend generally contains polytetrafluoroethy-
lene as a binder and lubricant. The blend may also contain a minor amount of
a gas suppressan~ such as gold hydroxide to insure the stability of the diva-
lent silver oxideO The following is a preferred depolarizer blend composition:
Ingredient Amount (% by wto)
Divalent Silver Oxide (AgO) 50
Monovalent Silver Oxide (Ag20) ~8.35
Polytetrafluoroethylene~ Teflon) 1.5
Gold Hydroxide - 0.15
~q ~ e nn~ ~5 ~ 9 ~
~)4~79
The silver layer (22) is formed in situ on the depolarizer blend after it is
consolidated in the cathode container (16) by immersing it in a 3% by weight
hydrazine solution in methanol for about S minutes. ~hen formed in this manner~
the silver layer is substantially con~inuous and electrolyte permeableO A
sleeve (241 is placed around the upper edge of the depolarizer blend, however,
this is not an essential component of the button cell constructionO If desired,
the entire surface of the depolarizer blend (23) can be reduced by carrying
out the reduction treatment prior to consolidation in container (16)o
The high drain rate~ primary alkaline cells of this invention are
specially designed and constructed as power sources for electronic watches
having a light emitting diode ~IED) display. These watches require a battery
which is capable of providing a high drain rate discharge in the form of pulsesO
It is essential in order to light the display for a reasonable number of p~ses
that the primary alkaline cells be capable of providing a flash current greater
than an average of 0.2 amperes per square centimeter of cell cross-sectional
areaO In addition, the cell system must have improved stability in the pre-
sence of alkaline electrolyte~ for the potassium hydroxide electrolyte requ1-
red for the high drain rate capability accentuates the propensity of the
divalent silver oxide to evolve gas in the presence of alkaline solutions. In
some cases it may be necessary to precondition the cell before using it as a
power source by short circuiting the cell for a few seconds. It has been dis-
covered that this preconditioning increases the flash current of the cell and
provides more uniform flash current performance.
Example 1
Primary alkaline button cells (RW 44 size having a cathode container
diameter of 0.450 inches and a height ranging from about 00150 to about 0.162
inches) having the construction illustrated in Figure 1 were tested to deter-
mine the effect of a silver layer placed on the depolarizer blend surface
for high rate cells (35% KOH t 1% ZnO aqueous electrolyte solution)O In
-- 10 --
~6~4~
addition to the mixture of divalent and monovalent silver oxides~ the depola-
rizer blend contained 1.5% by weight of polytetrafluoroethylene and 0.15% by
weight of gold hydroxide. The depolarizer blend was immersed, after consolida-
tion in the cathode container, in a 3% by weight hydrazine in methanol solution
for 3 minutes to f~rm the substantially continuous silver layer. The anode
was a zinc blend comprising 99.8% by weight of amalgamated zinc particles (7%
mercury) and 002% by weight of guar gum gelling agent. The closed circuit
voltage (CCV) was measured through a 167 ohm loadO The electrical properties
and stability were recorded as the average for 30 cellsO The flash current
was measured by electrically connecting a cell to a standard ammeter (having
an internal resistance of about 0.015 ohms~ and determining the current flow
at 0.5 secondsO The following results were recorded:
Cell
Electrical Properties Expansion
Flash 4 wks. at
% AgO in Electro- Silver Impedance OCV CCV Current 165 F
Depolarizer lyte Layer (ohms) (volts) (volts) (amps) (mils)
40 ~OH No34.4 1085 1.28 0015 2102
40 " Yes3.4 1.60 1-55 0.69 12.5
30 " No35.7 1.85 1.15 0013 2007
30 " ~es3.0 1060 1-55 0.71 806
The superior performance and properties of the cells having a silver layer on
the depolarizer blend is clearly demonstrated.
Example 2
Primary alkaline button cells (RW 44 size) having the construction
illustrated in Figure 1 were made to determine the effect of varying the AgO/
Ag20 ratio in combination with and without a hydrazine reduction treatment to
form a silver layer on the depolarizer blendO The hydrazine treatment consis_
ted of soaking the consolidated pellets in a sclution of 1% by weight hydra-
zine in methanol, with stirring, for 3 minutes. In each of the cells, the
sleeve around the depolarizer pellet was silver-platedO The electrolyte was a
_ 11 --
97~
40% KOH ~ 1% ~nO aqueous solution~ The following results were recorded:
Cell
Electrical Properties Expansion
7 days
% AgO in Silver Impedance OCV CCV(1670hms) at 165 F
Depolari7er Layer (ohms~ ~ (voltsl (mils)
No 98-4 1.86 1.33 804
Yes 2.9 1.61 1.55 4.4
No 97-4 1.86 1.34 7-0
Yes 2.7 1.61 1-55 6.2
No 93.6 1.86 1.37 15.4
Yes 9.9 1.61 1.54 16.4
No 99.4 1.86 1.34 7~4
Yes 51.1 1.64 1050 7.o
No 88.5 1.86 1035 10.4
Yes 28.5 1062 1053 9.2
The electrical properties were recorded as the average for 30 cells. The
superior performance and properties of the cells having the silver layer on
the depolarizer blend is clearly demonstratedO
Example 3
Primary alkaline button cells (RW 44 size) were treated with 2
difPerent strong reducing agents to form a silver layer on the depolarizer
blend~ and voltage and cell stability were determinedO The depolarizer blend
comprised 50~ by weight AgO mix, 49% by weight Ag20 and 1% by weight polytetra-
fluoroethylene. The AgO mix had the following composition:
Ingredient mount (~0 by wto)
AgO 9502
Ag powder 3.0
Polytetrafluoroethylene 105
- (Teflon)
Au (OH)2 0.3
All of the depolarizer blends were soaked for 1 minute in a 90/10 solution of
30% KOH/methanol, followed by rinsing and drying prior to the strong reducing
agent treatment. All cells had a silver-plated sleeve around the depolarizer
pellet.
Lot A was treated in a solution of 1% by weight hydrazine in
_ 12 -
. . .
1~42~7~
methanol for 3 minutes at room temperatureO Lot B was treated in approximately
100 ml. of 30% KOH aqueous solution to which 2mlO of 37% by weight formaldehyde
in methanol was added. The solution containing the consolidated depolarizer
blend was heated to 50C. and the treatment was carried out for 15 minutes.
Each lot comprised 40 cells with each cell having a zinc gel anode (99.8% by
weight amalgamated zinc particles ~ 002% by weight guar gum) and a 40% KOH
1% ZnO aqueous electrolyte solutionO The following results were recorded:
FlashCell Expansion
Lot Impedance Current-1 wk at 165F
Number OCVCCV (167 ohms) ~ s) _(amps)(mils)
A 1.62v. 1-55v~ 203 oO76 2.7
B 1061v. 1.57v. 2~3 0.77 7-
These results demonstrate that the formation of the silver layer on the depo-
larizer blend surface can be accomplished with any strong reducing agent capa-
ble of reducing AgO to Ag.
Eæample 4
Primary alkaline cells (RW 44 size~ having a construction similar to
the cell illustrated in Figure 1 were tested to determine the effect of using
varied proportions of divalent silver oxide (AgO) in the depolarizer blend.
All cells were made with a 40% potassium hydroxide aqueous solution containing
1% by weight zinc oxide. In addition to the silver oxides, the depolarizer
blend contained about 1.5% by weight of polytetrafluoroethylene. The cells in
Lots A-D were treated in a solution of 1% by weigh* hydrazine in methanol for
-~`- 6 minutes at room temperature~ and Lots E-I were treated in the hydrazine solu-
tion for 3 minutesO The electrical properties are reported as the average of
12 to 40 cells, with CCV measured through a 30 ohm load for Lots A-D and a 167
ohm load for Lots E-I, and the electrical data was recorded 1 day after closure
for Lots A-D and 2 weeks after closure for Lots E~Io The cell expansion data
was the average of 4 to 6 cellsO The following results were recorded:
- 13 -
~ ~ 4 Z 9 Flash Cell Expansion
Lot Impedance OCV CCV Current 1 wk at 160F~
Number ~ ~ A~O (ohms~ _ (volts~ (30 ohms) (amps)(milsl____
A 1088.5 2.7 1-59 1.43 0.53
B 2078.5 2.5 1-59 1.44 0057
C 3068.5 2.6 1.60 1-44 o.67 o
D 4 5805 2.4 1060 1.45 0.72 0
CW
(167 ohms)
E 5 4805 15.7 1.60 1.48 0.49 4
F 6038.5 7703 1.58 1049 oO58 7
G 7028.5 26.0 1.75 1047 0.53 8
H 8018.5 30.0 1.83 1046 0.55 12
I 9 8.5 26.5 1085 1.38 0.44 9
These results indicate that open circuit voltage and gassing stability
(cell expansion) were no problem until the depolarizer blend contained at least
about 50% AgO, and the cells with depolari3er blends containing at least about
80% AgO had open circuit voltages which were too high and had increased cell
expansionO
- 14 -
