JP4563002B2 - Flat non-aqueous electrolyte secondary battery - Google Patents
Flat non-aqueous electrolyte secondary battery Download PDFInfo
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- JP4563002B2 JP4563002B2 JP2003209084A JP2003209084A JP4563002B2 JP 4563002 B2 JP4563002 B2 JP 4563002B2 JP 2003209084 A JP2003209084 A JP 2003209084A JP 2003209084 A JP2003209084 A JP 2003209084A JP 4563002 B2 JP4563002 B2 JP 4563002B2
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- 239000011255 nonaqueous electrolyte Substances 0.000 title claims description 50
- 238000007789 sealing Methods 0.000 claims description 42
- 230000002093 peripheral effect Effects 0.000 claims description 37
- 229910052751 metal Inorganic materials 0.000 claims description 24
- 239000002184 metal Substances 0.000 claims description 23
- 229910000831 Steel Inorganic materials 0.000 claims 1
- 150000002739 metals Chemical class 0.000 claims 1
- 239000010959 steel Substances 0.000 claims 1
- 230000000052 comparative effect Effects 0.000 description 20
- 239000013543 active substance Substances 0.000 description 11
- 229910052744 lithium Inorganic materials 0.000 description 11
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 10
- -1 MnO 2 and V 2 O 5 Chemical class 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical class [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 239000011888 foil Substances 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 238000002788 crimping Methods 0.000 description 4
- 238000009783 overcharge test Methods 0.000 description 4
- 229920003026 Acene Polymers 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 239000003575 carbonaceous material Substances 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000011302 mesophase pitch Substances 0.000 description 3
- 150000002894 organic compounds Chemical class 0.000 description 3
- 239000007774 positive electrode material Substances 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 2
- 229910000733 Li alloy Inorganic materials 0.000 description 2
- 229910013870 LiPF 6 Inorganic materials 0.000 description 2
- 229910012465 LiTi Inorganic materials 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 2
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 2
- 239000010408 film Substances 0.000 description 2
- 150000002484 inorganic compounds Chemical class 0.000 description 2
- 229910010272 inorganic material Inorganic materials 0.000 description 2
- 239000001989 lithium alloy Substances 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 229920000767 polyaniline Polymers 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 229910052814 silicon oxide Inorganic materials 0.000 description 2
- 239000007784 solid electrolyte Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 229920003048 styrene butadiene rubber Polymers 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- ZZXUZKXVROWEIF-UHFFFAOYSA-N 1,2-butylene carbonate Chemical compound CCC1COC(=O)O1 ZZXUZKXVROWEIF-UHFFFAOYSA-N 0.000 description 1
- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 1
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 description 1
- 229910007857 Li-Al Inorganic materials 0.000 description 1
- 229910008029 Li-In Inorganic materials 0.000 description 1
- 229910008367 Li-Pb Inorganic materials 0.000 description 1
- 229910008365 Li-Sn Inorganic materials 0.000 description 1
- 229910013063 LiBF 4 Inorganic materials 0.000 description 1
- 229910013684 LiClO 4 Inorganic materials 0.000 description 1
- 229910012851 LiCoO 2 Inorganic materials 0.000 description 1
- 229910008447 Li—Al Inorganic materials 0.000 description 1
- 229910006670 Li—In Inorganic materials 0.000 description 1
- 229910006738 Li—Pb Inorganic materials 0.000 description 1
- 229910006759 Li—Sn Inorganic materials 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 239000003125 aqueous solvent Substances 0.000 description 1
- 229910021383 artificial graphite Inorganic materials 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000007606 doctor blade method Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000008202 granule composition Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000005518 polymer electrolyte Substances 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
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Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Sealing Battery Cases Or Jackets (AREA)
- Cell Electrode Carriers And Collectors (AREA)
- Secondary Cells (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は扁平形非水電解質二次電池、特に金属製の正極ケースと金属製の負極ケースとをガスケットを介して加締め封口した構造の扁平形非水電解質二次電池に係わり、さらに詳しくは加締め封口部分の封口性を向上させて安全性を高めた上記電池に関する。
【０００２】
【従来の技術】
正極作用物質にＭｎＯ２やＶ２Ｏ５などの金属酸化物、あるいはフッ化黒鉛などの無機化合物、あるいはポリアニリンやポリアセン構造体などの有機化合物を用い、負極に金属リチウム、あるいはリチウム合金、あるいはポリアセン構造体などの有機化合物、あるいはリチウムを吸蔵、放出可能な炭素質材料、あるいはチタン酸リチウムやリチウム含有珪素酸化物のような酸化物を用い、電解質にプロピレンカーボネート、エチレンカーボネート、ブチレンカーボネート、ジエチルカーボネート、ジメチルカーボネート、メチルエチルカーボネート、ジメトキシエタン、γ−ブチルラクトンなどの非水溶媒にＬｉＣｌＯ４、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＣＦ３ＳＯ３、ＬｉＮ（ＣＦ３ＳＯ２）２、ＬｉＮ（Ｃ２Ｆ５ＳＯ２）２などの支持塩を溶解した非水電解質を用いたコイン形やボタン形の扁平形非水電解質二次電池は既に商品化されており、放電電流が数〜数十μＡ程度の軽負荷で放電が行われるＳＲＡＭやＲＴＣのバックアップ用電源や電池交換不要腕時計の主電源といった用途に適用されている。
【０００３】
これら従来の扁平形非水電解質二次電池は構造が簡便であるため、小型化が可能であり、量産性、長期信頼性および安全性に優れているが、その反面、電極面積が制限されるため中〜重負荷放電には適していない。そのため、小型情報端末や携帯機器の主電源として採用することはできなかった。
【０００４】
これに対して、電池形状は変更せずに電極面積を大きくすることで、重負荷放電が可能な扁平形非水電解質二次電池が開発、提供されている（特許文献１および特許文献２参照）。
【０００５】
すなわち扁平形非水電解質二次電池の扁平面に垂直な方向の断面を見た場合、少なくとも３面以上の正極と負極がセパレータを介して対向している正負極対向面を有する電極群を配して、電極群内の正負極対向面積の総和を大きくすることで重負荷特性を著しく向上させた扁平形非水電解質二次電池である。これらの電池は、正負極対向面積の大きな電極群を小型のケースに収納するために、金属薄膜からなる集電体に正極活物質を塗着した正極板と、金属薄膜からなる負極集電板に負極活物質を塗着した負極板とをセパレータを介して捲回や積層することにより電極群とし、非水電解質を含浸させて、この電極群を内包するように金属製の正極ケースおよび金属製の負極ケースとをガスケットを介して加締めることで封口したものである。
【０００６】
【特許文献１】
特開２００１−０６８１６０号公報
【特許文献２】
特開２００１−０６８１４３号公報
【０００７】
【発明が解決しようとする課題】
しかしながら、このような重負荷特性の向上した電池の主たる用途は携帯機器であり、身体周辺に密着して用いることが多いため、電池の破裂および漏液に対する対策が必要である。
【０００８】
本発明はかかる問題に対してなされたもので、前記重負荷特性の向上した扁平形非水電解質二次電池において、電池の封口性を向上させることにより、過度な充電を行った際の電池の破裂および漏液を防止することを目的とするものである。
【０００９】
【課題を解決するための手段】
本発明者らは鋭意研究を重ねた結果、上記扁平型非水電解質二次電池の封口部の加締め加工を、上方からの投影で外装ケース最内周端部と封口ケース最外周端部との間の重なり合う長さを０．２ｍｍ以上０．４５ｍｍ以下とすると、過度の充電の際の破裂および漏液を防止することができることを見出し、本発明を完成するに至った。
【００１０】
すなわち本発明は、金属製の封口ケースと金属製の外装ケースが、絶縁ガスケットを介して嵌合され、加締め加工により加締められた封口構造を有し、その内部に少なくとも正極板、セパレータ、負極板を含む電極群と、非水電解質を内包し、かつ電極群のセパレータを介した正負極対向面積の総和が絶縁ガスケットの開口面積よりも大きい扁平形非水電解質二次電池において、上記封口ケースおよび上記外装ケースのいずれか一方が負極端子を兼ね、他方が正極端子を兼ねており、上方からの投影で外装ケース最内周端部と封口ケース最外周端部の重なり合う部分の長さが０．２ｍｍ以上０．４５ｍｍ以下であることを特徴とする扁平形非水電解質二次電池に関する。
【００１１】
次に、本発明の経緯を説明する。
正極ケースが加締め加工により加締められた封口構造を有する扁平形非水電解質二次電池では、その加締め加工後の形状は、外装ケース（例えば正極ケース）、封口ケース（例えば負極ケース）、絶縁ガスケットの形状により変化する。例えば絶縁ガスケットの厚さを増加すると、その圧縮性により封口性が改善されるが、絶縁ガスケットの厚さを増加することで電池内容積が減少する。また、封口ケースの外周縁部を外装ケース側に向けてＵ字状に折り返すことで、絶縁ガスケットの圧縮性を向上し、封口性を向上させることができるが、この場合は封口ケースの内容積を減少させてしまうので、電池放電容量を低下させる。
【００１２】
そこで、電池内容積を減少させることなく電池封口性を向上させるためには、絶縁ガスケットに対する圧縮性を落とさずに、封口部分の外装ケース、絶縁ガスケットおよび封口ケースの接する面積を大きくすることが重要であることがわかった。その結果、外装ケース最内周端部と封口ケース最外周端部との間の重なり合う長さを上記のように保持することによって、十分な密着性を得ることができることがわかった。ここで、「重なり合う」の意は、図２に示すように外装ケース（正極ケース）最内周端部が封口ケース（負極ケース最外周端部）より内側にあり、上から見たときに両者が重なった状態になっていることである。
【００１３】
なお、本発明は電池の封口部分の構造に主点を置いたものであり、正極作用物質については限定されるものではない。例えば、ＭｎＯ２、Ｖ２Ｏ５、Ｎｂ２Ｏ５、ＬｉＴｉ２Ｏ４、Ｌｉ４Ｔｉ５Ｏ１２、ＬｉＦｅ２Ｏ４、コバルト酸リチウム、ニッケル酸リチウム、マンガン酸リチウムなどの金属酸化物、あるいはフッ化黒鉛、ＦｅＳ２などの無機化合物、あるいはポリアニリンやポリアセン構造体などの有機化合物などあらゆるものが適用可能である。ただし、この中で作動電位が高く、サイクル特性に優れるという点でコバルト酸リチウム、ニッケル酸リチウム、マンガン酸リチウムやそれらの混合物やそれらの元素の一部を他の金属元素で置換したリチウム含有酸化物がより好ましく、長期間に渡り使用されることもある扁平形非水電解質二次電池においては高容量で電解液や水分との反応性が低く化学的に安定であるという点でコバルト酸リチウムがさらに好ましい。
【００１４】
また負極作用物質についても限定されるものではなく、金属リチウム、あるいはＬｉ−Ａｌ、Ｌｉ−Ｉｎ、Ｌｉ−Ｓｎ、Ｌｉ−Ｓｉ、Ｌｉ−Ｇｅ、Ｌｉ−Ｂｉ、Ｌｉ−Ｐｂなどのリチウム合金、あるいはＮｂ２Ｏ５、ＬｉＴｉ２Ｏ４、Ｌｉ４Ｔｉ５Ｏ１２、やＬｉ含有珪素酸化物のような酸化物などあらゆるものが適用可能であるが、サイクル特性に優れ、作動電位が低く、高容量であるという点でＬｉを吸蔵、放出可能な炭素質材料が好ましく、特に放電末期においても電池作動電圧の低下が少ないという点で天然黒鉛や人造黒鉛、膨張黒鉛、メソフェーズピッチ焼成体、メソフェーズピッチ繊維焼成体などのｄ００２の面間隔が０．３３８ｎｍ以下の黒鉛構造が発達した炭素質材料がより好ましい。
【００１５】
次に、電極については、正負極とも従来の顆粒合剤の成形方式や金属ネットの金属基盤に合剤を充填する方法を用いてもよいが、肉薄電極が作製しやすいという点で金属箔にスラリー状の合剤を塗布、乾燥したものがよく、さらにそれを圧延したものも用いることもできる。金属箔に作用物質を含む合剤層を塗工した電極を用いる場合は、電極群の内部に用いる電極は金属箔の両面に作用物質層を形成したものを用いるのが、容積効率の上から好ましい。電極群の両端の厚さ方向に貫通口を有する金属製薄板に接触する電極構成材露出部については接触抵抗を低減させるために電極構成材の内、特に金属箔を露出させるのが好ましい。これに関してはこの部分に限り片面にのみ作用物質層を形成した電極を用いてもよいし、一旦、両面に作用物質層を形成した後、片面のみ作用物質層を除去してもよい。
【００１６】
【発明の実施の形態】
（参考例１）
本参考例の扁平形非水電解質二次電池の断面図を図１に示す。また、その封口部分の拡大図を図２に示す。
【００１７】
以下に本参考例の電池の製造方法を説明する。
まず、ＬｉＣｏＯ２１００質量部に対し導電材としてアセチレンブラック５質量部と黒鉛粉末５質量部とを加え、結着剤としてポリフッ化ビニリデン５質量部を加え、Ｎ−メチルピロリドンで希釈、混合し、スラリー状の正極合剤を得た。次にこの正極合剤を、正極集電体である厚さ０．０２ｍｍのアルミ箔の片面にドクターブレード法により塗工、乾燥を行い、アルミ箔表面に正極作用物質含有層を形成した。以後、正極作用物質含有層の塗膜厚さが両面で０．１５ｍｍとなるまで塗工、乾燥を繰り返し、両面塗工正極を作製した。次に、この電極体の片面の端から正極ケースに接する部分の作用物質含有層を除去し、アルミ層を剥き出して通電部とし、幅１２ｍｍ、長さ１２０ｍｍ、厚さ０．１５ｍｍの長さに切り出した正極板３を作製した。
【００１８】
次に黒鉛化メソフェーズピッチ炭素繊維粉末１００質量部に結着剤としてスチレンブタジエンゴム（ＳＲＢ）とカルボキシメチルセルロース（ＣＭＣ）をそれぞれ２．５質量部を添加し、イオン交換水で希釈、混合し、スラリー状の負極合剤を得た。得られた負極合剤を負極集電体である厚さ０．０２ｍｍの銅箔に作用物質含有層の厚さが０．１５ｍｍとなるように正極の場合と同様に塗工、乾燥を繰り返し実施し、両面塗工負極を作製した。次に、この電極体の片面の端から負極ケースに接する部分の作用物質含有層を除去し、銅層を剥き出して通電部とし、幅１３ｍｍ、長さ１３０ｍｍ、厚さ０．１５ｍｍの長さに切り出した負極板４を作製した。
【００１９】
次に正負極各通電部面を外周巻き終わり側とし、これら正極と負極の間に厚さ２５μｍのポリエチレン微多孔膜からなるセパレータ８を介して渦巻き状に捲回し、これを扁平形電池の扁平面に対し水平方向に正負極対向部をもつような方向に加圧した。加圧は捲回電極の中心部の空間がなくなるまで行った。
【００２０】
作製した電極群を８５℃で１２時間乾燥した後、絶縁ガスケット７を一体化した負極金属ケース５（金属製ネット６が内面に溶接されている）の内底面に、電極群の片面塗工負極板の未塗工側が接するように配置した。次に、エチレンカーボネートとメチルエチルカーボネートを体積比１：１の割合で混合した溶媒に支持塩としてＬｉＰＦ６を１ｍｏｌ／ｌの割合で溶解せしめた非水電解質を、負極ケース内に満たされるまで注液し、さらに電極群の片面塗工正極板の未塗工側に接するように、ステンレス製の正極ケース１（金属製ネット２が内面に溶接されている。高さ２．７０ｍｍ）を嵌合し、上下反転後、正極ケースに加締め加工を施した。加締め加工部の断面形状は、図２に示すように、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０．０５ｍｍとなるようにした。このようにして、厚さ３．２ｍｍ、外径２４ｍｍ角の参考例１の扁平形非水電解質二次電池を製作した。
【００２１】
（実施例２）
加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０．２ｍｍとなるように封口した。それ以外は参考例１と同様にして扁平形非水電解質二次電池を製作した。
【００２２】
（実施例３）
加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０．４５ｍｍとなるように封口した。それ以外は参考例１と同様にして扁平形非水電解質二次電池を製作した。
【００２３】
（参考例４）
正極ケース高さが２．６ｍｍであり、加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０．０５ｍｍとなるように封口した。それ以外は参考例１と同様にして扁平形非水電解質二次電池を製作した。
【００２４】
（実施例５）
加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０．２ｍｍとなるように封口した。それ以外は参考例４と同様にして扁平形非水電解質二次電池を製作した。
【００２５】
（実施例６）
加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０．４５ｍｍとなるように封口した。それ以外は参考例４と同様にして扁平形非水電解質二次電池を製作した。
【００２６】
（参考例７）
正極ケース高さが２．９ｍｍであり、加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０．０５ｍｍとなるように封口した。それ以外は参考例１と同様にして扁平形非水電解質二次電池を製作した。
【００２７】
（実施例８）
加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０．２ｍｍとなるように封口した。それ以外は参考例７と同様にして扁平形非水電解質二次電池を製作した。
【００２８】
（実施例９）
加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０．４５ｍｍとなるように封口した。それ以外は参考例７と同様にして扁平形非水電解質二次電池を製作した。
【００２９】
（比較例１）
加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０ｍｍとなるように封口した。それ以外は参考例１と同様にして扁平形非水電解質二次電池を製作した。
【００３０】
（比較例２）
加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０ｍｍとなるように封口した。それ以外は参考例４と同様にして扁平形非水電解質二次電池を製作した。
【００３１】
（比較例３）
加締め加工部の断面形状は、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０ｍｍとなるように封口した。それ以外は参考例７と同様にして扁平形非水電解質二次電池を製作した。
【００３２】
（比較例４）
正極ケース高さが２．５ｍｍであり、加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０ｍｍとなるように封口した。それ以外は参考例１と同様にして扁平形非水電解質二次電池を製作した。
【００３３】
（比較例５）
加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０．０５ｍｍとなるように封口した。それ以外は比較例４と同様にして扁平形非水電解質二次電池を製作した。
【００３４】
（比較例６）
加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０．２ｍｍとなるように封口した。それ以外は比較例４と同様にして扁平形非水電解質二次電池を製作した。
【００３５】
（比較例７）
加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０．４５ｍｍとなるように封口した。それ以外は比較例４と同様にして扁平形非水電解質二次電池を製作した。
【００３６】
（比較例８）
加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０．６ｍｍとなるように封口した。それ以外は参考例１と同様にして扁平形非水電解質二次電池を製作した。
【００３７】
（比較例９）
加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０．６ｍｍとなるように封口した以外は参考例４と同様にして扁平形非水電解質二次電池を製作した。
【００３８】
（比較例１０）
加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０．６ｍｍとなるように封口した。それ以外は参考例７と同様にして扁平形非水電解質二次電池を製作した。
【００３９】
（比較例１１）
加締め加工部の断面形状が、上方からの投影で正極ケース最内周端部と負極ケース最外周端部の重なり合う部分の長さＡが０．６ｍｍとなるように封口した。それ以外は比較例４と同様にして扁平形非水電解質二次電池を製作した。
【００４０】
上記実施例２、３、５、６、８、９、参考例１、４、７および比較例１〜１１の電池を各５０個作製した。このうち、比較例８〜１１の電池において正極ケースと負極ケースが接触することによる外部短絡が発生した。その他の作製した電池は、２０℃雰囲気下で２日間静置し、その後５ｍＡ、４．２Ｖの定電流定電圧で２４時間充電を実施した。更に、３日間静置後、閉回路電圧を測定した。その結果、すべての電池において、４．１６Ｖ程度となった。５０ｍＡの定電流で閉回路電圧が３．０Ｖになるまで放電を実施し、放電容量を求めた。その結果、すべての電池で５５ｍＡｈ程度の放電容量を得ることができた。
【００４１】
続いて、これら電池を同条件で充電し、各々２０個の電池を２０℃雰囲気下で５０ｍＡ、１２Ｖの定電流定電圧で１２時間、過充電試験を行い、破裂、漏液の発生を確認した。
【００４２】
表１に各々の電池の過充電試験による破裂および漏液の個数を示す。
【００４３】
【表１】
表１に示すように、実施例２、３、５、６、８、９の電池では、過充電試験において、破裂、漏液は見られなかった。
【００４５】
一方、加締め加工部の断面形状の長さＡが０ｍｍとなるように封口した比較例１〜４の電池では、過充電試験において電圧が上昇し、これによって電解液が分解してガス圧が上昇し、この上昇したガス圧を抑えきれずに破裂した。
【００４６】
比較例４〜７および比較例１１では正極ケースの高さを２．５ｍｍとしたが、これらの電池について加締め加工部の断面形状を確認したところ、加締め加工を行った際に、正極ケースが負極ケースに倒れ込むように力がかかることで、負極ケースが内側へと倒れ込む現象が見られた。そのため、正極ケース高さ２．５ｍｍの部品を用いて作製した電池では、長さＡが０ｍｍから０．２ｍｍとなるようにしか封口できず、加締め加工部の断面形状で、長さＡをこれより大きく、例えば０．４５、０．６ｍｍとすることはできなかった。一方、長さＡが０、０．０５、０．２ｍｍでの電池では、負極ケースの側面部付近が変形を起こして漏液が発生してしまう。したがって、正極ケース高さは２．５ｍｍでは不適当であることがわかった。
【００４７】
正極ケース高さ３．０ｍｍの電池の作製も試みたが、正極ケース高さ３．０ｍｍの場合、正極ケースを加締め加工し、加締め加工部の断面形状を確認したところ、長さＡが０ｍｍから０．６ｍｍとなるように封口することはできたが、これを０ｍｍから０．４５ｍｍとした場合、絶縁ガスケットへの圧縮がうまく行われず、作製直後に漏液が発生した。０．６ｍｍとした場合には、正極ケースと負極ケースが接触することによって、外部短絡の発生を招いた。したがって正極ケース高さが３．０ｍｍの場合も不適当であることがわかった。
【００４８】
これらのことから、電池総高３．２ｍｍの場合には、正極ケースの高さは２．５ｍｍより大で３．０ｍｍより小が適当であり、２．６ｍｍ〜２．９ｍｍがより好ましいことがわかった。電池総高ｔに対する比としては、０．８１ｔ〜０．９１ｔの範囲が好ましい。
【００４９】
なお、本発明の実施例は、非水電解質に非水溶媒を用いた扁平形非水電解質二次電池を用いて説明したが、本発明は、非水電解質にポリマー電解質を用いたポリマー二次電池や固体電解質を用いた固体電解質二次電池についても適用可能である。また、正極ケースの加締め加工により封口する扁平形非水電解質二次電池をもとに説明したが、正負極電極を入れ替え、負極ケースの加締め加工により封口することも可能である。
【００５０】
【発明の効果】
以上説明したように、本発明によれば、扁平形非水電解質二次電池における封口性を向上させることができるので、過度な充電を行った際の電池の破裂および漏液を防止することができ、安全性を高めることができる。
【図面の簡単な説明】
【図１】 実施例および参考例の電池の断面図。
【図２】 図１の電池の封口部分の拡大図。
【符号の説明】
１ 外装ケース（正極ケース）
２ 金属製ネット（正極側）
３ 正極板
４ 負極板
５ 封口ケース（負極ケース）
６ 金属ネット（負極側）
７ 絶縁ガスケット
８ セパレータ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flat non-aqueous electrolyte secondary battery, and more particularly to a flat non-aqueous electrolyte secondary battery having a structure in which a metal positive electrode case and a metal negative electrode case are swaged and sealed via a gasket. It is related with the said battery which improved the sealing property of the crimping sealing part, and improved safety.
[0002]
[Prior art]
A metal oxide such as MnO 2 and V 2 O 5 , an inorganic compound such as fluorinated graphite, or an organic compound such as polyaniline or a polyacene structure is used as the positive electrode active material, and metal lithium, lithium alloy, or polyacene is used as the negative electrode. Organic compounds such as structures, carbonaceous materials capable of occluding and releasing lithium, or oxides such as lithium titanate and lithium-containing silicon oxide, and propylene carbonate, ethylene carbonate, butylene carbonate, diethyl carbonate as electrolytes LiClO 4 , LiPF 6 , LiBF 4 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiN (C 2 F 5 ) in a non-aqueous solvent such as dimethyl carbonate, methyl ethyl carbonate, dimethoxyethane, and γ-butyl lactone SO 2 ) Coin-shaped and button-shaped flat non-aqueous electrolyte secondary batteries using a non-aqueous electrolyte in which a supporting salt such as 2 is dissolved have already been commercialized, and the discharge current is light load of several to several tens of μA. This is applied to applications such as a backup power source for a discharged SRAM or RTC and a main power source for a battery replacement-free wristwatch.
[0003]
These conventional flat nonaqueous electrolyte secondary batteries have a simple structure and can be miniaturized, and are excellent in mass productivity, long-term reliability, and safety, but on the other hand, the electrode area is limited. Therefore, it is not suitable for medium to heavy load discharge. Therefore, it could not be adopted as a main power source for small information terminals and portable devices.
[0004]
In contrast, a flat nonaqueous electrolyte secondary battery capable of heavy load discharge has been developed and provided by increasing the electrode area without changing the battery shape (see Patent Document 1 and Patent Document 2). ).
[0005]
That is, when a cross-section in a direction perpendicular to the flat surface of the flat nonaqueous electrolyte secondary battery is viewed, an electrode group having positive and negative electrode facing surfaces in which at least three or more positive and negative electrodes are opposed via a separator is arranged. Thus, the flat nonaqueous electrolyte secondary battery has the heavy load characteristics remarkably improved by increasing the sum of the positive and negative electrode facing areas in the electrode group. These batteries include a positive electrode plate in which a positive electrode active material is applied to a current collector made of a metal thin film, and a negative electrode current collector plate made of a metal thin film, in order to accommodate an electrode group having a large positive and negative electrode facing area in a small case. A negative electrode plate coated with a negative electrode active material is wound and laminated through a separator to form an electrode group, impregnated with a non-aqueous electrolyte, and a metal positive electrode case and a metal so as to enclose the electrode group A negative electrode case made of metal is sealed by crimping via a gasket.
[0006]
[Patent Document 1]
JP 2001-068160 A [Patent Document 2]
Japanese Patent Laid-Open No. 2001-068143
[Problems to be solved by the invention]
However, the main application of such a battery with improved heavy load characteristics is a portable device, which is often used in close contact with the periphery of the body, and therefore measures against battery rupture and leakage are necessary.
[0008]
The present invention has been made to solve such a problem, and in the flat nonaqueous electrolyte secondary battery having improved heavy load characteristics, by improving the battery sealing performance, The purpose is to prevent rupture and leakage.
[0009]
[Means for Solving the Problems]
As a result of intensive studies, the inventors of the present invention have carried out a caulking process on the sealing portion of the flat type nonaqueous electrolyte secondary battery by projecting from above the outermost innermost end portion of the outer case and the outermost peripheral end portion of the sealing case. It has been found that if the length of the overlap between them is 0.2 mm or more and 0.45 mm or less, rupture and leakage during excessive charging can be prevented, and the present invention has been completed.
[0010]
That is, the present invention has a sealing structure in which a metal sealing case and a metal outer case are fitted via an insulating gasket and crimped by caulking, and at least a positive electrode plate, a separator, In the flat nonaqueous electrolyte secondary battery that includes the electrode group including the negative electrode plate and the nonaqueous electrolyte, and the sum of the positive and negative electrode facing areas through the separator of the electrode group is larger than the opening area of the insulating gasket, Either the case or the outer case serves as a negative electrode terminal, and the other serves as a positive electrode terminal, and the length of the overlapping portion of the outer case innermost end and the outer case end of the sealing case is projected from above. The present invention relates to a flat nonaqueous electrolyte secondary battery characterized by being 0.2 mm or more and 0.45 mm or less.
[0011]
Next, the background of the present invention will be described.
In a flat nonaqueous electrolyte secondary battery having a sealing structure in which a positive electrode case is crimped by caulking, the shape after the caulking process is an outer case (for example, a positive electrode case), a sealing case (for example, a negative electrode case), Varies depending on the shape of the insulating gasket. For example, when the thickness of the insulating gasket is increased, the sealing property is improved by its compressibility, but the battery internal volume is decreased by increasing the thickness of the insulating gasket. Moreover, the outer peripheral edge of the sealing case is folded back in a U-shape toward the outer case side, thereby improving the compressibility of the insulating gasket and improving the sealing property. In this case, the inner volume of the sealing case Battery discharge capacity is reduced.
[0012]
Therefore, in order to improve the battery sealing performance without reducing the battery internal volume, it is important to increase the contact area of the outer casing, the insulating gasket, and the sealing case of the sealing portion without reducing the compressibility of the insulating gasket. I found out that As a result, it was found that sufficient adhesion can be obtained by maintaining the overlapping length between the outermost end of the outer case and the outermost end of the sealing case as described above. Here, the meaning of “overlapping” means that the innermost end of the outer case (positive electrode case) is inside the sealing case (outermost end of the negative electrode case) as shown in FIG. Is in a state of overlapping.
[0013]
The present invention focuses on the structure of the sealing portion of the battery, and the positive electrode active substance is not limited. For example, metal oxides such as MnO 2 , V 2 O 5 , Nb 2 O 5 , LiTi 2 O 4 , Li 4 Ti 5 O 12 , LiFe 2 O 4 , lithium cobaltate, lithium nickelate, lithium manganate, or Any of inorganic compounds such as fluorinated graphite and FeS 2 or organic compounds such as polyaniline and polyacene structures can be applied. However, lithium-containing oxides in which lithium cobaltate, lithium nickelate, lithium manganate, mixtures thereof, or some of these elements are substituted with other metal elements are high in terms of operating potential and excellent cycle characteristics. Lithium cobaltate is a flat type non-aqueous electrolyte secondary battery that is more preferable and may be used for a long period of time because it is chemically stable with a high capacity and low reactivity with electrolyte and moisture. Is more preferable.
[0014]
Also, the negative electrode active substance is not limited, and is lithium metal, lithium alloy such as Li—Al, Li—In, Li—Sn, Li—Si, Li—Ge, Li—Bi, Li—Pb, or Nb 2 O 5 , LiTi 2 O 4 , Li 4 Ti 5 O 12 , and oxides such as Li-containing silicon oxide are all applicable, but excellent cycle characteristics, low operating potential, high capacity The carbonaceous material capable of occluding and releasing Li is preferable in that it is natural graphite, artificial graphite, expanded graphite, mesophase pitch fired body, mesophase pitch fiber, especially in that the battery operating voltage does not decrease much at the end of discharge. A carbonaceous material with a developed graphite structure having a d 002 spacing of 0.338 nm or less, such as a fired body, is more preferable.
[0015]
Next, with respect to the electrodes, both the positive and negative electrodes may be formed by using a conventional granule mixture molding method or a method of filling a metal base of a metal net with a mixture. What applied and dried the slurry-like mixture is good, and what rolled it further can also be used. When using an electrode in which a mixture layer containing an active substance is applied to a metal foil, the electrode used inside the electrode group is one in which an active substance layer is formed on both sides of the metal foil. preferable. In order to reduce contact resistance, it is preferable to expose the metal foil, particularly the metal foil, for the electrode component exposed portion that contacts the metal thin plate having through holes in the thickness direction at both ends of the electrode group. In this regard, an electrode in which an active substance layer is formed only on one side may be used only in this portion, or after an active substance layer is once formed on both sides, the active substance layer may be removed only on one side.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
(Reference Example 1)
A cross-sectional view of a flat nonaqueous electrolyte secondary battery of this reference example is shown in FIG. Moreover, the enlarged view of the sealing part is shown in FIG.
[0017]
The method for producing the battery of this reference example will be described below.
First, 5 parts by mass of acetylene black and 5 parts by mass of graphite powder are added as conductive materials to 100 parts by mass of LiCoO 2 , 5 parts by mass of polyvinylidene fluoride as a binder, and diluted and mixed with N-methylpyrrolidone. A slurry-like positive electrode mixture was obtained. Next, this positive electrode mixture was applied to one side of a 0.02 mm thick aluminum foil serving as a positive electrode current collector by a doctor blade method and dried to form a positive electrode active substance-containing layer on the aluminum foil surface. Thereafter, coating and drying were repeated until the coating film thickness of the positive electrode active material-containing layer became 0.15 mm on both sides, to produce a double-sided coated positive electrode. Next, the portion containing the active substance in contact with the positive electrode case is removed from one end of the electrode body, and the aluminum layer is peeled off to form a current-carrying portion, having a width of 12 mm, a length of 120 mm, and a thickness of 0.15 mm. The cut out
[0018]
Next, 2.5 parts by mass of styrene butadiene rubber (SRB) and carboxymethyl cellulose (CMC) as binders are added to 100 parts by mass of graphitized mesophase pitch carbon fiber powder, diluted with ion-exchanged water, mixed, and slurry A negative electrode mixture was obtained. The obtained negative electrode mixture was repeatedly applied and dried in the same manner as in the case of the positive electrode so that the thickness of the active substance-containing layer was 0.15 mm on a 0.02 mm thick copper foil as a negative electrode current collector. Then, a double-sided coated negative electrode was produced. Next, the active substance-containing layer in the portion in contact with the negative electrode case is removed from one end of the electrode body, and the copper layer is stripped to form a current-carrying portion, having a width of 13 mm, a length of 130 mm, and a thickness of 0.15 mm. The cut-out
[0019]
Next, the current-carrying surface of each positive and negative electrode is set as the outer winding end side, and is wound between the positive electrode and the negative electrode in a spiral shape through a
[0020]
After the produced electrode group is dried at 85 ° C. for 12 hours, a single-side coated negative electrode of the electrode group is formed on the inner bottom surface of the negative electrode metal case 5 (the
[0021]
(Example 2)
Sealing was performed so that the cross-sectional shape of the crimped portion was projected from above so that the length A of the overlapping portion of the innermost peripheral edge of the positive electrode case and the outermost peripheral edge of the negative electrode case was 0.2 mm. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Reference Example 1.
[0022]
(Example 3)
Sealing was performed so that the cross-sectional shape of the crimped portion was projected from above so that the length A of the overlapping portion of the innermost peripheral edge of the positive electrode case and the outermost peripheral edge of the negative electrode case was 0.45 mm. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Reference Example 1.
[0023]
(Reference Example 4)
The height of the positive electrode case is 2.6 mm, and the cross-sectional shape of the crimped portion is a length A of a portion where the positive electrode case innermost end and the negative electrode case outermost end overlap with each other when projected from above. Sealed to become. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Reference Example 1.
[0024]
(Example 5)
Sealing was performed so that the cross-sectional shape of the crimped portion was projected from above so that the length A of the overlapping portion of the innermost peripheral edge of the positive electrode case and the outermost peripheral edge of the negative electrode case was 0.2 mm. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Reference Example 4.
[0025]
(Example 6)
Sealing was performed so that the cross-sectional shape of the crimped portion was projected from above so that the length A of the overlapping portion of the innermost peripheral edge of the positive electrode case and the outermost peripheral edge of the negative electrode case was 0.45 mm. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Reference Example 4.
[0026]
(Reference Example 7)
The height of the positive electrode case is 2.9 mm, and the cross-sectional shape of the crimped portion is a length A of the overlapping portion of the innermost end portion of the positive electrode case and the outermost end portion of the negative electrode case as projected from above is 0.05 mm. Sealed to become. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Reference Example 1.
[0027]
(Example 8)
Sealing was performed so that the cross-sectional shape of the crimped portion was projected from above so that the length A of the overlapping portion of the innermost peripheral edge of the positive electrode case and the outermost peripheral edge of the negative electrode case was 0.2 mm. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Reference Example 7.
[0028]
Example 9
Sealing was performed so that the cross-sectional shape of the crimped portion was projected from above so that the length A of the overlapping portion of the innermost peripheral edge of the positive electrode case and the outermost peripheral edge of the negative electrode case was 0.45 mm. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Reference Example 7.
[0029]
(Comparative Example 1)
Sealing was performed so that the cross-sectional shape of the swaged portion was 0 mm when the length A of the overlapping portion between the innermost peripheral edge of the positive electrode case and the outermost peripheral edge of the negative electrode case was projected from above. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Reference Example 1.
[0030]
(Comparative Example 2)
Sealing was performed so that the cross-sectional shape of the swaged portion was 0 mm when the length A of the overlapping portion between the innermost peripheral edge of the positive electrode case and the outermost peripheral edge of the negative electrode case was projected from above. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Reference Example 4.
[0031]
(Comparative Example 3)
The cross-sectional shape of the crimped portion was sealed so that the length A of the overlapping portion of the innermost end of the positive electrode case and the outermost peripheral end of the negative electrode case was 0 mm as projected from above. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Reference Example 7.
[0032]
(Comparative Example 4)
The height of the positive electrode case is 2.5 mm, and the cross-sectional shape of the crimped portion is 0 mm when the length A of the overlapping portion between the innermost peripheral edge of the positive electrode case and the outermost peripheral edge of the negative electrode case is projected from above. Sealed. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Reference Example 1.
[0033]
(Comparative Example 5)
Sealing was performed so that the cross-sectional shape of the crimped portion was projected from above so that the length A of the overlapping portion of the innermost peripheral edge of the positive electrode case and the outermost peripheral edge of the negative electrode case was 0.05 mm. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Comparative Example 4.
[0034]
(Comparative Example 6)
Sealing was performed so that the cross-sectional shape of the crimped portion was projected from above so that the length A of the overlapping portion of the innermost peripheral edge of the positive electrode case and the outermost peripheral edge of the negative electrode case was 0.2 mm. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Comparative Example 4.
[0035]
(Comparative Example 7)
Sealing was performed so that the cross-sectional shape of the crimped portion was projected from above so that the length A of the overlapping portion of the innermost peripheral edge of the positive electrode case and the outermost peripheral edge of the negative electrode case was 0.45 mm. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Comparative Example 4.
[0036]
(Comparative Example 8)
Sealing was performed so that the cross-sectional shape of the crimped portion was projected from above so that the length A of the overlapping portion between the innermost peripheral edge of the positive electrode case and the outermost peripheral edge of the negative electrode case was 0.6 mm. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Reference Example 1.
[0037]
(Comparative Example 9)
Reference Example 4 except that the cross-sectional shape of the crimped portion was sealed so that the length A of the overlapping portion of the innermost peripheral edge of the positive electrode case and the outermost peripheral edge of the negative electrode case was 0.6 mm as projected from above. A flat nonaqueous electrolyte secondary battery was manufactured in the same manner as described above.
[0038]
(Comparative Example 10)
Sealing was performed so that the cross-sectional shape of the crimped portion was projected from above so that the length A of the overlapping portion between the innermost peripheral edge of the positive electrode case and the outermost peripheral edge of the negative electrode case was 0.6 mm. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Reference Example 7.
[0039]
(Comparative Example 11)
Sealing was performed so that the cross-sectional shape of the crimped portion was projected from above so that the length A of the overlapping portion between the innermost peripheral edge of the positive electrode case and the outermost peripheral edge of the negative electrode case was 0.6 mm. Otherwise, a flat nonaqueous electrolyte secondary battery was produced in the same manner as in Comparative Example 4.
[0040]
50 batteries of Examples 2, 3, 5, 6, 8, 9, Reference Examples 1, 4, 7 and Comparative Examples 1 to 11 were prepared. Among these, in the batteries of Comparative Examples 8 to 11, an external short circuit occurred due to contact between the positive electrode case and the negative electrode case. The other produced batteries were left to stand in an atmosphere of 20 ° C. for 2 days, and then charged at a constant current and a constant voltage of 5 mA and 4.2 V for 24 hours. Furthermore, after standing for 3 days, the closed circuit voltage was measured. As a result, it was about 4.16V in all the batteries. Discharging was performed at a constant current of 50 mA until the closed circuit voltage reached 3.0 V, and the discharge capacity was determined. As a result, a discharge capacity of about 55 mAh could be obtained with all the batteries.
[0041]
Subsequently, these batteries were charged under the same conditions, and each of the 20 batteries was subjected to an overcharge test at a constant current and a constant voltage of 12 V at 20 mA in an atmosphere of 20 ° C. for 12 hours to confirm the occurrence of rupture and leakage. .
[0042]
Table 1 shows the number of ruptures and leakages of each battery in the overcharge test.
[0043]
[Table 1]
As shown in Table 1, in the batteries of Examples 2, 3, 5, 6, 8, and 9, no rupture or leakage was observed in the overcharge test.
[0045]
On the other hand, in the batteries of Comparative Examples 1 to 4 sealed so that the length A of the cross-sectional shape of the crimped portion is 0 mm, the voltage rises in the overcharge test, which causes the electrolyte to decompose and the gas pressure to increase. The gas pressure rose and burst without being able to hold down the increased gas pressure.
[0046]
In Comparative Examples 4 to 7 and Comparative Example 11, the height of the positive electrode case was 2.5 mm. When the cross-sectional shape of the crimped portion was confirmed for these batteries, the positive electrode case was As a result of the force applied to the negative electrode case, the negative electrode case collapsed inward. Therefore, in a battery manufactured using a component having a positive electrode case height of 2.5 mm, the length A can be sealed only so that the length A is from 0 mm to 0.2 mm. It could not be larger than this, for example, 0.45 or 0.6 mm. On the other hand, in a battery having a length A of 0, 0.05, or 0.2 mm, the vicinity of the side surface portion of the negative electrode case is deformed, resulting in leakage. Therefore, it was found that the height of the positive electrode case is not appropriate when the height is 2.5 mm.
[0047]
The production of a battery having a positive electrode case height of 3.0 mm was also attempted. However, when the positive electrode case height was 3.0 mm, the positive electrode case was crimped and the cross-sectional shape of the crimped portion was confirmed. Although it was possible to seal from 0 mm to 0.6 mm, when this was changed from 0 mm to 0.45 mm, the compression to the insulating gasket was not performed well, and liquid leakage occurred immediately after production. In the case of 0.6 mm, the positive electrode case and the negative electrode case contacted each other, thereby causing an external short circuit. Therefore, it was found that the case where the positive electrode case height is 3.0 mm is inappropriate.
[0048]
Therefore, when the total battery height is 3.2 mm, the height of the positive electrode case is suitably larger than 2.5 mm and smaller than 3.0 mm, more preferably 2.6 mm to 2.9 mm. all right. The ratio to the total battery height t is preferably in the range of 0.81t to 0.91t.
[0049]
In addition, although the Example of this invention was demonstrated using the flat type nonaqueous electrolyte secondary battery which used the nonaqueous solvent for the nonaqueous electrolyte, this invention is the polymer secondary using the polymer electrolyte for the nonaqueous electrolyte. The present invention can also be applied to a battery or a solid electrolyte secondary battery using a solid electrolyte. Moreover, although it demonstrated based on the flat type nonaqueous electrolyte secondary battery sealed by the crimping process of a positive electrode case, it is also possible to replace a positive / negative electrode and seal by a crimping process of a negative electrode case.
[0050]
【The invention's effect】
As described above, according to the present invention, the sealing property of the flat non-aqueous electrolyte secondary battery can be improved, so that the battery can be prevented from rupture and leakage when excessively charged. Can improve safety.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of batteries of Examples and Reference Examples.
2 is an enlarged view of a sealing portion of the battery of FIG. 1. FIG.
[Explanation of symbols]
1 Exterior case (positive electrode case)
2 Metal net (positive side)
3
6 Metal net (negative electrode side)
7 Insulating
Claims (4)
上記封口ケースおよび上記外装ケースのいずれか一方が負極端子を兼ね、他方が正極端子を兼ねており、
上方からの投影で外装ケース最内周端部と封口ケース最外周端部の重なり合う部分の長さが０．２ｍｍ以上０．４５ｍｍ以下であり、
電池総高ｔｍｍに対して、外装ケース高さが０．８１ｔ以上０．９１ｔ以下であることを特徴とする扁平形非水電解質二次電池。 Metals made of a sealing case and a metallic steel outer casing, is fitted via an insulating gasket has a caulking was sealed structure by caulking, at least the positive electrode plate therein, a separator, a negative electrode plate In the flat non-aqueous electrolyte secondary battery that includes the electrode group including the non-aqueous electrolyte and the sum of the positive and negative electrode facing areas through the separator of the electrode group is larger than the opening area of the insulating gasket,
Either the sealing case or the outer case serves as a negative electrode terminal, and the other serves as a positive electrode terminal,
The length of the overlapping portions of the outer casing innermost peripheral edge and the sealing case outermost peripheral end projection of from above 0. 2 mm more than 0.45mm Ri der below,
The battery total height tmm, flat-shaped non-aqueous electrolyte secondary battery outer case height and said der Rukoto than 0.91t less 0.81T.
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| CN101453002A (en) | 2007-11-29 | 2009-06-10 | 比亚迪股份有限公司 | Battery and method for preparing the same |
| CN201146200Y (en) | 2007-12-18 | 2008-11-05 | 比亚迪股份有限公司 | Casing for battery and battery set including the same |
| US8865335B2 (en) | 2007-12-25 | 2014-10-21 | Byd Co. Ltd. | Electrochemical storage cell |
| US8276695B2 (en) | 2007-12-25 | 2012-10-02 | Byd Co. Ltd. | Battery electrode sheet |
| US8420254B2 (en) | 2007-12-25 | 2013-04-16 | Byd Co. Ltd. | End cover assembly for an electrochemical cell |
| US20090159354A1 (en) | 2007-12-25 | 2009-06-25 | Wenfeng Jiang | Battery system having interconnected battery packs each having multiple electrochemical storage cells |
| WO2009082956A1 (en) * | 2007-12-25 | 2009-07-09 | Byd Company Limited | Electrochemical storage cell with blow out vents |
| JP6372821B2 (en) * | 2014-01-21 | 2018-08-15 | セイコーインスツル株式会社 | Nonaqueous electrolyte secondary battery |
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|---|---|---|---|---|
| JPH0163065U (en) * | 1987-10-16 | 1989-04-24 | ||
| JPH08106910A (en) * | 1994-10-06 | 1996-04-23 | Fuji Elelctrochem Co Ltd | Coin battery |
| WO2002013305A1 (en) * | 2000-08-09 | 2002-02-14 | Matsushita Electric Industrial Co., Ltd. | Coin-shaped battery |
| JP2002100408A (en) * | 2000-09-21 | 2002-04-05 | Toshiba Battery Co Ltd | Flat nonaqueous electrolyte secondary battery |
| JP2002134071A (en) * | 2000-10-30 | 2002-05-10 | Matsushita Electric Ind Co Ltd | Flattened square type battery |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0163065U (en) * | 1987-10-16 | 1989-04-24 | ||
| JPH08106910A (en) * | 1994-10-06 | 1996-04-23 | Fuji Elelctrochem Co Ltd | Coin battery |
| WO2002013305A1 (en) * | 2000-08-09 | 2002-02-14 | Matsushita Electric Industrial Co., Ltd. | Coin-shaped battery |
| JP2002100408A (en) * | 2000-09-21 | 2002-04-05 | Toshiba Battery Co Ltd | Flat nonaqueous electrolyte secondary battery |
| JP2002134071A (en) * | 2000-10-30 | 2002-05-10 | Matsushita Electric Ind Co Ltd | Flattened square type battery |
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