US007566515B2
`
`US 7,566,515 B2
`(10) Patent No.:
`a2) United States Patent
`Suzukietal.
`(45) Date of Patent:
`Jul, 28, 2009
`
`
`(54) FLAT NON-AQUEOUS ELECTROLYTE
`SECONDARY CELL
`
`(75)
`
`Inventors: Masami Suzuki, Kawasaki (JP);
`Muneto Hayami, Takasaki (JP); Kazuo
`Udagawa, Tokyo (JP); Kazuo Tizuka,
`Takasaki (JP); Naomi Ishihara, Annaka
`(JP); Satoshi Hirahara, Annaka (JP);
`Hirotaka Sakai, Usui-gun (JP); Kiyoto
`Yoda, Kawasaki (JP); Masataka
`Shikota, Yokohama (JP)
`
`(52) U.S.C occ 429/162; 429/94; 429/127;
`429/124; 429/185; 429/128; 429/176; 429/175
`(58) Field of Classification Search .....0....0.0.0... None
`See application file for complete search history.
`:
`References Cited
`U.S. PATENT DOCUMENTS
`
`(56)
`
`2,971,999 A
`
`2/1961 Jacquier
`
`(Continued)
`FOREIGN PATENT DOCUMENTS
`
`(73) Assignee: Toshiba Battery Co., Ltd., Tokyo (JP)
`
`(*) Notice:
`
`Subject to any disclaimer, the term ofthis
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 801 days.
`
`EP
`JP
`Jp
`JP
`JP
`
`1011163 Al
`08-031394
`10-255733
`10-289707
`2001-164259
`
`6/2000
`2/1996
`9/1998
`10/1998
`6/2000
`
`(21) Appl. No.: 11/176,400
`
`(22)
`
`Filed:
`
`Jul. 8, 2005
`
`Primary Examiner—Patrick Ryan
`Assistant Examiner—Angela Martin
`(74) Attorney, Agent, or Firm—Oblon, Spivak, McClelland,
`Maier & Neustadt, P.C.
`
`(65)
`
`Prior Publication Data
`US 2005/0271938 Al
`Dee. 8, 2005
`
`Related U.S. Application Data
`
`(62) Division of application No. 10/318,177, filed on Dec.
`13, 2002, now Pat. No. 7,378,186, which is a division
`of application No. 09/641,267,filed on Aug. 17, 2000,
`now Pat. No. 6,521,373.
`
`ABSTRACT
`(67)
`A non-aqueouselectrolyte secondary cell containing an elec-
`tricity-generating elementwith at least a cathode, a separator
`and an anode and a non-aqueouselectrolyte inside a cathode
`case, electrode units each consisting of the cathode and the
`anode opposite to each anothervia the separator laminated to
`form an electrode group, or an electrode unit in a sheet form
`consisting of the cathode and the anode opposite to each
`another via the separator wound to form an electrode group,
`Foreign Application Priority Data
`(30)
`oF a sheet-shape cathode wrapped with the separator except
`Aug. 27,1999
`(IP)
`sessssssssssteseesssnseee 11-240964
`for a part contacting at inner face of cathode case and a
`Aug. 27,1999
`(IP)
`ssssssssessesesssenseenee 11-241299
`
`Nov. 18, 1999 ssssssssesseseessnseenee 11-327679_Sheet-shaped anodeset on the sheet-shapedcathodein a right(IP)
`
`seesessssssssssssssssseeeees 2000-183000
`Fun. 19,2000
`(IP)
`angled position each other and bent alternately to form an
`
`sessessessssseneeessee 2000-183001
`Jum. 19,2000
`(SP)
`electrode group,and the total sum ofthe areas ofthe opposing
`cathode and anodein the electrode group larger than the area
`ofthe opening ofan insulating gasket in a sealed portion in the
`cathode caseor than the area ofan opening ina sealedplate in
`a sealed portion in the cathode case.
`
`(51)
`
`Int.Cl.
`HOIM 2/02
`HOIM 2/08
`HOIM 4/58
`HOIM 10/40
`
`(2006.01)
`(2006.01)
`(2006.01)
`(2006.01)
`
`33 Claims, 13 Drawing Sheets
`
`AAa ALV
`
`1
`
`5
`
`2
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`4
`
`3
`
`6
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`515thtrtritertrhn
`
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`SS Ss
`Ss
`>
`—_'AwSSSSaS
`
`
`
`
`
`
`
`
`JLab/Cambridge, Exh. 1013, p. 1
`
`JLab/Cambridge, Exh. 1013, p. 1
`
`

`

`US 7,566,515 B2
`
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`4,356,240 A
`4,830,940 A
`5,707,756 A
`
`10/1982 Deyet al.
`5/1989 Keister etal.
`1/1998 Inoueet al.
`
`6,312,848 BI* 11/2001 Kilbetal. we 429/162
`6,617,074 BI*
`9/2003 Watarai etal.
`......... 429/231.95
`6,638,662 B2
`10/2003 Kanedaetal.
`
`* cited by examiner
`
`JLab/Cambridge, Exh. 1013, p. 2
`
`JLab/Cambridge, Exh. 1013, p. 2
`
`

`

`U.S. Patent
`
`Jul. 28, 2009
`
`Sheet 1 of 13
`
`US 7,566,515 B2
`
`2a
`
`4b
`
`5
`4a
`6
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`
`
`SYPSLOPLILIZIILILIN KW
`LL LLLLLAMALALLbfoffLY
`’S
`LS AS SSQe) Wy
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`2b
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`2b
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`FIG.
`
`2
`
`JLab/Cambridge, Exh. 1013, p. 3
`
`JLab/Cambridge, Exh. 1013, p. 3
`
`

`

`U.S. Patent
`
`Jul. 28, 2009
`
`Sheet 2 of 13
`
`US 7,566,515 B2
`
`TIN
`
`Y.
`
`CLLLLANLL
`SOSSSSSSSSSS
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`LL
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`DDIDDIDIID
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`JLab/Cambridge, Exh. 1013, p. 4
`
`JLab/Cambridge, Exh. 1013, p. 4
`
`

`

`U.S. Patent
`
`Jul. 28, 2009
`
`Sheet 3 of 13
`
`US 7,566,515 B2
`
`11
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`JLab/Cambridge, Exh. 1013, p. 5
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`JLab/Cambridge, Exh. 1013, p. 5
`
`

`

`U.S. Patent
`
`Jul. 28, 2009
`
`Sheet 4 of 13
`
`US 7,566,515 B2
`
`aAAAYA
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`JLab/Cambridge, Exh. 1013, p. 6
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`JLab/Cambridge, Exh. 1013, p. 6
`
`

`

`U.S. Patent
`
`Jul. 28, 2009
`
`Sheet 5 of 13
`
`US 7,566,515 B2
`
`
`
`4
`
`FIG.
`
`9
`
`1a
`
`FIG.
`
`10
`
`JLab/Cambridge, Exh. 1013, p. 7
`
`JLab/Cambridge, Exh. 1013, p. 7
`
`

`

`U.S. Patent
`
`Jul. 28, 2009
`
`Sheet 6 of 13
`
`US 7,566,515 B2
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`
`
`JLab/Cambridge, Exh. 1013, p. 8
`
`JLab/Cambridge, Exh. 1013, p. 8
`
`

`

`U.S. Patent
`
`Jul. 28, 2009
`
`Sheet 7 of 13
`
`US 7,566,515 B2
`
`4
`
`ot.
`
`1b
`
`FIG.
`
`13
`
`
`
`PFDFPIIEOD
`
`
`|
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`
`
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`
`JLab/Cambridge, Exh. 1013, p. 9
`
`JLab/Cambridge, Exh. 1013, p. 9
`
`

`

`U.S. Patent
`
`Jul. 28, 2009
`
`Sheet 8 of 13
`
`US 7,566,515 B2
`
`FIG.
`
`15
`
`6
`
`6
`
`5e
`
`1
`
`5
`
`5 f
`
`1
`
`5
`
`FIG.
`
`16
`
`JLab/Cambridge, Exh. 1013, p. 10
`
`JLab/Cambridge, Exh. 1013, p. 10
`
`

`

`U.S. Patent
`
`Jul. 28, 2009
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`Sheet 9 of 13
`
`US 7,566,515 B2
`
`FIG.
`
`17
`
`6
`
`og
`
`6
`
`1
`
`D
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`og
`
`1
`
`5
`
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`
`FIG.
`
`18
`
`JLab/Cambridge, Exh. 1013, p. 11
`
`JLab/Cambridge, Exh. 1013, p. 11
`
`

`

`U.S. Patent
`
`Jul. 28, 2009
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`Sheet 10 of 13
`
`US 7,566,515 B2
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`Di
`
`1
`
`5
`
`5 1 S
`
`j
`
`FIG.
`
`19
`
`6
`
`6
`
`FIG. 20
`
`JLab/Cambridge, Exh. 1013, p. 12
`
`JLab/Cambridge, Exh. 1013, p. 12
`
`

`

`U.S. Patent
`
`Jul. 28, 2009
`
`Sheet 11 of 13
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`US 7,566,515 B2
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`5 1 5
`
`k
`
`1
`
`5
`
`FIG. 21
`
`6
`
`6
`
`FIG. 22
`
`JLab/Cambridge, Exh. 1013, p. 13
`
`JLab/Cambridge, Exh. 1013, p. 13
`
`

`

`U.S. Patent
`
`Jul. 28, 2009
`
`Sheet 12 of 13
`
`US 7,566,515 B2
`
`FIG. 23
`
`
`
`
`FIG.
`
`24
`
`JLab/Cambridge, Exh. 1013, p. 14
`
`JLab/Cambridge, Exh. 1013, p. 14
`
`

`

`1
`
`5
`
`2
`
`4
`
`3
`
`U.S. Patent
`
`Jul. 28, 2009
`
`Sheet 13 of 13
`
`US 7,566,515 B2
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`6
`
`FIG.
`
`26
`
`JLab/Cambridge, Exh. 1013, p. 15
`
`JLab/Cambridge, Exh. 1013, p. 15
`
`

`

`1
`FLAT NON-AQUEOUS ELECTROLYTE
`SECONDARY CELL
`
`US 7,566,515 B2
`
`This application is a Divisional ofU.S. application Ser. No.
`10/318,177, filed Dec. 13, 2002 now U.S. Pat. No. 7,378,186,
`whichis a Divisional application of U.S. application Ser. No.
`09/641,267, filed on Aug. 17, 2000 now U.S. Pat. No. 6,521,
`373.
`
`BACKGROUND OF THE INVENTION
`
`10
`
`1. Field of the Invention
`
`2
`current-collecting body consisting of a metal foil or metal net
`with an active materiallayer to form an electrode, then weld-
`ing a tab terminalinto the centerofthe electrode, and winding
`or laminating it to form an electrode group, complicatedly
`bending the tab terminal from the center of the electrode
`group and welding the terminal into a safety element, an
`opening-sealed pin or a cell can. However, these cells have
`been constructed in such a complicated process that they are
`inferior in workability and the miniaturizationofparts therein
`is also difficult. Further, these cells should be provided therein
`with a space for preventing the tab terminal from short-cir-
`cuiting or for integrating a large number of parts such as
`Thepresentinventionrelatesto a flat non-aqueouselectro-
`safety element into the cells, and thus there is a limit to the
`lyte secondary cell and in particular to a flat non-aqueous
`miniaturization of these cells at present.
`electrolyte secondary cell with improvements in heavy load-
`For miniaturization of the cells under these circumstances,
`ing discharge characteristics.
`the present inventors have attempted not at miniaturizing
`2. Description of the Prior Art
`cylindrical or rectangular lithium ion secondary cells or
`In recent years, there are commercially available coin- or
`nickel hydride secondary cells, but at achieving a higher
`button-shaped flat non-aqueous electrolyte secondary cells
`output of the flat non-aqueous electrolyte secondary cells
`wherein metal oxides such as MnO, and V,O,, inorganic
`described above. That is, the present inventors have used
`compounds such as fluorinated graphite, or organic com-
`lithium cobaltate of high capacity and high potential as the
`pounds such as polyaniline and polyacene structural com-
`cathode active material and a graphitized carbon material of
`poundsare used as the cathode active material, while metal
`high capacity excellent in voltage evenness as the anode
`lithium orlithium alloys, organic compoundssuch as poly-
`active material, and according to the process andstructure of
`acene structural compounds, carbon materials capable of
`the conventional flat non-aqueouselectrolyte secondary cell,
`occluding and releasing lithium, or oxides such as lithium
`the inventors have processed the cathode and anodeinto tab-
`titanate or lithitum-containing silicon oxides are used in the
`lets smaller than a gasket, to prepareacell.
`anode, and non-aqueouselectrolytes containing a supporting
`However,this cell though attaining superior characteristics
`electrolyte such as LiClO,, LiPF., LiBF,, LiCF;SO;, LiN
`to the conventional flat non-aqueous electrolyte secondary
`(CF,SO,), and LiN(C,F,SO,), dissolved in a non-aqueous
`cell is not satisfactory when discharged in a large current
`solvent such as propylene carbonate, ethylene carbonate,
`required of a main powersource in compactportable devices,
`butylene carbonate, diethyl carbonate, dimethyl carbonate,
`thus failing to achieve levels satisfactory as a main power
`methyl ethyl carbonate, dimethoxyethane and y-buty] lactone
`source in compactportable devices. Accordingly, the devel-
`are used as the electrolyte. These cells are used as power
`opment of techniques for permitting the heavy-loading dis-
`sources for backing up SRAM and RTC where an electric
`charge characteristics of the compact flat non-aqueous sec-
`current is discharged for light loading of about several to
`ondary cell to reach levels not achieved in the prior art is
`necessary.
`dozens A, or as main power sources for wristwatches not
`requiring cell exchange.
`In general, these coin- or button-shaped flat non-aqueous
`electrolyte secondary cells have the structure shown in FIG.4.
`That is, a metallic anode case 5 also serving as an anode
`terminal and a metallic cathode case 1 also serving as a
`cathode terminalare fit to each other via an insulating gasket
`6, and further the cathode case 1 has a sealed opening struc-
`ture caulked by caulking, and in the inside ofthis structure,
`tablet-shaped cathode 12 and anode 14 having a smaller
`diameter than the opening ofthe insulating gasket 6 are set up
`against each other via a single- or multi-ply separator 13
`impregnated with a non-aqueouselectrolyte.
`The coin- or button-shaped flat non-aqueous electrolyte
`secondary cells as described above have the advantage that
`they are easily producible, excellent in mass-productivity,
`and superior in long-term reliability and safety. Further, by
`virtueof their simple structure, the most distinctive feature of
`these cells is that their miniaturization is feasible.
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`55
`
`SUMMARY OF THE INVENTION
`
`This invention was made in view of the circumstances
`described above, and the object ofthis invention is to provide
`a flat non-aqueous electrolyte secondary cell, which is
`remarkably superior in heavy-loading discharge characteris-
`tics.
`
`inventors made extensive study on the
`The present
`improvement of the heavy-loading discharge characteristics
`of the flat non-aqueouselectrolyte secondary cell described
`above. As a result, they found that the heavy-loading dis-
`charge characteristics are significantly improved by allowing
`the area of the electrodes to be significantly larger than in the
`conventional flat non-aqueous electrolyte secondary cell, to
`arrive at the present invention.
`That is, the present invention relates to a flat non-aqueous
`electrolyte secondary cell comprising a metallic anode case
`also serving as an anodeterminal and a metallic cathode case
`also serving as a cathode terminal fit to each other via an
`insulating gasket, the anode or cathode case having an open-
`ing-sealed structure caulked by caulking and having in the
`inside thereof an electricity-generating element including at
`least a cathode, a separator and an anode and a non-aqueous
`electrolyte, wherein a plurality of electrode units each con-
`sisting of the cathode and the anode opposite to each another
`via the separator are laminated to form an electrode group, or
`a sheet-shaped electrode unit consisting of the cathode and
`the anode opposite to each anothervia the separator is wound
`to form an electrode group, or a sheet-shape cathode is
`JLab/Cambridge, Exh. 1013, p. 16
`
`Meanwhile, the miniaturization of devices (mainly com-
`pact information terminals) such as portable telephones and
`PDA is promoted, thus making it essential to miniaturize
`secondary cells as their main power sources. In these power
`sources, there have been used cylindrical or rectangular alkali
`secondary cells such aslithium ion secondary cells wherein
`lithium-containing oxides such as lithium cobaltate is used as
`the cathode active material while a carbon material is used in
`
`the anode, or nickel hydride secondary cells wherein nickel
`oxyhydroxide is used as the cathode active material and a
`hydrogen-occluding alloy is used as the anode active mate-
`rial. These cells have been constructed by coating orfilling a
`
`JLab/Cambridge, Exh. 1013, p. 16
`
`

`

`US 7,566,515 B2
`
`4
`FIG. 11. Sectional drawingofflat non-aqueouselectrolyte
`secondary cell with one or two grooves.
`FIG. 12. Opening-sealed portion of cathode case with
`groove.
`FIG. 13. Sectional drawing of cathode case.
`FIG. 14. Anode case with shattering groove.
`FIG. 15. Top view of anode case with shattering groove.
`FIG. 16. Top view of anode case having shattering groove
`of concave shape.
`FIG. 17. Top view ofanode case with shattering groove and
`circular shape.
`FIG. 18. Top view of anodecase with half-roundshattering
`groove along circumference.
`FIG. 19. Top view of anode case with linear section con-
`cave shaped groove.
`FIG. 20. Top view of anode case with shattering grooves
`gatheredat central.
`FIG. 21. Top view of anode case with five lines of shatter-
`ing groove.
`FIG. 22. Top view of anode case, cathode case having no
`shattering groove.
`FIG. 23. Sectional drawing of cell with cathode or anode
`case having protrusions.
`FIG. 24. Top view of cell having cathode and anode cases
`with protrusions.
`FIG. 25. Sectional drawing of cell with bent alternating
`cathode and anodesheet.
`
`FIG.26. Sectional drawing of cell having alternating cath-
`ode sheet and anodesheet.
`
`DETAILED DESCRIPTION OF THE INVENTION
`
`10
`
`15
`
`20
`
`25
`
`30
`
`To improvethe heavy-loading discharge characteristics, it
`is considered effective to increase the area of the electrodes.
`
`35
`
`3
`wrapped with the separator except for a part contacting at
`inner face of cathode case and a sheet-shaped anodeis set on
`the sheet-shaped cathodein a right angled position each other
`and then these cathode and anodeare bent alternately to form
`an electrode group, and the total sum of the areas of the
`opposing cathode and anodein this electrode group is larger
`thanthe area of the opening ofsaid insulating gasket.
`Further, the present inventionrelatesto a flat non-aqueous
`electrolyte secondary cell comprising a metallic cell case also
`serving as an electrode terminal, an opening-sealing plate for
`sealing an opening in said cell case, and another electrode
`terminal arrangedvia an insulator in an opening provided in
`a part of the opening-sealing plate, said cell case being pro-
`vided inside with an electricity-generating element including
`at least a cathode, a separator and an anode and a non-aqueous
`electrolyte, wherein an electrode group consisting of an elec-
`trode unit having the cathode and the anode opposite to each
`another via the separator is formed, and the total sum of the
`areas of the opposing cathode and anode in this electrode
`groupis larger than the area of the opening of said opening-
`sealing plate.
`Asthe forms wherethe total sum ofthe areas ofthe oppos-
`ing cathode and anodein the electrode group is larger than the
`area of the opening of the insulating gasket in the present
`invention as described above, there is the form (1) wherein a
`plurality of the above-described electrode units are laminated
`to form an electrode group, and the total sum of the areas of
`the opposing cathodes and anodesin this electrode group is
`larger than the area ofthe opening of the insulating gasket, or
`the form (2) wherein the above electrode units are in the form
`ofa sheet, and said sheet-formed electrode units are wound to
`form an electrode group, andthe total sum ofthe areas of the
`opposing cathodes and anodesinthis electrode groupis larger
`than the area of the opening of the insulating gasket, or the
`form (3) wherein a sheet-shape cathode is wrapped with the
`separator exceptfor a part contacting at inner face of cathode
`case and a sheet-shaped anode is set on the sheet-shaped
`cathode in a right angled position each other and then these
`cathode and anodeare bent alternately to form an electrode
`group, and the total sum ofthe areas ofthe opposing cathodes
`and anodesinthis electrode group1s larger than thearea ofthe
`opening of the insulating gasket.
`Asdescribed above, the total sum ofthe areas ofthe oppos-
`ing cathodes and anodesin the electrode group is made larger
`than the area of the opening of the insulating gasket or the
`opening-sealed plate, whereby the heavy-loading discharge
`characteristics of the flat non-aqueouselectrolyte secondary
`cell can be significantly improved.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1. Non-aqueouselectrolyte secondary cell.
`FIG. 2. Non-aqueouselectrolyte secondary cell with cath-
`ode and anodein sheet form, sectional view of present inven-
`tion.
`FIG. 3. Non-aqueous solvent secondary cell, sectional
`drawing.
`FIG. 4. A coin-shaped or button-shaped flat non-aqueous
`electrolyte secondary cell.
`FIG.5. Flat non-aqueouselectrolyte secondary cell.
`FIG.6. Sectional drawing of a cell with a metal net.
`FIG.7. Sectional drawing of cell containing non-metallic
`thermalinsulator.
`
`40
`
`45
`
`50
`
`55
`
`60
`
`In the conventional flat non-aqueous electrolyte secondary
`cell, however, a cathode and an anode, both in a tablet form,
`are accommodatedrespectively to contact with an insulating
`gasket in the cell, so that the area of the cathode and anode
`opposing to each other via a separator will inevitably be
`smaller than the area of the openingofthe insulating gasket.
`Evenif the area of the opposing electrodes can be enlarged to
`some degrees by thinning the gasket, the opposing electrodes
`having a larger area than the area of the opening of the gasket
`can theoretically not be accommodated inthe cell.
`Accordingly, the present inventors have solved this prob-
`lem from a different viewpoint from the prior art by laminat-
`ing electrode units each consisting of a cathode, an anode and
`a separator, or by winding an electrode unit, or by bending
`alternately the sheet-shaped cathode and the sheet-shaped
`anodesettled in a right angled position each other, in a cell
`case for the very small coin- or button-shaped flat cell, to
`permit the total sum ofthe areas of the opposing cathode(s)
`and anode(s) in the electrode group to be larger than the area
`of the opening ofthe insulating gasket.
`In the conventional cylindrical or rectangular large second-
`ary cells described above, there are cases where dozenselec-
`trode layers are accommodatedin one cell, but such cells have
`the complicated structure as described above, soit is difficult
`to apply the electrode structure of such cells to the coin- or
`button-shaped, compactflat non-aqueouselectrolyte second-
`ary cell. Even if such a structure can be successfully applied,
`the advantages ofthe flat non-aqueous electrolyte secondary
`cell, for example miniaturizablility and high productivity,
`cannot be maintained. Accordingly, there has been no study
`attempting at permitting an electrode group whose opposing
`cathode and anode have a larger area than the area of the
`JLab/Cambridge, Exh. 1013, p. 17
`
`FIG.8. Sectional drawing of cell containing non-metallic
`thermalinsulator.
`
`65
`
`FIG. 9. Cathode case with cutting.
`FIG. 10. Cathode case with cutting.
`
`JLab/Cambridge, Exh. 1013, p. 17
`
`

`

`US 7,566,515 B2
`
`5
`opening of an insulating gasket to be accommodated in the
`coin- or button-shaped, compactflat non-aqueouselectrolyte
`secondary cell.
`In the coin- or button-shaped, compact flat non-aqueous
`electrolyte secondary cell in the present invention, the elec-
`trode group is constituted as shown above in (1), (2) and (3)
`thereby maximizing the area of the electrodes and minimiz-
`ing the numberofparts, thus succeeding in accommodating
`the electrode group and an amountof the non-aqueouselec-
`trolyte necessary for discharge in the space of the compact
`cell. Further, the electrodes can be easily produced according
`to this accommodation method andthusare suitable for mass-
`
`production by virtue of superiority in productivity and pro-
`duction costs.
`When the electrode units are laminated to form the elec-
`trode group in the present invention, the number of faces
`where a cathode is opposite an anode in the electrode unit is
`preferably at least 3. Cathode and anodeplates, each provided
`with an electrically connecting portion at a part (terminal)
`thereof, are arranged as the electrodes such that they are
`opposite to each another via a separator, wherein the electri-
`cally connecting portion of each cathode plate is exposed in
`onedirection of the separator, while the electrically connect-
`ing portion of each anode plate is exposed in the opposite
`direction of the separator, and thereafter the electrodes are
`laminated such thatthe electrically connecting portions ofthe
`cathodes are exposed to and electrically connected at the
`same side, while the electrically connecting portions of the
`anodesare exposedto andelectrically connectedat the oppo-
`site side. By arranging the electrically connecting portions of
`the cathodes opposite the electrically connecting portions of
`the anodes, internal short-circuiting upon contact between the
`cathode and anodeelectrically connecting portions can be
`prevented even in the coin- or button-shaped, compactflat
`non-aqueouselectrolyte secondary cell.
`Now, the method of connecting the electrode group to a
`metal case is described.
`In the cylindrical or rectangular, relatively large lithium ion
`secondary cell as described above, a tab terminal is welded for
`current collection into the center ofthe electrode group or into
`a core of the woundelectrode group, then bend and welded
`into a safety element or an opening-sealed pin. However, the
`technique of bending processing is complicated and thus
`inferior in productivity, and further the cell should be pro-
`vided therein with a space for preventing internal short-cir-
`cuiting, or an insulating plate should be inserted between the
`electrode group andthe tab terminal. Furthermore,if stress is
`appliedto the part where the tab terminal was weldedinto the
`electrode, the separator may be broken andthe electrode may
`be deformed, thus making it necessary to protect the tab
`terminal by an insulating tape or to provide the wound core
`with a space. Accordingly, the method of current collection
`for the cylindrical or rectangularlithium ion secondary cells
`cannot be applied to the coin-shaped or button-shaped,flat
`non-aqueouselectrolyte secondary cells having a small inter-
`nal volume.
`
`Accordingly, the present inventors have secured current
`collection for the electrode group andthe cell case by expos-
`ing an electrically conductive constituent material ofthe cath-
`ode at one edge face of the laminated electrode group (face
`parallel to the flat plane of the flat cell) while exposing an
`electrically conductive constituent material of the anode at
`the other edge face and then bringing the respective exposed
`electrode constituent materials into contact with the cathode
`
`and anodecell cases, respectively. According to this method,
`the discharge capacity can be increased without providing
`any spaceorinsulating plate betweenthe electrode group and
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`6
`the cell case. In addition, because no short-circuiting occurs
`between the cell case or the electrode andthe tab terminal, the
`cell is superior in safety and reliability.
`Further, the area of contact between the electrode consti-
`tutional material and the cell case can be madesignificantly
`larger than the area of contact between the conventional tab
`terminal andthe cell case, to achieve stable current collection,
`and the conventionally inevitable operation ofwelding the tab
`terminal into the electrode case can be omitted.
`
`As a matter of course, the goodelectrical contact between
`the electrode constitutional material and the cell case,
`achieved in the method of collecting current in the present
`invention, can be further improved by welding the electrode
`constitutional material into the cell case or by fixing these
`membersvia a conductive adhesive or via a current collecting
`net betweenthe electrode constitutional material andthe cell
`case.
`
`Whenthe electrode unit is wound to form the electrode
`
`group in the present invention, the face where the cathode is
`opposite the anodein the electrode unit may bein either the
`parallel or perpendicular directionto theflat plane ofthe flat
`cell, preferably the parallel direction. This is because the
`structure for securing current collection is made by exposing
`a conductive constituent material of the cathodeat one termi-
`nal of the electrode group while exposing the conductive
`constituent material of the anode at the other terminal and
`then bringing each material into contact with thecell case.
`In the case of the wound electrode group, the method of
`collecting current involves exposing an electrically conduc-
`tive constituent material ofthe cathodeat one edge face ofthe
`electrode group (face parallel to the flat plane ofthe flat cell)
`while exposing an electrically conductive constituent mate-
`rial of the anodeat the other edge face and then bringing the
`respective exposed electrode constituent materials into con-
`tact with the cathode and anode cell cases, respectively.
`According to this structure, the discharge capacity can be
`increased without providing any space or insulating plate
`between the electrode group and the cell case. In addition,
`because noshort-circuiting occurs between the cell case or
`the electrode andthetab terminal, the cell is superior in safety
`and reliability.
`A large numberof systems can be used for winding the
`electrode group. In a preferable system, the cathode and the
`anode, both in a sheet form, are woundto be opposite to each
`other via a separator as shown in FIG. 2. According to this
`winding system, the electrode from the start to the end of
`winding can beefficiently used. Further, there is no space in
`the center of a core of the woundelectrodes, so that when a
`spiral form ofthe flat electrodesis used, the electrodes can be
`effectively utilizable because boththe electrodes are opposite
`to each other from the start of winding.
`The woundelectrode group may be used as such, but after
`being wound,it is preferably compressed to improve adhe-
`sion of the cathode via the separator to the anode. In the coin-
`or button-shaped,flat non-aqueouselectrolyte secondary cell
`whose internal volume is small, if there is no space in the
`center ofa core ofthe woundelectrodes, the electrodes can be
`additionally accommodatedtherein, and further the adhesion
`ofthe cathode via the separator to the anode can be improved.
`The flat electrodes in a spiral form, constructed by bending
`and winding the opposing electrodes such that the face where
`the cathodeis opposite the anodeis parallel to the flat plane of
`theflat cell, followed by compressingthe electrodes, have the
`advantage that they are firmly wound and excellent in adhe-
`sion. Furthermore the above advantage is obtainedbysticking
`any tapes on R part of side of electrode group.
`JLab/Cambridge, Exh. 1013, p. 18
`
`JLab/Cambridge, Exh. 1013, p. 18
`
`

`

`US 7,566,515 B2
`
`7
`Furthermore,in the flat cell having such an opening-sealed
`structure as in the present invention, stress was applied in the
`perpendicular direction to the flat plane of the cathode and
`anode cases upon caulking of the cell case, whereby the
`adhesion between the electrode group and the cell case is
`improved, charge/discharge can be conducted smoothly, and
`the characteristics of the cell are improved. The exposed
`portions ofthe electrode constituent materials ofthe electrode
`group may contact the electrode case directly or electrically
`indirectly via a metalfoil, a metal net, metal powder, carbon
`fillers or a conductive coating.
`Now,the electrodes are described. For both the cathode and
`anode,it is possible to use a conventional method of forming
`a granular depolarizing mix for cell or a methodoffilling a
`metal substrate such as metal net or foamed nickel with a
`
`20
`
`depolarizing mix for cell. Preferably, a depolarizing mix for
`cell in aslurry form is applied onto a metalfoil, then dried and
`optionally further rolled so that a thin electrode can be easily
`prepared.Ifthe electrodes on which the depolarizing mix for
`cell containing the active material is applied on a metalfoil as
`described above are used, it is preferable for volumeeffi-
`ciency that the inner electrodes in the electrode group are
`those wherein a layerof the active material is formed on both
`sides of the metal foil, while the outermost electrodes in the
`electrode group, thatis, the electrodes in contact with the cell
`case, are preferably those wherein particularly the metal foil
`in the electrode materials is exposed in order to reduce contact
`resistance. In this case, the active material layer may be
`formed on only oneside of the outermost electrode, or after
`the active material later is formed on both sides of the outer-
`most electrode, the active material layer may be removed
`from oneside.
`
`8
`calcinated mesophasepitch fiber are preferable in respect of
`less reduction in the working voltage of the cell in the end of
`discharge.
`In the flat non-aqueouselectrolyte secondary cell having
`an electrode group in a laminate, wound or bent form as
`described above, the degree of adhesion between the cathode
`and anodecell cases and the electrode group has a significant
`influence on cell
`impedance and cell performance. For
`example, when the cell is stored for a long time in a high-
`temperature atmosphere at about 60° C., the non-aqueous
`electrolyte is decomposed,thecell is expanded, the adhesion
`betweenthe cell case and the electrode groupis significantly
`worsened, and the performanceofthe cell is deteriorated. In
`addition, when the flat non-aqueous electrolyte secondary
`cell is placed in an abnormalstate such as short-circuiting, the
`cell causes a significant increase in temperature, resulting in
`decomposition of the non-aqueouselectrolyte or gasification
`ofthe solvent thereby increasing the innerpressurein thecell
`to cause the problem ofcell breakage.
`This problem was solved in the present invention by using
`ethylene carbonate (EC) and y-butyrolactone (GBL) as the
`major solvent for the non-aqueous electrolyte and lithium
`borofluoride as the supporting electrolyte. By this constitu-
`tion, gas generation can be suppressed even at high tempera-
`ture to prevent cell breakage.
`A mixed solvent of EC and GBLis stable to a graphitized
`carbon anode and hardly decomposedatthe side ofthe anode.
`Further, the stability of the mixed solvent at high potentialis
`also high, and even ifleft for a long time ina high-temperature
`atmosphere, the non-aqueous electrolyte is hardly decom-
`posedat the side of the cathode, thus hardly generating gas.
`Further, both EC and GBL have high boiling points (about
`240° C. and about 200° C., respectively) so that even ifthe cell
`is heated upon short-circuiting or placed in an abnormal
`Now, the cathode and anode active materials used in the
`atmosphere at about 150° C., the vaporpressure of the mixed
`cell of the present invention are described.
`solvent can be kept low, and its decomposition hardly occurs.
`In the present invention, special attention is paid to the
`Accordingly, the increase in the inner pressure in the cell and
`structure of the cell including the electrodes, so there is no
`the breakage of the cell can be prevented.
`limit to the cathode active materials. Itis possible to use metal
`In the mixed solvent of EC and GBL, the volumeratio of
`oxides such as MnO,, V,0;, Nb,O;, LiTi,0,, Li,71;0,,,
`EC to GBLis preferably 0.3 to 1.0. This is because if the
`LiFe,O,,
`lithium cobaltate,
`lithium nickelate and lithium
`volume ratio of EC is too low, a protective coating is not
`manganate, inorganic compoundssuchas fluorinated graph-
`sufficien