Electrical cells and batteries and methods of making the same

A laminar triplex structure for use in the manufacture of electrical cells and batteries, cells and batteries made therefrom, and methods of making the same. The laminate comprises a thin flat sheet of separator material, a layer of metallic particles on one surface of the separator sheet and adhered thereto with a binder, and a layer of conductive plastic adhered to the layer of metal particles. The laminate is made by the process of coating a dispersion of metal particles in a solution of a polymeric binder in an organic solvent over the separator, drying to remove the solvent, coating over the dried metal layer with a dispersion of conductive particles in a solution of a polymer in an organic solvent, and drying to remove the solvent.

This invention relates to electrical cells and batteries, and particularly 
to novel thin flat laminar cells and batteries and to methods and articles 
for making the same. 
It has been found possible to make thin flat laminar batteries with 
sufficiently low internal impedance to suit them for use in very high 
current drain applications. A particularly efficient form of battery of 
this kind is shown and described in copending U.S. application for Letters 
Pat. Ser. No. 761,651, filed on Jan. 24, 1977 by Edwin H. Land for 
Electrical Cells and Batteries and assigned to the assignee of this 
application. The object of this invention is to simplify the manufacture 
of batteries characterized by series connected cells comprising thin, flat 
laminar cell components. 
Briefly, the above and other objects of the invention are attained by 
forming a triplex laminate comprising a conductive plastic intercell 
connector, a laminar electrode and a separator adhered together in an 
integral structural unit. The laminate may be made in long runs of sheet 
by continuous coating processes. In a particular and presently preferred 
embodiment of the invention, the separator is made of unplasticized 
cellophane, and the coated electrode material is powdered zinc. A 
dispersion of the zinc powder and carbon black is made in a solution of a 
polymeric binder in an organic solvent. This dispersion is coated on one 
side of the cellophane, and the solvent removed by drying in heated air. 
The dispersion coating may be a continuous one, but may alternatively be 
deposited only in predetermined electrode site regions, as by extrusion. 
The zinc coated side of the coated cellophane is then coated with a 
dispersion of carbon particles in a solution of an elastomer in an organic 
solvent. The solvent is then removed by drying in heated air, to form the 
finished laminate. In the manufacture of cells from this laminate, a wet 
slurry cathode containing aqueous electrolyte is applied to a central 
region of the cellophane side of the laminate, causing the cellophane and 
thence the zinc layer to be wet by the electrolyte to complete a cell. 
Batteries may be made by the superposition of cells of this kind, in a 
manner which will be apparent from the following detailed description, 
together with the accompanying drawings, of various illustrative 
embodiments of the invention.

Referring to FIG. 1, the process of making a triplex laminate according to 
one embodiment of the invention begins with the coating of an electrode 
dispersion on a web of separator material. As the separator material, any 
of those commonly employed in the battery art can be used, such as paper 
and various woven and non-woven natural and/or synthetic liquid permeable 
materials. However, there are particular advantages in the use of 
regenerated cellulose as the separator in a LeClanche system, and the 
process of the invention has been found to take advantage of certain quite 
peculiar properties of regenerated cellulose that enhance its value in 
such systems. Accordingly, while it should be understood that the 
invention in its broader aspects can be practiced with other suitable 
materials, it will be particularly described in connection with its 
preferred embodiment in which regenerated cellulose, and specifically a 
sheet of cellophane free of humectants and plasticizers, serves as a 
separator. A particularly suitable form of cellophane for this purpose is 
PUD-O cellophane, 1.34 mils in thickness, as made and sold by E. I. 
duPont de Nemours & Co. of Wilmington, Del. 
As illustrated in FIG. 1, the separator may be conveniently supplied as a 
web 1 from a supply reel 2, whence, after coating, it is ultimately taken 
upon on a take-up reel 3 that is driven in any conventional manner. As 
will be obvious to those skilled in the art, intermediate guide, drive and 
tensioning rolls, idler rolls, reversing rolls and the like may be 
employed in the path between the supply reel 2 and the take-up reel 3, but 
as such are conventional in the coating art and not material to the 
invention, they will not be specifically described. 
The web 1 passes from the supply reel 2 over a guide roller 4 so that it 
moves upward past a coating station comprising a conventional doctor blade 
5 that is adjusted to a fixed height in dependence on the thickness of the 
coating desired. Electrode dispersion 8 is pumped from a suitable 
container 6 and deposited by a supply tube 7 on the cellophane sheet 1. 
The coated thickness is regulated by the doctor blade 5. 
The coated web moves from the guide roller 4 through a conventional dryer 
schematically indicated at 10, where the coated slurry 8 is dried in 
heated air to remove the solvent and form a dry layer 9. In industrial 
practice, the solvent would preferably be recovered by conventional means, 
as schematically illustrated. The dried coated product, comprising a layer 
9 of electrode particles adhered to the cellophane sheet 1, is taken up on 
the supply reel, where it may be stored for second coating in a manner to 
be described. Alternatively, the dried and coated web material may be 
passed directly to the next coating operation. 
The electrode dispersion 8 generally comprises a dispersion of metal 
particles, for example, zinc, magnesium, silver, cadmium or aluminum 
particles or the like, depending on the electrochemical system to be used 
in the batteries to be produced. However, in accordance with the preferred 
embodiment of the invention, powdered zinc, or powdered zinc together with 
a little carbon black, are preferably dispersed in an organic solvent. A 
polymer is added to the solvent to act as a binder for the zinc and carbon 
particles when the solvent is removed. 
It has been found essential to use an organic solvent to prepare the 
electrode slurry, because an aqueous slurry, while readily coated, will, 
upon drying, cause such distortion of the cellophane that the product will 
be useless for the purposes here described. Organic solvents that may be 
employed are alcohols, Ketones, esters and aromatics. Toluene is the 
presently preferred solvent. 
Compositions that have been found especially successful for use as the 
electrode dispersion 8 are described in copending U.S. application Ser. 
No. 811,471, filed concurrently with this application by Charles K. 
Chiklis for Conductive Compositions and Coating Compositions For Making 
The Same, and assigned to the assignee of this application. The presently 
preferred composition for this purpose is as follows, in percent by weight 
based on the total weight of coating composition: 
______________________________________ 
Powdered zinc 56.9 
Carbon black 1.7 
Polymeric binder 4.6 
Toluene 36.8 
Total 100.0 
______________________________________ 
The polymeric binder in the above composition was a radial teleblock 
copolymer of 70 parts by weight of butadiene and 30 parts by weight of 
styrene based on the total weight of polymer and available as Solprene 
411C from Phillips Petroleum Company. Other soluble or dispersable 
polymeric binders with adequate power to bind the zinc and carbon black to 
the cellophane, and later to assist to some extent in bonding the coated 
zinc layer to the conductive plastic layer to be added, may be employed. 
However, preferred materials are elastomeric in nature to reduce the 
brittleness and the tendency to chalk and flake characteristic of anodic 
compositions with a high metal content. The composition given above, when 
dried on a cellophane web, is 90.1 percent zinc powder, 2.6 percent carbon 
black, and 7.3 percent copolymer, based on the total weight of dried 
composition. 
Drying conditions in the dryer 10 will, of course, be determined in part by 
the exact nature of the composition of the electrode slurry 8, and by the 
vapor pressure of the chosen solvent or solvent blend employed. For the 
electrode slurry described above as the preferred example, a two stage 
dryer 10 was used, with temperature of 110.degree. F. in the first stage 
and 120.degree. F. in the second stage. The coating weight is adjusted so 
that the final thickness of the layer 9 is from about 1/2 mil to 21/2 
mils, and preferably about 2 mils in total thickness. 
The dried coating should be smooth, even, free from defects, and relatively 
adherent to the cellophane. In this regard, it is noted that coatings of 
this type have been attained on cellophane, and that the coated material 
can readily be handled without damage or loss of the zinc coating while 
the cellophane is dry. After the cellophane becomes wet during assembly of 
the battery in the manner to be described, however, the bond will be 
affected. This matter will be discussed in more detail below. 
FIG. 2 illustrates the application of a conductive plastic layer to 
cellophane coated with a dried zinc layer 9. This material may be supplied 
to the coating apparatus from the roll 3, whence it is passed over a guide 
roll 13 past a coating station at which there is a doctor blade 14. 
With the exception of details to be noted, the coating apparatus may be the 
same as that described above in connection with FIG. 1. In fact, the same 
apparatus has been used, with suitable adjustment of the doctor blade 14, 
and of the temperatures in the dryer to be described. 
A conductive plastic slurry 12 is supplied from a suitable storage 
container 16 and is pumped from the container 16 by any conventional 
means, not shown, through a supply conduit 17, from which it is deposited 
as a constant reservoir on the coating 9 on the cellophane sheet 1. 
The wet coating 12 from the coating station is carried through a dryer 20 
where it is dried with heated air, as discussed above, to form a dry layer 
15. It has been found that temperatures in the neighborhood of 
200.degree.-210.degree. F. are appropriate for drying the dispersion layer 
12. The dispersion 12 is preferably coated to a greater thickness than the 
zinc coating, so that somewhat higher temperatures and longer drying times 
are required because of the increased solvent load. From the dryer 20, the 
triplex laminate, which now has a dry coating 15 of conductive plastic, is 
taken up on a suitable take-up reel 21 in the manner similar to that 
described above with respect to the duplex coating of FIG. 1. 
The formulation 12 is preferably a dispersion of carbon particles in an 
organic solution of a suitable thermoplastic material. The carbon is 
preferably carbon black, and most preferably Shawinigan Black as made and 
sold by Shawinigan Products Corp. of New York, N.Y. A rubbery binder is 
strongly preferred for the thermoplastic constituent of the conductive 
plastic slurry, as the carbon filled film formed when the solvent is 
evaporated tends to be tougher, more resilient and less prone to damage 
caused by stress through handling of the product. The presently preferred 
elastomer is the radial teleblock copolymer of styrene and butadiene 
described in the above cited copending U.S. application Ser. No. 811,471. 
Organic solvents are presently preferred for use in making up coating the 
dispersion 12. Aqueous systems can sometimes cause distortion of the 
cellophane during coating. A presently preferred coating composition for 
use as the slurry 12 is as follows, in percent by weight based on the 
total weight of slurry: 
______________________________________ 
Carbon black 6.5 
Elastomer 18.6 
Toluene 74.9 
Total 100.0 
______________________________________ 
The elastomer used was Solprene 411C, described above. This composition 
dried to a composition of 25.9 percent carbon black and 74.1 percent 
elastomer, based on the total weight of dried conductive plastic 15. 
The conductive plastic layer 15 has been made and used successfully in 
thickness from 1/2 mil to about 5 to 7 mils. Very successful batteries 
have been made with the 1/2 mil coatings 15, but the presently preferred 
range is about 3 to 4 mils in thickness. The higher coating thickness is 
desirable, because it is found that the conductive plastic formed is 
sufficiently conductive that the thickness is not critical, while the 
added insurance against defects makes it easier to manufacture a product 
of uniformly high quality. If desired, the conductive plastic coating may 
be applied in two or more sequential layers, with intermediate drying, as 
another means of minimizing the occurrence of defects. FIG. 3 shows the 
elements of the finished web in relative thicknesses close to those 
preferably employed. 
Following manufacture of the triplex laminate just described, it is cut 
into convenient pieces for the manufacture of batteries. FIGS. 4 and 5 
show such a piece 25 of the laminate in the form of a rectangular sheet 
adhered to a frame 26 to form a subassembly useful in the manufacture of 
cells and batteries by a process to be described below. The frame 26 may 
be of any suitable thermoplastic material which can be sealed to itself 
and to the conductive plastic layer 15. 
One suitable material for the frame 26, and other frames to be described, 
is Versalon 1140 polyamide resin, as made and sold by General Mills 
Company of Minneapolis, Minn. A currently preferred material, however, is 
a radial teleblock copolymer of styrene and butadiene containing 30 
percent styrene and 70 percent butadiene by weight of copolymer, 
essentially the same as the copolymer preferably used in the conductive 
plastic composition described above, but preferably of a lower molecular 
weight. A suitable composition for this purpose is Solprene 416S, as made 
and sold by Philips Petroleum Company. This material may be compounded 
with from 0 to 30 percent by weight, based on the total weight of 
plastics, of high flow polystyrene. In practice, the thermoplastic 
constituents are blended in a Banbury mixer, with conventional 
antioxidants and a small amount of stearic acid, then milled, extruded, 
cooled, and chopped into beads. The beads are then remelted and extruded 
into sheets, from 5 mils to 25 mils in thickness. About 15 mils is 
presently preferred. The more polystyrene that is included, the stiffer 
the material becomes. About 75 percent of the radial teleblock copolymer 
and 25 percent of polystyrene by weight based on the weight of polymers is 
a desirable ratio in the range of 15-20 mils in thickness. 
The frame 26 is formed with an internal rectangular opening 27 that is well 
within the confines of the laminate 25 and forms a central opening to 
receive other cell components to be described. The laminate 25 and the 
frame 26 are preferably heat sealed together to form a unitary subassembly 
28 for manufacture, as will next be described in connection with FIG. 6. 
Referring to FIG. 6, manufacture of a battery in accordance with the 
invention may begin with the preparation of a cathode terminal subassembly 
29 comprising three laminae adhered together and consisting of a base 
sheet 30, of 5 mil kraft paper or the like, which may serve as a part of a 
carrier web to be used in manufacturing batteries in a manner known in the 
art per se, but which in any case extends outwardly slightly beyond the 
other components for purposes of insulation, convenience in transport and 
registration of components, ease in cutting following assembly, and the 
like. 
The sheet 30 may be formed with an aperture 31 which will later serve to 
admit contacts of electrical apparatus to engage a cathode metal end 
terminal sheet 32, which may consist of aluminum, tinned steel, or the 
like, and is preferably about 2 mils in thickness. Adhered to this metal 
terminal sheet 32 is a cathode current collector sheet 33 of conductive 
plastic, such as Condulon conductive vinyl sheet as made and sold by 
Pervel Industries, Inc, and, for example, of about 2 mils in thickness. 
Alternatively, the current collector 33 may be made by the process of 
casting the coating composition 12 of FIG. 2 onto suitably primed steel or 
aluminum sheets. A suitable primer for steel is described in copending 
U.S. application for Letters Pat. Ser. No. 742,837, filed on Nov. 18, 1976 
by Neal F. Kelly for Conductive Laminate And Methods And Compositions For 
Making The Same, and assigned to the assignee of this application. A 
suitable primer for aluminum is described in U.S. application for Letters 
Pat. Ser. No. 801,519, filed on May 31, 1977 by Herbert N. Schlein for 
Methods And Compositions For Adhering Metal to Plastic and assigned to the 
assignee of this application. Said applications Ser. Nos. 742,837 and 
801,519 are incorporated herein by reference, and are referred to for the 
details of the priming compositions and methods of application. 
As suggested in FIG. 6, to the cathode subassembly just described is added 
a frame 34 of insulating material. One suitable material is the Versalon 
1140 polyamide hot metl adhesive resin described above. The frame 34 may 
be heat sealed to the conductive plastic surface of the collector 33, to 
form a liquid tight seal. The Versalon 1140 resin mentioned above can be 
sealed in this manner by the application of heat, with or without 
pressure. 
The thickness of the frame 34 is not particularly critical, but if desired 
it can be relatively thin, as the frame 34 serves only an insulating 
purpose to be described; it incidentially serves as part of the battery 
seal in the final assembly, as will appear, but this function itself could 
be performed by other framing elements to be described. 
When the frame 34 is assembled onto the end cell assembly 29 and there 
sealed as just described, the combination is passed to a conventional 
extruder 35 which receives a supply of cathode slurry from a suitable 
supply vessel 36 and applies a layer of cathode slurry over the surface of 
the current collector 33 within the opening provided in the frame 34. It 
should be noted that the frame 34 protrudes slightly beyond the edges of 
the end terminal comprising the current collector 33 and the metal 
terminal sheet 32 to perform a desired insulating function. 
As suggested in the drawing, when a thin frame 34 is used, the first 
cathode layer 37a may protrude above the surface of the frame. 
The next operation in the assembly of a battery in accordance with this 
embodiment of the invention is the addition of one of the subassemblies 
28, described above in connection with FIGS. 4 and 5, to the frame 34, in 
such a manner that the cellophane separator portion will contact the 
cathode slurry layer 37a. As shown in FIG. 6, the assembly 28 is placed 
onto the frame 34 for this purpose with the conductive plastic side 15 up. 
The result is the subassembly illustrated at 40 in FIG. 6. 
Next, a layer of cathode slurry is extruded onto the surface of the 
conductive plastic 15a of the first subassembly 28a within the opening in 
the frame 26a to form a subassembly 41 having a cathode layer 37b as 
indicated in FIG. 6. Onto this assembly 41 is next placed a second 
subassembly 28b, by an operation repetitive of that just described and not 
shown in FIG. 6, followed by the extrusion of another cathode layer onto 
the opening of the frame, as suggested by the block 42 in FIG. 6, 
whereupon the next subassembly 28c is added as shown by the block 43 in 
FIG. 6. The final cathode slurry layer 37d is added by repeating the 
process shown by the block 42, and the result is a subassembly indicated 
at 44 in FIG. 6 that is ready for an anode terminal assembly. 
The anode terminal assembly 56 is prepared from a subassembly indicated in 
FIG. 6 as a metal end terminal sheet 50 of tinned steel, aluminum, or the 
like, preferably about 2 mils in thickness, to which there is adhered a 
conductive plastic anode terminal collector 51 which may be of the same 
material and thicknes as the cathode current collector sheet 33. A thin 
layer 52, which may be a glassine overwrap layer substantially coextensive 
with the area of the finished battery and employed for aid in sealing in 
the manner described in U.S. Pat. No. 4,019,251, granted Apr. 26, 1977 to 
Thomas P. McCole for Flat Battery and Method of Manufacture, and assigned 
to the assignee of this application, may be adhered to the steel 50 at 
this stage, or if desired, may be added at a later stage. 
On the anode current collector sheet 51 is deposited a zinc anode patch 53. 
In accordance with one practice of the invention, this anode patch 53 was 
made as a thin layer of zinc powder with a binder extruded onto the 
surface of the conductive plastic anode current collector 51 in a 
conventional manner, and dried. In accordance with this particular 
embodiment, the current collector 51 was made of 2 mil Condulon conductive 
vinyl resin as described above, and the zinc anode patch 53 was made from 
the following composition, expressed in parts by weight: 
______________________________________ 
Zinc powder 1,000 
H.sub.2 O 149.2 
Benton LT .61 
Tetrasodium pyrophosphate 
.25 
Shawinigan Black 5 
Polytex 6510 latex 39.05 
______________________________________ 
Polytex 6510 is an acrylic emulsion resin made and sold by Celanese 
Corporation of Newark, New Jersey. Benton Lt is an organic derivative of 
hydrous magnesium silicate as made and sold by National Lead Company, 
Inc., of New York, N.Y. 
Over the dried patch 53 is next placed a framed separator subassembly 
comprising a frame 54, which may be of insulating material and, for 
example, of the same thermoplastic composition as for the frames 26 and 34 
described above. To this frame 54 is temporarily heat sealed a cellophane 
separator 55. As suggested in FIG. 6, the frame is inverted and placed 
down over the anode collector 51 with the cellophane separator 55 in 
contact with the zinc patch 53. The frame 54 is then heat sealed to the 
surface of the conductive plastic 51 to form the anode terminal 
subassembly 56 as shown in FIG. 6. In practice, best results have been 
obtained by coating the zinc patch 53 with a layer of about 5.4 mils of 
gel electrolyte, of a composition to be described below, before the frame 
54 and cellophane separator 55 are put in place. Operable batteries can be 
made without this layer of gel electrolyte, but better results have been 
obtained with it. 
The subassembly 56 just described, with or without the gel electrolyte, is 
inverted and placed down over the subassembly 44 to produce an unsealed 
battery suggested at 57 in FIG. 6. As indicated, the end 60 of the 
collector sheet 50 and metal terminal 51 projects outwardly from the body 
of the battery. The purpose of this extension is to allow the terminal to 
be folded around over the insulating kraft paper layer 30 to the other 
side of the battery, making the anode terminal accessible on the same side 
as the cathode terminal. Since this is a conventional matter which does 
not form a part of the present invention, it will not be elaborated upon. 
FIG. 7 shows the details of the battery 57 of FIG. 6 following sealing. 
Sealing is carried out by applying heat and pressure around the edges of 
the battery in a known manner, and so effects some compaction as suggested 
in FIG. 7. Sealing is carried out under conditions such that the edges of 
the triplex laminates 25a, 25b and 25c are well buried in a thermoplastic 
frame, so that when the cellophane separators 1a, 1b and 1c become wet, 
the resulting loss of bond between the cellophane and the frame and the 
zinc layers will not cause leakage. The composition of the cathode slurry 
used to make the layers 37a, 37b and 37c and 37d is selected to provide 
sufficient moisture to wet both the cellophane separators and the zinc 
anode layers 9a, 9b, 9c and 53. For this purpose, compositions such as 
that disclosed in the above-cited U.S. application Ser. No. 761,651 have 
been successfully employed, except that it is preferred to use additional 
water in the mix, and to add a corrosion inhibitor such as mercuric 
chloride. A presently preferred composition is as follows, in percent by 
weight based on the total weight of slurry: 
______________________________________ 
H.sub.2 O 28.83 
NH.sub.4 Cl 9.89 
ZnCl.sub.2 4.99 
HgCl.sub.2 1.88 
Shawinigan Black 6.10 
MnO.sub.2 48.81 
Total 100.00 
______________________________________ 
While the adhesive bonds between the cellophane and adjacent layers may be 
affected by the wetting process, the presence of the initial bond between 
the cellophane and the zinc layer 9 has been found to be very helpful in 
the process of activating the battery by liquid electrolyte diffusing from 
the cathode slurry through the separator into the initially dry zinc anode 
layers. Unplasticized cellophane swells when in contact with aqueous 
electrolyte solutions, and is prone to wrinkle, especially if initially 
constrained. However, it has been found that when the constraint takes the 
form of an even binding over the whole surface of the separator, as 
achieved with the zinc layers 9, then during wetting the cellophane 
apparently tends to swell uniformly, and thus remain smooth without 
wrinkling while the battery comes to equilibrium. 
The function of the frame 34 in the structure of FIG. 7 is to insulate the 
first triplex laminate 25a from the conductive plastic cathode current 
collector 33. It might be supposed that as good results could be attained 
by placing the frame 26a and the laminate 25a directly in contact with the 
current collector 33 and there sealing it. However, when this has been 
done it has been found that a short circuit may develop between the zinc 
layer 9a and the current collector 33. This occurs when the cellophane 
separator 1a is wet, and a little of the zinc comes down around the edges 
of the very thin separator. This problem is solved by the inclusion of the 
frame 34, even though the frame may be relatively thin, i.e., 5 mils or 
less. 
FIGS. 8 and 9 illustrate a framed triplex subassembly in accordance with a 
modification of the invention. As in FIGS. 4 and 5 described above, the 
subassembly comprises a rectangular sheet of triplex laminate generally 
designated 100, made as described above and confined and sealed between 
two frame elements 101 and 102 that are sealed together to form a unitary 
subassembly 103. As indicated, an electrode area defining recess 104 is 
formed in the frame 101, and a corresponding recess 105 is formed in the 
frame 102. The frames 101 and 102, preferably of a hot melt adhesive with 
sufficient flow properties such as the Versalon 1140 polyamide resin or 
the particular copolymer of styrene and butadiene described above, are 
heated under pressure sufficiently to cause the frame elements 101 and 102 
to fuse together and to periphery of the conductive plastic layer 15 to 
encapsulate the subassembly 100, and thereby forestall leakage after the 
frame subassembly 103 has been installed in the battery. 
FIG. 10 illustrates modifications in the process of FIG. 6 occasioned by 
the use of subassemblies such as 103 of FIGS. 8 and 9, and also 
illustrates alternatives in other details of the process. 
Referring to FIG. 10, a cathode terminal subassembly 129, which correspond 
in detail to the subassembly 29 of FIG. 6, is used as the starting point. 
A supply of cathode slurry in a container 136 is pumped by conventional 
means, not shown, to a conventional extruder 135, which deposits a first 
layer of cathode slurry 137a in the region of the cathode current 
collector 133 suggested by the dotted lines. 
A subassembly 103, conductive plastic side up, is next put in position over 
the current collector 133 with the cellophane separator in contact with 
the cathode slurry 137a to produce a subassembly indicated at 140 in FIG. 
10. Next, the extruder 135 adds over this subassembly 140 the next cathode 
slurry layer 137b. The process continues with the addition of a 
subassembly 103b and another layer 137c of cathode slurry in a manner not 
shown in detail, essentially as in FIG. 6 above, and continues until the 
final subassembly 103d has been completed with the addition of its cathode 
slurry 137d. There is thus produced a subassembly 145 which is ready for 
the addition of an end anode half cell subassembly. 
As suggested in FIG. 10, the anode half cell assembly comprises an anode 
metal terminal sheet 150 prelaminated to a conductive plastic current 
collector 151 with an anode patch 153 that may be the same as the 
corresponding components 50, 51 and 53 in FIG. 6. The glassine layer has 
been omitted from FIG. 10 for clarity. As indicated, a gel extruder 175 
applies a layer of gel electrolyte 176 over the anode patch 153 in 
accordance with this embodiment. The composition of the gel electrolyte 
may be as follows, in parts by weight: 
______________________________________ 
NH.sub.4 Cl 21.8 
ZnCl.sub.2 9.9 
HgCl.sub.2 1.9 
H.sub.2 O 63.5 
Natrosol 250 HHR 2.9 
______________________________________ 
Natrosol 250 HHR is hydroxyethyl cellulose as sold by Hercules, Inc. of 
Wilmington, Delaware. 
This composition is coated over the zinc anode patch to a thickness of 
about 5.4 mils. 
A subassembly 177 is next completed in the manner generally described above 
but better illustrated in FIG. 10. This subassembly 177 is inverted and 
placed over the subassembly 145 to produce the substantially complete 
battery 157 shown in FIG. 10. This battery may be completed by the 
addition of the glassine overwrap described above in connection with FIG. 
6 and sealed under heat and pressure to produce a structure shown in 
illustrative detail in FIG. 11. 
As indicated in FIG. 11, the lowermost frame element 101a performs the same 
insulative function relative to the first triplex subassembly 100a as did 
the initial frame 34 in the structure described in connection with FIG. 6. 
The layer of gel electrolyte 176 has been found to minimize the effects of 
wrinkling of the separator 155 during assembly and later stabilization of 
the battery, as the gel 176 fills the hills and valleys that occur when 
the cellophane 155 wrinkles. Without the layer 176, this curling can 
impart a significant inpedance term to the overall internal impedance of 
the battery. 
The practice of the invention will next be illustrated with reference to 
the following detailed examples. 
EXAMPLE I 
Seven four-cell batteries were made from a triplex laminate formed by 
coating 1.34 mil PUD-O cellophane with the specific anode coating 
composition given above to a dry thickness of 1 mil, followed as described 
above by a first coating with the specific conductive plastic composition 
given above to a dry thickness of 1.8 mils. A second coating with the same 
conductive plastic coating composition was made to a dry thickness of 1.7 
mils, forming a conductive plastic layer 3.5 mils in thickness. This 
triplex laminate was cut into pieces 2.63 inches by 3.23 inches. The 
conductive plastic sides of the cut pieces of laminate were each 
heat-sealed to the inner borders of a frame made of 22 to 24 mil Versalon 
1140 hot melt adhesive each 2.88 inches by 3.52 inches and formed with a 
central rectangular opening 2.10 inches by 2.77 inches. Each cathode 
comprised 2.5 grams of the specific slurry composition described above. 
The end cell used a cellophane separator (55) 3.2 inches by 2.1 inches of 
1.34 mil PUD-O cellophane, a 2 mil tinned steel end terminal (50) 3.9 
inches by 3.4 inches laminated to a 2 mil sheet of Condulon conductive 
plastic (51) of the same size, on which there was a zinc dry patch 1 mil 
in thickness of the specific dry patch composition given above coated with 
a 5.4 mil layer of the gel electrolyte composition given above. 
These batteries, identified as Examples IA-IG below, were measured on the 
day of assembly for open circuit voltage OCV and closed circuit voltage 
CCV with a current interval of 0.1 second through a 3.3 ohm load. Under 
these particular test conditions, the internal impedance Ri, in ohms, can 
be calculated from the relation Ri = 3.3 (OCV/CCV-1), and is given in 
Table I below together with the measured values of OCV and CCV. 
TABLE I 
______________________________________ 
EXAMPLE OCV CCV Ri 
______________________________________ 
IA 6.80 6.27 .28 
IB 6.83 6.15 .37 
IC 6.82 6.34 .25 
ID 6.84 6.16 .36 
IE 6.84 6.08 .41 
IF 6.84 6.13 .38 
IG 6.85 6.50 .18 
Ri ave. .32 
______________________________________ 
The average value for Ri for the seven batteries of Example I above is 0.08 
ohms per cell. 
EXAMPLE II 
A four cell battery was made exactly as described above, except using 3.5 
grams of slurry for each cathode, and with a triplex laminate as described 
above except that the conductive plastic layer was coated to a dry 
thickness of 1/2 mil. The OCV was 6.86 volts, the CCV was 6.53 volts, and 
the corresponding value of Ri is 0.17 ohms, or 0.04 ohms per cell. As a 
control, a four cell battery was made in the manner described in detail in 
the above cited Application Ser. No. 761,651, using 3.5 gram cathodes of 
the preferred composition described therein. This battery had an OCV of 
6.70 volts, a CCV of 6.30 volts, and a corresponding value of Ri=0.21 
ohms, or 0.05 ohms per cell. These batteries, identified as Example II and 
Control below, were tested in the following manner: 
A Polaroid SX-70 Land camera was fitted with an electronic flash unit 
having a light output of about thrity seven watt seconds, and an input 
energy requirement of about 80 watt seconds. The flash unit was connected 
so as to be charged from the battery under test. The battery was also used 
to energize the camera to perform the functions of exposure control and 
film advance in the normal manner, except that, experience having shown 
that advancing film units through the processing rolls made no detectable 
difference in the test, no film units were employed. In the test, the 
initially discharged flash unit was charged until its ready light glowed. 
The shutter button of the camera was then operated, causing the camera to 
go through its cycle, during which time the flash unit was discharged. The 
battery was then electrically disconnected, and allowed 30 seconds to 
recover. This cycle is estimated to require a total energy of about 90 to 
100 watt seconds, and was carried out 15 times for each battery. Each time 
the flash unit was charged during the test, the time between the start of 
charge and the time when the ready light glowed and charging was stopped 
was noted. 
The results of the above test are given below in terms of photographic 
cycle N, observed recharge time .DELTA.t, and cumulative recharge time S. 
TABLE II 
______________________________________ 
BATTERY EXAMPLE II CONTROL 
N .DELTA.t 
S .DELTA.t 
S 
______________________________________ 
1 3.6 3.6 3.2 3.2 
2 3.0 6.6 3.0 6.2 
3 3.2 9.8 3.2 9.4 
4 3.4 13.2 3.2 12.6 
5 3.4 16.6 3.4 16.0 
6 3.6 20.2 3.4 19.4 
7 3.4 23.6 3.4 22.8 
8 3.6 27.2 3.6 26.4 
9 3.8 31.0 3.6 30.0 
10 3.6 34.6 3.6 33.6 
11 3.8 38.4 3.6 37.2 
12 3.8 42.2 3.6 40.8 
13 4.0 46.2 3.8 44.6 
14 4.0 50.2 3.8 48.4 
15 4.0 54.2 3.8 52.2 
______________________________________ 
The above results are impressive from any point of view. For example, 
considered for use with the SX-70 Land camera and flash unit described 
above, for the ten shot sequence required with a Polaroid SX-70 film, the 
battery of Example II offers recharge times of under 4 seconds for each of 
ten shots. The average recharge time for 15 shots is only 3.6 seconds. The 
performance of the control battery is comparable and possibly a little 
better, although the results are too close together to form the bsis for a 
conclusion from a single test, and the manufacture and assembly of the 
control battery are more complex. 
FIGS. 12, 13 and 14 illustrate an especially useful modification of the 
invention in which the cellophane separator is coated with discrete anode 
patches. As indicated in FIG. 12, discrete anodes 200 are formed in spaced 
regions on a sheet of cellophane 201, as by extrusion. The zinc anode 
coating composition given above has been found to be extrudable in the 
thin layers desired; i.e., about 1/2 gram of dried anode material for an 
anode 1.875 inches by 2.5 inches, or 165.3 grams per square meter of 
electrode surface. After extrusion and drying to remove the organic 
solvent, the sheet 201 and anode patches 200 are overcoated with the 
conductive plastic composition described above, in the manner described in 
connection with FIG. 2. The triplex sheet so formed can then be cut into 
individual subassemblies, as shown at 202 in FIGS. 13 and 14. Each of the 
subassemblies 202 comprises a cellophane separator 201a adhered in a 
central region to a zinc anode 200a, and at the edges to the conductive 
plastic 203. In the coating process, the intercell connector 203 will be 
formed thinner in the region overlying the anode patch; for example, if 
the anode patch is 2 mils in thickness, the coating 203 may be made 4 mils 
in thickness in the regions around the anode patch, and 2 mils in 
thickness over the anode patch. In other words, the thickness of the 
laminate is uniform over the patch and between the patches, with the 
thickness of the coating 203 varying as dictated by the doctor blade to 
make up for the difference, as shown in FIG. 14. 
The triplex components 202 may be used to form framed subassemblies such as 
described above in connection with FIGS. 4, 5, 8 and 9, and made into 
cells and batteries by the processes described above. 
One advantage of the patch anode construction just described is that 
intercell insulation is improved. For example, the frame such as 34 in 
FIG. 7 may be omitted if desired. A second and more significant advantage 
has been found which is related to the manner in which the zinc anode is 
amalgamated after the battery is assembled. With the full coated triplex 
constructions first described, it has been observed that mercuric ions 
from the cathode diffuse through the cellophane so directly into the 
confronting anode region that the anode surface is amalgmated only in the 
region in registry with the cathode. This effect is thought to contribute 
to reduce shelf life. With the anode located in a patch confined to a 
region in registry with the anode, such differential amalgamation will not 
occur. 
Triplex laminates in accordance with the invention may be employed in other 
acidic or alkaline electrochemical systems than the Leclanche system. In 
some instances, it may be desired to form the electrode layer in the 
laminate of cathodic particles, rather than of anodic particles. As a 
specific example of an alkaline system in which a triplex laminate could 
be employed, an alkaline zinc-manganese dioxide battery could be made by 
the procedures detailed above, except that the zinc chloride and ammonium 
chloride in the electrolyte used would be replaced by potassium hydroxide. 
Both the radical teleblock copolymer of butadiene and styrene and the 
Versalon 1140 resin described above are stable to caustic solutions. 
While the invention has been described with respect to the details of 
various illustrative embodiments, many changes and variations will occur 
to those skilled in the art upon reading this description. Such can 
obviously be made without departing from the scope of the invention.