JP3375434B2

JP3375434B2 - Explosion-proof sealed battery

Info

Publication number: JP3375434B2
Application number: JP27581194A
Authority: JP
Inventors: 宏山本; 徹夫川合
Original assignee: Hitachi Maxell Energy Ltd
Current assignee: Hitachi Maxell Energy Ltd
Priority date: 1994-10-14
Filing date: 1994-10-14
Publication date: 2003-02-10
Anticipated expiration: 2018-02-10
Also published as: JPH08115715A

Description

【発明の詳細な説明】【０００１】【産業上の利用分野】本発明は、防爆形密閉電池に関
し、さらに詳しくは、リード体取り付け部材と防爆弁と
の溶接部分の剥離や亀裂がなく、かつ密閉性が高く、し
かも過充電時や短絡時においても電流を遮断させて発火
や破裂を防止することができる防爆形密閉電池に関す
る。【０００２】【従来の技術】最近は、たとえばリチウム電池やリチウ
ム二次電池などの有機溶媒系電解液を用いた密閉電池
が、時計やカメラなどの携帯用機器の電源として広く使
用されている。【０００３】ところが、このような有機溶媒系の電解液
を用いた密閉電池は、電池内部の発電要素が化学変化を
起こして、電池内部の圧力が上昇し、高圧下で破裂する
場合がある。【０００４】たとえば、リチウム二次電池を過充電状態
にしたり、あるいは短絡状態になって大電流が流れる
と、電解液が分解し、その結果、電池内部にガスが発生
し、その発生したガスによって電池内部の圧力が上昇
し、最後には電池が高圧下で破裂してしまうことがあ
る。【０００５】また、リチウム一次電池においても、強制
的に過充電や過放電したり、あるいは他の電池からの強
制放電などによって、電池内部の圧力が上昇し、最後に
は発火にいたるおそれがあった。【０００６】そこで、従来からも、電池内部に発生した
ガスを電池外部へ放出して、電池の高圧下での破裂を防
止する、いわゆる防爆機能を電池に備えさせることが行
われている。【０００７】たとえば、図８に示すように、封口板を兼
ねるリード体取り付け部材１の中央部に薄肉部１ａとそ
の周囲にガスが通過し得る圧力導入口１ｂを設け、端子
板２にガス排出孔２ａを設け、電池内圧の上昇に伴い内
圧方向に変形を生じる防爆弁３の中央部を突出させて、
その突出部３ａを上記リード体取り付け部材１の薄肉部
１ａに溶接し、過充電あるいは短絡などによる異常反応
により電池内部にガスが発生して電池の内圧が上昇した
場合には、そのガス圧によって防爆弁３が変形して、薄
肉部１ａを破断させるか、あるいは上記リード体取り付
け部材１の薄肉部１ａと防爆弁３の突出部３ａとの溶接
部分５を剥離させ、初期の段階で電流を遮断して上記異
常反応を停止させ、充電電流または短絡電流による温度
上昇を抑制し、電池の発火や破裂を防止する防爆構造が
採用されている。【０００８】このような防爆構造部分では、環状ガスケ
ット７の内部にリード体取り付け部材１、絶縁パッキン
グ４、防爆弁３を挿入し、防爆弁３に設けた突出部３ａ
とリード体取り付け部材１に設けた薄肉部１ａとを溶接
した後、リード体８を上記リード体取り付け部材１に溶
接することによって組み立てられる。【０００９】しかしながら、上記防爆構造では、図９に
示すように、リード体取り付け部材１とリード体８の溶
接部分９が平面状であるため（なお、図９では、溶接部
分９をわかりやすくするために、リード体８の溶接部分
に相当する部分に網目状に斜線を入れ、そこに参照符号
９を付けている）、溶接時に大きな出力と加圧力を必要
とし、その結果、先に溶接した防爆弁３の突出部３ａと
リード体取り付け部材１の薄肉部１ａとの溶接部分５が
剥離したり、あるいは上記溶接部分５に亀裂が発生し、
電路として機能しないという問題が発生する。また、溶
接時の加圧力による影響でリード体取り付け部材１が変
形し、電池としての密閉性が低下するという問題もあっ
た。【００１０】上記以外の組立方法として、環状ガスケッ
ト７にリード体取り付け部材１を挿入した後、リード体
８を溶接し、その後、絶縁パッキング４、防爆弁３を挿
入し、防爆弁３の突出部３ａとリード体取り付け部材１
の薄肉部１ａとを溶接する方法も考えられるが、この方
法による場合、防爆弁３の突出部３ａとリード体取り付
け部材の薄肉部１ａとの溶接部分５の剥離や上記溶接部
分５の亀裂発生は解消されるが、生産性が著しく低いと
いう問題があった。【００１１】【発明が解決しようとする課題】本発明は、上記のよう
な従来の防爆形密閉電池が持っていた防爆弁とリード体
取り付け部材との溶接部分が剥離したり、上記溶接部分
に亀裂が生じるという問題点を解消し、防爆弁とリード
体取り付け部材との溶接部分の剥離や亀裂の発生がな
く、かつ密閉性の優れた防爆形密閉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】上記課題を解決するため
の本発明の構成を、その実施例に対応する図１〜図７を
用いて説明すると、本発明は、リード体取り付け部材１
の薄肉部１ａの外周部分の同一円周上に発電要素側に先
端部を有する環状の凸部１ｃを少なくとも１個設けるか
または円弧状の凸部１ｃを複数個設け、上記凸部１ｃに
リード体８を溶接する構造とすることによって、上記目
的を達成したものである。【００１３】すなわち、リード体取り付け部材１に凸部
１ｃを設けておくことにより、リード体取り付け部材１
とリード体８との溶接部分９が面状から線状に変化し、
溶接時の出力および加圧力を小さくすることができるよ
うになる。その結果、先に溶接しておいた防爆弁３とリ
ード体取り付け部材１との溶接部分５の剥離や亀裂が生
じなくなり、電路としての信頼性が向上する。また、リ
ード体取り付け部材１に凸部１ｃを設けたことにより、
リード体取り付け部材１の強度が向上し、これと上記の
ようにリード体８とリード体取り付け部材１との溶接に
大きな加圧力を要しなくなったこととが相乗的に働い
て、リード体取り付け部材１の変形が防止され、電池と
しての密閉性の低下が防止され、密閉性が向上する。【００１４】【実施例】つぎに、本発明の実施例を図面に基づいて説
明する。ただし、本発明は実施例に例示のもののみに限
定されることはない。【００１５】図１は本発明の防爆形密閉電池の一実施例
を示す縦断面図である。図２は上記図１に示す防爆形密
閉電池に使用されているリード体取り付け部材を示すも
のであり、図２の（ａ）はその底面図、図２の（ｂ）は
その縦断面図である。ただし、この図２は、その（ａ）
でリード体取り付け部材の底面を示していることからも
明らかなように、図１とは上下を反転させた状態で示し
ている。図３は上記図１に示す防爆形密閉電池に使用さ
れている防爆弁を示すものであり、図３の（ａ）はその
平面図、図３の（ｂ）はその縦断面図である。図４はリ
ード体取り付け部材とリード体との溶接部分とその周辺
の拡大斜視図である。この図４も図１とは上下を反転さ
せた状態で示している。図５は図１に示す防爆形密閉電
池の防爆弁が電池内圧を受けて内圧方向に変形し、リー
ド体取り付け部材に設けた薄肉部が破断した時の状態を
示す要部拡大縦断面図である。図６は図１に示す防爆形
密閉電池の防爆弁が電池内圧を受けて内圧方向に変形
し、リード体取り付け部材と防爆弁との溶接部分が剥離
した時の状態を示す要部拡大縦断面図である。図７は本
発明の防爆形密閉電池に使用されるリード体取り付け部
材の他の実施例を拡大して示すもので、（ａ）はその底
面図、（ｂ）はその縦断面図である。この図７も図１と
は上下を反転させた状態で示している。【００１６】まず、図１により、電池の構成部材を概略
的に説明すると、１はリード体取り付け部材、２は端子
板、３は防爆弁、４は絶縁パッキング、５は溶接部分、
６は電池ケース、７は環状ガスケット、８は正極側のリ
ード体、９はリード体取り付け部材１の凸部１ｃとリー
ド体８との溶接部分、１０は正極、１１は負極、１２は
セパレータ、１３は電解液、１４は絶縁体、１５は絶縁
体、１６は負極側のリード体である。【００１７】リード体取り付け部材１は、封口板として
の機能を有するものであり、このリード体取り付け部材
１はアルミニウム、チタン、ニッケル、ステンレス鋼な
どからなり、円板状をしていて、その中央部には薄肉部
１ａが設けられ、図２に詳しく示されるように、防爆弁
３に電池内圧を作用させるための圧力導入口１ｂとして
４カ所に孔が設けられ、さらに上記薄肉部１ａの外周部
分の同一円周上に凸部１ｃが設けられている。この凸部
１ｃは発電要素側（すなわち、正極１０や負極１１など
に向く側）に先端部を有するものであるが、この図２は
図１とは上下を反転させた状態で示している関係で、先
端部は上方を向いている。また、この実施例に示すもの
では、凸部１ｃを環状に設けているが、図７に示すよう
に、円弧状の凸部１ｃを複数個設けてもよい。そして、
上記薄肉部１ａの上面に防爆弁３の突出部３ａの下面が
溶接され、溶接部分５を構成している。【００１８】なお、上記のリード体取り付け部材１に設
けた薄肉部１ａや凸部１ｃ、防爆弁３の突出部３ａなど
は、図面上での理解がしやすいように、切断面のみを図
示しており、切断面後方の輪郭線は図示を省略してい
る。また、リード体取り付け部材１の薄肉部１ａと防爆
弁３の突出部３ａとの溶接部分５も、図面上での理解が
容易なように、実際よりは誇張した状態に図示されてい
る。【００１９】端子板２は、鉄にニッケルメッキを施した
金属材料、ステンレス鋼あるいはステンレス鋼にニッケ
ルメッキを施した金属材料で形成され、周縁部が鍔状に
なった帽子状をしており、この端子板２にはガス排出孔
２ａが設けられている。【００２０】防爆弁３は、アルミニウム、チタン、ニッ
ケル、ステンレス鋼などの金属材料からなり、円板状を
しており、その中央部には発電要素側に先端部を有する
突出部３ａが設けられ、前記したように、その突出部３
ａの下面がリード体取り付け部材１の薄肉部１ａの上面
に溶接され、溶接部分５を構成している。【００２１】絶縁パッキング４は、ポリプロピレンなど
の耐電解液性を有する合成樹脂で形成されていて、環状
をしており、リード体取り付け部材１と防爆弁３とを絶
縁するとともに、両者の間から電解液が漏れないように
両者の間隙を封止する。【００２２】電池ケース６は鉄にニッケルメッキを施し
た金属材料、あるいはステンレス鋼などの金属材料で形
成されており、環状ガスケット７はポリプロピレンなど
の耐電解液性を有する合成樹脂で形成されている。リー
ド体８はアルミニウム、チタン、ステンレス鋼などの金
属材料からなり、このリード体８の上端部は前記リード
体取り付け部材１の凸部１ｃの下面に溶接され、溶接部
分９を構成し、それによって、前記リード体取り付け部
材１と正極１０とを電気的に接続している。なお、この
溶接部分９についても、図面上での理解がしやすいよう
に、実際よりは誇張した状態に図示している。また、図
４では、溶接部分９をわかりやすくするために、リード
体８の溶接部分に相当する部分に網目状に斜線を入れ、
そこに参照符号９を付けている。【００２３】正極１０は、たとえば、ＭｎＯ₂、ＴｉＳ
₂、ＭｏＳ₂、Ｖ₂Ｏ₅、Ｌｉ_xＭｎＯ_y、Ｌｉ_xＮｉ
Ｏ₂、Ｌｉ_xＣｏＯ₂などを活物質とし、これに必要に
応じてカーボンブラックなどの導電助剤とポリテトラフ
ルオロエチレンなどの結着剤などを加えて混合して調製
した正極合剤を成形したものであり、その成形にあたっ
てはステンレス鋼製網などが集電作用を兼ねた芯材とし
て使用されているが、この図１では繁雑化を避けるた
め、ステンレス鋼製網などの芯材は図示していない。【００２４】負極１１は、たとえば、金属リチウム、リ
チウム合金、リチウムをドープしかつ脱ドープし得るカ
ーボンなどを用いて作製されたものであり、この負極１
１の作製にあたってもステンレス鋼製網などが集電作用
を兼ねた支持体として使用されているが、この図１では
繁雑化を避けるため、ステンレス鋼製網などの支持体は
図示していない。【００２５】セパレータ１２は、ポリプロピレン不織
布、ポリエチレン不織布などの合成繊維不織布からな
り、前記正極１０と負極１１はこのセパレータ１２を介
在させて重ね合わせられ、渦巻状に巻回して渦巻状電極
体として電池ケース６内に収容されている。【００２６】電解液１３は、たとえば、プロピレンカー
ボネート、エチレンカーボネート、１，２−ジメトキシ
エタン、１，２−ジエトキシエタン、γ−ブチロラクト
ン、テトラヒドロフラン、２−メチルテトラヒドロフラ
ン、１，３−ジオキソラン、ジエチルエーテル、スルホ
ランなどの有機溶媒の単独または２種以上の混合溶媒に
ＬｉＣｌＯ₄、ＬｉＰＦ₆、ＬｉＳｂＦ₆、ＬｉＡｓＦ
₆、ＬｉＢＦ₄、Ｌｉ（Ｃ₆Ｈ₅）₄、、ＬｉＣＦ₃Ｓ
Ｏ₃、ＬｉＣ₄Ｆ₉ＳＯ₃、（ＣＦ₃ＳＯ₂）₂ＮＬ
ｉ、（ＣＦ₃ＳＯ₂）₃ＣＬｉなどの電解質を溶解させ
たものからなり、電池ケース６内に注入されている。【００２７】上記電池ケース６の底部にはポリテトラフ
ルオロエチレンシートなどからなる絶縁体１４が設置さ
れ、前記正極１０、負極１１およびセパレータ１２から
なる渦巻状電極体や、電解液１３、渦巻状電極体上部の
絶縁体１５などは、この電池ケース６内に収容されてい
る。そして、それらの収容後、電池ケース６の開口端近
傍部分に底部が内方に突出した環状の溝が形成される。【００２８】そして、上記電池ケース６の開口部に環状
ガスケット７を入れ、そこに前記のリード体取り付け部
材１と絶縁パッキング４と防爆弁３とを挿入し、防爆弁
３の突出部３ａの下面とリード体取り付け部材１の薄肉
部１ａの上面とをたとえば抵抗溶接、超音波溶接、レー
ザ溶接などの溶接手段により溶接して溶接部分５を構成
し、リード体８をリード体取り付け部材１の凸部１ｃに
上記と同様の溶接手段によって溶接し、その上から端子
板２を挿入し、電池ケース６の溝から先の部分を内方に
締め付けることによって電池ケース６の開口部が封口さ
れている。【００２９】上記のような電池組立にあたっては、あら
かじめ負極１１と電池ケース６とをニッケル、銅、ステ
ンレス鋼などの金属製のリード体１６で接続しておくの
が好ましい。【００３０】従来技術に従い、図８〜９に示すように、
リード体８をリード体取り付け部材１に面状で溶接して
いた場合には、たとえば、超音波溶接で出力８０〜１０
０％、加圧力３〜４ｋｇ／ｃｍ²で溶接を行っていた
が、上記のようにリード体取り付け部材１に凸部１ｃを
設け、該凸部１ｃにリード体８を溶接する場合には、超
音波溶接で出力３０〜５０％、加圧力０．５〜２ｋｇ／
ｃｍ²で溶接することができるようになり、その結果、
リード体取り付け部材１の薄肉部１ａと防爆弁３の突出
部３ａとの溶接部分５の剥離や亀裂発生などが大幅に減
少した。【００３１】そして、上記のようにして組み立てられた
電池においては、リード体取り付け部材１の薄肉部１ａ
と防爆弁３の突出部３ａとが溶接部分５で接触し、防爆
弁３の周縁部と端子板２の周縁部とが接触し、正極１０
とリード体取り付け部材１とはリード体８で接続されて
いるので、正極１０と端子板２とはリード体８、リード
体取り付け部材１、防爆弁３およびそれらの溶接部分５
によって電気的接続が得られ、電路として正常に機能す
る。【００３２】そして、電池に異常事態がおこり、電池内
部にガスが発生して電池の内圧が上昇した場合には、そ
の内圧上昇により、図５に示すように、防爆弁３の中央
部が内圧方向（図５では、上側の方向）に変形し、それ
によって、薄肉部１ａに剪断力が働いて、該薄肉部１ａ
が破断するか、または図６に示すように、防爆弁３の突
出部３ａとリード体取り付け部材１の薄肉部１ａとの溶
接部分５が剥離して消失し、それによって、正極１０と
端子板２との電気的接続が消失して、電流が遮断される
ようになる。【００３３】なお、上記防爆弁３には薄肉部３ｂが設け
られており、たとえば、充電が極度に進行して電解液や
活物質などの発電要素が分解し、大量のガスが発生した
場合は、防爆弁３が変形して、防爆弁３の突出部３ａと
リード体取り付け部材１の薄肉部１ａとの溶接部分５が
剥離した後、この防爆弁３に設けた薄肉部３ｂが開裂し
てガスを端子板２のガス排出孔２ａから電池外部に排出
させて電池の破裂を防止することができる。【００３４】つぎに、図１に示す構造で、正極活物質と
して二酸化マンガンを用い、負極にリチウムを用い、電
解液としてエチレンカーボネートと１，３−ジオキソラ
ンとの体積比１：２の混合溶媒にＬｉＣＦ₂ＳＯ₃を
０．６ｍｏｌ／ｌ溶解させたものを用いて防爆形密閉電
池を製造した。【００３５】また、図８に示すように、リード体８をリ
ード体取り付け部材１の下面に面状で溶接し、それ以外
は上記実施例の電池と同一の構成の電池を製造した。【００３６】なお、上記実施例の電池では、リード体８
とリード体取り付け部材１の凸部１ｃとの溶接は、超音
波溶接で出力４０％、加圧力１ｋｇ／ｃｍ²で溶接する
ことができたが、図８に示す従来構成の電池では、リー
ド体８をリード体取り付け部材１の下面に面状で溶接す
るため、上記実施例と同一条件では溶接することができ
ず、超音波溶接で出力９０％、加圧力３．５ｋｇ／ｃｍ
²で溶接した。【００３７】上記実施例の電池と図８に示す従来構成の
電池１００個ずつについて２０℃で内部抵抗を測定した
ところ、実施例の電池には内部抵抗が１０Ωを超えるも
のがまったくなかったが、図８に示す従来構成の電池に
は内部抵抗が１０Ωを超えるものが５２個もあった。【００３８】また、上記実施例の電池と図８に示す従来
構成の電池１００個ずつについて６０℃、相対湿度９０
％の雰囲気中で１００日貯蔵し、漏液が発生する電池個
数を調べたところ、実施例の電池には漏液の発生するも
のがまったくなかったが、図８に示す従来構成の電池に
は漏液の発生したものが３４個もあった。【００３９】以上の結果を次の表１にまとめて表示す
る。なお、表１では、上記実施例の電池は本発明と表示
し、図８に示す従来構成の電池は従来例と表示した。そ
して、試験に供した電池個数を分母に示し、内部抵抗不
良発生電池個数（すなわち、内部抵抗が１０Ωを越えた
電池個数）や漏液の発生した電池個数を分子に示す態様
で表示した。【００４０】【表１】【００４１】上記実施例の電池について、試験雰囲気２
０℃、２．８Ａ定電流充電の条件下で過充電試験を行っ
たところ、過充電状態になると、充電電流が遮断され
て、電池温度が降下した。これは、過充電状態になる
と、電池内圧の上昇によって防爆弁３が内圧方向に変形
し、リード体取り付け部材１に設けた薄肉部１ａが破断
したり、あるいはリード体取り付け部材１と防爆弁３と
の溶接部分５が剥離して、正極１０と端子板２との電気
的接続が消失し、充電電流を遮断するからである。そし
て、その充電電流の遮断によって、電池の発火や破裂が
防止されるようになる。【００４２】上記実施例では、リード体取り付け部材１
の凸部１ｃを連続した環状に設けたが、それに代えて、
たとえば、図７に示すように複数個の円弧状の凸部１ｃ
を薄肉部１ａの外周部分の同一円周上に設けてもよい。【００４３】【発明の効果】以上説明したように、本発明では、リー
ド体取り付け部材１の薄肉部１ａの外周部分の同一円周
上に発電要素側に先端部を有する環状の凸部１ｃを少な
くとも１個設けるかまたは円弧状の凸部１ｃを複数個設
け、該凸部１ｃにリード体８を溶接することによって、
上記溶接時にリード体取り付け部材１と防爆弁３との溶
接部分５に剥離が生じたり、亀裂が発生するのを防止
し、リード体取り付け部材１と防爆弁３との溶接部分５
の信頼性が高く、かつ密閉性が優れた防爆形密閉電池を
提供することができた。【００４４】また、本発明の電池は、過充電や短絡など
の異常反応により、電池内圧が上昇して所定の圧力に達
したときに、防爆弁３がその内圧を受けて内圧方向に変
形し、それによって、薄肉部１ａに剪断力が働いて該薄
肉部１ａが破断するか、または防爆弁３とリード体取り
付け部材１との溶接部分５が剥離して、電流を遮断する
ので、過充電時や短絡時においても電池の発火や破裂を
防止することができるという、高い安全性を備えてい
る。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an explosion-proof sealed battery, and more particularly, to a non-peeled or cracked welded portion between a lead member mounting member and an explosion-proof valve. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an explosion-proof sealed battery that has high hermeticity and can prevent ignition or explosion by interrupting current even during overcharge or short circuit. 2. Description of the Related Art Recently, sealed batteries using an organic solvent-based electrolyte such as lithium batteries and lithium secondary batteries have been widely used as power supplies for portable devices such as watches and cameras. However, in a sealed battery using such an organic solvent-based electrolyte, a power generation element inside the battery undergoes a chemical change, the pressure inside the battery increases, and the battery sometimes bursts under high pressure. [0004] For example, when a lithium secondary battery is overcharged or short-circuited and a large current flows, the electrolytic solution is decomposed, and as a result, gas is generated inside the battery. The pressure inside the battery increases, and eventually the battery may burst under high pressure. [0005] In addition, even in a lithium primary battery, the pressure inside the battery may increase due to forced overcharge or overdischarge, or forced discharge from another battery, and finally fire may occur. Was. Therefore, conventionally, a battery is provided with a so-called explosion-proof function of discharging gas generated inside the battery to the outside of the battery to prevent the battery from bursting under high pressure. For example, as shown in FIG. 8, a thin portion 1a and a pressure inlet 1b through which gas can pass therethrough are provided in the center of a lead member mounting member 1 also serving as a sealing plate, and gas is exhausted to a terminal plate 2. A hole 2a is provided, and a central portion of the explosion-proof valve 3, which is deformed in the direction of the internal pressure as the internal pressure of the battery rises, is protruded.
The protruding portion 3a is welded to the thin portion 1a of the lead mounting member 1, and when gas is generated inside the battery due to an abnormal reaction due to overcharging or short circuit and the internal pressure of the battery rises, the gas pressure increases. The explosion-proof valve 3 is deformed to break the thin-walled portion 1a, or the welding portion 5 between the thin-walled portion 1a of the lead body mounting member 1 and the protruding portion 3a of the explosion-proof valve 3 is peeled off. An explosion-proof structure is adopted which shuts off the abnormal reaction, suppresses a rise in temperature due to a charging current or a short-circuit current, and prevents ignition or explosion of the battery. In such an explosion-proof structure, the lead member mounting member 1, the insulating packing 4, and the explosion-proof valve 3 are inserted into the annular gasket 7, and the protrusion 3a provided on the explosion-proof valve 3 is provided.
After welding the thin portion 1a provided on the lead body attaching member 1, the lead body 8 is assembled by welding the lead body 8 to the lead body attaching member 1. However, in the above explosion-proof structure, as shown in FIG. 9, the welded portion 9 between the lead body attaching member 1 and the lead body 8 is flat (in FIG. 9, the welded portion 9 is made easy to understand). For this reason, a portion corresponding to the welded portion of the lead body 8 is hatched in a mesh shape and the reference numeral 9 is attached thereto), and a large output and a large pressing force are required at the time of welding, and as a result, the welding is performed first. The welding portion 5 between the projecting portion 3a of the explosion-proof valve 3 and the thin portion 1a of the lead body mounting member 1 is peeled off, or a crack is generated in the welding portion 5,
The problem of not functioning as an electric circuit occurs. Further, there is also a problem that the lead body attaching member 1 is deformed by the influence of the pressing force at the time of welding, and the hermeticity of the battery is reduced. As an assembling method other than the above, after inserting the lead body attaching member 1 into the annular gasket 7, the lead body 8 is welded, and then the insulating packing 4 and the explosion-proof valve 3 are inserted. 3a and lead body attaching member 1
A method of welding the thin portion 1a of the explosion-proof valve 3 is also conceivable. However, in this method, the welding portion 5 is separated from the projection 3a of the explosion-proof valve 3 and the thin portion 1a of the lead member attaching member, and the crack of the welding portion 5 However, there is a problem that productivity is extremely low. SUMMARY OF THE INVENTION The present invention relates to a conventional explosion-proof type sealed battery as described above, in which a welded portion between an explosion-proof valve and a lead member mounting member is peeled off, It is an object of the present invention to provide an explosion-proof sealed battery that eliminates the problem of cracks, does not cause peeling or cracking of a welded portion between an explosion-proof valve and a lead member mounting member, and has excellent hermeticity. The structure of the present invention for solving the above-mentioned problem will be described with reference to FIGS. 1 to 7 corresponding to the embodiment. 1
At least one annular convex portion 1c having a tip portion on the power generation element side or a plurality of arc-shaped convex portions 1c is provided on the same circumference of the outer peripheral portion of the thin portion 1a, and a lead is provided on the convex portion 1c. The above object has been achieved by adopting a structure in which the body 8 is welded. That is, by providing the protrusion 1c on the lead mounting member 1, the lead mounting member 1 is provided.
And the welding portion 9 between the lead body 8 and the lead body 8 changes from planar to linear,
The output and welding force during welding can be reduced. As a result, peeling or cracking of the previously welded portion 5 between the explosion-proof valve 3 and the lead member mounting member 1 does not occur, and the reliability of the electric circuit is improved. Also, by providing the protrusion 1c on the lead body mounting member 1,
The strength of the lead body mounting member 1 is improved, and the fact that the welding of the lead body 8 and the lead body mounting member 1 does not require a large pressing force as described above works synergistically, so that the lead body mounting member 1 is attached. The deformation of the member 1 is prevented, the sealing property of the battery is prevented from lowering, and the sealing property is improved. Next, an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to only those illustrated in the embodiments. FIG. 1 is a longitudinal sectional view showing an embodiment of an explosion-proof sealed battery according to the present invention. 2A and 2B show a lead member mounting member used in the explosion-proof sealed battery shown in FIG. 1, wherein FIG. 2A is a bottom view and FIG. 2B is a longitudinal sectional view. is there. However, FIG. 2 shows (a)
1 shows the bottom surface of the lead member mounting member, it is apparent from FIG. 3 shows an explosion-proof valve used in the explosion-proof sealed battery shown in FIG. 1, wherein FIG. 3 (a) is a plan view thereof, and FIG. 3 (b) is a longitudinal sectional view thereof. FIG. 4 is an enlarged perspective view of a welded portion between the lead body attaching member and the lead body and its periphery. FIG. 4 also shows FIG. 1 in an upside-down state. FIG. 5 is an enlarged vertical sectional view of an essential part showing a state when the explosion-proof valve of the explosion-proof sealed battery shown in FIG. 1 is deformed in the direction of the internal pressure by receiving the internal pressure of the battery and the thin portion provided on the lead member attaching member is broken. is there. FIG. 6 is an enlarged longitudinal sectional view showing a state where the explosion-proof valve of the explosion-proof sealed battery shown in FIG. 1 is deformed in the direction of the internal pressure due to the internal pressure of the battery and the welded portion between the lead member mounting member and the explosion-proof valve is peeled off. FIG. FIGS. 7A and 7B are enlarged views of another embodiment of the lead member mounting member used in the explosion-proof sealed battery of the present invention, wherein FIG. 7A is a bottom view and FIG. 7B is a longitudinal sectional view. FIG. 7 also shows FIG. 1 in an upside-down state. First, the components of the battery will be schematically described with reference to FIG. 1. 1 is a lead member attaching member, 2 is a terminal plate, 3 is an explosion-proof valve, 4 is an insulating packing, 5 is a welded portion,
Reference numeral 6 denotes a battery case, 7 denotes an annular gasket, 8 denotes a lead body on the positive electrode side, 9 denotes a welded portion between the protrusion 1c of the lead body mounting member 1 and the lead body 8, 10 denotes a positive electrode, 11 denotes a negative electrode, 12 denotes a separator, 13 is an electrolyte, 14 is an insulator, 15 is an insulator, and 16 is a lead on the negative electrode side. The lead member attaching member 1 has a function as a sealing plate. The lead member attaching member 1 is made of aluminum, titanium, nickel, stainless steel or the like, has a disk shape, and has a central portion. The portion is provided with a thin portion 1a, and as shown in detail in FIG. 2, four holes are provided as pressure introduction ports 1b for applying an internal pressure of the battery to the explosion-proof valve 3, and furthermore, the outer periphery of the thin portion 1a is provided. The protrusion 1c is provided on the same circumference of the portion. The convex portion 1c has a tip portion on the power generation element side (that is, the side facing the positive electrode 10 or the negative electrode 11). FIG. 2 shows the relationship shown in FIG. The tip is facing upward. In this embodiment, the convex portions 1c are provided in a ring shape. However, as shown in FIG. 7, a plurality of arc-shaped convex portions 1c may be provided. And
The lower surface of the projection 3a of the explosion-proof valve 3 is welded to the upper surface of the thin portion 1a to form a welded portion 5. The thin portion 1a and the convex portion 1c provided on the lead body mounting member 1 and the protruding portion 3a of the explosion-proof valve 3 are shown only in a cut plane so as to be easily understood in the drawings. The contour line behind the cut surface is not shown. Also, the welded portion 5 between the thin portion 1a of the lead member mounting member 1 and the protruding portion 3a of the explosion-proof valve 3 is shown in an exaggerated state in order to facilitate understanding in the drawings. The terminal plate 2 is made of a metal material in which iron is plated with nickel, stainless steel or a metal material in which stainless steel is plated with nickel, and has a hat-like shape having a flanged peripheral portion. The terminal plate 2 is provided with a gas discharge hole 2a. The explosion-proof valve 3 is made of a metal material such as aluminum, titanium, nickel, and stainless steel, has a disk shape, and has a central portion provided with a protruding portion 3a having a tip on the power generation element side. , As described above, the protrusion 3
The lower surface of “a” is welded to the upper surface of the thin portion 1 a of the lead body mounting member 1 to form a welded portion 5. The insulating packing 4 is made of a synthetic resin having an electrolytic solution resistance such as polypropylene, and has an annular shape. The gap between the two is sealed so that the electrolyte does not leak. The battery case 6 is formed of a metal material obtained by plating nickel on iron or a metal material such as stainless steel, and the annular gasket 7 is formed of a synthetic resin having an electrolytic solution resistance such as polypropylene. . The lead body 8 is made of a metal material such as aluminum, titanium, stainless steel, or the like. The upper end of the lead body 8 is welded to the lower surface of the projection 1c of the lead body mounting member 1 to form a welded portion 9, The lead mounting member 1 and the positive electrode 10 are electrically connected. It is to be noted that the welded portion 9 is illustrated in an exaggerated state in order to facilitate understanding in the drawings. In FIG. 4, in order to make the welded portion 9 easier to understand, a portion corresponding to the welded portion of the lead body 8 is hatched like a mesh.
The reference numeral 9 is attached thereto. The positive electrode 10 is made of, for example, MnO ₂ , TiS
_{_{_{2, MoS 2, V 2 O}}} 5, Li x MnO y, Li x Ni
A positive electrode mixture prepared by mixing O ₂ , Li _x CoO _2, etc. as an active material, adding a conductive aid such as carbon black and a binder such as polytetrafluoroethylene, etc. as necessary A stainless steel mesh or the like is used as a core material that also has a current collecting function in forming the core material. However, in FIG. 1, in order to avoid complication, the core material such as a stainless steel mesh is not illustrated. Not shown. The negative electrode 11 is made of, for example, lithium metal, a lithium alloy, carbon capable of doping and undoping lithium, and the like.
Also in the production of No. 1, a stainless steel net or the like is used as a support having a current collecting function, but in FIG. 1, a support such as a stainless steel net is not shown in order to avoid complication. The separator 12 is made of a synthetic fiber non-woven fabric such as a polypropylene non-woven fabric or a polyethylene non-woven fabric. The positive electrode 10 and the negative electrode 11 are overlapped with the separator 12 interposed therebetween, spirally wound and formed into a spiral electrode body as a battery. It is housed in the case 6. The electrolytic solution 13 is, for example, propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolan, diethyl ether LiClO ₄ , LiPF ₆ , LiSbF ₆ , LiAsF or a mixture of two or more organic solvents such as
₆ , LiBF ₄ , Li (C ₆ H ₅ ) ₄ , LiCF ₃ S
O ₃ , LiC ₄ F ₉ SO ₃ , (CF ₃ SO ₂ ) ₂ NL
i, which is formed by dissolving an electrolyte such as (CF ₃ SO ₂ ) ₃ CLi, and is injected into the battery case 6. An insulator 14 made of a polytetrafluoroethylene sheet or the like is provided at the bottom of the battery case 6. A spiral electrode body comprising the positive electrode 10, the negative electrode 11 and the separator 12, an electrolytic solution 13, a spiral electrode The insulator 15 at the upper part of the body is housed in the battery case 6. After these are accommodated, an annular groove whose bottom is protruded inward is formed in the vicinity of the open end of the battery case 6. An annular gasket 7 is inserted into the opening of the battery case 6, and the lead mounting member 1, the insulating packing 4 and the explosion-proof valve 3 are inserted into the annular gasket 7, and the lower surface of the projection 3a of the explosion-proof valve 3 is inserted. The upper surface of the thin portion 1a of the lead member mounting member 1 is welded by a welding means such as resistance welding, ultrasonic welding, laser welding or the like to form a welded portion 5, and the lead member 8 is formed by projecting the lead member mounting member 1. The terminal 1 is welded to the portion 1c by the same welding means as described above, the terminal plate 2 is inserted from above, and the portion of the battery case 6 beyond the groove is tightened inward, whereby the opening of the battery case 6 is sealed. . In assembling the battery as described above, it is preferable to connect the negative electrode 11 and the battery case 6 in advance with a lead 16 made of a metal such as nickel, copper, or stainless steel. According to the prior art, as shown in FIGS.
When the lead body 8 is welded to the lead body mounting member 1 in a planar manner, for example, the output is 80 to 10 by ultrasonic welding.
Welding was performed at 0% and a pressing force of 3 to 4 kg / cm ^2. However, in the case where the protrusion 1c is provided on the lead body mounting member 1 and the lead body 8 is welded to the protrusion 1c as described above, 30-50% output with ultrasonic welding, 0.5-2kg /
will be able to be welded in cm ^2, as a result,
Peeling or cracking of the welded portion 5 between the thin portion 1a of the lead member mounting member 1 and the protruding portion 3a of the explosion-proof valve 3 was greatly reduced. In the battery assembled as described above, the thin portion 1a of the lead mounting member 1 is provided.
And the protruding portion 3a of the explosion-proof valve 3 comes into contact at the welded portion 5, the periphery of the explosion-proof valve 3 and the periphery of the terminal plate 2 come into contact, and the positive electrode 10
The positive electrode 10 and the terminal plate 2 are connected to the lead body 8, the lead body mounting member 1, the explosion-proof valve 3, and their welded parts 5 because the lead member 8 is connected to the lead body mounting member 1.
As a result, an electrical connection is obtained and functions normally as an electric circuit. When an abnormal situation occurs in the battery and gas is generated inside the battery and the internal pressure of the battery rises, the internal pressure rises, as shown in FIG. Direction (in the upper direction in FIG. 5), whereby a shearing force acts on the thin portion 1a, and the thin portion 1a is deformed.
6 or, as shown in FIG. 6, the welded portion 5 between the projection 3a of the explosion-proof valve 3 and the thin portion 1a of the lead body attaching member 1 is separated and disappears, whereby the positive electrode 10 and the terminal plate are removed. 2 is lost, and the current is interrupted. The explosion-proof valve 3 is provided with a thin portion 3b. For example, when charging proceeds extremely and power generation elements such as an electrolytic solution and an active material are decomposed and a large amount of gas is generated, After the explosion-proof valve 3 is deformed and the welded portion 5 between the projection 3a of the explosion-proof valve 3 and the thin portion 1a of the lead body mounting member 1 is peeled off, the thin portion 3b provided on the explosion-proof valve 3 is cleaved. Gas can be discharged to the outside of the battery from the gas discharge holes 2a of the terminal plate 2 to prevent the battery from bursting. Next, in the structure shown in FIG. 1, manganese dioxide was used as a positive electrode active material, lithium was used as a negative electrode, and a mixed solvent of ethylene carbonate and 1,3-dioxolane having a volume ratio of 1: 2 was used as an electrolytic solution. An explosion-proof sealed battery was manufactured using LiCF ₂ SO _{3 in} which 0.6 mol / l was dissolved. As shown in FIG. 8, a lead body 8 was welded to the lower surface of the lead body mounting member 1 in a planar manner, and a battery having the same configuration as that of the battery of the above embodiment was manufactured. In the battery of the above embodiment, the lead 8
The welding between the lead member 1 and the projection 1c of the lead member mounting member 1 could be performed by ultrasonic welding with an output of 40% and a pressing force of 1 kg / cm ^2. However, in the battery of the conventional configuration shown in FIG. 8 is welded to the lower surface of the lead member mounting member 1 in a planar manner, so that welding cannot be performed under the same conditions as in the above embodiment, and the output is 90% by ultrasonic welding and the pressing force is 3.5 kg / cm.
Welded with ² . When the internal resistance was measured at 20 ° C. for each of the battery of the above example and 100 batteries of the conventional configuration shown in FIG. 8, none of the batteries of the example had an internal resistance exceeding 10Ω. As shown in FIG. 8, there were 52 conventional batteries having an internal resistance exceeding 10Ω. The battery of the above embodiment and 100 batteries of the conventional configuration shown in FIG.
% Was stored for 100 days and the number of batteries that caused liquid leakage was examined. As a result, none of the batteries of the example produced a liquid leakage, but the battery of the conventional configuration shown in FIG. There were 34 leaks. The above results are collectively shown in Table 1 below. In Table 1, the battery of the above embodiment is indicated as the present invention, and the battery of the conventional configuration shown in FIG. 8 is indicated as the conventional example. Then, the number of batteries subjected to the test is indicated by a denominator, and the number of batteries having an internal resistance failure (that is, the number of batteries having an internal resistance exceeding 10Ω) and the number of batteries having a leak are indicated by numerators. [Table 1] With respect to the battery of the above example, test atmosphere 2
When an overcharge test was performed under the condition of 0 ° C. and 2.8 A constant current charge, when the battery was overcharged, the charge current was interrupted and the battery temperature dropped. This is because when the battery is overcharged, the explosion-proof valve 3 is deformed in the direction of the internal pressure due to an increase in the internal pressure of the battery, and the thin portion 1a provided on the lead body mounting member 1 is broken, or the lead body mounting member 1 and the explosion-proof valve 3 Is removed, the electrical connection between the positive electrode 10 and the terminal plate 2 is lost, and the charging current is interrupted. Then, the interruption of the charging current prevents the battery from firing or exploding. In the above embodiment, the lead member attaching member 1
Is provided in a continuous annular shape, but instead of this,
For example, as shown in FIG.
May be provided on the same circumference of the outer peripheral portion of the thin portion 1a. As described above, according to the present invention, the annular convex portion 1c having the tip portion on the power generation element side is formed on the same circumference as the outer peripheral portion of the thin portion 1a of the lead body attaching member 1. By providing at least one or a plurality of arc-shaped protrusions 1c and welding the lead body 8 to the protrusions 1c,
At the time of the welding, the welding portion 5 between the lead body mounting member 1 and the explosion-proof valve 3 is prevented from peeling or cracking, and the welding portion 5 between the lead body mounting member 1 and the explosion-proof valve 3 is prevented.
Has provided a highly reliable and explosion-proof sealed battery having excellent hermeticity. Further, when the internal pressure of the battery rises to a predetermined pressure due to an abnormal reaction such as overcharging or short circuit, the explosion-proof valve 3 receives the internal pressure and deforms in the direction of the internal pressure. As a result, a shearing force acts on the thin portion 1a to break the thin portion 1a, or the welding portion 5 between the explosion-proof valve 3 and the lead body mounting member 1 peels off to cut off the current, so that overcharging is performed. The battery has high safety in that the battery can be prevented from being ignited or ruptured even in the event of a short circuit or short circuit.

【図面の簡単な説明】【図１】本発明の防爆形密閉電池の一実施例を示す縦断
面図である。【図２】図１に示す防爆形密閉電池に使用されたリード
体取り付け部材を拡大して示すもので、（ａ）はその底
面図、（ｂ）はその縦断面図である。この図２は図１と
は上下を反転させた状態で示している。【図３】図１に示す防爆形密閉電池に使用された防爆弁
を拡大して示すもので、（ａ）はその平面図、（ｂ）は
その縦断面図である。【図４】図１に示す防爆形密閉電池のリード体取り付け
部材とリード体との溶接部分とその周辺の拡大斜視図で
ある。ただし、この図４は図１とは上下を反転させた状
態で示している。【図５】図１に示す電池の防爆弁が電池内圧を受けて内
圧方向に変形し、リード体取り付け部材に設けた薄肉部
が破断した状態を拡大して示す要部縦断面図である。【図６】図１に示す電池の防爆弁が電池内圧を受けて内
圧方向に変形し、防爆弁とリード体取り付け部材との溶
接部分が剥離した状態を拡大して示す要部縦断面図であ
る。【図７】本発明の防爆形密閉電池に使用されるリード体
取り付け部材の他の実施例を拡大して示すもので、
（ａ）はその底面図、（ｂ）はその縦断面図である。こ
の図７は図１とは上下を反転させた状態で示している。【図８】従来の防爆形密閉電池の要部縦断面図である。【図９】図８に示す従来の防爆形密閉電池のリード体取
り付け部材とリード体との溶接部分とその周辺の拡大斜
視図である。【符号の説明】１リード体取り付け部材１ａ薄肉部１ｂ圧力導入口１ｃ凸部２端子板２ａガス排出孔３防爆弁３ａ突出部４絶縁パッキング５溶接部分６電池ケース７環状ガスケット８リード体９溶接部分１０正極１１負極１２セパレータ１３電解液BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing one embodiment of an explosion-proof sealed battery according to the present invention. FIGS. 2A and 2B are enlarged views of a lead member mounting member used in the explosion-proof sealed battery shown in FIG. 1, wherein FIG. 2A is a bottom view and FIG. FIG. 2 is shown in a state where it is turned upside down from FIG. 3 is an enlarged view of an explosion-proof valve used for the explosion-proof sealed battery shown in FIG. 1, wherein (a) is a plan view and (b) is a longitudinal sectional view. 4 is an enlarged perspective view of a welded portion between the lead member attaching member and the lead member of the explosion-proof sealed battery shown in FIG. 1 and the periphery thereof. However, FIG. 4 is shown in an upside-down state with respect to FIG. FIG. 5 is a longitudinal sectional view of an essential part showing an enlarged state in which the explosion-proof valve of the battery shown in FIG. 1 is deformed in the direction of the internal pressure in response to the internal pressure of the battery and the thin portion provided on the lead member attaching member is broken. FIG. 6 is an enlarged fragmentary longitudinal sectional view showing a state in which the explosion-proof valve of the battery shown in FIG. 1 is deformed in the direction of the internal pressure in response to the internal pressure of the battery and the welded portion between the explosion-proof valve and the lead member mounting member is peeled off. is there. FIG. 7 is an enlarged view showing another embodiment of the lead member mounting member used in the explosion-proof sealed battery of the present invention.
(A) is a bottom view thereof, and (b) is a longitudinal sectional view thereof. FIG. 7 shows a state in which FIG. 1 is turned upside down. FIG. 8 is a longitudinal sectional view of a main part of a conventional explosion-proof sealed battery. FIG. 9 is an enlarged perspective view of a welded portion between the lead member attaching member and the lead member of the conventional explosion-proof sealed battery shown in FIG. [Description of Signs] 1 Lead mounting member 1a Thin portion 1b Pressure inlet 1c Convex portion 2 Terminal plate 2a Gas exhaust hole 3 Explosion-proof valve 3a Projection 4 Insulation packing 5 Welding part 6 Battery case 7 Annular gasket 8 Lead body 9 Welding Part 10 Positive electrode 11 Negative electrode 12 Separator 13 Electrolyte

───────────────────────────────────────────────────── フロントページの続き (56)参考文献特開平６−251758（ＪＰ，Ａ) 特開平６−203818（ＪＰ，Ａ) 特開平７−94161（ＪＰ，Ａ) 実開平４−24262（ＪＰ，Ｕ) (58)調査した分野(Int.Cl.⁷，ＤＢ名) H01M 2/34 H01M 2/12 101 H01M 10/40 ──────────────────────────────────────────────────続き Continuation of the front page (56) References JP-A-6-251758 (JP, A) JP-A-6-203818 (JP, A) JP-A-7-94161 (JP, A) 24262 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 2/34 H01M 2/12 101 H01M 10/40

Claims

(1) An explosion-proof valve ( 3 ) that deforms in the direction of internal pressure as the internal pressure of the battery rises, and a lead body mounting member ( 1 ) provided with a thin portion ( 1a ) in the center. welded the door, a explosion-proof sealed battery attaching lead body (8) to the lead body attachment member (1), the lead body attachment member (1)
A plurality of at least one provided Luke or arc-shaped convex portions protruding portions of the annular having a tip portion toward the power generating element side on the same circumference of the outer peripheral portions (1c) of the thin portion (1a) (1c) of Pieces
Provided, explosion-proof sealed battery, wherein the lead body (8) is welded to the convex portion (1c).