JP3569936B2

JP3569936B2 - Cylindrical non-aqueous electrolyte battery

Info

Publication number: JP3569936B2
Application number: JP30052493A
Authority: JP
Inventors: 雅之影山
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 1993-11-30
Filing date: 1993-11-30
Publication date: 2004-09-29
Anticipated expiration: 2019-09-29
Also published as: JPH07153488A

Description

【０００１】
【産業上の利用分野】
本発明は、円筒型の電池缶内に巻回電極体を収納した円筒型非水電解質電池に関する。
【０００２】
【従来の技術】
近年の電子技術のめざましい進歩は、電子機器の小型・軽量化を次々と実現させている。それに伴い移動用電源としての電池に対しても益々小型・軽量かつ高エネルギー密度のものが求められている。
【０００３】
従来、一般用途の二次電池としては鉛電池、ニッケル・カドミウム電池等の水溶液系電池が主流であった。しかし、これら水溶液系電池は、サイクル特性には優れるものの電池重量やエネルギー密度の点で十分満足できるものとは言えない。
【０００４】
そこで、最近、リチウムやリチウム合金もしくは炭素材料のような，リチウムイオンのドープ・脱ドープが可能な物質を負極に用い、リチウムコバルト複合酸化物等のリチウム複合酸化物を正極に使用する非水電解液二次電池の研究・開発が行われている。この電池は電池電圧が高く、高いエネルギー密度を有している。
【０００５】
ところで、これら非水電解液二次電池の用途としては、高エネルギー密度が得られるという特長を活かして、ビデオ・カメラやラップ・トップ・パソコン等の比較的消費電流の大きな携帯用電子機器の供給電源が想定されている。
【０００６】
電池を比較的消費電流の大きな電子機器の供給電源として用いる場合には、電極形式として巻回電極体形式を採ることが望ましい。巻回電極体は、帯状正極と帯状負極とを間にセパレータを介して積層し、この積層体を渦巻状に巻回することで作製されるものであり、電極面積が広くとれ、耐重負荷放電に耐え得るものである。
【０００７】
ここで、このような巻回電極体では、セパレータと、帯状正極，帯状負極の幅を全く同一にすると、作製過程で帯状正極，帯状負極とが高さ方向にずれたときに、セパレータより帯状正極，帯状負極の一部がはみ出して、互いに接触して内部短絡が誘発される虞れがある。
【０００８】
このため、セパレータとして帯状正極，帯状負極よりも幅が大なるものを用いて、積層体を巻回した状態でセパレータの一部が帯状正極，帯状負極より上下にはみ出すようにし、帯状負極，帯状正極が少し位上下にずれても、セパレータを越えて接触するといったことのないような、余裕を持った設計とされるのが通常である。
【０００９】
【発明が解決しようとする課題】
しかしながら、このようにセパレータの一部が帯状正極，帯状負極より上下にはみ出すような設計にすると、電池缶にも、当然そのセパレータのはみ出し分に相当する余分な容積を確保することが必要になってくる。
【００１０】
巻回電極体を用いる非水電解液二次電池では、この電池容量に関与しない余分なスペースを確保する必要があることから、電極の実質的な充填量の増大が制限され、体積当たりのエネルギーを十分に高めることができないのが実情である。
【００１１】
本発明は、このような従来の実情に鑑みて提案されたものであり、セパレータより帯状正極、帯状負極とがはみ出して内部短絡が誘発されるといったことがなく、電極の実質的な充填量を増大させることができ、高容量の円筒型非水電解質電池を提供することを目的とする。
【００１２】
【課題を解決するための手段】
上述の目的を達成するために、本発明は、集電体の両面に活物質を成型した帯状正極と集電体の両面に炭素質材料を含む活物質を成型した帯状負極との間にセパレータを介在させて渦巻状に巻回した巻回電極体を、非水電解液が注入された電池缶に収納した非水電解質電池であり、この電池の巻回電極体は、上記帯状正極及び上記帯状負極よりも幅が大なるセパレータが上記帯状負極及び上記帯状正極の上下にはみ出して巻回されるとともに、上記セパレータの上記帯状負極及び上記帯状正極の上下にはみ出した部分が、加熱成型によって上記帯状正極及び上記帯状負極の上下をそれぞれ覆うように当該巻回電極体の内側又は外側に折り曲げられ、且つ、上記セパレータの折り曲げられた部分が上記非水電解液の移行を可能とする状態で重ね合わせられている。
【００１３】
本発明に係る円筒型非水電解質電池の巻回電極体を構成する帯状正極は、活物質として遷移金属とリチウムとの複合化合物を用い、集電体として金属箔が用いられる。
【００１４】
本発明に係る円筒型非水電解質電池を構成する巻回電極体は、図１に示すように、セパレータ３として帯状正極２、帯状負極１よりも幅が大なるものが用いられる。巻回電極体は、帯状正極２と帯状負極３との間にセパレータ３を介在させた積層体を巻回して形成される。このとき、巻回電極体は、帯状正極２及び帯状負極３の上下にセパレータ３の一部がはみ出すように巻回される。セパレータ３の帯状正極２及び帯状負極３の上下にはみ出した部分は、図２に示すように、帯状正極２及び帯状負極３の上下を覆うように巻回電極体の内側に向かって折り曲げられる。この折り曲げは、セパレータ３のはみ出した部分を加熱成型して行われる。なお、セパレータ３の帯状正極２及び帯状負極３の上下にはみ出した部分は、巻回電極体の外側に向かって折り曲げるようにしてもよい。
【００１５】
このように積層体を巻回した状態で帯状正極２，帯状負極１よりはみ出したセパレータ３の一部を加熱成型によって内側または外側に曲折するようにすると、セパレータ３とセパレータ３の間の帯状正極２あるいは帯状負極１が配置されているスペース４が、セパレータの曲折部によっていわば蓋をされた状態になる。したがって、帯状負極１，帯状正極２とが何らかの原因で上下にずれたとしても、セパレータを越えて互いに接触するといったことはなく、帯状正極２，帯状負極１同士の接触による内部短絡が防止される。
【００１６】
また、このように帯状正極２，帯状負極１より上下にはみ出したセパレータ３が曲折されている巻回電極体では、セパレータ３のはみ出し分がそのまま高さ方向に延在されている巻回電極体に比べて高さが低く抑えられる。したがって、
電池缶容積を低減でき、実質的な電極充填密度が大きく、容量の大なる円筒型非水電解質二次電池が得られることになる。
【００１７】
なお、電池の内部短絡を確実に防止するためには、巻回電極体全体の高さと帯状負極１，帯状正極２の高さのバランスが重要である。
【００１８】
すなわち、図１に示すように加熱成型していない状態のセパレータ３の高さをｈ_１，電極のうち長さの長い方の電極１の高さをｈ_２とし、図２に示すように加熱成型した状態の巻回電極体全体の高さをＨ_１，電極のうち長さの長い方の電極１の高さをＨ_２としたときに、ｈ_１とｈ_２が０．８ｈ_１≦ｈ_２≦ｈ_１より好ましくは０．９ｈ_１≦ｈ_２≦０．９８ｈ_１なる条件を満たし、Ｈ_１とＨ_２が０．９４Ｈ_１≦Ｈ_２≦Ｈ_１より好ましくは、０．９５Ｈ_１≦Ｈ_２≦０．９９Ｈ_１なる条件を満たすことが望ましい。
【００１９】
帯状電極１，２の高さが上記範囲を超える場合には、加熱成型した状態の電極配置スペース４において蓋となるセパレータ３の曲折部と帯状電極１，２端部の間に余裕がないために、該曲折部とそれと隣り合うセパレータ３の間の僅かな隙間から帯状電極１，２端部が露出し、これが内部短絡の原因になる。
【００２０】
逆に、帯状電極１，２の高さが上記範囲を下回る場合には、巻回電極体当たりのセパレータ３使用面積が増大することを意味し、材料コストの面から好ましくない。
【００２１】
上記セパレータ３としては、通常、非水電解質電池において用いられているものがいずれも使用可能であり、ポリプロピレン，ポリエチレン，ポリブチレン等のポリオレフィン系樹脂、ナイロン、セルロースアセテート、ニトロセルロース、ポリスルホン、ポリアクリロニトリル、ポリフッ化ビニリデン等よりなる微多孔性フィルムが用いられる。
【００２２】
これらセパレータ３を加熱成型する方法は特に限定されないが、セパレータ３に対して熱風を吹きつけることで成型する熱風ブロー方式、加熱治具により上下から圧力を印加することで成型する加熱加圧方式等が採用できる。
【００２３】
但し、加熱成型の際の加熱温度は、セパレータ３を軟化させ且つ溶融させない温度、すなわちセパレータ３の軟化点以上、融点未満に設定することが望ましい。加熱温度をセパレータ３の融点以上に設定した場合には、セパレータ３が溶融して空孔の一部が埋まる、溶融したセパレータ３と、それと隣合うセパレータ３とが融着一体化する等により、電極配置スペース４に非水電解液が移行し難い状況になる。これにより、電極１，２の電解液含浸量が不足し、放電容量の低下につながる。
本発明においては、セパレータ３は、軟化点以上、融点未満の加熱温度で加熱成型されるので、折り曲げられて重なり合う部分での融着することがなく、電極配置スペース４に非水電解液が移行可能な状態にある。
【００２４】
一方、帯状負極１，帯状正極２は、帯状の電極集電体に、電極活物質を含有する電極合剤を塗布することで作製されるものである。
【００２５】
負極活物質としては、リチウム，リチウム合金，ポリアセチレン等の導電性ポリマー，コークス等の炭素材料等を用いることができる。
【００２６】
正極活物質としては、二酸化マンガン，五酸化バナジウムのような遷移金属化合物や、硫化鉄等の遷移金属カルコゲン化合物、さらにはこれらとリチウムとの複合化合物を用いることができる。
【００２７】
また、電解液としては、例えばリチウム塩を電解質とし、これを有機溶媒に溶解した電解液が用いられる。
有機溶媒としては、特に限定されるものではないが、例えばプロピレンカーボネート、エチレンカーボネート、ジエチルカーボネート、１，２−ジメトキシエタン、１，２−ジエトキシエタン、ｒ−ブチロラクトン、テトラヒドロフラン、１，３−ジオキソラン、４−メチル−１，３−ジエキソラン、ジエチルエーテル、スルホラン、メチルスルホラン、アセトニトリル、プロピオニトリル等の単独もしくは二種類以上の混合溶媒が使用できる。
電解質にも、従来より公知のものがいずれも使用でき、ＬｉＣｌＯ_４，ＬｉＡｓＦ_６，ＬｉＰＦ_６，ＬｉＢＦ_４，ＬｉＢ（Ｃ_６Ｈ_５）_４，ＬｉＣｌ，ＬｉＢｒ，ＣＨ_３ＳＯ_３Ｌｉ，ＣＦ_３ＳＯ_３Ｌｉ等がある。
【００２８】
【作用】
本発明に係る円筒型非水電解質電池を構成する巻回電極体は、帯状正極と帯状負極とを間にセパレータを介して積層し、この積層体を渦巻き状に巻回することで作製される。
【００２９】
このようにして巻回電極体を作製するに際して、セパレータとして帯状正極，帯状負極よりも幅が大なるものを用いて、積層体を巻回した状態で帯状正極，帯状負極よりセパレータの一部が上下にはみ出すようにし、このはみ出したセパレータの一部を加熱成型によって内側または外側に曲折するようにすると、内部短絡を招くことなく容量の大なる円筒型非水電解質二次電池が作製される。
【００３０】
すなわち、積層体を巻回した状態で帯状正極，帯状負極よりはみ出したセパレータの一部を加熱成型によって内側または外側に曲折するようにすると、セパレータとセパレータの間の帯状正極あるいは帯状負極が配置されたスペースが、セパレータの曲折部によっていわば蓋をされた状態になる。したがって、帯状負極，帯状正極とが何らかの原因で上下にずれたとしても、セパレータを越えて互いに接触するといったことはなく、帯状正極，帯状負極同士の接触による内部短絡が防止される。
【００３１】
また、このように帯状正極，帯状負極より上下にはみ出したセパレータが曲折されている巻回電極体では、セパレータのはみ出し分がそのまま高さ方向に延在されている巻回電極体に比べて高さが低く抑えられる。したがって、電池缶容積を低減でき、実質的な電極充填密度が大きく、容量の大なる円筒型非水電解質二次電池が獲得される。
【００３２】
【実施例】
本発明の好適な実施例について実験結果に基づいて説明する。
【００３３】
実施例１
本実施例で作製する円筒型非水電解質電池の縦断面図を図３に示す。このような構成の円筒型非水電解質電池を以下のようにして作製した。
【００３４】
まず、帯状負極２１を次のようにして作製した。
【００３５】
出発原料として石油ピッチを用い、これに酸素を含む官能基を１０〜２０％重量導入（いわゆる酸素架橋）した後、不活性ガス気流中，温度１０００℃で焼成して、ガラス状炭素に近い性質を持った炭素質材料を得た。この炭素質材料について、Ｘ線回折測定を行った結果、（００２）面の面間隔は３．７６Åであった。またピクノメータ法により真比重を測定したところ、１．５８ｇ／ｃｍ^３であった。この炭素質材料を粉砕し、平均粒径１０μｍの炭素質材料粉末とした。
このようにして得た炭素質材料粉末を負極活物質担持体とし、この炭素質材料粉末９０重量部、結着材となるポリフッ化ビリニデン（ＰＶＤＦ）１０重量部を混合し、負極合剤を調製した。この負極合剤を、溶剤であるＮ−メチルピロリドンに分散させて負極スラリー（ペースト状）とした。
【００３６】
負極集電体２９として厚さ１０μｍの帯状の銅箔を用い、この負極集電体の両面に上記負極合剤スラリーを塗布、乾燥させた後、圧縮成型して帯状負極１を作製した。なお、この帯状負極２１の電極の寸法は、幅４３．４ｍｍ、長さ７００ｍｍとし、成型後の合剤厚さは両面共に８０μｍで同一とした。
【００３７】
次に、帯状正極２２を以下のようにして作製した。
【００３８】
炭酸リチウム０．５モルと炭酸コバルト１モルを混合し、空気中，温度９００℃で５時間焼成してＬｉＣｏＯ_２を得た。ＬｉＣｏＯ_２を正極活物質とし、これの９１重量部、導電剤となるグラファイト６重量部及び結着剤となるポリフッ化ビリニデン３重量部を混合し、正極合剤を調製した。この正極合剤をＮ−メチルプロリドンに分散させて正極スラリー（ペースト状）とした。
【００３９】
正極集電体３０として厚さ２０μｍの帯状のアルミニウム箔を用い、この正極集電体３０の両面に均一に上記正極合剤スラリーを塗布、乾燥させた後、圧縮成型して帯状正極２２を作製した。なお、この帯状正極２２の電極の寸法は、幅４１．４ｍｍ、長さ６５０ｍｍとし、成型後の合剤厚さは両面共に８０μｍで同一とした。
【００４０】
以上のようにして作製された幅４３．４ｍｍ，長さ７００ｍｍの帯状負極２１と、幅４１．４ｍｍ，長さ６５０ｍｍの帯状正極２２を、厚さ２５μｍ、幅４５．９ｍｍの微多孔性ポリプロピレンフィルムをセパレータ２３として、帯状負極２１、セパレータ２３、帯状正極２２、セパレータ２３の順に積層し、この積層体を幅方向が巻回体の高さ方向になるような向きで多数回巻回した。そして、最外周に位置するセパレータ最終端部を、幅４０ｍｍのテープで固定することで、直径１９．６ｍｍ，高さ４５．９ｍｍの巻回電極体を作製した。この巻回体は、帯状負極２１，帯状正極２２よりセパレータ２３が上下にはみ出しており、巻回体の全高さに対する帯状負極２１の高さの割合が９４．６％であった。
【００４１】
次に、この巻回体の上下にはみ出した状態になっているセパレータのはみ出し部分を、内側に折り曲げ、この状態で温度１５０℃に加熱したアルミニウム製治具を用いて圧力３．８ｋｇ／ｃｍ^２で約５秒間加圧した。その結果、高さが４４．０ｍｍ、全高さに対する帯状負極２１の高さの割合が９８．６％の巻回電極体が得られた。
【００４２】
このようにして作製された巻回電極体をニッケルめっきを施した鉄製電池缶２５に、巻回電極体上下両面に絶縁体板２４を配置して収納した。そして、アルミニウム製正極リード３２を正極集電体から導出して電池蓋２７に、ニッケル製負極リード３１を負極集電体から導出して電池缶２５に溶接した。
【００４３】
この電池缶２５の中に、プロピレンカーボネートとジエチルカーボネートとの等容量混合溶媒中に、ＬｉＰＦ_６を１モル／リットルの割合で溶解した電解液を注入した。そして、アスファルトで表面を塗布した絶縁封口ガスケット２６を介して電池缶２５をかしめることにより、電流遮断機構を有する安全弁装置８並びに電池蓋２７を固定し、電池内の気密性を保持させることで、直径２０ｍｍ、高さ５０ｍｍの円筒型非水電解質電池を作製した。
【００４４】
実施例２
セパレータとなる幅４８．４ｍｍの微多孔性ポリプロピレンフィルムと、実施例１と同様にして作製された幅４３．４ｍｍ，長さ７００ｍｍの帯状負極と、幅４１．４ｍｍ，長さ６５０ｍｍの帯状正極を、帯状負極，セパレータ，帯状正極，セパレータの順に積層し、この積層体を渦巻き型に多数回巻回した。そして、最外周のセパレータ端部を、幅４０ｍｍのテープで固定して直径１９．６ｍｍ，高さ４８．４ｍｍの巻回体を作製した。この巻回体は、帯状負極，帯状正極よりセパレータが上下にはみ出しており、巻回体の全高さに対する帯状負極の高さの割合は８９．７％であった。
【００４５】
次に、この上下にはみ出した状態になっているセパレータのはみ出し部分を、内側に折り曲げ、実施例１と同様な条件にて加圧成型した。その結果、高さが４４．０ｍｍ、全高さに対する帯状負極の高さの割合が９８．６％の巻回電極体が得られた。
【００４６】
この巻回電極体を実施例１と同様の電池缶内に収納し、リードの溶接，電解液の注入，電池蓋の固定を行うことで、直径２０ｍｍ、高さ５０ｍｍの円筒型非水電解質電池を作製した。
【００４７】
実施例３
セパレータとなる幅４４．４ｍｍの微多孔性ポリプロピレンフィルムと、実施例１と同様にして作製された幅４３．４ｍｍ，長さ７００ｍｍの帯状負極と、幅４１．４ｍｍ，長さ６５０ｍｍの帯状正極を、帯状負極，セパレータ，帯状正極，セパレータの順に積層し、この積層体を渦巻き型に多数回巻回した。そして、最外周のセパレータ端部を、幅４０ｍｍのテープで固定して直径１９．６ｍｍ，高さ４４．４ｍｍの巻回体を作製した。この巻回体は、帯状負極，帯状正極よりセパレータが上下にはみ出しており、巻回体の全高さに対する帯状負極の高さの割合は９７．７％であった。
【００４８】
次に、この上下にはみ出した状態になっているセパレータのはみ出し部分を、内側に折り曲げ、実施例１と同様な条件にて加圧成型した。その結果、高さが４４．０ｍｍ、全高さに対する帯状負極の高さの割合が９８．６％の巻回電極体が得られた。
【００４９】
この巻回電極体を実施例１と同様の電池缶内に収納し、リードの溶接，電解液の注入，電池蓋の固定を行うことで、直径２０ｍｍ、高さ５０ｍｍの円筒型非水電解質電池を作製した。
【００５０】
実施例４
セパレータとなる幅４４．４ｍｍの微多孔性ポリプロピレンフィルムと、実施例１と同様にして作製された幅４３．４ｍｍ，長さ７００ｍｍの帯状負極と、幅４１．４ｍｍ，長さ６５０ｍｍの帯状正極を、帯状負極，セパレータ，帯状正極，セパレータの順に積層し、この積層体を渦巻き型に多数回巻回した。そして、最外周のセパレータ端部を、幅４０ｍｍのテープで固定して直径１９．６ｍｍ，高さ４４．４ｍｍの巻回体を作製した。この巻回体は、帯状負極，帯状正極よりセパレータが上下にはみ出しており、巻回体の全高さに対する帯状負極の高さの割合は９８．６％であった。
【００５１】
次に、この巻回電極体を実施例１と同様な条件にて加圧成型した。その結果、高さが４４．０ｍｍ、全高さに対する帯状負極の高さの割合が９８．６％の巻回電極体が得られた。
【００５２】
この巻回電極体を実施例１と同様の電池缶内に収納し、リードの溶接，電解液の注入，電池蓋の固定を行うことで、直径２０ｍｍ、高さ５０ｍｍの円筒型非水電解質電池を作製した。
【００５３】
比較例１
セパレータとなる幅４４．４ｍｍの微多孔性ポリプロピレンフィルムと、電極幅をそれぞれ４１．５ｍｍ，３９．５ｍｍに設定すること以外は実施例１と同様にして作製された帯状負極，帯状正極を、帯状負極，セパレータ，帯状正極，セパレータの順に積層し、この積層体を渦巻き型に多数回巻回した。そして、最外周のセパレータ端部を、幅４０ｍｍのテープで固定して直径１９．６ｍｍ，高さ４４．４ｍｍの巻回体を作製した。この巻回体は、帯状負極，帯状正極より上下にセパレータがはみ出しており、巻回体の全高さに対する帯状負極の高さの割合は９４．３％であった。
【００５４】
この巻回体を加熱成型せずに、実施例１と同様の電池缶内に収納し、リードの溶接，電解液の注入，電池蓋の固定を行うことで、直径２０ｍｍ、高さ５０ｍｍの円筒型非水電解質電池を作製した。
【００５５】
以上、実施例１〜実施例４及び比較例１に準じた方法で各々合計１００本の電池を作製し、それぞれについて上限電圧４．２Ｖ，電流３００ｍＡの条件で定電流充電を８時間行い、この充電状態のまま温度２３℃条件下、１ヵ月間保存した。そして、上限電圧４．２Ｖ，電流１Ａの条件で定電流充電を２．５時間行った後、電流４００ｍＡ，終止電圧２．７５Ｖの条件で放電を行うといった充放電サイクルを２回繰り返し、この２サイクル目の放電容量を測定した。
【００５６】
表１に、各電池について、加熱成型前後における巻回電極体の全高さに対する電極の高さの割合，電極はみ出し不良数及び２サイクル目の放電容量を示す。
【００５７】
【表１】

【００５８】
表１からわかるように、セパレータを加熱成型して巻回電極体の高さを低くした実施例１〜実施例４の電池は、セパレータを加熱成型していない比較例１の電池と比較して、電池缶内に収納する電極充填密度を高く設計でき、これを反映して高い放電容量が得られている。
【００５９】
このことから、セパレータを加熱成型して巻回電極体全体の高さを低くすることは、電池の体積当たりの放電容量の増大を図る上で有効であることがわかる。
【００６０】
なお、セパレータを加熱成型した実施例１〜実施例４の電池について、電極はみ出し不良数を比較すると、電極はみ出し不良数は、加熱成型されていない状態での、巻回体の全高さに対する電極の高さの割合に大きく関与していることがわかる。
【００６１】
加熱成型されていない状態の巻回体での、全高さに対する電極高さの割合が小さい場合、すなわち、電極よりはみ出すセパレータのはみ出し長さが小さい場合（例えば実施例３，実施例４）には、加熱成型した状態で電極の端部が、セパレータ曲折部と、それと隣合うセパレータの僅かな隙間から露出し、これが原因して内部短絡が多発する。
【００６２】
このような電極のはみ出し不良は、実施例１，実施例２のように、電極からのセパレータのはみ出し量が大きくなる程、確実に抑えられるようになる。
【００６３】
すなわち、加熱成型していない状態での巻回体全体の高さと電極の高さの割合は８０〜１００％以内、好ましくは９０〜９８％以内が適当であり、加熱成型した状態での、巻回電極体全体の高さと電極の高さの割合は９４〜９９％以内の範囲が適当である。
【００６４】
但し、以上の例ではいずれもセパレータの加熱成型温度を１５０℃に設定しているが、この加熱温度を１７５℃に設定して実施例１と同様に電池を作製すると、７８０ｍＡｈと放電容量が小さい電池しか得られない。これは加熱成型温度が高過ぎるために、セパレータと隣合うセパレータとが融着して一体化する，セパレータの空孔の一部が埋まり、電極に電解液が含浸し難い状態になるからである。したがって、セパレータの加熱成型温度は、セパレータを軟化させ且つ溶融させない温度，すなわちセパレータの軟化点以上，融点未満に設定することが望ましい。
【００６５】
【発明の効果】
上述したように、本発明は、セパレータとして帯状正極、帯状負極よりも幅が大なるものを用い、これらの積層体を巻回した状態で帯状正極と帯状負極の上端部、下端部からセパレータの一部がはみ出すようにし、この帯状正極と帯状負極からはみ出したセパレータの一部を融着させることがない温度で加熱成型して内側または外側に曲折して巻回電極体を形成しているので、セパレータから帯状正極、帯状負極とがはみ出して互いに接触するといったことがなく、且つ、電極の実質的な充填量を増大することができ、容量の大なる円筒型非水電解質電池を得ることができる。
【図面の簡単な説明】
【図１】加熱成型していない状態の巻回電極体を示す模式図である。
【図２】加熱成型した状態の巻回電極体を示す模式図である。
【図３】本発明の製造方法で製造された円筒型非水電解質電池を示す概略縦断面図である。
【符号の説明】
１・・・帯状負極
２・・・帯状正極
３・・・セパレータ[0001]
[Industrial applications]
The present invention relates to a cylindrical nonaqueous electrolyte battery in which a wound electrode body is housed in a cylindrical battery can.
[0002]
[Prior art]
2. Description of the Related Art In recent years, remarkable progress in electronic technology has realized a reduction in size and weight of electronic devices one after another. Along with this, batteries that are smaller and lighter and have higher energy densities are increasingly demanded for batteries as mobile power supplies.
[0003]
Conventionally, aqueous secondary batteries such as lead batteries and nickel-cadmium batteries have been the mainstream as secondary batteries for general use. However, although these aqueous batteries are excellent in cycle characteristics, they cannot be said to be sufficiently satisfactory in terms of battery weight and energy density.
[0004]
Therefore, recently, non-aqueous electrolysis using a lithium composite oxide such as a lithium cobalt composite oxide as a positive electrode, using a substance capable of doping and undoping lithium ions, such as lithium, a lithium alloy, or a carbon material, as a negative electrode. Research and development of liquid secondary batteries are being conducted. This battery has a high battery voltage and a high energy density.
[0005]
By the way, these non-aqueous electrolyte secondary batteries are used for the supply of portable electronic devices with relatively large current consumption, such as video cameras and laptops, taking advantage of the fact that high energy density can be obtained. Power supply is assumed.
[0006]
When a battery is used as a power supply for an electronic device that consumes a relatively large amount of current, it is desirable to use a wound electrode body as an electrode. The wound electrode body is manufactured by laminating a band-shaped positive electrode and a band-shaped negative electrode with a separator interposed therebetween, and winding the laminated body in a spiral shape. Can withstand.
[0007]
Here, in such a wound electrode body, if the width of the separator and the band-shaped positive electrode and the band-shaped negative electrode are made completely the same, when the band-shaped positive electrode and the band-shaped negative electrode are displaced in the height direction in the manufacturing process, the band-shaped electrode is shifted from the separator. A part of the positive electrode and the strip-shaped negative electrode may protrude and come into contact with each other to cause an internal short circuit.
[0008]
Therefore, a separator having a width larger than that of the band-shaped positive electrode or the band-shaped negative electrode is used, and a part of the separator is protruded above and below the band-shaped positive electrode or the band-shaped negative electrode in a state where the laminate is wound. In general, the positive electrode is designed to have a sufficient margin so that even if the positive electrode slightly shifts up and down, the positive electrode does not contact beyond the separator.
[0009]
[Problems to be solved by the invention]
However, if the design is such that a part of the separator protrudes above and below the strip-shaped positive electrode and the strip-shaped negative electrode, it is naturally necessary to secure an extra volume in the battery can corresponding to the protrusion of the separator. Come.
[0010]
In a non-aqueous electrolyte secondary battery using a spirally wound electrode body, it is necessary to secure an extra space that does not contribute to the battery capacity, so that a substantial increase in the filling amount of the electrode is limited, and energy per volume is limited. The fact is that it is not possible to raise the value sufficiently.
[0011]
The present invention has been proposed in view of such a conventional situation, and the band-shaped positive electrode and the band-shaped negative electrode do not protrude from the separator to cause an internal short circuit, and the substantial filling amount of the electrode is reduced. It is an object to provide a cylindrical nonaqueous electrolyte battery which can be increased and has a high capacity.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a separator between a belt-shaped positive electrode formed by molding an active material on both surfaces of a current collector and a band-shaped negative electrode formed by molding an active material containing a carbonaceous material on both surfaces of the current collector. Is a non-aqueous electrolyte battery containing a spirally wound spirally wound electrode body in a battery can into which a non-aqueous electrolytic solution has been injected. A separator having a width larger than the band-shaped negative electrode protrudes above and below the band-shaped negative electrode and the band-shaped positive electrode and is wound, and a portion of the separator protruding above and below the band-shaped negative electrode and the band-shaped positive electrode is heated and molded. The strip-shaped positive electrode and the strip-shaped negative electrode are bent inward or outward of the wound electrode body so as to cover the upper and lower portions, respectively, and the bent portion of the separator is overlapped in a state where the nonaqueous electrolyte can be transferred. It has been Align.
[0013]
The band-shaped positive electrode constituting the spirally wound electrode body of the cylindrical nonaqueous electrolyte battery according to the present invention uses a composite compound of a transition metal and lithium as an active material, and a metal foil as a current collector.
[0014]
As the wound electrode body constituting the cylindrical nonaqueous electrolyte battery according to the present invention, as shown in FIG. 1, a separator 3 having a width larger than the band-shaped positive electrode 2 and the band-shaped negative electrode 1 is used. The wound electrode body is formed by winding a laminate in which a separator 3 is interposed between a strip-shaped positive electrode 2 and a strip-shaped negative electrode 3. At this time, the wound electrode body is wound so that a part of the separator 3 protrudes above and below the strip-shaped positive electrode 2 and the strip-shaped negative electrode 3. As shown in FIG. 2, the portion of the separator 3 protruding above and below the strip-shaped positive electrode 2 and the strip-shaped negative electrode 3 is bent toward the inside of the wound electrode body so as to cover the strip-shaped positive electrode 2 and the strip-shaped negative electrode 3. This bending is performed by heating and molding the protruding portion of the separator 3. The portions of the separator 3 protruding above and below the strip-shaped positive electrode 2 and the strip-shaped negative electrode 3 may be bent toward the outside of the wound electrode body.
[0015]
When a part of the separator 3 protruding from the band-shaped positive electrode 2 and the band-shaped negative electrode 1 is bent inward or outward by heat molding in a state where the laminate is wound, the band-shaped positive electrode between the separators 3 is formed. The space 4 where the negative electrode 2 or the strip-shaped negative electrode 1 is arranged is covered with the bent portion of the separator. Therefore, even if the strip-shaped negative electrode 1 and the strip-shaped positive electrode 2 are vertically displaced for some reason, the strip-shaped negative electrode 1 and the strip-shaped negative electrode 1 do not come into contact with each other beyond the separator, and an internal short circuit due to the contact between the strip-shaped positive electrode 2 and the strip-shaped negative electrode 1 is prevented. .
[0016]
Further, in the wound electrode body in which the separator 3 protruding above and below the band-shaped positive electrode 2 and the band-shaped negative electrode 1 is bent, the wound electrode body in which the protruding portion of the separator 3 is directly extended in the height direction. The height can be kept low compared to. Therefore,
As a result, a cylindrical nonaqueous electrolyte secondary battery having a large battery capacity, a substantial electrode packing density, and a large capacity can be obtained.
[0017]
In order to reliably prevent the internal short circuit of the battery, the balance between the height of the whole wound electrode body and the heights of the strip-shaped negative electrode 1 and the strip-shaped positive electrode 2 is important.
[0018]
That is, as shown in FIG. 1, the height of the separator 3 in a state where it is not heat-formed is h ₁ , the height of the longer electrode 1 is h _2, and the heating is performed as shown in FIG. 2. When the height of the whole wound electrode body in the molded state is H ₁ and the height of the longer electrode 1 among the electrodes is H ₂ , h ₁ and h ₂ are 0.8h ₁ ≦ h. ₂ ≦ _h preferably from ₁ satisfies 0.9h _₁ ≦ _{h 2} ≦ 0.98h ₁ becomes conditions, _{H 1} and _{H 2} is preferably from _{_{_{0.94H 1 ≦ H 2 ≦ H 1}}} , 0.95H 1 ≦ H it is desirable ₂ ≦ 0.99H ₁ becomes satisfying.
[0019]
When the height of the strip electrodes 1 and 2 exceeds the above range, there is no room between the bent portion of the separator 3 serving as a lid and the end portions of the strip electrodes 1 and 2 in the electrode arrangement space 4 in a state of being heat molded. Then, the ends of the strip-shaped electrodes 1 and 2 are exposed from a slight gap between the bent portion and the separator 3 adjacent thereto, which causes an internal short circuit.
[0020]
Conversely, if the height of the strip electrodes 1 and 2 is less than the above range, it means that the use area of the separator 3 per wound electrode body increases, which is not preferable in terms of material cost.
[0021]
As the separator 3, any one usually used in non-aqueous electrolyte batteries can be used, and polyolefin resins such as polypropylene, polyethylene, and polybutylene, nylon, cellulose acetate, nitrocellulose, polysulfone, polyacrylonitrile, A microporous film made of polyvinylidene fluoride or the like is used.
[0022]
The method of heating and molding these separators 3 is not particularly limited, but a hot air blowing method in which hot air is blown onto the separators 3, a heating and pressing method in which pressure is applied from above and below by a heating jig, and the like. Can be adopted.
[0023]
However, the heating temperature at the time of heat molding is desirably set to a temperature at which the separator 3 is softened and not melted, that is, a temperature equal to or higher than the softening point of the separator 3 and lower than the melting point. When the heating temperature is set to be equal to or higher than the melting point of the separator 3, the separator 3 is melted to partially fill the pores, and the melted separator 3 and the adjacent separator 3 are fused and integrated. The situation is such that the non-aqueous electrolyte does not easily migrate to the electrode arrangement space 4. As a result, the amount of electrolyte impregnated in the electrodes 1 and 2 becomes insufficient, which leads to a decrease in discharge capacity.
In the present invention, since the separator 3 is heat-molded at a heating temperature equal to or higher than the softening point and lower than the melting point, the non-aqueous electrolyte moves to the electrode arrangement space 4 without being fused at the overlapping and overlapping portions. It is possible.
[0024]
On the other hand, the strip-shaped negative electrode 1 and the strip-shaped positive electrode 2 are manufactured by applying an electrode mixture containing an electrode active material to a strip-shaped electrode current collector.
[0025]
As the negative electrode active material, a conductive polymer such as lithium, lithium alloy, and polyacetylene, and a carbon material such as coke can be used.
[0026]
As the positive electrode active material, a transition metal compound such as manganese dioxide or vanadium pentoxide, a transition metal chalcogen compound such as iron sulfide, or a composite compound of these and lithium can be used.
[0027]
As the electrolytic solution, for example, an electrolytic solution in which a lithium salt is used as an electrolyte and this is dissolved in an organic solvent is used.
The organic solvent is not particularly limited, but for example, propylene carbonate, ethylene carbonate, diethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, r-butyrolactone, tetrahydrofuran, 1,3-dioxolane , 4-methyl-1,3-diexolan, diethyl ether, sulfolane, methylsulfolane, acetonitrile, propionitrile and the like, or a mixture of two or more solvents.
Any known electrolyte can be used as the electrolyte. LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiB (C ₆ H ₅ ) ₄ , LiCl, LiBr, CH ₃ SO ₃ Li, CF ₃ SO ₃ Li and the like.
[0028]
[Action]
The wound electrode body constituting the cylindrical nonaqueous electrolyte battery according to the present invention is manufactured by laminating a band-shaped positive electrode and a band-shaped negative electrode with a separator interposed therebetween, and spirally winding the laminated body. .
[0029]
In producing the wound electrode body in this manner, a separator having a width larger than that of the band-shaped positive electrode and the band-shaped negative electrode is used, and a part of the separator is wound from the band-shaped positive electrode and the band-shaped negative electrode in a state where the laminate is wound. When the protruding separator is bent inward or outward by heat molding so as to protrude up and down, a cylindrical nonaqueous electrolyte secondary battery having a large capacity without causing an internal short circuit is produced.
[0030]
That is, when a part of the separator protruding from the band-shaped positive electrode and the band-shaped negative electrode is bent inward or outward by heat molding in a state where the laminate is wound, the band-shaped positive electrode or the band-shaped negative electrode is arranged between the separators. The space thus formed is in a state of being covered, so to speak, by the bent portion of the separator. Therefore, even if the strip-shaped negative electrode and the strip-shaped positive electrode are displaced up and down for some reason, they do not contact each other beyond the separator, and an internal short circuit due to the contact between the strip-shaped positive electrode and the strip-shaped negative electrode is prevented.
[0031]
Further, in the wound electrode body in which the separator protruding above and below the band-shaped positive electrode and the band-shaped negative electrode is bent, the protruding portion of the separator is higher in height than the wound electrode body extending in the height direction. Is kept low. Therefore, it is possible to obtain a cylindrical nonaqueous electrolyte secondary battery in which the capacity of the battery can can be reduced, the substantial electrode packing density is large, and the capacity is large.
[0032]
【Example】
Preferred embodiments of the present invention will be described based on experimental results.
[0033]
Example 1
FIG. 3 shows a vertical cross-sectional view of the cylindrical nonaqueous electrolyte battery manufactured in this example. A cylindrical nonaqueous electrolyte battery having such a configuration was manufactured as follows.
[0034]
First, the strip-shaped negative electrode 21 was manufactured as follows.
[0035]
A petroleum pitch is used as a starting material, and a functional group containing oxygen is introduced by 10 to 20% by weight (so-called oxygen cross-linking), and then calcined at a temperature of 1000 ° C. in an inert gas stream to obtain a property close to glassy carbon. Was obtained. X-ray diffraction measurement of this carbonaceous material showed that the (002) plane spacing was 3.76 °. Further, the true specific gravity was measured by a pycnometer method and found to be 1.58 g / cm ³ . This carbonaceous material was pulverized to obtain a carbonaceous material powder having an average particle size of 10 μm.
The carbonaceous material powder thus obtained was used as a negative electrode active material carrier, and 90 parts by weight of the carbonaceous material powder and 10 parts by weight of polyvinylidene fluoride (PVDF) as a binder were mixed to prepare a negative electrode mixture. did. This negative electrode mixture was dispersed in N-methylpyrrolidone as a solvent to obtain a negative electrode slurry (paste).
[0036]
A 10 μm-thick strip-shaped copper foil was used as the negative electrode current collector 29. The negative electrode mixture slurry was applied to both surfaces of the negative electrode current collector, dried, and then compression-molded to produce the strip-shaped negative electrode 1. The dimensions of the electrodes of the strip-shaped negative electrode 21 were 43.4 mm in width and 700 mm in length, and the thickness of the mixture after molding was 80 μm on both sides and was the same.
[0037]
Next, the belt-shaped positive electrode 22 was produced as follows.
[0038]
0.5 mol of lithium carbonate and 1 mol of cobalt carbonate were mixed and calcined in air at 900 ° C. for 5 hours to obtain LiCoO ₂ . LiCoO ₂ was used as a positive electrode active material, and 91 parts by weight thereof, 6 parts by weight of graphite as a conductive agent, and 3 parts by weight of polyvinylidene fluoride as a binder were mixed to prepare a positive electrode mixture. This positive electrode mixture was dispersed in N-methylprolidone to form a positive electrode slurry (paste).
[0039]
A 20 μm-thick strip-shaped aluminum foil is used as the positive electrode current collector 30, and the positive electrode mixture slurry is uniformly applied to both surfaces of the positive electrode current collector 30, dried, and then compression-molded to form the strip-shaped positive electrode 22. did. The dimensions of the electrodes of the strip-shaped positive electrode 22 were 41.4 mm in width and 650 mm in length, and the thickness of the mixture after molding was 80 μm on both sides and was the same.
[0040]
A band-shaped negative electrode 21 having a width of 43.4 mm and a length of 700 mm and a band-shaped positive electrode 22 having a width of 41.4 mm and a length of 650 mm were microporous polypropylene film having a thickness of 25 μm and a width of 45.9 mm. As a separator 23, a band-shaped negative electrode 21, a separator 23, a band-shaped positive electrode 22, and a separator 23 were laminated in this order, and the laminate was wound many times in such a direction that the width direction became the height direction of the wound body. Then, the final end of the separator located at the outermost periphery was fixed with a tape having a width of 40 mm, thereby producing a wound electrode body having a diameter of 19.6 mm and a height of 45.9 mm. In this wound body, the separator 23 protruded vertically from the strip-shaped negative electrode 21 and the strip-shaped positive electrode 22, and the ratio of the height of the strip-shaped negative electrode 21 to the total height of the wound body was 94.6%.
[0041]
Next, the protruding portion of the separator protruding above and below the wound body is bent inward, and a pressure of 3.8 kg / cm ² is applied using an aluminum jig heated to a temperature of 150 ° C. in this state. For about 5 seconds. As a result, a wound electrode body having a height of 44.0 mm and a ratio of the height of the strip-shaped negative electrode 21 to the total height of 98.6% was obtained.
[0042]
The wound electrode body produced in this way was placed in an iron battery can 25 plated with nickel, and the insulator plates 24 were placed on the upper and lower surfaces of the wound electrode body and stored. Then, the aluminum positive electrode lead 32 was led out of the positive electrode current collector and was welded to the battery lid 27, and the nickel negative electrode lead 31 was led out of the negative electrode current collector and welded to the battery can 25.
[0043]
An electrolytic solution obtained by dissolving LiPF ₆ at a rate of 1 mol / liter in a mixed solvent of propylene carbonate and diethyl carbonate in the same volume was injected into the battery can 25. Then, by caulking the battery can 25 via an insulating sealing gasket 26 coated on the surface with asphalt, the safety valve device 8 having the current interrupting mechanism and the battery lid 27 are fixed, and the airtightness in the battery is maintained. A cylindrical nonaqueous electrolyte battery having a diameter of 20 mm and a height of 50 mm was produced.
[0044]
Example 2
A microporous polypropylene film having a width of 48.4 mm serving as a separator, a band-shaped negative electrode having a width of 43.4 mm and a length of 700 mm produced in the same manner as in Example 1, and a band-shaped positive electrode having a width of 41.4 mm and a length of 650 mm were prepared. Then, a band-shaped negative electrode, a separator, a band-shaped positive electrode, and a separator were stacked in this order, and the stacked body was spirally wound many times. Then, the end of the outermost separator was fixed with a tape having a width of 40 mm to prepare a wound body having a diameter of 19.6 mm and a height of 48.4 mm. In this wound body, the separator protruded up and down from the strip-shaped negative electrode and the strip-shaped positive electrode, and the ratio of the height of the strip-shaped negative electrode to the entire height of the wound body was 89.7%.
[0045]
Next, the protruding portion of the separator protruding upward and downward was bent inward, and pressure-molded under the same conditions as in Example 1. As a result, a wound electrode body having a height of 44.0 mm and a ratio of the height of the strip-shaped negative electrode to the total height of 98.6% was obtained.
[0046]
This wound electrode body was housed in the same battery can as in Example 1, and the welding of the lead, the injection of the electrolyte solution, and the fixing of the battery cover were performed to obtain a cylindrical nonaqueous electrolyte battery having a diameter of 20 mm and a height of 50 mm. Was prepared.
[0047]
Example 3
A microporous polypropylene film having a width of 44.4 mm serving as a separator, a band-shaped negative electrode having a width of 43.4 mm and a length of 700 mm produced in the same manner as in Example 1, and a band-shaped positive electrode having a width of 41.4 mm and a length of 650 mm were prepared. Then, a band-shaped negative electrode, a separator, a band-shaped positive electrode, and a separator were stacked in this order, and the stacked body was spirally wound many times. Then, the outermost end of the separator was fixed with a tape having a width of 40 mm to produce a wound body having a diameter of 19.6 mm and a height of 44.4 mm. In this wound body, the separator protruded above and below the strip-shaped negative electrode and the strip-shaped positive electrode, and the ratio of the height of the strip-shaped negative electrode to the total height of the wound body was 97.7%.
[0048]
Next, the protruding portion of the separator protruding upward and downward was bent inward, and pressure-molded under the same conditions as in Example 1. As a result, a wound electrode body having a height of 44.0 mm and a ratio of the height of the strip-shaped negative electrode to the total height of 98.6% was obtained.
[0049]
This wound electrode body was housed in the same battery can as in Example 1, and the welding of the lead, the injection of the electrolyte solution, and the fixing of the battery cover were performed to obtain a cylindrical nonaqueous electrolyte battery having a diameter of 20 mm and a height of 50 mm. Was prepared.
[0050]
Example 4
A microporous polypropylene film having a width of 44.4 mm serving as a separator, a band-shaped negative electrode having a width of 43.4 mm and a length of 700 mm produced in the same manner as in Example 1, and a band-shaped positive electrode having a width of 41.4 mm and a length of 650 mm were prepared. Then, a band-shaped negative electrode, a separator, a band-shaped positive electrode, and a separator were stacked in this order, and the stacked body was spirally wound many times. Then, the outermost end of the separator was fixed with a tape having a width of 40 mm to produce a wound body having a diameter of 19.6 mm and a height of 44.4 mm. In this wound body, the separator protruded above and below the strip-shaped negative electrode and the strip-shaped positive electrode, and the ratio of the height of the strip-shaped negative electrode to the entire height of the wound body was 98.6%.
[0051]
Next, this wound electrode body was pressure-molded under the same conditions as in Example 1. As a result, a wound electrode body having a height of 44.0 mm and a ratio of the height of the strip-shaped negative electrode to the total height of 98.6% was obtained.
[0052]
This wound electrode body was housed in the same battery can as in Example 1, and the welding of the lead, the injection of the electrolyte solution, and the fixing of the battery cover were performed to obtain a cylindrical nonaqueous electrolyte battery having a diameter of 20 mm and a height of 50 mm. Was prepared.
[0053]
Comparative Example 1
A microporous polypropylene film having a width of 44.4 mm serving as a separator, and a strip-shaped negative electrode and a strip-shaped positive electrode produced in the same manner as in Example 1 except that the electrode width was set to 41.5 mm and 39.5 mm, respectively, A negative electrode, a separator, a strip-shaped positive electrode, and a separator were laminated in this order, and the laminated body was spirally wound many times. Then, the outermost end of the separator was fixed with a tape having a width of 40 mm to produce a wound body having a diameter of 19.6 mm and a height of 44.4 mm. In this wound body, the separator protruded above and below the band-shaped negative electrode and the band-shaped positive electrode, and the ratio of the height of the band-shaped negative electrode to the entire height of the wound body was 94.3%.
[0054]
This rolled body was housed in the same battery can as in Example 1 without heat molding, and the lead was welded, the electrolyte was injected, and the battery lid was fixed, so that a cylinder having a diameter of 20 mm and a height of 50 mm was obtained. A non-aqueous electrolyte battery was fabricated.
[0055]
As described above, a total of 100 batteries were manufactured by the method according to Examples 1 to 4 and Comparative Example 1, and constant current charging was performed for 8 hours under the conditions of an upper limit voltage of 4.2 V and a current of 300 mA, respectively. The battery was stored for one month under the condition of a temperature of 23 ° C. in a charged state. After a constant current charge of 2.5 hours under the condition of an upper limit voltage of 4.2 V and a current of 1 A, a charge / discharge cycle of repeating discharge twice under a condition of a current of 400 mA and a cutoff voltage of 2.75 V is repeated twice. The discharge capacity at the cycle was measured.
[0056]
Table 1 shows, for each battery, the ratio of the electrode height to the total height of the wound electrode body before and after the heat molding, the number of electrode protrusion failures, and the discharge capacity at the second cycle.
[0057]
[Table 1]

[0058]
As can be seen from Table 1, the batteries of Examples 1 to 4 in which the height of the wound electrode body was reduced by heating and molding the separator were compared with the batteries of Comparative Example 1 in which the separator was not heated and molded. In addition, the packing density of the electrodes housed in the battery can can be designed to be high, and a high discharge capacity is obtained reflecting this.
[0059]
From this, it can be seen that it is effective to reduce the height of the whole wound electrode body by heating and molding the separator in order to increase the discharge capacity per volume of the battery.
[0060]
For the batteries of Examples 1 to 4 in which the separator was heat-molded, when comparing the number of electrode protrusion failures, the number of electrode protrusion failures was in the state where the electrode was not heat-molded, and the electrode height relative to the total height of the wound body. It can be seen that it is greatly related to the height ratio.
[0061]
In the case where the ratio of the electrode height to the total height of the wound body in a state in which the molding is not heat-formed is small, that is, when the protrusion length of the separator protruding from the electrode is small (for example, Example 3 and Example 4), In the state where the electrode is heated and formed, the end of the electrode is exposed from the bent portion of the separator and a slight gap between the separator and the separator adjacent thereto, which causes internal short circuit frequently.
[0062]
Such an electrode protruding failure can be more reliably suppressed as the amount of protruding separator from the electrode increases as in the first and second embodiments.
[0063]
That is, the ratio between the height of the whole wound body and the height of the electrode in a state where the heat molding is not performed is suitably within 80 to 100%, and preferably within 90 to 98%. The ratio between the height of the entire electrode body and the height of the electrode is suitably in the range of 94 to 99%.
[0064]
However, in each of the above examples, the heat molding temperature of the separator is set to 150 ° C., but when this heating temperature is set to 175 ° C. and a battery is manufactured in the same manner as in Example 1, the discharge capacity is 780 mAh, which is small. Only batteries can be obtained. This is because the heat molding temperature is too high, the separator and the adjacent separator are fused and integrated, a part of the pores of the separator are filled, and the electrode is hardly impregnated with the electrolyte. . Therefore, it is desirable to set the heat molding temperature of the separator to a temperature at which the separator is softened and not melted, that is, a temperature equal to or higher than the softening point of the separator and lower than the melting point.
[0065]
【The invention's effect】
As described above, the present invention uses a band-shaped positive electrode as the separator, the one having a width larger than that of the band-shaped negative electrode, and the upper end of the band-shaped positive electrode and the band-shaped negative electrode in a state where these laminates are wound; Since a part of the separator protrudes, the part of the separator protruding from the band-shaped positive electrode and the band-shaped negative electrode is heated and molded at a temperature that does not cause fusion, and bent inward or outward to form a wound electrode body . Thus, the strip-shaped positive electrode and the strip-shaped negative electrode do not protrude from the separator and come into contact with each other, and the substantial filling amount of the electrode can be increased, so that a cylindrical nonaqueous electrolyte battery having a large capacity can be obtained. it can.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a spirally wound electrode body in a state where it is not subjected to heat molding.
FIG. 2 is a schematic diagram showing a spirally wound electrode body in a state of being heated and molded;
FIG. 3 is a schematic longitudinal sectional view showing a cylindrical nonaqueous electrolyte battery manufactured by the manufacturing method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Strip negative electrode 2 ... Strip positive electrode 3 ... Separator

Claims

A spiral electrode wound spirally with a separator interposed between a band-shaped positive electrode with active material molded on both sides of the current collector and a band-shaped negative electrode with active material containing carbonaceous material molded on both surfaces of the current collector In a non-aqueous electrolyte battery containing the body in a battery can into which a non-aqueous electrolyte has been injected,
The wound electrode body,
A separator having a width larger than that of the band-shaped positive electrode and the band-shaped negative electrode is wound up and down above and below the band-shaped negative electrode and the band-shaped positive electrode, and is wound.
The portion of the separator protruding above and below the strip-shaped negative electrode and the strip-shaped positive electrode is bent inside or outside the wound electrode body so as to respectively cover the upper and lower portions of the strip-shaped positive electrode and the strip-shaped negative electrode by heat molding ,
A cylindrical nonaqueous electrolyte battery wherein the bent portions of the separator are overlapped with each other so as to allow the transfer of the nonaqueous electrolyte.

2. The cylindrical nonaqueous electrolyte battery according to claim 1, wherein the band-like positive electrode has a configuration in which the active material is a composite compound of a transition metal and lithium, and the current collector is a metal foil. 3.