O
`4,487,819
`[11] Patent Number:
`[19]
`Ullltfid States Patent
`Koga
`[45] Date of Patent:
`Dec. 11, 1984
`
`
`[54] FLAT BATTERY
`.
`.
`RyOJi Koga, Kawaguchlko, Japan
`Inventor:
`[75]
`'
`,
`,
`,
`.
`[73] ASSIgnee: Kawaguchlko Selmitsu Company
`Lilnited, Yamanashl, Japan
`
`[21] Appl- No.2 452,391
`[22] Filed:
`Dec. 22: 1982
`[30]
`Foreign Application Priority Data
`Dec. 26, 1981 [JP]
`Japan ................................ 56-213908
`
`.......................... 57-16875
`Feb. 4, 1982 [JP]
`Japan
`.......................... 57-26547
`Feb. 19, 1982 [JP]
`Japan
`Feb. 27, 1982 [JP]
`Japan .................................. 57-31050
`[51]
`Int. Cl.3 ........................ H01M 2/12; H01M 2/08
`[52] US. Cl. ...................................... 429/82; 429/163;
`429/174
`[58] Field of Search ............... 429/ 174, 162, 163, 164,
`429/166, 171, 172, 173, 185, 82, 219
`References Cited
`U.S. PATENT DOCUMENTS
`
`[56]
`
`2,843,650
`3,723,184
`
`7/1958 Jacquier .............................. 429/174
`3/1973 Stark et a1.
`.......................... 429/174
`
`F REIGN PATENT D UM TS
`0
`0C
`EN
`
`8/1980 Japan ................................... 429/174
`111060
`1/1982 Japan ........................... 429/174
`13665
`95066
`6/1982 Japan ................................... 429/174
`Primary Examiner—~Donald L. Walton
`Attorney, Agent, or Firm—Koda and Androlia
`[57]
`ABSTRACT
`A flat battery for use in a micro-size device, including a
`cathode can having a substantially U-shaped cross-sec-
`tion, an anode can having a substantially inverted U-
`shaped crOSS-section, an anode and cathode active sub-
`stances accommodated in a battery cell constituted by
`the cathode and anode cans, a separator provided be-
`tween the anode and cathode active substances, and an
`insulative film provided at an upstanding portion of the
`cathode can to isolate the cathode can from the anode
`can and the anode active substance.
`
`2,307,764
`
`1/1943 Deibel et a1.
`
`........................ 429/164
`
`26 Claims, 46 Drawing Figures
`
`26a
`
`27
`
`
`
`JLab/Cambridge, Exh. 1028, p. 1
`
`JLab/Cambridge, Exh. 1028, p. 1
`
`

`

`U.S.. Patent Dec. '11, 1984
`
`Sheet 1 of 19
`
`4,487,819
`
`
`
`WWI/IIhIIIIIIA
`
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`
`36
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`JLab/Cambridge, Exh. 1028, p. 2
`
`JLab/Cambridge, Exh. 1028, p. 2
`
`

`

`US Patent Dec.>11, 1984
`
`Sheet 2 of 19
`
`4,487,819
`
`FIG.3
`
`30
`
`32
`
`
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`
`28
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`32
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`
`28
`
`JLab/Cambridge, Exh. 1028, p. 3
`
`JLab/Cambridge, Exh. 1028, p. 3
`
`

`

`US. Patent Dec. '11, 1984
`
`Sheet 3 of 19
`
`4,487,819
`
`FIG.5
`
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`JLab/Cambridge, Exh. 1028, p. 4
`
`JLab/Cambridge, Exh. 1028, p. 4
`
`

`

`US. Patent Dec..11, 1984
`
`Sheet40frl9
`
`4,487,819
`
`FIG.7
`
`26a
`
`26c
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`30
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`JLab/Cambridge, Exh. 1028, p. 5
`
`JLab/Cambridge, Exh. 1028, p. 5
`
`

`

`US. Patent Dec. '11, 1984
`
`Sheet 5 of 19 , 4,487,819
`
`FIG.9
`
`24
`
`22d
`
` 22b
`
`
`
`JLab/Cambridge, Exh. 1028, p. 6
`
`JLab/Cambridge, Exh. 1028, p. 6
`
`

`

`US. Patent Dec.'11, 1984
`
`Sheet6of 19
`
`4,487,819
`
`FIG.11
`
`
`
`26
`
`26c
`
`FIG.12
`
`
`
`
`
`40 ,A
`
`
`
`JLab/Cambridge, Exh. 1028, p. 7
`
`JLab/Cambridge, Exh. 1028, p. 7
`
`

`

`US. Patent Dec. 11,1984
`
`Sheet7 of19
`
`4,487,819
`
`FIG.13
`
`
`
`42
`
`30
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`
`JLab/Cambridge, Exh. 1028, p. 8
`
`JLab/Cambridge, Exh. 1028, p. 8
`
`

`

`US. Patent Dec. 11,1984
`
`‘Sheet8 of19
`
`4,487,819
`
`FIG.15
`
`423'
`
`42
`
`30 ‘
`
`FIG.16
`
`42a
`
`42
`
`30
`
`30a
`
`28
`
`30
`
`32
`
`JLabflSambfidge,Exh.1028,p.9
`
`JLab/Cambridge, Exh. 1028, p. 9
`
`

`

`US... Patent Dec. '11, 1984
`
`Sheet 9 of 19
`
`4,487,819
`
`FIG.18
`
`32 VII/I’ll],IIIIIIIIIIIIIIIIIIIIIAl
`
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`
`Lab/Cambridge, Exh. 1028, p. 10
`
`JLab/Cambridge, Exh. 1028, p. 10
`
`

`

`US. Patent Dec. 11,1984
`
`Sheet 10 ofl9 4,487,819
`
`FIG.20 I
`
`
`
`JLab/Cambridge, Exh. 1028, p. 11
`
`JLab/Cambridge, Exh. 1028, p. 11
`
`

`

`U.S.. Patent Dec.‘11, 1984
`
`Sheet 11 of 19
`
`4,487,819
`
`
`
`JLab/Cambridge, Exh. 1028, p. 12
`
`JLab/Cambridge, Exh. 1028, p. 12
`
`

`

`US“. Patent Dec. 11, 1984
`
`Sheet 12 of 19
`
`4,487,819
`
`FIG.27
`
`F 16.28
`
`22
`
`30
`
`30b
`
`30b
`
`22 30
`
`30’
`
`FIG.29
`
`F 16.30
`
`JLab/Cambridge, Exh. 1028, p. 13
`
`JLab/Cambridge, Exh. 1028, p. 13
`
`

`

`U.S., Patent Dem-11,1984
`
`Sheet 13 of19
`
`4,487,819
`
`F1631
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`
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`JLab/Cambridge, Exh. 1028, p. 14
`
`JLab/Cambridge, Exh. 1028, p. 14
`
`

`

`US“ Patent Dec.11,1984
`
`Sheet 14 of19
`
`4,487,819
`
`26
`
`265
`
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`
`JLab/Cambridge, Exh. 1028, p. 15
`
`JLab/Cambridge, Exh. 1028, p. 15
`
`

`

`US Patent Dec.'11, 1984
`
`Sheet 15 of 19
`
`4,487,819
`
`FIG. 43
`
`
`
`JLab/Cambridge, Exh. 1028, p. 16
`
`JLab/Cambridge, Exh. 1028, p. 16
`
`

`

`U..S.,. Patent Dec. 11,1984
`
`Sheet 16 of19
`
`4,487,819
`
`FIG.33
`
`30
`
`26a
`
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`
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`
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`
`JLab/Cambridge, Exh. 1028, p. 17
`
`JLab/Cambridge, Exh. 1028, p. 17
`
`

`

`U.S.. Patent Dec. 11, 1984
`
`Sheet 17 of 19
`
`4,487,819
`
`F1635
`
`FIG.36
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`JLab/Cambridge, Exh. 1028, p. 18
`
`JLab/Cambridge, Exh. 1028, p. 18
`
`

`

`US. Patent Dec. ’11, 1984
`
`Sheet 13 of19
`
`4,487,819
`
`F 16.38
`
`26
`
`26 a
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`JLab/Cambridge, Exh. 1028, p. 19
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`JLab/Cambridge, Exh. 1028, p. 19
`
`

`

`US“. Patent Dec.'11, 1984
`
`Sheet 19 of 19
`
`4,487,819
`
`FIG.“
`
`30
`
`263
`
`26
`
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`JLabflSambfidge,Exh.1028,p.20
`
`JLab/Cambridge, Exh. 1028, p. 20
`
`

`

`1
`
`FLAT BATTERY
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`This invention relates to a flat battery for use in a
`micro—size device such as a wristwatch, handy measur-
`ing or caluculating instruments and so on.
`2. Prior Art
`The construction of the conventional battery cell of
`this type consist of a cup-shaped anode can, a cap-
`shaped cathode can and a gasket provided between the
`anode and cathode cans. An anode active substance, an
`electrolyte, a cathode active substance and a separator
`are contained in such cell construction.
`The sealing structure of the conventional battery
`above mentioned is performed by establishing close
`pressing contiguity among the gasket, the anode and
`cathode cans through use of the compressive counter-
`force of the gasket in which it is deformed. Therefore,
`it is necessary to obtain a large compressive counter-
`force by increasing the thickness of the gasket. How-
`ever, by increasing the thickness of the gasket, the vol-
`ume which is occupied by the gasket is increased, for
`this reason, the size of the battery becomes enlarged, or
`the net capacity of the cell diminishes. Otherwise, it is
`necessary to reduce the thickness of the plates constitut-
`ing the anode and cathode cans for increasing the dis-
`charge capacity in the same size cell. Furthermore,
`when the compressive force of the gasket is enlarged in
`order to ensure the leakproof property,
`the internal
`pressure of the battery cell increases, this lead to one of
`the causes of leakage.
`SUMMARY OF THE INVENTION
`
`Main object of the present invention intend to present
`the construction of the micro battery cell to accomplish
`the improvement of the leakage of the electrolyte and
`the increasing of the discharge capacity in the definite
`dimension of the cell. Therefore, the contents which are
`contained in the cell construction presented hereof is
`adaptable the heretofore conventional and widly used
`members that are the anode active substance, the sepa-
`rator, the cathode active substance and the electrolyte.
`And then, it is also acceptable for this present invention
`to use the material which will be hereafter improved.
`It is another object of the present invention to pro-
`vide a flat battery which can overcome the shortcom-
`ings encountered in the prior art.
`It is another object of the present invention to pro-
`vide a flat battery which provides an anlargement of the
`internal volume without enlarging a size of the battery
`cell, an increase of the discharge capacity and reliable
`leakproof.
`To realize the principles of the present invention, the
`above-mentioned objects are accomplished by a flat
`battery, comprising: a cathode can including a bottom
`portion and a cylindrical upstanding portion extending
`upward from the outer circumference of said bottom
`portion; an insulative film provided at said cylindrical
`upstanding portion of said cathode can; a cathode active
`substance electrically contacted to said cathode can; an
`anode can including an upper portion and a cylindrical
`portion extending downward from the outer circumfer-
`ence of said upper portion; an anode active substance
`electrically contacted to said anode can; and a separator
`isolating said cathode active substance and anode active
`substance to prevent an electrical short-circuit; wherein
`
`10
`
`15
`
`20
`
`25
`
`3O
`
`35
`
`45
`
`50
`
`55
`
`65
`
`4,487,819
`
`2
`said cylindrical portion of said anode can is fitted to said
`cylindrical upstanding portion of said cathode can
`through the intermediary of said insulative film for
`setting said anode can on said cathode can.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`Other and further objects, features and advantage of
`the present invention will be more apparent by refer-
`ence to the following detailed description of the inven-
`tion taken in connection with the accompanying draw~
`ings, in which: .
`FIG. 1 is a longitudinal sectional view of a conven-
`tional flat battery, showing one-half of the battery;
`FIG. 2 is a longitudinal sectional view of an embodi-
`ment of a flat battery according to the present inven-
`tion, showing one-half of the battery;
`'
`FIG. 3 is a longitudinal sectional view of another
`embodiment of a flat battery according to the present
`invention, showing one-half of the battery;
`FIG. 4 is an illustrative view for describing the instal-
`lation of a separator in the flat battery in FIG. 3;
`FIG. 5 is a longitudinal sectional view of another
`preferred embodiment of a flat battery according to the
`present invention, showing one-half of the battery;
`FIG. 6 is a partially enlarged view showing the fitted
`cans portion of the flat battery shown in FIG. 5;
`FIG. 7 is a longitudinal sectional view of a modifica-
`tion of the flat battery shown in FIG. 5;
`FIG. 8 is a partially enlarged view showing the dis-
`tance A less than the distance B of the flat battery
`shown in FIG. 7;
`FIG. 9 is a partially enlarged view showing the‘dis-
`tance A larger than the distance B shown in FIG. 7;
`FIG. 10 is an enlarged view illustrating a portion of
`the insulative film interposed between the cathode can
`and anode can of another modification of the flat bat-
`tery shown in FIG. 2 or 5;
`FIG. 11 is a longitudinal sectional view of a modifica-
`tion of the flat battery shown in FIG. 2 or 5;
`FIG. 12 is an enlarged view showing a principal
`portion of the flat battery shown in FIG. 11;
`FIG. 13 is a longitudinal sectional view of another
`modification of the flat battery shown in FIG. 2 or 5;
`FIG. 14 is a longitudinal sectional view of one-half of
`the battery, illustrating the state of the thermal conduc-
`tive metal which is on the anode active substance before
`fitting the anode can onto the cathode can in the flat
`battery of FIG. 13;
`FIGS. 15 and '16 are longitudinal sectional views of
`modifications of the plate shown in FIG. 13;
`FIG. 17 is a longitudinal sectional view of another
`modification of the flat battery shown in FIG. 2 or 5;
`FIG. 18 is a view illustrating the state of the graphite
`layer which is on the anode active substance before
`fitting-the anode can onto the cathode can in the flat
`battery of FIG. 17;
`FIG. 19 is a longitudinal sectional view of another
`modification of the flat battery shown in FIG. 2 or 5;
`FIGS. 20 and 21 are partially enlarged views of prin-
`cipal portion of the flat battery illustrated in FIG. 19;
`FIG. 22 is a longitudinal sectional view of another
`modification of the flat battery shown in FIG. 2 or 5;
`FIGS. 23 to 26 are partially enlarged views of an air
`venting portion of the flat battery shown in FIG. 22;
`FIG. 27 is a top view of another modification of the
`flat battery shown in FIG. 2 or 5, with the anode can
`removed;
`
`JLab/Cambridge, Exh. 1028, p. 21
`
`JLab/Cambridge, Exh. 1028, p. 21
`
`

`

`4,487,819
`
`3
`FIG. 28 is a top view of the flat battery as an example,
`with the anode can removed;
`FIGS. 29 and 30 are top views of another modifica-
`tion of the anode active substance shown in FIG. 28;
`FIG. 31 is a longitudinal sectional view of another
`modification of the flat battery shown in FIG. 2 or 5;
`FIG. 32 is a longitudinal sectional view of another
`modification of the flat battery shown in FIG. 2, 5 or 31;
`FIG. 33 is a longitudinal sectional view of another
`modification of the flat battery shown in FIG. 2 or 5;
`FIG. 34 is a longitudinal sectional view of a modifica-
`tion of the flat battery shown in FIG. 33;
`FIGS. 35 and 36 are partially enlarged views of the
`principal portion of another modification of the flat
`battery shown in FIG. 33;
`-
`FIG. 37 is a longitudinal sectional view of another
`modification of the flat battery shown in FIG. 33 with
`a assembly jig and fixture;
`FIG. 38 is an enlarged View of the principal portion
`of another modification of the flat battery shown in
`FIG. 33;
`FIG. 39 is a longitudinal sectional view of the flat
`battery shown in FIG. 38 for illustrating the state which
`is deformed the anode can using metal mold and die;
`FIGS. 40 A, B and C are longitudinal sectional views
`of steps of the fitting operation of the anode can with
`prior deformation onto the cathode can;
`FIG. 41 is a longitudinal sectional view of another
`modification of the flat battery shown in FIG. 2;
`FIG. 42 is a longitudinal sectional view of a modifica~
`tion of the flat battery shown in FIG. 41;
`FIG. 43 is a longitudinal sectional View of the flat
`battery shown in FIG. 5, in which the circular part is
`utilized;
`FIG. 44 is a longitudinal sectional view of a modifica-
`tion of the anode active substance shown in the other
`figures.
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`The construction of the conventional battery of this
`type is described with reference to the longitudinal
`sectional view of FIG. 1, showing one—half of the bat—
`tery.
`In FIG. 1, the battery comprises a cup-shaped anode
`can 10 made of a metallic material, and a capshaped
`cathode can 12 also made of a metallic material. A gas-
`ket 14 comprising an insulator is located between the
`anode can 10 and a curled portion 12a of the cathode
`can 12, and is held the compressed state by bending
`inwardly the rim at the upper opening 100 of the anode
`can 10. An anode active substance 16, an electrolyte, a
`cathode active substance 18 and a separator 20 which
`isolate said anode active substance 16 from said cathode
`active substance are contained in the battery cell.
`The anode and cathode cans 10, 12 of this conven-
`tional flat battery are insulated by the gasket 14 which
`makes the compressive counterforce between the two
`cans 10, 12, whereby the sealing structure of the con-
`ventional flat battery is performed. In addition,
`it is
`necessary to increase the thickness of the gasket 14 for
`the sake of the acquisition of a suitable compressive
`counterforce. However, the volume which is occupied
`by the gasket 14 is in propotion to the thickness of the
`gasket 14, then it is necessary to either reduce the thick-
`ness of the plates constituting the cans or increase the
`overall volume of the battery for the purpose of increas-
`ing the discharge capacity at the definite dimension of
`
`4
`the cell. Furthermore, when the compressive force of
`the gasket 14 is enlarged in order to ensure the leak-
`proof property, the curled portion 120 of the cathode
`can 12 is moved inwardly by the compressive force of
`the gasket 14. Consequently the internal pressure of the
`battery cell increases. In addition, the creep deteriora-
`tion of the gasket 14 is advanced by increasing the com-
`pressive force of the gasket 14, this lead to one of the
`causes of leakage.
`FIG. 2 is a longitudinal sectional view of the embodi-
`ment of the flat battery according to the present inven-
`tion, showing one-half of the battery. The arrangement
`of the cans is inverted relative to the conventional ar-
`rangement of FIG. 1 in view of the assembly operation.
`In FIG. 2, a cathode can 22 has a substantially U-shaped
`cross-section and is made of a metallic material consist-
`ing of brass or steel having nickel layer on a surface
`thereof, or the like. The cathode can 22 is basically
`constituted by a bottom portion 220 and a cylindrical
`upstanding portion 22b extending vertically upward
`from the outer circumference of the bottom flat portion
`220. The upper surface and the surfaces of the outer and
`inner sides of the upstanding portion 22b is coated with
`a insulative film 24 composed of a fluorine-type film or
`the like to insulate from the anode can 26- and anode
`active substance. The insulative film 24 which coats the
`cathode can may be provided to any place where is
`necessary for preventing the inner short-circuit, for
`example contact portion of the cathode can and the
`anode can or anode active substance. The anode can 26
`has a substantially inverted U-shaped cross-section and
`is made of a metallic material consisting of brass or steel
`having nickel layer on a surface thereof, or the like. The
`anode can 26 is constituted by an upper flat portion 26a
`and a cylindrical portion 26b bent vertically downward
`from the outer circumference of the upper portion 26a.
`The cylindrical portion 26b of the anode can 26 is fit on
`the outer circumferential surface of the upstanding por-
`tion 22b of the cathode can 22 by the shrinkage- or
`press-fitting process, whereby a secure water-tight fit is
`achieved through the intermediary of the insulative film
`24. Numeral 28 represents generally a cathode active
`substance consisting of zinc as a principal ingredient and
`containing an electrolyte consisting of NaOH, KOH or
`the like. Numeral 30 denotes an anode active substance
`consisting of silver oxide, silver peroxide, manganese
`dioxide, mercury oxide, nickel hydroxide or the like as
`a principal ingredient,
`in tablet form. A separator 32
`isolates the cathode active substance 28 and anode ac-
`tive substance 30 to prevent an electrical short-circuit.
`The separator 30 consists of non-weaving cloth, viny-
`lon, cellophane or the like.
`In this embodiment, the can 22 comes in contact with
`the cathode active substance 28 and therefore serves
`also as a cathode terminal, while the can 26 comes in
`contact with the anode active substance 30 and, hence,
`serves also an anode terminal. Though not illustrated,
`the arrangement of the cathode active substance 28 and
`anode active substance 30 shown in FIG. 2 may be
`inverted according to the requirment.
`The flat battery in this embodiment is assembled by
`containing such contents as the cathode active sub-
`stance 28, anode active substance 30 and separator 24 in
`the cathode can 22, and then, finally, pressure-fitting the
`cylindrical portion 26b of the anode can 26 on the up-
`standing portion 22b of the cathode can 22 using the
`shrinkage- or press-fitting process.
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55‘
`
`60
`
`6S
`
`
`
`JLab/Cambridge, Exh. 1028, p. 22
`
`JLab/Cambridge, Exh. 1028, p. 22
`
`

`

`5
`Suitable materials for the insulative film 24 are ethyl-
`ene tetrafluoride and ethylene chlorotrifluoride. If there
`are other materials above mentioned and which have
`resistance against deterioration by electrolytes, an elec-
`trical insulative property, repellent property for electro-
`lyte, elasticity and heat resistance against the high tem-
`perature at the shrinkage-fitting process. Such materi-
`als, e. g. silicon-, polyamide-, polyphenylene sulfide-,
`polyimide-based material, may be adaptable to the em-
`bodiment.
`
`In accordance with the embodiment, since a packing
`member similar to the conventional gasket illustrated in
`FIG. 1 is not employed in this embodiment, it is possible
`to increase the ratio of the internal volume to the over-
`all battery volume and improve the battery discharge
`capacity by a wide margin. Because the insulative film
`24 having the excellent elasticity is sandwiched between
`the cylindrical portion 26b of the anode can 26 and the
`outer circumferential surface of the upstanding portion
`22b of the cathode can 22, and the thickness of the film
`24 is very thinner than the conventional gasket, and also
`the synergy between the internal stress occured by the
`pressure fitting and the film 24 having the electrolyte-
`repellent property prevent the creep of the electrolyte
`out of the inside of the cell, whereby the leakage of the
`electrolyte of the cell is perfected.
`In FIG. 2, in addition the leak-proof property can be
`ensured if a sealing material 34 such as tar or silicon
`grease is introduced into the space portion which is
`constituted of the end face of the upstanding portion
`22b of the cathode can 22 and the bent root of the cylin-
`drical portion 26b of the anode can 26. It should be
`noted that the portion indicated by the broken line 36 in
`the figure is the core piece, which is purposing to sup-
`port the separator can be prepared when necessary.
`FIG. 3 shows a modification of the flat battery shown
`in FIG. 2. Like elements corresponding to those of
`FIG. 2 are indicated by like numerals. An outer diame-
`ter of a separator 32 of this embodiment is made larger
`than the inner diameter of the cathode can 22. As shown
`in FIG. 4, the separator 32 is placed upon the upstand-
`ing portion 22b of the cathode can 22, then the anode
`active substance 30 is located on the separator 32, both
`the separator and the anode active substance 30 are
`pressed down into the cathode can 22 which is placed
`the cathode active substance 28 previously. In this case,
`this method gives the effect that the circumference of
`the separator gets the radial tension force in all direction
`and the separator adheres closely to the anode active
`substance 30 avoiding unnecessary air between the sep-
`arator and the active substance.
`the problem which is
`Beside in this embodiment,
`comprised in assembly difficulties caused when there is
`a variance in the diameter of the separator or an internal
`short—circuit caused when the diameter is too small are
`eliminated. Further, the separator 32 can be smoothly
`pressed into the cathode can 22.
`FIG. 5 shows another preferred embodiment of a flat
`battery according to the present invention, with like
`parts bearing the same reference numerals as these used
`in FIG. 2.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`In FIG. 5, the inner wall of the upstanding portion
`22b of the cathode can 22 is projected with a step 22c at
`the middle part thereof. As shown in the partially en-
`larged view of FIG. 6, an inner surface 22b", outer
`surface 22d’ and upper surface 22b of the upstanding
`portion 22b and the step 22c are continuously coated
`with the insulative film 24.
`
`65
`
`4,487,819
`
`6
`The outer circumferential portion of the separator 32
`set upon the step 22c of the cathode can 22 and isolates
`the cathode active substance 28 from anode active sub-
`stance 30 to prevent an electrical short-circuit.
`The flat battery in this embodiment is assembled as
`the following steps.
`(1) The electrolyte-containing cathode active sub-
`stance 28 is introduced into the cathode can 22.
`
`(2) Then, the separator 32 is inserted by placing its
`outer peripheral portion on the insulated step 22c of
`the cathode can 22.
`(3) The tablet-shaped anode active substance 30 is set
`on the separator 32 and in the insulated inside of the
`cathode can 22.
`
`(4) Finally, the cylindrical portion 26b of the anode
`can 26 is hermetically fitted on the insulated outer
`circumferential surface of the upstanding portion
`22b of the cathode can 22 in such a manner that the
`anode can 26 covers the battery components.
`In FIG. 5, the outer circumferential portion of the
`separator 32 is sandwiched between the step 22c of the
`cathode can 22 and the anode active substance 30,
`therefore, it is possible to certainly retain the separator
`32 in the construction of the cell.
`
`As shown in FIG. 6, the leak-proof property can be
`further ensured if a sealing material 34 such as tar or
`silicon grease is used into the space portion which is
`comprised between the end face of the upstanding por-
`tion 22b of cathode can 22 and the bent root of the
`cylindrical portion 26b of the anode can 26. In FIG. 6,
`a ring-shaped groove 27, indicated by the broken line,
`provided near the outer circumferential portion of the
`flat upper portion 26a of the anode can 26 is proposing
`to increase the bending elasticity of the cylindrical por-
`tion 26 when it is fitted onto the upstanding portion 22b.
`The groove 27 is formed when so desired.
`FIG. 7 shows a modification of the flat battery shown
`in FIG. 5. FIG. 8 is a partially enlarged View of the flat
`battery shown in FIG. 7.
`As shown in FIG. 8, the distance A from the step 22c
`of the cathode can 22 to the upper surface 22d of the
`upstanding portion 22b is, in this modification, so de-
`signed as to be less than the total thickness B which is
`determined by the anode active substance 30 and the
`fully compressed separator 32. Accordingly, even when
`the anode can 26 is pressure-fit on the cathode can 22
`while pressuring the anode active substance 30, a gap G
`in FIG. 7 will be maintained between the inner surface
`
`26c of the anode can 26 and the upper surface 22d of the
`upstanding portion 22b of cathode can 22.
`As shown in FIG. 9, if the distance A from the step
`22c of the cathode can 22 to the upper surface 22d of the
`upstanding portion 22b were larger than the total thick-
`ness B of the separator 32 and anode active substance
`30, the insulative film 24 on the upper surface 22d of the
`upstanding portion 22b would be pressed by the anode
`can 26. In this case, the film 24 may be torn by the fitting
`pressure of the anode can 26 when the anode can 26 is
`fit tightly on the cathode can 22. Further, since the
`anode can 26 is brought into abutting contact with the
`upper surface 22d of the upstanding portion 22b of the
`cathode can 22 before the separator 32 is compressed
`sufficiently through the intermediary of the anode ac-
`tive substance 30, the sufficient compression of the sepa-
`rator 32 cannot be achieved. This causes the creation of
`a portion through which the electrolyte may flow and
`gives rise to voltage instability and self-induced deterio-
`ration owing to an internal short-circuit.
`
`JLab/Cambridge, Exh. 1028, p. 23
`
`JLab/Cambridge, Exh. 1028, p. 23
`
`

`

`4,487,819
`
`7
`In accordance with this modification, the upper sur-
`face 22d of the upstanding portion 22b of the cathode
`can 22 does not contact to the inner surface 26c of the
`anode can 26, as set forth above. It is, therefore, possible
`to settle the above-mentioned problems which are
`brought by the pressure-fitting of the anode can 26 to
`the cathode can 22.
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`8
`Reference numeral 42 denotes a metal plate of a low
`thermal conductivity, consisting of stainless
`steel,
`chrome or the like, which is sandwiched the upper flat
`portion 260 of the anode can 26 and the anode active
`substance 30. When the anode can 26 is shrinkage-fit on
`the cathode can 22, the low thermally conductive metal
`plate 42 prevents the heat coming off the anode can 26
`from being applied directly to the anode active sub-
`stance 30.
`
`In shrinkage-fitting the anode can 26 on the cathode
`can 22, it is necessary to fit the anode can 26 on the
`cathode can 22 while the tablet-formed anode active
`substance 30 is pressed by the upper flat portion 26a of
`the anode can 26, thereby pressing the outer circumfer—
`ential portion of the separator 32 into abutting contact
`with the step 22c of the cathode can 22 to prevent a
`short-circuit. If the low thermally conductive metal
`plate 42 is not provided, the anode can 26 and anode
`active substance 30 would come into direct contact.
`Since the anode can 26 is herted to a temperature of
`from 200° to 300° C. at such time, the heat would be
`directly transmitted to the anode active substance 30. In
`a case in which silver oxide is used for the anode active
`substance 30, when the silver oxide is heated to a tem-
`perature of above 160° C., the silver oxide gives off
`oxygen. The oxygen being given off in this manner
`elevates the internal pressure of the battery, causing the
`anode can to be raised so that a deterioration in electri-
`cal contact between the anode can 26 and anode active
`substance 30 is conceivable. If the anode can 26 should
`be raised,
`it is even conceivable that a short-circuit
`might occur owing to a. reduction in the force restrain~
`ing the separator 32.
`In this modification, the low thermally conductive
`metal plate 42 is provided between the anode can 26 and
`anode active substance 30. The heat given off by the
`anode can 26 during shrinkage-fitting is transmitted to
`the anode active substance 30 after travelling through'
`the metal conductive plate 42. Therefore, the anode can
`26 can be fit on perfectly followed by rapid cooling of
`the anode can 26, before the heat is transmitted to the
`anode active substance 30. In consequence, the anode
`can 26 is capable of being assembled by shrinkage-fit
`without having any influence to the anode active sub-
`stance 30.
`
`Also, a further improvement in leak-proof property is
`made possible by putting a water-repellent filler which
`has fluidity, such as tar or polyacetal, in the gap G in
`FIG. 7 between the inner surface 26c of the anode can
`26 and the upper surface 22d of the upstanding portion
`22b of the cathode can 22.
`FIG. 10 shows still another modified form of the flat
`battery shown in FIG. 2 or 5 (a modification of the flat
`battery shown in FIG. 5 is only given in the following
`as an example), and is an enlarged view illustrating a
`portion of the insulative film 24 interposed between the
`cathode can 22 and anode can 26.
`Numeral 38 denotes glass beads blended in the insula-
`tive film 24. The glass bead 38 has a diameter greater
`than the total roughness of the surfaces of the cathode
`can 22 and anode can 26 and therefore prevents direct
`contact between the surfaces of the cathode can 22 and
`anode can 26. When the anode can 26 and the cathode
`can 22 are assembled by shrinkage fits, therefore the
`anode can 26 and cathode can 22 will not come into
`direct contact with each other even if the insulative film
`24 should tear owing to the partial formation of thinned
`sections thereof with a reduction in breakdown strength
`and soon caused by heat. Adopting an inclusion rate of
`l to 20% for the glass beads 38 prevents the glass beads
`from overlapping in the direction of thickness of the
`insulative film 24. The rate of inclusion of the glass
`beads is suppressed on the assumption that the overlap-
`ping thereof in the direction of film thickness will cause
`the glass beads 38 to migrate within the insulative film
`24 when the anode can 26 is shrinkage-fit on the cath-
`ode can 22, such migration being accompanied by flaw-
`ing of the insulative film 24.
`FIG. 11 shows still another modified form of the flat
`battery shown in FIG. 2 or 5 (a modification of the flat
`battery shown in FIG. 5 is only given in the following
`as an example). FIG. 12 is an enlarged View showing a
`principal portion of the flat battery illustrated in FIG.
`11.
`
`As stated before, where the insulative film 24 may
`tear owing to a decline in the Young’s modulus and
`breakdown strength thereof caused by heat, or where
`the insulative film 24 may be damaged by an externally
`applied force at such time that the anode can 26 is
`shrinkage- or press-fit onto the cathode can 22, in this
`modification, an insulative metallic oxide layer 40 is
`applied on the inner circumferential surface of the cylin=
`drical portion 26b and on a portion of the inner surface
`26c of the upper flat portion 260 of the anode can 26.
`Therefore, the application is such that the anode can 26
`and cathode can 22 will not be short-circuited even if
`the insulative film 24 should be damaged.
`The insulative metallic oxide layer 40 comprises an
`iron oxide (Fe3O4) layer provided by subjecting the part
`of the anode can 26 to an iron oxide treatment, or a
`chrome oxide (CrO) layer formed by subjecting said
`part of the anode can 26 to black chrome plating.
`FIGS. 13 through 16 show still another modified
`form of the flat battery shown in FIG. 2 or 5(a modifica-
`tion of the flat battery shown in FIG. 5 is only given in
`the following as an example).
`
`45
`
`50
`
`55
`
`60
`
`65
`
`FIG. 14 is a longitudinal sectional view of one-half of
`the battery, illustrating the state of the thermal co