JP4649698B2 - Secondary battery - Google Patents

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JP4649698B2
JP4649698B2 JP2000036135A JP2000036135A JP4649698B2 JP 4649698 B2 JP4649698 B2 JP 4649698B2 JP 2000036135 A JP2000036135 A JP 2000036135A JP 2000036135 A JP2000036135 A JP 2000036135A JP 4649698 B2 JP4649698 B2 JP 4649698B2
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current collector
negative electrode
positive electrode
plate
electrode current
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JP2001229972A (en
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登志一 浦
誠一 上本
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Panasonic Corp
Panasonic Holdings Corp
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Panasonic Corp
Matsushita Electric Industrial Co Ltd
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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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  • Secondary Cells (AREA)
  • Sealing Battery Cases Or Jackets (AREA)
  • Connection Of Batteries Or Terminals (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、電気自動車等に用いられる高出力密度を必要とする二次電池に関するものである。
【０００２】
【従来の技術】
近年、電子機器の小型化，軽量化が急速に進んでおり、その電源としての電池に対しても小型・軽量化と高容量化の要望が高まっている。
【０００３】
その要望に対して、負極活物質として炭素系材料を用い、正極活物質にＬｉＣｏＯ2 等のリチウム含有遷移金属酸化物を用いたリチウムイオン二次電池が実用化されている。このリチウムイオン二次電池は、負極活物質として金属リチウムあるいはリチウム合金を用いたリチウム二次電池のように充電により負極上へのリチウムの析出が発生しないため、良好なサイクル特性が得られている。そのため、現在電子機器への搭載が進む等、リチウムイオン二次電池の開発が盛んに行われている。
【０００４】
また、地球環境問題、あるいはエネルギー問題を解決する手段としても、リチウム二次電池の開発が盛んに行われている。地球環境を良好に保全しつつ電力の安定確保を図っていく方策の一つとして負荷の平準化技術の実用化が望まれているが、一般家庭等で小規模に夜間電力を貯蔵する電池電力貯蔵装置を普及させると、大きな負荷平準化効果が期待できる。また、自動車の排気ガスによる大気汚染やＣＯ2 による温暖化防止を図るために、動力源の全部または一部を二次電池にとって代るようにした電気自動車の普及も望まれている。
【０００５】
以下に従来の二次電池について説明する。
【０００６】
従来、二次電池は特開平１０−８３８３３号公報に記載されたものが知られている。その二次電池の断面図を図４に示す。この従来例によれば、正極集電体２１ａに正極材料２１ｂを塗着させた正極板２１と負極集電体２２ａに負極材料２２ｂを塗着させた負極板２２とをセパレータ２３を介して渦巻き状に巻回する。その際、これら正極板２１とセパレータ２３と負極板２２は、それぞれ少しずつ上下にずらして巻回することにより、たとえば上端側には巻回された正極板２１の正極集電体２１ａの一部を突出させ、下端側には巻回された負極板２２の負極集電体２２ａの一部を突出させるようにする。そして、このように構成された極板群２４の上端面には正極タブ２５が溶接された正極集電板２６を、下端面には負極集電板２７をそれぞれ溶接する。そして、この極板群２４は、電解液と共に電池容器２８内に収容され、正極タブ２５をこの電池容器２８の正極端子となる電池蓋２９の内面に、負極集電板２７を負極端子となる電池缶３０の内底面にそれぞれ接続して二次電池とする。
【０００７】
【発明が解決しようとする課題】
しかしながら上記の従来の構成では、正極集電体２１ａおよび負極集電体２２ａにアルミニウム箔や銅箔等を用いた場合には、集電体自身の強度が低い上、集電体の厚みが薄いので正極集電体２１ａと正極集電板２６、負極集電体２２ａと負極集電板２７との溶接も弱くなることが考えられる。このような二次電池を電気自動車等に用い繰り返し振動や衝撃を受けた場合、極板群２４の自重による衝撃で正極集電体２１ａと正極集電板２６、負極集電体２２ａと負極集電板２７のそれぞれの溶接部が離れたり、正極集電体２１ａや負極集電体２２ａが破損したりすることにより、集電効率が著しく低下するという問題点を有していた。
【０００８】
なお、このような問題を解決する手段として、たとえば特開平１０−９２４６９号公報には、極板群の中心部に金属製の軸芯が配置されると共に、この金属製の軸芯を電池容器に固着または当接挟持したり、弾性体を介して挟持したものが開示されている。しかし、その場合は軸芯が必要であったり、軸芯の重量による衝撃荷重の増大によって電池容器の強度を上げなければならなくなるという問題点がある。
【０００９】
本発明は上記従来の問題点を解決するもので、集電体に強度の低い箔材等を用いても、振動や衝撃により集電体と集電板が離反することなく集電効率を維持する二次電池を提供することを目的とする。
【００１０】
【課題を解決するための手段】
この目的を達成するために本発明の二次電池は、正極集電体に正極材料を塗着させた正極板と、負極集電体に負極材料を塗着させた負極板とをセパレータを介して渦巻き状に巻回し、正極集電体の突出部と負極集電体の突出部を反対方向に突出させて構成した極板群と、前記正極集電体の突出部と負極集電体にそれぞれ接合された一対の平板状の正極集電板ならびに負極集電板と、前記極板群の巻回軸方向長さよりも大なる幅を持つ樹脂製の最外周フィルムと、これらを電解液と共に収納した電池容器とを有し、前記樹脂製の最外周用フィルムは前記極板群の最外周に巻回され、かつ前記一対の正極集電板ならびに負極集電板の端部を覆っている構成とした。
【００１１】
この構成によって、振動や衝撃により集電体と集電板が離反することなく集電効率を維持する二次電池が得られる。
【００１２】
【発明の実施の形態】
本発明の請求項１に記載の発明は、正極集電体に正極材料を塗着させた正極板と負極集電体に負極材料を塗着させた負極板とをセパレータを介して渦巻き状に巻回し、その両端部において正極負極、各々の極板の集電体を突出させた極板群と、前記突出部に接合された一対の平板状の集電板と、前記極板群の巻回軸方向長さよりも大なる幅を持つ樹脂製フィルムと、これらを電解液と共に収納した電池容器とからなり、前記樹脂製フィルムは前記極板群の最外周に巻回され、かつ前記一対の集電板の一部を覆っているとしたものである。この請求項１記載に係る構成を実施の形態とすることにより、振動や衝撃により集電体と集電板が離反することなく集電効率を維持することができる。
【００１３】
また、請求項２に記載の発明は、極板群の最外周に巻回された樹脂製フィルムは一軸または二軸延伸を施して製造されたものであり、その両端部を熱収縮させることにより集電板の端部を覆うこととしたものである。
【００１４】
従ってこの請求項２記載に係る構成を実施の形態とすることにより、安価な構成で作業性もよく集電効率を維持することができる。
【００１５】
また、請求項３に記載の発明は、樹脂製フィルムは極板群に巻回されているセパレータより幅の広いセパレータの機能を果すこととしたものである。
【００１６】
従ってこの請求項３記載に係る構成を実施の形態とすることにより、最外周のフィルムによる注液性の低下を防止することができる。
【００１７】
以下、本発明の実施の形態について、図１から図３を用いて具体的に説明する。
【００１８】
図１は、本発明の二次電池の断面図であり、１は正極板、２は負極板で、微多孔ポリエチレンフィルムから成るセパレータ３を介して互いに対向された状態で渦巻き状に巻回されて極板群４が構成され、この極板群４が電解液と共に電池容器５内に収納配置されている。電池容器５は負極端子となる円筒容器状の電池缶６と正極端子となる電池蓋７によって構成され、電池缶６の上端開口部内周と電池蓋７の外周との間に介装された絶縁パッキング８によって相互に絶縁されると共に電池容器５が密閉されている。
【００１９】
正極板１は、正極集電体１ａの両面に正極材料１ｂを塗工して構成されると共に、その正極集電体１ａの一側部が正極材料１ｂの塗工部より突出して正極突出部１ｃが形成されている。また、負極板２は、負極集電体２ａの他端部が負極材料２ｂの塗工部より突出して負極突出部２ｃが形成されている。ポリオレフィン系樹脂製のセパレータ３（本実施例では微多孔ポリエチレンを用いたが、このほかポリプロピレンあるいはそれらを貼り合わせたもの等でもよい）は正極板１および負極板２の塗工部の両端側よりも突出されている。正極集電体１ａのセパレータ３より突出した正極突出部１ｃには、正極集電板９が接合され、同様に、負極集電体２ａのセパレータ３より突出した負極突出部２ｃには、負極集電板１０が接合されている。また、正極集電板９には、正極タブ１１が所定の場所に溶接されている。１２は極板群４よりも大なる幅を有し、かつセパレータ３と同様の微多孔ポリエチレンから成る２軸延伸により作製された最外周フィルムである。最外周フィルム１２は、図２に示すように、極板群４に正極集電板９と正極タブ１１および負極集電板１０が接合された後に極板群４の最外周に数周巻回され、巻回後に端部１２ａ，１２ｂに熱風を当てることにより熱収縮させることにより図３の如く正極集電板９と負極集電板１０の外周部を覆っている。そして、正極タブ１１および負極集電板１０は、それぞれ電池蓋７の内面と電池缶６の内底面に接続されている。
【００２０】
正極板１，負極板２および電解液について詳細に説明すると、正極集電体１ａはアルミニウム箔等から成り、その両面に正極活物質と結着剤を含む正極材料１ｂを塗工して正極板１が構成されており、その正極活物質としては、ＬｉＣｏＯ2 ，ＬｉＭｎ2Ｏ4 ，ＬｉＮｉＯ2 、若しくはこれらＣｏ，Ｍｎ，Ｎｉの一部を他の遷移金属で置換したもの、あるいはそれ以外のリチウム含有金属酸化物が用いられる。
【００２１】
負極集電体２ａは銅箔等から成り、その両面に負極活物質と結着剤を含む負極材料２ｂを塗工して負極板２が構成されており、その負極活物質としては、グラファイト，石油コークス類，炭素繊維，有機高分子焼成物等の炭素質材料を用いるか、リチウムを吸蔵，放出が可能な金属、あるいは酸化物、若しくはこれらの複合化材料が用いられる。
【００２２】
また、電解液は、溶質として６フッ化リン酸リチウム（ＬｉＰＦ6 ），過塩素酸リチウム（ＬｉＣｌＯ4 ），ホウフッ化リチウム（ＬｉＢＦ4 ）等のリチウム塩、溶媒としてエチレンカーボネイト，プロピレンカーボネイト，ジエチレンカーボネイト，エチレンメチルカーボネイト等の非水溶媒単独、若しくはそれらの混合溶媒を用い、この溶媒に溶質を０．５ｍｏｌ／ｄｍ3 〜２ｍｏｌ／ｄｍ3 の濃度に溶解したものが使用される。
【００２３】
具体例を示すと、正極板１は、電解二酸化マンガン（ＥＭＤ：ＭｎＯ2 ）と炭酸リチウム（Ｌｉ2Ｃｏ3 ）とをＬｉ／Ｍｎ＝１／２となるように混合し、８００℃で２０時間大気中で焼成して製造した正極活物質のＬｉＭｎ2Ｏ4 と、導電材のアセチレンブラックと、結着剤のポリフッ化ビニリデンとを、それぞれ重量比で９２：３：５の割合で混合したものを正極材料１ｂとした。なお、正極材料１ｂをペースト状に混練するために結着剤としてポリフッ化ビニリデンはＮメチルピロリドンディスパージョン液を用いた。上記混合比率は固形分としての割合である。この正極ペーストを、厚み２０μｍのアルミニウム箔から成る正極集電体１ａの両面に一側縁部に幅１０ｍｍの非塗工部を残した状態で塗工し、正極材料層を形成した。正極材料層の両膜厚は同じで、塗工，乾燥後の両膜厚の和は２８０μｍで、正極板１の厚さを３００μｍとした。その後、正極板１の厚みが２００μｍになるように直径３００ｍｍのプレスロールにより圧縮成形した。このとき、正極材料密度は３．０ｇ／ｃｍ3 であった。
【００２４】
負極板２は、人造黒鉛と結着剤のスチレンブタジエンゴムとを重量比９７：３の割合で混合したものを負極材料２ｂとした。なお、負極材料２ｂをペースト状に混練するために結着剤としてのスチレンブタジエンゴムは水溶性のディスパージョン液を用いた。上記混合比率は固形分としての割合である。この負極合剤ペーストを厚み１４μｍの銅箔から成る負極集電体２ａの両面に一側縁部に１０ｍｍの非塗工部を残した状態で塗工し、負極材料層を形成した。その後、負極板２の厚みが１７０μｍになるように直径３００ｍｍのプレスロールにより圧縮成型した。このとき、負極材料密度は１．４ｇ／ｃｍ3 であった。
【００２５】
電解液は、エチレンカーボネイトとジエチレンカーボネイトを体積比１：１の配合比で混合した混合溶媒に、溶質として６フッ化リン酸リチウム（ＬｉＰＦ6 ）を１ｍｏｌ／ｄｍ3 の濃度に溶解したものを用いた。
【００２６】
このリチウムイオン二次電池の製造に当たっては、上記のように作製した正極板１と負極板２をセパレータ３を介して対向させ、かつそれらの正極集電体１ａの正極突出部１ｃと負極集電体２ａの負極突出部２ｃをそれぞれ反対方向の両端に突出させた状態で渦巻き状に巻回して極板群４を形成する。そして、正極タブ１１が溶接された正極集電板９と負極集電板１０を、正極集電体１ａの正極突出部１ｃと負極集電体２ａの負極突出部２ｃに図１の如く変形するまで押しつけるように配置して両者を圧接させた状態で、正極集電板９，負極集電板１０の表面の周方向複数箇所を中心部から外周縁まで放射状にレーザ溶接する。その後、この正極集電板９，負極集電板１０を接合した極板群４に、図２に示すように極板群４よりも幅の広い最外周フィルム１２を数周巻回し、端部１２ａと１２ｂに熱風を当てて両端部１２ａ，１２ｂを収縮させることにより図３の如く正極集電板９と負極集電板１０の外周部を覆っている。
【００２７】
その後、この最外周フィルム１２を巻回された極板群４は、電解液と共に電池缶６内に収容され真空注液される。このとき、最外周フィルム１２は、微多孔ポリエチレン製であるため、最外周フィルム１２からも電解液は浸透可能となり、最外周フィルム１２の有無による注液時間の差はない。
【００２８】
そして、正極タブ１１および負極集電板１０はそれぞれ電池蓋７の内面と電池缶６の内底面にレーザ溶接等にて接続される。その後、電池缶６に電池蓋７を密閉する。
【００２９】
以上のように本実施の形態によれば、正極板１と負極板２とをセパレータ３を介して渦巻き状に巻回し、その両端部に正極集電体１ａの正極突出部１ｃと負極集電体２ａの負極突出部２ｃを突出させた極板群４と、その正極突出部１ｃ，負極突出部２ｃに接合された一対の平板状の正極集電板９，負極集電板１０に、極板群４の最外周に巻回軸方向長さよりも大なる幅を持つ最外周フィルム１２が数周巻回され、かつ正極集電板９，負極集電板１０の端部を覆っているので、振動や衝撃により集電体と集電板が離れることなく集電効率を維持することができる。また、二次電池は仕様用途によりその容量を合わせるのが一般的であるので、極板群４の大きさは画一的ではなく数種類用意される。そして、電気自動車に使用される電池としては大きくなることが予想されるため、その振動や衝撃では小型電池に比べて大きな荷重が発生することが予想されるが、そのような場合は、最外周フィルム１２の巻回回数を増加させることによって強度向上がはかられるので、あらゆる大きさの二次電池に対して有効となる。
【００３０】
また、極板群４の最外周に巻回された最外周フィルム１２は一軸または二軸延伸を施して製造されたものであり、その端部１２ａ，１２ｂを熱収縮させることにより正極集電板９，負極集電板１０の端部を覆うようにしたものであると、安価な構成で作業性もよく集電効率を維持することができる。
【００３１】
また、最外周フィルム１２は極板群４に巻回されているセパレータ３より幅の広いセパレータとしての機能をすると、最外周フィルム１２による注液性の低下を防止することができる。
【００３２】
【発明の効果】
以上のように本発明は、正極板と負極板とをセパレータを介して渦巻き状に巻回し、その両端部に両極板の集電体を突出させた極板群と、その突出部に接合された一対の平板状の集電板に、極板群の最外周に巻回軸方向長さよりも大なる幅を持つ樹脂製の最外周用フィルムが巻回され、その最外周フィルムが集電板の端部を覆っているので、振動や衝撃により集電体と集電板が離れることなく集電効率を維持することができる。
【００３３】
また、極板群の最外周に巻回された樹脂製の最外周フィルムは一軸または二軸延伸を施して製造されたものを使用することにより、その両端部を熱収縮させることにより集電板の端部を覆うようにしたものであり、安価な構成で作業性もよく集電効率を維持することができる。
【００３４】
また、樹脂製の最外周フィルムは極板群に巻回されているセパレータより幅が広くてセパレータとしての機能を果すものであり、最外周フィルムによる注液性の低下を防止することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態における二次電池の断面図
【図２】同極板群を説明するための斜視図
【図３】図２に示す状態の加工後の極板群を説明するための斜視図
【図４】従来の二次電池の断面図
【符号の説明】
１ 正極板
１ａ 正極集電体
１ｂ 正極材料
１ｃ 正極突出部
２ 負極板
２ａ 負極集電体
２ｂ 負極材料
２ｃ 負極突出部
３ セパレータ
４ 極板群
５ 電池容器
９ 正極集電板
１０ 負極集電板
１１ 正極タブ
１２ 最外周フィルム
１２ａ，１２ｂ 端部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a secondary battery that requires a high power density and is used in an electric vehicle or the like.
[0002]
[Prior art]
In recent years, electronic devices are rapidly becoming smaller and lighter, and there is an increasing demand for smaller, lighter and higher capacity batteries as power sources.
[0003]
In response to this demand, a lithium ion secondary battery using a carbon-based material as a negative electrode active material and a lithium-containing transition metal oxide such as LiCoO 2 as a positive electrode active material has been put into practical use. Since this lithium ion secondary battery does not cause lithium deposition on the negative electrode due to charging unlike the lithium secondary battery using metallic lithium or lithium alloy as the negative electrode active material, good cycle characteristics are obtained. . For this reason, lithium ion secondary batteries are being actively developed, for example, as they are currently being installed in electronic devices.
[0004]
In addition, lithium secondary batteries are actively developed as means for solving global environmental problems or energy problems. As one of the measures to ensure stable power supply while preserving the global environment well, practical use of load leveling technology is desired. If storage devices are spread, a large load leveling effect can be expected. In addition, in order to prevent air pollution due to automobile exhaust gas and global warming due to CO 2, it is also desired to popularize electric vehicles in which all or part of the power source is replaced by secondary batteries.
[0005]
A conventional secondary battery will be described below.
[0006]
Conventionally, a secondary battery described in JP-A-10-83833 is known. A cross-sectional view of the secondary battery is shown in FIG. According to this conventional example, the positive electrode plate 21 in which the positive electrode material 21 b is applied to the positive electrode current collector 21 a and the negative electrode plate 22 in which the negative electrode current collector 22 a is applied with the negative electrode material 22 b are swirled through the separator 23. Wrap in a shape. At that time, the positive electrode plate 21, the separator 23, and the negative electrode plate 22 are slightly shifted up and down and wound, for example, a part of the positive electrode current collector 21 a of the positive electrode plate 21 wound on the upper end side. And a part of the negative electrode current collector 22a of the wound negative electrode plate 22 is protruded on the lower end side. The positive electrode current collector plate 26 having the positive electrode tab 25 welded thereto is welded to the upper end surface of the electrode plate group 24 thus configured, and the negative electrode current collector plate 27 is welded to the lower end surface thereof. The electrode plate group 24 is housed in the battery container 28 together with the electrolytic solution, the positive electrode tab 25 is used as the inner surface of the battery lid 29 that serves as the positive electrode terminal of the battery container 28, and the negative electrode current collector plate 27 is used as the negative electrode terminal. Respectively connected to the inner bottom surface of the battery can 30, a secondary battery is obtained.
[0007]
[Problems to be solved by the invention]
However, in the above-described conventional configuration, when an aluminum foil or a copper foil is used for the positive electrode current collector 21a and the negative electrode current collector 22a, the current collector itself has low strength and the current collector is thin. Therefore, the welding of the positive electrode current collector 21a and the positive electrode current collector plate 26, and the negative electrode current collector 22a and the negative electrode current collector plate 27 may be weakened. When such a secondary battery is used in an electric vehicle or the like and repeatedly subjected to vibration or impact, the positive electrode current collector 21a and the positive electrode current collector plate 26, the negative electrode current collector 22a and the negative electrode current collector are affected by the impact of the electrode plate group 24 due to its own weight. When the welded portions of the electric plate 27 are separated from each other or the positive electrode current collector 21a and the negative electrode current collector 22a are damaged, there is a problem that the current collection efficiency is remarkably lowered.
[0008]
As a means for solving such a problem, for example, in Japanese Patent Application Laid-Open No. 10-92469, a metal shaft core is arranged at the center of the electrode plate group, and the metal shaft core is used as a battery container. Are fixed or abutted to each other, or are held via an elastic body. However, in that case, there is a problem that the shaft core is necessary or the strength of the battery container has to be increased due to an increase in impact load due to the weight of the shaft core.
[0009]
The present invention solves the above-mentioned conventional problems, and maintains the current collection efficiency without causing the current collector and the current collector plate to separate due to vibration or impact even when a foil material with low strength is used as the current collector. An object of the present invention is to provide a secondary battery.
[0010]
[Means for Solving the Problems]
In order to achieve this object, the secondary battery according to the present invention includes a positive electrode plate in which a positive electrode material is applied to a positive electrode current collector and a negative electrode plate in which a negative electrode material is applied to a negative electrode current collector through a separator. The electrode plate group is formed by spirally winding the protruding portion of the positive electrode current collector and the protruding portion of the negative electrode current collector in opposite directions, and the protruding portion of the positive electrode current collector and the negative electrode current collector. A pair of plate-like positive and negative current collectors joined together, a resin outermost film having a width larger than the length of the electrode plate group in the winding axis direction, and these together with the electrolyte The resin outermost film is wound around the outermost periphery of the electrode plate group and covers the ends of the pair of positive electrode current collector plates and the negative electrode current collector plate. The configuration.
[0011]
With this configuration, it is possible to obtain a secondary battery that maintains the current collection efficiency without causing the current collector and the current collector plate to separate due to vibration or impact.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
According to the first aspect of the present invention, a positive electrode plate in which a positive electrode material is applied to a positive electrode current collector and a negative electrode plate in which a negative electrode material is applied to a negative electrode current collector are spirally formed via a separator. A positive electrode negative electrode, a group of electrode plates in which current collectors of the respective electrode plates protrude from both ends thereof, a pair of flat current collector plates joined to the protrusion, and winding of the electrode plate group A resin film having a width larger than the length in the direction of the rotation axis, and a battery container containing these together with the electrolyte, the resin film being wound around the outermost periphery of the electrode plate group, and the pair of It is supposed to cover a part of the current collector plate. By adopting the configuration according to claim 1 as an embodiment, the current collection efficiency can be maintained without the current collector and the current collector plate separating due to vibration or impact.
[0013]
Further, in the invention according to claim 2, the resin film wound around the outermost periphery of the electrode plate group is manufactured by uniaxial or biaxial stretching, and both ends thereof are thermally contracted. The end of the current collector plate is covered.
[0014]
Therefore, by adopting the configuration according to claim 2 as an embodiment, it is possible to maintain current collection efficiency with an inexpensive configuration and good workability.
[0015]
According to a third aspect of the present invention, the resin film fulfills the function of a separator wider than the separator wound around the electrode plate group.
[0016]
Therefore, by adopting the configuration according to claim 3 as an embodiment, it is possible to prevent a decrease in liquid injection property due to the outermost peripheral film.
[0017]
Hereinafter, embodiments of the present invention will be specifically described with reference to FIGS. 1 to 3.
[0018]
FIG. 1 is a cross-sectional view of a secondary battery of the present invention, in which 1 is a positive electrode plate, 2 is a negative electrode plate, and is wound in a spiral shape with a separator 3 made of a microporous polyethylene film facing each other. The electrode plate group 4 is configured, and the electrode plate group 4 is housed and disposed in the battery container 5 together with the electrolytic solution. The battery container 5 is constituted by a cylindrical container-shaped battery can 6 serving as a negative electrode terminal and a battery lid 7 serving as a positive electrode terminal, and is interposed between the inner periphery of the upper end opening of the battery can 6 and the outer periphery of the battery cover 7. The battery container 5 is sealed while being insulated from each other by the packing 8.
[0019]
The positive electrode plate 1 is configured by applying a positive electrode material 1b to both surfaces of a positive electrode current collector 1a, and one side portion of the positive electrode current collector 1a protrudes from a coating portion of the positive electrode material 1b to protrude from the positive electrode. 1c is formed. In the negative electrode plate 2, the other end of the negative electrode current collector 2a protrudes from the coating portion of the negative electrode material 2b to form a negative electrode protrusion 2c. A separator 3 made of a polyolefin resin (microporous polyethylene was used in this embodiment, but polypropylene or a laminate of these may also be used) from both ends of the coated portions of the positive electrode plate 1 and the negative electrode plate 2. Is also protruding. A positive electrode current collector plate 9 is joined to the positive electrode protrusion 1c protruding from the separator 3 of the positive electrode current collector 1a. Similarly, the negative electrode protrusion 2c protruding from the separator 3 of the negative electrode current collector 2a is connected to the negative electrode protrusion 2c. The electric plate 10 is joined. A positive electrode tab 11 is welded to the positive electrode current collector plate 9 at a predetermined location. Reference numeral 12 denotes an outermost peripheral film having a width larger than that of the electrode plate group 4 and made by biaxial stretching made of the same microporous polyethylene as that of the separator 3. As shown in FIG. 2, the outermost peripheral film 12 is wound several times around the outermost periphery of the electrode plate group 4 after the positive electrode current collector plate 9, the positive electrode tab 11 and the negative electrode current collector plate 10 are joined to the electrode plate group 4. The outer peripheral portions of the positive electrode current collector plate 9 and the negative electrode current collector plate 10 are covered as shown in FIG. 3 by heat shrinking by applying hot air to the end portions 12a and 12b after winding. The positive electrode tab 11 and the negative electrode current collector plate 10 are connected to the inner surface of the battery lid 7 and the inner bottom surface of the battery can 6, respectively.
[0020]
The positive electrode plate 1, the negative electrode plate 2 and the electrolyte will be described in detail. The positive electrode current collector 1a is made of an aluminum foil or the like, and a positive electrode material 1b containing a positive electrode active material and a binder is applied on both surfaces thereof. 1 is composed of LiCoO 2 , LiMn 2 O 4 , LiNiO 2 , or a part of these Co, Mn, Ni substituted with another transition metal, or other lithium A contained metal oxide is used.
[0021]
The negative electrode current collector 2a is made of copper foil or the like, and the negative electrode material 2b containing a negative electrode active material and a binder is applied to both surfaces thereof to form a negative electrode plate 2. The negative electrode active material includes graphite, A carbonaceous material such as petroleum coke, carbon fiber, and fired organic polymer is used, or a metal that can occlude and release lithium, an oxide, or a composite material thereof.
[0022]
In addition, the electrolyte is a lithium salt such as lithium hexafluorophosphate (LiPF 6 ), lithium perchlorate (LiClO 4 ), lithium borofluoride (LiBF 4 ) as a solute, and ethylene carbonate, propylene carbonate, diethylene carbonate as a solvent. the non-aqueous solvent alone such as ethylene methyl carbonate, or using a mixed solvent thereof, those solutes in the solvent was dissolved in a concentration of 0.5mol / dm 3 ~2mol / dm 3 are used.
[0023]
As a specific example, the positive electrode plate 1 is prepared by mixing electrolytic manganese dioxide (EMD: MnO 2 ) and lithium carbonate (Li 2 Co 3 ) so that Li / Mn = 1/2, and at 800 ° C. for 20 hours. A mixture of LiMn 2 O 4 as a positive electrode active material manufactured by firing in the atmosphere, acetylene black as a conductive material, and polyvinylidene fluoride as a binder in a weight ratio of 92: 3: 5, respectively. Was used as the positive electrode material 1b. In order to knead the positive electrode material 1b into a paste, N-methylpyrrolidone dispersion liquid was used as the polyvinylidene fluoride as a binder. The mixing ratio is a ratio as a solid content. This positive electrode paste was applied on both surfaces of a positive electrode current collector 1a made of an aluminum foil having a thickness of 20 μm, leaving a non-coated portion having a width of 10 mm on one side edge portion, thereby forming a positive electrode material layer. Both film thicknesses of the positive electrode material layer were the same, the sum of both film thicknesses after coating and drying was 280 μm, and the thickness of the positive electrode plate 1 was 300 μm. Thereafter, the positive electrode plate 1 was compression-molded by a press roll having a diameter of 300 mm so that the thickness of the positive electrode plate 1 was 200 μm. At this time, the positive electrode material density was 3.0 g / cm 3 .
[0024]
The negative electrode plate 2 was obtained by mixing artificial graphite and a binder styrene butadiene rubber at a weight ratio of 97: 3 as a negative electrode material 2b. In order to knead the negative electrode material 2b into a paste, a water-soluble dispersion liquid was used as the styrene butadiene rubber as a binder. The mixing ratio is a ratio as a solid content. This negative electrode mixture paste was applied on both surfaces of a negative electrode current collector 2a made of a copper foil having a thickness of 14 μm, leaving a non-coated portion of 10 mm on one side edge portion to form a negative electrode material layer. Thereafter, the negative electrode plate 2 was compression-molded by a press roll having a diameter of 300 mm so that the thickness of the negative electrode plate 2 was 170 μm. At this time, the negative electrode material density was 1.4 g / cm 3 .
[0025]
The electrolyte used is a mixed solvent in which ethylene carbonate and diethylene carbonate are mixed at a mixing ratio of 1: 1 by volume, and lithium hexafluorophosphate (LiPF 6 ) as a solute is dissolved at a concentration of 1 mol / dm 3 . It was.
[0026]
In manufacturing the lithium ion secondary battery, the positive electrode plate 1 and the negative electrode plate 2 produced as described above are opposed to each other with the separator 3 interposed therebetween, and the positive electrode protruding portion 1c of the positive electrode current collector 1a and the negative electrode current collector are provided. The electrode plate group 4 is formed by winding the negative electrode protrusions 2c of the body 2a in a spiral shape with the negative electrode protrusions 2c protruding from both ends in opposite directions. Then, the positive electrode current collector plate 9 and the negative electrode current collector plate 10 to which the positive electrode tab 11 is welded are deformed into a positive electrode protrusion 1c of the positive electrode current collector 1a and a negative electrode protrusion 2c of the negative electrode current collector 2a as shown in FIG. In such a state that the two are pressed against each other and are in pressure contact with each other, laser welding is performed radially from a central portion to an outer peripheral edge at a plurality of circumferential positions on the surfaces of the positive electrode current collector plate 9 and the negative electrode current collector plate 10. Thereafter, the outermost peripheral film 12 having a width wider than that of the electrode plate group 4 is wound around the electrode plate group 4 to which the positive electrode current collector plate 9 and the negative electrode current collector plate 10 are joined, as shown in FIG. The outer peripheral portions of the positive electrode current collector plate 9 and the negative electrode current collector plate 10 are covered as shown in FIG. 3 by applying hot air to 12a and 12b to contract both ends 12a and 12b.
[0027]
Thereafter, the electrode plate group 4 around which the outermost peripheral film 12 is wound is accommodated in the battery can 6 together with the electrolytic solution and vacuum-injected. At this time, since the outermost peripheral film 12 is made of microporous polyethylene, the electrolytic solution can permeate from the outermost peripheral film 12, and there is no difference in injection time depending on the presence or absence of the outermost peripheral film 12.
[0028]
The positive electrode tab 11 and the negative electrode current collector plate 10 are respectively connected to the inner surface of the battery lid 7 and the inner bottom surface of the battery can 6 by laser welding or the like. Thereafter, the battery lid 7 is sealed in the battery can 6.
[0029]
As described above, according to the present embodiment, the positive electrode plate 1 and the negative electrode plate 2 are spirally wound via the separator 3, and the positive electrode protrusion 1c of the positive electrode current collector 1a and the negative electrode current collector are provided at both ends thereof. The electrode plate group 4 in which the negative electrode protruding portion 2c of the body 2a is protruded, and the positive electrode protruding portion 1c and the pair of flat plate positive electrode current collecting plate 9 and negative electrode current collecting plate 10 joined to the negative electrode protruding portion 2c Since the outermost peripheral film 12 having a width larger than the length in the winding axis direction is wound several times around the outermost periphery of the plate group 4 and covers the ends of the positive electrode current collector plate 9 and the negative electrode current collector plate 10. The current collection efficiency can be maintained without the current collector and the current collector plate being separated by vibration or impact. Moreover, since it is common to match the capacity | capacitance of a secondary battery with a specification application, the magnitude | size of the electrode group 4 is not uniform but several types are prepared. And since it is expected that the battery used in an electric vehicle will be larger, it is expected that a large load will be generated compared to a small battery due to its vibration and impact. Since the strength can be improved by increasing the number of windings of the film 12, it is effective for secondary batteries of any size.
[0030]
Further, the outermost peripheral film 12 wound around the outermost periphery of the electrode plate group 4 is manufactured by uniaxial or biaxial stretching, and its end portions 12a and 12b are thermally shrunk to cause a positive current collector plate. 9. If the end of the negative electrode current collector plate 10 is covered, the current collection efficiency can be maintained with good workability and low cost.
[0031]
Further, when the outermost peripheral film 12 functions as a separator having a width wider than that of the separator 3 wound around the electrode plate group 4, it is possible to prevent the liquid injection property from being deteriorated by the outermost peripheral film 12.
[0032]
【The invention's effect】
As described above, according to the present invention, the positive electrode plate and the negative electrode plate are spirally wound through the separator, and the electrode plate group in which the current collectors of both electrode plates protrude from both ends thereof, and the protrusions are joined to each other. A pair of flat plate current collector plates is wound with a resin outermost film having a width larger than the length of the winding axis around the outermost periphery of the electrode plate group, and the outermost peripheral film is the current collector plate. The current collection efficiency can be maintained without leaving the current collector and the current collector plate due to vibration or impact.
[0033]
In addition, the outermost peripheral film made of resin wound around the outermost periphery of the electrode plate group is made of uniaxially or biaxially stretched, and the current collector plate is thermally contracted at both ends. Thus, the current collecting efficiency can be maintained with good workability and low cost.
[0034]
Moreover, the resin outermost peripheral film is wider than the separator wound around the electrode plate group and functions as a separator, and can prevent the deterioration of the liquid injection property due to the outermost peripheral film.
[Brief description of the drawings]
1 is a cross-sectional view of a secondary battery according to an embodiment of the present invention. FIG. 2 is a perspective view for explaining the same electrode plate group. FIG. 3 is an explanation of the processed electrode plate group in the state shown in FIG. FIG. 4 is a cross-sectional view of a conventional secondary battery.
DESCRIPTION OF SYMBOLS 1 Positive electrode plate 1a Positive electrode collector 1b Positive electrode material 1c Positive electrode protrusion part 2 Negative electrode plate 2a Negative electrode collector 2b Negative electrode material 2c Negative electrode protrusion part 3 Separator 4 Electrode plate group 5 Battery container 9 Positive electrode current collector plate 10 Negative electrode current collector plate 11 Positive electrode tab 12 outermost peripheral film 12a, 12b end

Claims (2)

正極集電体に正極材料を塗着させた正極板と、負極集電体に負極材料を塗着させた負極板とをセパレータを介して渦巻き状に巻回し、正極集電体の突出部と負極集電体の突出部を反対方向に突出させて構成した極板群と、前記正極集電体の突出部と負極集電体の突出部にそれぞれ接合された一対の平板状の正極集電板ならびに負極集電板と、前記極板群の巻回軸方向長さよりも大なる幅を持つ樹脂製の最外周フィルムと、これらを電解液と共に収納した電池容器とを有し、前記樹脂製の最外周フィルムは前記極板群の最外周に巻回され、かつ前記一対の正極集電板ならびに負極集電板の端部を覆っていることを特徴とする二次電池。  A positive electrode plate coated with a positive electrode material on a positive electrode current collector and a negative electrode plate coated with a negative electrode material on a negative electrode current collector are spirally wound through a separator, An electrode plate group configured by projecting the protruding portion of the negative electrode current collector in the opposite direction, and a pair of flat plate current collectors joined to the protruding portion of the positive electrode current collector and the protruding portion of the negative electrode current collector, respectively And a negative electrode current collector plate, a resin outermost peripheral film having a width larger than the length in the winding axis direction of the electrode plate group, and a battery container containing these together with an electrolyte, and made of the resin The outermost peripheral film is wound around the outermost periphery of the electrode plate group, and covers the ends of the pair of positive electrode current collector plates and the negative electrode current collector plate. 極板群の最外周に巻回された樹脂製の最外周フィルムは一軸または二軸延伸を施して製造されたものであり、その両端部を熱収縮させることにより正極集電板ならびに負極集電板の端部を覆うことを特徴とする請求項１記載の二次電池。  The resin outermost film wound around the outermost periphery of the electrode plate group is manufactured by uniaxial or biaxial stretching, and the positive electrode current collector plate and the negative electrode current collector are thermally contracted at both ends thereof. The secondary battery according to claim 1, wherein an end portion of the plate is covered.
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