JP3840896B2

JP3840896B2 - Square non-aqueous electrolyte battery

Info

Publication number: JP3840896B2
Application number: JP2000366933A
Authority: JP
Inventors: 竹規石津; 亮小島; 満小関
Original assignee: Shin Kobe Electric Machinery Co Ltd
Current assignee: Shin Kobe Electric Machinery Co Ltd
Priority date: 2000-12-01
Filing date: 2000-12-01
Publication date: 2006-11-01
Anticipated expiration: 2020-12-01
Also published as: JP2002170595A

Description

【０００１】
【発明の属する技術分野】
本発明は角形非水電解液電池に係り、特に、正極板、負極板及びセパレータを積層し角形電池ケース内に収容された電極群と、該電極群から導電され電池ケース上面に固定された正極及び負極端子と、を備えた角形非水電解液電池に関する。
【０００２】
【従来の技術】
現在、非水電解液電池としてリチウム一次電池、リチウム二次電池などが実用化されている。これらの電池のうち、電気容量が１．５Ａｈ程度の小型リチウム二次電池では、例えば、ＰＴＣ(Positive Temperature Coefficient) 素子を発電素子と直列に挿入して温度上昇時に電流を遮断する電流遮断機構を付加したり、電池内部と外部との境界に金属薄膜を形成して電池の内圧上昇時に金属薄膜を破断させ電池内部の発生ガスを放出し、電池容器の損傷を防ぐ内圧低減機構を付加する等、非水電解液電池の安全性を確保している。
【０００３】
このように小型電池においても安全性を重視しており、電気容量が１０Ａｈを越えるような大型電池であれば、安全性を確保することが更に重要であることはいうまでもない。安全性を重視した大型電池として、例えば、特開平第９−９２２４９号公報には電池内部の発生ガスを放出するために開放弁を備えた二次電池の技術が開示されている。同公報の開放弁によれば、開放圧を再現性よく設定でき、開放圧力を低く設定できることから、圧力開放時の衝撃力を和らげることができる。
【０００４】
【発明が解決しようとする課題】
しかしながら、同公報の技術では開放弁の明確な位置を記述するには至っていない。また、同公報は円筒形電池についての技術であり、その構造上の特性から電池ケースの耐圧が低い角形電池では、安全性を確保するために、電池内部の発生ガスを放出する内圧低減機構がより一層重要となる。
【０００５】
また、上記した金属薄膜を破断させて発生ガスを放出させる内圧低減機構では、その金属薄膜の配置位置又はその開裂機構を十分に考慮しなければ安全機能を発揮できない場合がある。すなわち、例えば、ある物体が金属薄膜の直上に配置された場合には、電池異常時に内圧が上昇し金属薄膜が破断して内部発生ガスを放出しようとしても、該物体がガス放出経路を遮断しているので放出することができず、電池容器自体の損傷を招くことも考えられる。
【０００６】
更に、電池異常時に内部発生したガスは、金属薄膜が破断すると同時に勢いよく放出する。このとき、電極群等の電池内容物は、流出ガスとともに圧力が下がった金属薄膜破断部方向に移動するので、ガス放出口を閉塞させ電池容器の損傷を引き起こす、という問題がある。
【０００７】
本発明は上記事案に鑑み、安全性に優れた角形非水電解液電池を提供することを目的とする。
【０００８】
【課題を解決するための手段】
上記目的を達成するために本発明は、正極板、負極板及びセパレータを積層し角形電池ケース内に収容された電極群と、該電極群から導電され前記電池ケース上面に固定された正極及び負極端子と、を備え、前記電池ケースの上面には所定内圧で開裂し該開裂圧が異なる複数の脆弱部が形成されており、前記脆弱部のうちの２つが、前記電池ケース内側に配置され該脆弱部が開裂したときに該脆弱部の閉塞を防止する閉塞防止部材の直上に配置された角形非水電解液電池において、前記２つの脆弱部は、それぞれ、一端が前記正極板に接続され他端が前記正極端子に接続された長尺状のアルミニウム製導電部材、及び、一端が負極板に接続され他端が前記負極端子に接続された長尺状の銅製導電部材を有する異種の前記閉塞防止部材の直上に配置されており、前記脆弱部のうち、前記銅製導電部材の直上に配置された脆弱部の開裂圧が最も小さいことを特徴とする。
【０００９】
本発明では、閉塞防止部材を電池ケース内側に配置し、その直上に脆弱部が形成されているので、電池内圧の上昇により脆弱部が開裂したとき、ガス放出に伴う電池内容物が閉塞防止部材に係止されて脆弱部の閉塞が防止され、内部発生ガスを確実に電池外部に放出することができる。また、脆弱部が電池ケース上面に形成されているので、角形電池の上面以外の５面が他の物体により密着され、その５面に形成された脆弱部が閉塞された場合でも、正極及び負極端子のような凹凸のある電池ケース上面は閉塞されずに、確実に内部発生ガスを電池外部へ放出することができると共に、複数の脆弱部が電池ケース上面に形成されているので、それらの脆弱部のうち何れかが他の物体により閉塞されていても確実に内部発生ガスを電池外部に放出することができる。更に、一端が正極板に接続され他端が正極端子に接続された長尺状の導電部材、及び、一端が負極板に接続され他端が負極端子に接続された長尺状の導電部材を閉塞防止部材として用いたので、新たに閉塞防止部材を設ける必要がなく、また、閉塞防止部材を長尺状の簡易な構造とすることで電池内容物を閉塞防止部材に係止させガス放出経路を確保することができると共に、閉塞防止部材に、正極板に接続されたアルミニウム製導電部材と、負極板に接続された銅製導電部材を用いたので、閉塞防止部材に耐電圧性を持たせ腐蝕を防止し閉塞防止部材が脆弱化することを防止することができ、閉塞防止部材に金属材料を用いたので、樹脂材料を使用した場合に比べ放出される高温ガスに対し融点が高く、ガス放出時に閉塞防止部材の変形・溶融を防止することができる。なお、閉塞防止部材には、純アルミニウム製の他にアルミニウム合金製のものや（正極端子側）、純銅製の他に銅合金製のもの（負極端子側）を使用するようにしてもよい。そして、脆弱部のうち、銅製導電部材の直上に配置された脆弱部の開裂圧を最も小さくしたので、アルミニウムよりも高融点の銅を使用している負極端子側に開裂圧が最も小さい脆弱部が配置されるため、確実にガス放出可能な位置が特定されガス放出経路を確保でき、安全性を向上させることができる。なお、脆弱部を形成には、例えば、電池ケースの一部を薄肉化したり、強度の脆い異なる材質とする等の態様を採ることができる。
【００１２】
本発明において、導電部材と、この導電部材から電気的に絶縁され、導電部材と脆弱部との間に導電部材の長手方向に直交するように配置された長尺部材と、で閉塞防止部材を構成すれば、導電部材を通過した電池内容物を導電部材と直交するように配置された長尺部材で閉塞防止部材に係止させることができるので、より確実に脆弱部の閉塞を防止することができる。
【００１４】
【発明の実施の形態】
以下、図面を参照して本発明に係る角形非水電解液電池の実施の形態について説明する。
【００１５】
図１に示すように、本実施形態の角形非水電解液電池２０は、容器となる角形でステンレス製の電池缶７を備えている。電池缶７の中央部には、矩形状で上部方向に耳部が張り出した正極板５及び負極板６を両極板が直接接触しないように図示しないセパレータを挟んで複数枚積層した電極群が収容されている。正極板５はアルミニウム箔を正極集電体とし、正極集電体両面に正極活物質合剤が塗布されている。一方、負極板５は銅箔を負極集電体とし、負極集電体両面に負極活物質合剤が塗布されている。また、角形非水電解液電池２０は、ステンレス製の電池蓋８を備えており、電極群を電池缶７に挿入した後、電池缶７の開口部周縁とこの電池蓋８の周縁とを溶接することで封止されている。
【００１６】
正極板５の耳部上端は厚さ２ｍｍの薄板状のアルミニウム板３に超音波接合されている。電池蓋８の一側には、アルミニウム製のねじ棒からなる正極端子１が図示しないシール材を介して電池蓋８と螺合するようにねじ穴が形成されている。正極端子１の先端部は電池蓋８の上部にナットにより固定されており、アルミニウム板３の超音波接合側反対端部と正極端子１の先端部反対端とはボルトとナットにより締め付け接触されている。一方、負極板６の耳部上端は厚さ２ｍｍの薄板状の銅板４に超音波接合されている。電池蓋８の正極端子１固定側とは反対側には、銅製のねじ棒からなる負極端子２が図示しないシール材を介して電池蓋８と螺合するようにねじ穴が形成されている。負極端子２の先端部は電池蓋８の上部にナットにより固定されており、銅板４の超音波接合側反対端部と負極端子２の先端部反対端とはボルトとナットにより締め付け接触されている。従って、正極端子１はアルミニウム板３を介して正極板５に、負極端子２は銅板４を介して負極板６に、それぞれ電気的に導通されている。
【００１７】
図１乃至図３に示すように、電池蓋８には、正極端子１側と負極端子２側とにステンレス箔を溶接した薄膜円形状の脆弱部としての安全弁９が溶接されている。後述するように、これらの安全弁９の肉厚は異なっている。安全弁９の下部には、「一」文字状（長尺状）で大きさが２ｍｍ×２ｍｍ×２５ｍｍのステンレス製の閉塞防止部材１０の両端上面部が電池蓋８の背面に固定されている。安全弁９は、閉塞防止部材１０並びにアルミニウム板３又は銅板４のそれぞれの直上に配置され、閉塞防止部材１０とアルミニウム板３又は銅板４とは電気的に絶縁されている。また、閉塞防止部材１０とアルミニウム板３又は銅板４とは直交する位置関係にあり、それぞれの長手方向が交差するように配置されている。
【００１８】
図１に示すように、電池蓋８には注液口１１が形成されており、本実施形態の角形非水電解液電池２０では、この注液口１１からエチレンカーボネートとジメチルカーボネートとの混合溶媒に６フッ化リン酸リチウム（ＬｉＰＦ_６）を溶解した非水電解液を注入し、電解液注入後、図示しない液口栓により注液口１１を密閉している。
【００１９】
次に、本実施形態の角形非水電解液電池２０の作用について説明する。
【００２０】
本実施形態の角形非水電解液電池２０では、安全弁９が閉塞防止部材１０とアルミニウム板３、銅板４とがそれぞれの長手方向に交差した直上に配置されている。このため、角形非水電解液電池２０の内圧が上昇して安全弁９が開裂したときに、電極群の内容物（正極活物質、負極活物質等）がガスとともに安全弁９の方向に移動しても、交差する閉塞防止部材１０及びアルミニウム板３、銅板４に当接係止されて安全弁９の開裂部を閉塞することはない。従って、角形非水電解液電池２０の内部で発生したガスは確実に安全弁９から外部に放出されるので、内圧で角形非水電解液電池２０を損傷させることはない。
【００２１】
また、角形非水電解液電池は、高電圧又は高容量を得るために、複数個が直列又は並列に接続されて使用される場合がある。このような用途では、複数個の角形非水電解液電池の総容積をできるだけ小さくするために、一般に角形非水電解液電池の上下面を除く４側面が又はこの４側面のいずれかが他の角形非水電解液電池の側面に接触して配置される。また、角形非水電解液電池の下面は角形非水電解液電池の重量を支えるために一般に平面とされている。従って、角形非水電解液電池は、６面のうち５面が他の角形非水電解液電池及び載置床面に密着されることがある。本実施形態の角形非水電解液電池２０では、正極端子１、負極端子２により凹凸が形成された上面に複数の安全弁９を設けるようにしたので、これらの安全弁９が角形非水電解液電池２０の配置の関係で更に上面の１つの安全弁９が閉塞されても他の安全弁９により確実にガスを外部に排出することができる。
【００２２】
更に、角形非水電解液電池２０は、アルミニウム板３及び銅板４がそれぞれ正極板５、負極板６の各集電体と同一材質（それぞれアルミニウム及び銅）とされている。このため、電蝕犠牲となり脆弱化することない。従って、電極群の内容物がガスとともに安全弁９の方向に移動したときにも強度を保つことができる。また、閉塞防止部材１０をアルミニウム板３、銅板４と絶縁するようにしたので、外部短絡を招くおそれもない。しかも、閉塞防止部材１０、アルミニウム板３及び銅板４は全て金属であり樹脂と比較して高温ガスに対して融点が高く、ガス放出時に変形や溶融によって電極群内容物が係止不能となる事態を防止することができる。更に、角形非水電解液電池２０は、安全弁９の肉厚が異なっている。従って、アルミニウム板３より融点の高い銅板４側、すなわち、負極端子２側、の安全弁９の肉厚を薄くすることで、高温ガスによる変形・溶融をより確実に防止することができ、肉厚を薄くした負極端子２側の安全弁９側から早期かつ確実に高温高圧ガスの外部排出が可能となり、安全弁９全体の信頼性を更に高めることができる。
【００２３】
なお、本実施形態では、安全弁９の開裂時の閉塞を防止するために、アルミニウム板３、銅板４とは別に電気的に独立した閉塞防止部材１０を設けた例について述べたが、閉塞防止部材１０は特に有しなくてもよい。例えば、図４及び図５に示すように、角形非水電解液電池２１は、閉塞防止部材１０を有しておらず、銅板４が安全弁９の開裂時に電極群の内容物を係止させ閉塞しないようにしたものである。この角形非水電解液電池２１では、アルミニウム板３、銅板４を、それぞれ、正極板５から正極端子１、負極板６から負極端子２への導電部材として使用すると共に、安全弁９の閉塞を防止するようにしたので、角形非水電解液電池２０より部品数を少なくすることができる。
【００２４】
また、本実施形態では、正負極の安全弁９を同材質のステンレスを用い肉厚を薄くすることにより開裂圧を設定したが、材質を異ならせることにより安全弁９の開裂圧を設定するようにしてもよい。更に、本実施形態では、アルミニウム板３、銅板４に文字通りアルミニウム、銅を使用したが、アルミニウム合金、銅合金等を使用するようにしてもよい。また、本実施形態では、閉塞防止部材１０にステンレスを使用したが、他の金属、耐熱性樹脂、難燃性樹脂等も使用してもよい。そして、本発明は上述の実施形態に限らず本発明の要旨を逸脱することなくその他種々の構成を採り得ることはいうまでもない。
【００２５】
【実施例】
次に、以上の実施形態に従って作製した角形非水電解液電池２０（２１）の実施例について説明する。なお、比較のために作製した比較例の電池についても併記する。
【００２６】
（実施例１）
図１乃至図３に示した角形非水電解液電池２０と同一で、正極端子１側と負極端子２側にそれぞれ１つずつ２個の安全弁９を設け、安全弁９を閉塞防止部材１０並びにアルミニウム板３又は銅板４のそれぞれ直上に配置し、安全弁９の肉厚が正極端子１側より負極端子２側の方が薄い電池。
【００２７】
（実施例２）
図４及び図５に角形非水電解液電池２１と同一で、正極端子１側と負極端子２側にそれぞれ１つずつ２個の安全弁９を設け、安全弁９をアルミニウム板３又は銅板４のそれぞれ直上に配置し、安全弁９の肉厚が正極端子１側より負極端子２側の方が薄い電池。
【００２８】
（実施例３）
図１乃至図３に示した角形非水電解液電池２０と同一で、正極端子１側と負極端子２側にそれぞれ１つずつ２個の安全弁９を設け、安全弁９を閉塞防止部材１０並びにアルミニウム板３又は銅板４のそれぞれ直上に配置し、安全弁９の肉厚が負極端子２側より正極端子１側の方が薄い電池。
【００２９】
（実施例４）
図４及び図５に角形非水電解液電池２１と同一で、正極端子１側と負極端子２側にそれぞれ１つずつ２個の安全弁９を設け、安全弁９をアルミニウム板３又は銅板４のそれぞれ直上に配置し、安全弁９の肉厚が負極端子２側より正極端子１側の方が薄い電池。
【００３０】
（比較例１）
アルミニウム板３及び銅板４を用いずに電極群中の正極板５及び負極板６からリード（線）により直接それぞれ正極端子１及び負極端子２に導電させたこと以外は実施例４と同様に作製した電池。
【００３１】
＜試験・評価＞
[試験]
次に、以上のように作製した実施例及び比較例の各電池について、正極端子１と負極端子２とを電池外部で短絡させる外部短絡試験を実施した。検査方法として、外部短絡試験後、損傷、発火の有無を確認した。
【００３２】
[試験結果]
外部短絡試験の検査結果を下表１に示す。なお、表１において、「○」は８０％以上損傷・発火なし、「△」は５０％以上８０％未満損傷・発火なし、「×」は５０％未満損傷・発火なし、「●」は安全弁９の作動側に規則性あり（負極端子２側の安全弁９が早期に開裂）、「◆」は安全弁９の作動側に規則性なしとなったものをそれぞれ示している。
【００３３】
【表１】

【００３４】
[評価]
表１に示すように、外部短絡試験の結果、比較例１の電池は過半数が損傷・発火した。実施例３、４の電池は５０％以上が損傷・発火せず、電池の安全性が向上している。実施例１、２の電池では、８０％以上が損傷・発火せず安全性が一段と高まっている。また、実施例１、２の電池では、常に負極端子２側の安全弁９が正極端子１側の安全弁９より先に開裂することが確認された。
【００３５】
このことから、安全弁９開裂時の閉塞を妨げる機能を有する部材（アルミニウム板３及び／又は銅板４及び／又は閉塞防止部材１０）を設けることにより安全性が向上し、更に、安全弁９の肉厚を正極端子１側より負極端子２側を薄くすることにより、正極端子１側の安全弁９が確実に早期に作動することが分かる。
【００３６】
【発明の効果】
以上説明したように、本発明によれば、閉塞防止部材を電池ケース内側に配置し、その直上に脆弱部が形成されているので、電池内圧の上昇により脆弱部が開裂したとき、ガス放出に伴う電池内容物が閉塞防止部材に係止されて脆弱部の閉塞が防止され、内部発生ガスを確実に電池外部に放出することができ、脆弱部が電池ケース上面に形成されているので、角形電池の上面以外の５面が他の物体により密着され、その５面に形成された脆弱部が閉塞された場合でも、正極及び負極端子のような凹凸のある電池ケース上面は閉塞されずに、確実に内部発生ガスを電池外部へ放出することができ、複数の脆弱部が電池ケース上面に形成されているので、それらの脆弱部のうち何れかが他の物体により閉塞されていても確実に内部発生ガスを電池外部に放出することができ、更に、一端が正極板に接続され他端が正極端子に接続された長尺状の導電部材、及び、一端が負極板に接続され他端が負極端子に接続された長尺状の導電部材を閉塞防止部材として用いたので、新たに閉塞防止部材を設ける必要がなく、また、閉塞防止部材を長尺状の簡易な構造とすることで電池内容物を閉塞防止部材に係止させガス放出経路を確保することができると共に、閉塞防止部材に、正極板に接続されたアルミニウム製導電部材と、負極板に接続された銅製導電部材を用いたので、閉塞防止部材に耐電圧性を持たせ腐蝕を防止し閉塞防止部材が脆弱化することを防止することができ、閉塞防止部材に金属材料を用いたので、樹脂材料を使用した場合に比べ放出される高温ガスに対し融点が高く、ガス放出時に閉塞防止部材の変形・溶融を防止することができ、また、脆弱部のうち、銅製導電部材の直上に配置された脆弱部の開裂圧を最も小さくしたので、アルミニウムよりも高融点の銅を使用している負極端子側に開裂圧が最も小さい脆弱部が配置されるため、確実にガス放出可能な位置が特定されガス放出経路を確保でき、安全性を向上させることができる、という効果を得ることができる。
【図面の簡単な説明】
【図１】本発明が適用可能な実施形態の角形非水電解液電池の一部破断正面図である。
【図２】実施形態の角形非水電解液電池の安全弁付近の拡大側断面図である。
【図３】実施形態の角形非水電解液電池の安全弁付近を電極群側から見たときの拡大図である。
【図４】本発明が適用可能な別の実施形態の角形非水電解液電池の一部破断正面図である。
【図５】別の実施形態の角形非水電解液電池の安全弁付近を電極群側から見たときの拡大図である。
【符号の説明】
１正極端子
２負極端子
３アルミニウム板（導電部材、閉塞防止部材の一部）
４銅板（導電部材、閉塞防止部材の一部）
５正極板
６負極板
７電池缶（電池ケースの一部）
８電池蓋（電池ケースの一部）
９安全弁（脆弱部）
１０閉塞防止部材
２０、２１角形非水電解液電池[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a prismatic nonaqueous electrolyte battery, and in particular, an electrode group in which a positive electrode plate, a negative electrode plate, and a separator are stacked and accommodated in a rectangular battery case, and a positive electrode that is conductive from the electrode group and fixed to the upper surface of the battery case. And a negative electrode terminal.
[0002]
[Prior art]
Currently, lithium primary batteries, lithium secondary batteries, and the like are put to practical use as non-aqueous electrolyte batteries. Among these batteries, a small lithium secondary battery having an electric capacity of about 1.5 Ah has, for example, a current cutoff mechanism that interrupts current when the temperature rises by inserting a PTC (Positive Temperature Coefficient) element in series with the power generation element. Addition of an internal pressure reduction mechanism to prevent damage to the battery container by forming a metal thin film at the boundary between the inside and outside of the battery and breaking the metal thin film when the internal pressure of the battery rises to release gas generated inside the battery This ensures the safety of non-aqueous electrolyte batteries.
[0003]
As described above, safety is emphasized also in a small battery, and it goes without saying that it is more important to ensure safety if the battery has a large capacity with an electric capacity exceeding 10 Ah. As a large battery with an emphasis on safety, for example, Japanese Patent Application Laid-Open No. 9-92249 discloses a technology of a secondary battery provided with an open valve in order to release gas generated inside the battery. According to the open valve of the publication, the open pressure can be set with good reproducibility, and the open pressure can be set low, so that the impact force when the pressure is released can be reduced.
[0004]
[Problems to be solved by the invention]
However, the technique of the publication does not describe a clear position of the open valve. In addition, this publication is a technology for a cylindrical battery, and in order to ensure safety in a prismatic battery whose battery case has a low withstand voltage due to its structural characteristics, an internal pressure reduction mechanism that releases the generated gas inside the battery is provided. It becomes even more important.
[0005]
Further, in the internal pressure reduction mechanism that breaks the metal thin film and releases the generated gas, the safety function may not be exhibited unless the arrangement position of the metal thin film or the cleavage mechanism thereof is sufficiently taken into consideration. That is, for example, when an object is placed immediately above the metal thin film, even if the internal pressure rises when the battery is abnormal and the metal thin film breaks and tries to release the internally generated gas, the object blocks the gas release path. Therefore, it cannot be released, and the battery container itself may be damaged.
[0006]
Further, the gas generated inside when the battery is abnormal is released vigorously as the metal thin film breaks. At this time, the battery contents such as the electrode group move in the direction of the metal thin film rupture portion where the pressure is reduced together with the outflow gas, so that there is a problem that the gas discharge port is closed and the battery container is damaged.
[0007]
An object of the present invention is to provide a prismatic nonaqueous electrolyte battery excellent in safety in view of the above-mentioned cases.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an electrode group in which a positive electrode plate, a negative electrode plate and a separator are laminated and accommodated in a rectangular battery case, and a positive electrode and a negative electrode which are conductive from the electrode group and fixed on the upper surface of the battery case. e Bei a terminal, and the the upper surface of the battery case is cleaved the open burst pressure is a plurality of weak portions with different forms at a given pressure, wherein two of the weakened portion is disposed inside the battery case in arranged angular type nonaqueous electrolyte battery immediately above the occlusion-preventing member fragile portion to prevent clogging of the fragile portion when cleaved, the two weak portions are respectively connected to the one end positive electrode plate A long aluminum conductive member having the other end connected to the positive electrode terminal, and a long copper conductive member having one end connected to the negative electrode plate and the other end connected to the negative electrode terminal. Directly above the blocking prevention member It is location, the one weak portion, rupturing pressure of the deployed fragile portion directly above the copper conductive member, characterized in that the smallest.
[0009]
In the present invention, the blockage preventing member is disposed inside the battery case, and the weak portion is formed immediately above. Therefore, when the weak portion is cleaved due to an increase in the internal pressure of the battery, the battery contents accompanying the gas release are blocked. The fragile portion is prevented from being blocked by being locked to the inside, and the internally generated gas can be reliably discharged to the outside of the battery. Further, since the weak portion is formed on the upper surface of the battery case, even when the five surfaces other than the upper surface of the prismatic battery are in close contact with each other and the weak portion formed on the five surfaces is closed, the positive electrode and the negative electrode The upper surface of the uneven battery case such as the terminal is not blocked, and the generated gas can be surely released to the outside of the battery, and a plurality of weak parts are formed on the upper surface of the battery case. Even if any of the parts is blocked by another object, the internally generated gas can be reliably discharged to the outside of the battery. Furthermore, a long conductive member having one end connected to the positive electrode plate and the other end connected to the positive electrode terminal, and a long conductive member having one end connected to the negative electrode plate and the other end connected to the negative electrode terminal Since it is used as a blockage prevention member, it is not necessary to provide a new blockage prevention member, and the blockage prevention member has a long and simple structure so that the battery contents can be locked to the blockage prevention member and the gas discharge path. Since an aluminum conductive member connected to the positive electrode plate and a copper conductive member connected to the negative electrode plate are used as the blockage prevention member, the blockage prevention member is corroded with voltage resistance. The blockage prevention member can be prevented from becoming brittle, and since the metal material is used for the blockage prevention member, the melting point is higher than the high temperature gas released compared to the case of using a resin material, and the gas release Sometimes deformation of anti-blocking member It is possible to prevent melting. In addition, as an obstruction | occlusion prevention member, you may make it use the thing made from an aluminum alloy other than the product made from pure aluminum (positive electrode terminal side), and the product made from copper alloy other than the pure copper (negative electrode terminal side). And since the cracking pressure of the brittle part arranged right above the copper conductive member among the brittle parts was minimized, the brittle part having the smallest cracking pressure on the negative electrode terminal side using copper having a melting point higher than that of aluminum. Therefore, a position where gas can be reliably discharged is specified, a gas discharge path can be secured, and safety can be improved. For forming the fragile portion, it is possible to adopt a mode in which, for example, a part of the battery case is thinned or made of a different material with weak strength.
[0012]
In the present invention, the blocking member is composed of a conductive member and a long member that is electrically insulated from the conductive member and disposed between the conductive member and the fragile portion so as to be orthogonal to the longitudinal direction of the conductive member. If configured, the battery contents that have passed through the conductive member can be locked to the blockage prevention member with a long member arranged so as to be orthogonal to the conductive member, so that the fragile portion can be more reliably prevented from being blocked. Can do.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a rectangular nonaqueous electrolyte battery according to the present invention will be described with reference to the drawings.
[0015]
As shown in FIG. 1, the rectangular nonaqueous electrolyte battery 20 of the present embodiment includes a rectangular and stainless steel battery can 7 serving as a container. The central portion of the battery can 7 accommodates an electrode group in which a positive electrode plate 5 and a negative electrode plate 6 that are rectangular in shape and projecting in the upper direction are stacked with a separator (not shown) interposed therebetween so that the two electrode plates do not directly contact each other. Has been. The positive electrode plate 5 uses aluminum foil as a positive electrode current collector, and a positive electrode active material mixture is applied to both surfaces of the positive electrode current collector. On the other hand, the negative electrode plate 5 uses copper foil as a negative electrode current collector, and a negative electrode active material mixture is applied to both surfaces of the negative electrode current collector. The rectangular nonaqueous electrolyte battery 20 includes a stainless steel battery lid 8, and after the electrode group is inserted into the battery can 7, the periphery of the opening of the battery can 7 and the periphery of the battery lid 8 are welded. It is sealed by doing.
[0016]
The upper end of the ear portion of the positive electrode plate 5 is ultrasonically bonded to a thin plate-like aluminum plate 3 having a thickness of 2 mm. A screw hole is formed on one side of the battery lid 8 so that the positive electrode terminal 1 made of an aluminum screw rod is screwed to the battery lid 8 via a sealing material (not shown). The tip of the positive electrode terminal 1 is fixed to the upper part of the battery lid 8 with a nut, and the opposite end of the aluminum plate 3 on the ultrasonic bonding side and the opposite end of the positive electrode terminal 1 are tightened and contacted by a bolt and a nut. Yes. On the other hand, the upper end of the ear portion of the negative electrode plate 6 is ultrasonically bonded to a thin plate-like copper plate 4 having a thickness of 2 mm. A screw hole is formed on the opposite side of the battery lid 8 to the fixed side of the positive electrode terminal 1 so that the negative electrode terminal 2 made of a copper screw rod is screwed to the battery lid 8 via a sealing material (not shown). The tip of the negative electrode terminal 2 is fixed to the upper part of the battery lid 8 with a nut, and the opposite end of the copper plate 4 on the ultrasonic bonding side and the opposite end of the tip of the negative electrode terminal 2 are tightened and contacted by a bolt and a nut. . Therefore, the positive electrode terminal 1 is electrically connected to the positive electrode plate 5 via the aluminum plate 3, and the negative electrode terminal 2 is electrically connected to the negative electrode plate 6 via the copper plate 4.
[0017]
As shown in FIGS. 1 to 3, the battery lid 8 is welded with a safety valve 9 as a thin film circular fragile portion in which stainless steel foil is welded to the positive electrode terminal 1 side and the negative electrode terminal 2 side. As will be described later, the thicknesses of these safety valves 9 are different. At the bottom of the safety valve 9, upper surface portions of both ends of a stainless steel blockage prevention member 10 having a “one” character shape (long shape) and a size of 2 mm × 2 mm × 25 mm are fixed to the back surface of the battery lid 8. The safety valve 9 is disposed immediately above the blockage prevention member 10 and the aluminum plate 3 or the copper plate 4, and the blockage prevention member 10 and the aluminum plate 3 or the copper plate 4 are electrically insulated. Further, the blocking prevention member 10 and the aluminum plate 3 or the copper plate 4 are in a perpendicular positional relationship, and are arranged so that their longitudinal directions intersect each other.
[0018]
As shown in FIG. 1, a liquid injection port 11 is formed in the battery lid 8. In the rectangular nonaqueous electrolyte battery 20 of the present embodiment, a mixed solvent of ethylene carbonate and dimethyl carbonate is supplied from the liquid injection port 11. A nonaqueous electrolytic solution in which lithium hexafluorophosphate (LiPF ₆ ) is dissolved is injected into the liquid injection port. After the electrolytic solution is injected, the liquid injection port 11 is sealed with a liquid port stopper (not shown).
[0019]
Next, the operation of the rectangular nonaqueous electrolyte battery 20 of the present embodiment will be described.
[0020]
In the rectangular non-aqueous electrolyte battery 20 of the present embodiment, the safety valve 9 is disposed immediately above the obstruction prevention member 10, the aluminum plate 3, and the copper plate 4 intersecting each longitudinal direction. Therefore, when the internal pressure of the prismatic nonaqueous electrolyte battery 20 rises and the safety valve 9 is cleaved, the contents of the electrode group (positive electrode active material, negative electrode active material, etc.) move together with the gas in the direction of the safety valve 9. However, the clogging prevention member 10 and the aluminum plate 3 and the copper plate 4 that intersect each other are not contacted and locked to block the cleaved portion of the safety valve 9. Therefore, the gas generated inside the rectangular non-aqueous electrolyte battery 20 is surely released to the outside from the safety valve 9, so that the rectangular non-aqueous electrolyte battery 20 is not damaged by the internal pressure.
[0021]
Moreover, in order to obtain a high voltage or a high capacity, a plurality of prismatic nonaqueous electrolyte batteries may be used connected in series or in parallel. In such an application, in order to make the total volume of a plurality of prismatic nonaqueous electrolyte batteries as small as possible, in general, the four side surfaces other than the upper and lower surfaces of the prismatic nonaqueous electrolyte battery or any one of the four side surfaces is the other. It arrange | positions in contact with the side surface of a square nonaqueous electrolyte battery. Further, the lower surface of the prismatic nonaqueous electrolyte battery is generally flat to support the weight of the prismatic nonaqueous electrolyte battery. Therefore, in the prismatic nonaqueous electrolyte battery, five of the six surfaces may be in close contact with other prismatic nonaqueous electrolyte batteries and the mounting floor surface. In the prismatic nonaqueous electrolyte battery 20 of the present embodiment, a plurality of safety valves 9 are provided on the upper surface on which irregularities are formed by the positive electrode terminal 1 and the negative electrode terminal 2, so that these safety valves 9 are prismatic nonaqueous electrolyte batteries. Even if one safety valve 9 on the upper surface is further closed due to the arrangement of 20, the other safety valve 9 can surely discharge the gas to the outside.
[0022]
Further, in the rectangular nonaqueous electrolyte battery 20, the aluminum plate 3 and the copper plate 4 are made of the same material (aluminum and copper, respectively) as the current collectors of the positive electrode plate 5 and the negative electrode plate 6, respectively. For this reason, it does not become weak at the expense of electric corrosion. Therefore, the strength can be maintained even when the contents of the electrode group move in the direction of the safety valve 9 together with the gas. Further, since the blocking prevention member 10 is insulated from the aluminum plate 3 and the copper plate 4, there is no possibility of causing an external short circuit. In addition, the blocking member 10, the aluminum plate 3, and the copper plate 4 are all metal and have a high melting point with respect to the high-temperature gas compared to the resin, and the contents of the electrode group cannot be locked due to deformation or melting when the gas is released. Can be prevented. Furthermore, the thickness of the safety valve 9 is different in the rectangular nonaqueous electrolyte battery 20. Therefore, by reducing the thickness of the safety valve 9 on the copper plate 4 side having a higher melting point than that of the aluminum plate 3, that is, on the negative electrode terminal 2 side, deformation / melting due to high-temperature gas can be prevented more reliably. Accordingly, the high temperature and high pressure gas can be discharged from the safety valve 9 side on the negative electrode terminal 2 side having a reduced thickness early and reliably, and the reliability of the entire safety valve 9 can be further enhanced.
[0023]
In this embodiment, in order to prevent the safety valve 9 from being blocked at the time of tearing, an example in which the blocking member 10 that is electrically independent from the aluminum plate 3 and the copper plate 4 is provided is described. There is no need to have 10 in particular. For example, as shown in FIGS. 4 and 5, the rectangular non-aqueous electrolyte battery 21 does not have the blocking prevention member 10, and the copper plate 4 locks the contents of the electrode group when the safety valve 9 is opened. This is what I did not. In this rectangular non-aqueous electrolyte battery 21, the aluminum plate 3 and the copper plate 4 are used as conductive members from the positive electrode plate 5 to the positive electrode terminal 1 and from the negative electrode plate 6 to the negative electrode terminal 2, respectively, and the safety valve 9 is prevented from being blocked. As a result, the number of components can be reduced as compared with the prismatic nonaqueous electrolyte battery 20.
[0024]
In this embodiment, the positive and negative safety valves 9 are made of the same material stainless steel and the thickness is made thin, but the cleavage pressure is set by changing the material, but the safety valve 9 is made to have a different cleavage pressure. Also good. Furthermore, in this embodiment, although aluminum and copper were used literally for the aluminum plate 3 and the copper plate 4, an aluminum alloy, a copper alloy, or the like may be used. In the present embodiment, stainless steel is used for the blocking prevention member 10, but other metals, heat resistant resins, flame retardant resins, and the like may be used. The present invention is not limited to the above-described embodiment, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.
[0025]
【Example】
Next, examples of the rectangular nonaqueous electrolyte battery 20 (21) manufactured according to the above embodiment will be described. In addition, it describes together about the battery of the comparative example produced for the comparison.
[0026]
Example 1
The same as the rectangular nonaqueous electrolyte battery 20 shown in FIG. 1 to FIG. 3, two safety valves 9 are provided on each of the positive electrode terminal 1 side and the negative electrode terminal 2 side. A battery that is disposed immediately above each of the plate 3 and the copper plate 4 and the thickness of the safety valve 9 is thinner on the negative electrode terminal 2 side than on the positive electrode terminal 1 side.
[0027]
(Example 2)
4 and 5 are the same as the prismatic nonaqueous electrolyte battery 21, and two safety valves 9 are provided on each of the positive electrode terminal 1 side and the negative electrode terminal 2 side, and the safety valve 9 is provided on each of the aluminum plate 3 and the copper plate 4. A battery which is arranged directly above and whose safety valve 9 is thinner on the negative electrode terminal 2 side than on the positive electrode terminal 1 side.
[0028]
Example 3
The same as the rectangular nonaqueous electrolyte battery 20 shown in FIG. 1 to FIG. 3, two safety valves 9 are provided on each of the positive electrode terminal 1 side and the negative electrode terminal 2 side. A battery that is disposed immediately above each of the plate 3 and the copper plate 4, and the thickness of the safety valve 9 is thinner on the positive electrode terminal 1 side than on the negative electrode terminal 2 side.
[0029]
Example 4
4 and 5 are the same as the prismatic nonaqueous electrolyte battery 21, and two safety valves 9 are provided on each of the positive electrode terminal 1 side and the negative electrode terminal 2 side, and the safety valve 9 is provided on each of the aluminum plate 3 and the copper plate 4. A battery that is disposed directly above and whose safety valve 9 is thinner on the positive electrode terminal 1 side than on the negative electrode terminal 2 side.
[0030]
(Comparative Example 1)
Fabricated in the same manner as in Example 4 except that the positive electrode plate 5 and the negative electrode plate 6 in the electrode group were directly conducted to the positive electrode terminal 1 and the negative electrode terminal 2 by leads (wires) without using the aluminum plate 3 and the copper plate 4, respectively. Batteries.
[0031]
<Test and evaluation>
[test]
Next, the external short circuit test which short-circuits the positive electrode terminal 1 and the negative electrode terminal 2 outside a battery was implemented about each battery of the Example produced as mentioned above and a comparative example. As an inspection method, after the external short circuit test, the presence or absence of damage or ignition was confirmed.
[0032]
[Test results]
The inspection results of the external short circuit test are shown in Table 1 below. In Table 1, “○” indicates 80% or more without damage / ignition, “△” indicates 50% or more and less than 80% damage / ignition, “×” indicates less than 50% damage / ignition, and “●” indicates a safety valve. 9 indicates regularity (the safety valve 9 on the negative electrode terminal 2 side is prematurely opened), and “♦” indicates that the safety valve 9 is not regular.
[0033]
[Table 1]

[0034]
[Evaluation]
As shown in Table 1, as a result of the external short circuit test, the majority of the batteries of Comparative Example 1 were damaged and ignited. 50% or more of the batteries of Examples 3 and 4 are not damaged or ignited, and the safety of the battery is improved. In the batteries of Examples 1 and 2, 80% or more were not damaged or ignited, and safety was further improved. In the batteries of Examples 1 and 2, it was confirmed that the safety valve 9 on the negative electrode terminal 2 side always cleaves before the safety valve 9 on the positive electrode terminal 1 side.
[0035]
For this reason, the safety is improved by providing a member (aluminum plate 3 and / or copper plate 4 and / or blockage preventing member 10) having a function of preventing blockage when the safety valve 9 is opened. It can be seen that by making the negative electrode terminal 2 side thinner than the positive electrode terminal 1 side, the safety valve 9 on the positive electrode terminal 1 side reliably operates early.
[0036]
【The invention's effect】
As described above, according to the present invention, the blocking prevention member is arranged inside the battery case, and the fragile portion is formed immediately above, so that when the fragile portion is cleaved due to an increase in the internal pressure of the battery, gas is released. The accompanying battery contents are locked to the blocking prevention member to prevent the fragile portion from being blocked, and the generated gas can be surely released to the outside of the battery, and the fragile portion is formed on the upper surface of the battery case, so Even when 5 surfaces other than the upper surface of the battery are closely adhered by other objects and the weakened portion formed on the 5 surface is closed, the battery case upper surface with unevenness such as the positive electrode and the negative electrode terminal is not closed, The internal generated gas can be reliably discharged to the outside of the battery, and a plurality of fragile parts are formed on the upper surface of the battery case, so even if any of these fragile parts is blocked by another object Internally generated gas battery Can be released into the section, is further connected, elongated conductive member having one end and the other end connected to the positive electrode plate is connected to the positive terminal and the other end is connected one end of the negative electrode plate negative electrode terminal Since the long conductive member is used as a blockage prevention member, there is no need to provide a new blockage prevention member, and the blockage prevention member has a long and simple structure to prevent the battery contents from being blocked. It is possible to secure the gas release path by being locked to the member, and since the blocking prevention member uses an aluminum conductive member connected to the positive electrode plate and a copper conductive member connected to the negative electrode plate, the blocking prevention member It has high voltage resistance to prevent corrosion and prevent the blockage prevention member from becoming brittle. Since a metal material is used for the blockage prevention member, the high temperature gas released compared to the case of using a resin material The melting point is higher than Sometimes the blockage prevention member can be prevented from being deformed and melted, and among the fragile portions, the cracking pressure of the fragile portion arranged immediately above the copper conductive member is minimized, so that copper having a melting point higher than that of aluminum is used. Since the fragile part with the smallest cleavage pressure is arranged on the negative electrode terminal side being used, the position where gas can be discharged reliably is specified, the gas discharge path can be secured, and the safety can be improved. Obtainable.
[Brief description of the drawings]
FIG. 1 is a partially broken front view of a prismatic nonaqueous electrolyte battery according to an embodiment to which the present invention is applicable.
FIG. 2 is an enlarged side sectional view of the vicinity of the safety valve of the prismatic nonaqueous electrolyte battery according to the embodiment.
FIG. 3 is an enlarged view when the vicinity of the safety valve of the rectangular nonaqueous electrolyte battery according to the embodiment is viewed from the electrode group side.
FIG. 4 is a partially cutaway front view of a prismatic nonaqueous electrolyte battery according to another embodiment to which the present invention is applicable.
FIG. 5 is an enlarged view of the vicinity of a safety valve of a prismatic nonaqueous electrolyte battery according to another embodiment when viewed from the electrode group side.
[Explanation of symbols]
1 Positive terminal 2 Negative terminal 3 Aluminum plate (conductive member, part of blocking member)
4 Copper plate (conductive member, part of blocking prevention member)
5 Positive electrode plate 6 Negative electrode plate 7 Battery can (part of battery case)
8 Battery cover (part of battery case)
9 Safety valve (fragile part)
10

Blocking prevention member

20, 21 Square non-aqueous electrolyte battery

Claims

The positive electrode plate, an electrode assembly housed in the negative electrode plate and laminating a separator in a rectangular battery case, and positive and negative terminals which are conductive fixed to the battery case upper surface from the electrode group, Bei give a, of the battery case the upper surface is cleaved the open burst pressure is a plurality of weak portions with different forms at a given pressure, wherein two of the weakened portion, the fragile portion when the arranged battery case inside the fragile part is cleaved in arranged angular type nonaqueous electrolyte battery immediately above the obstruction prevention member for preventing the clogging, the two weak portions, respectively, one end of the other end connected to the positive electrode plate is connected to the positive terminal A long aluminum conductive member and a long copper conductive member having one end connected to the negative electrode plate and the other end connected to the negative electrode terminal are disposed immediately above the dissimilar blocking member. Of the vulnerable parts, Serial prismatic nonaqueous electrolyte battery rupturing pressure of the deployed fragile portion is characterized in that the smallest directly above the copper conductive members.

The blocking prevention member includes the conductive member and a long member that is electrically insulated from the conductive member and is disposed between the conductive member and the fragile portion so as to be orthogonal to the longitudinal direction of the conductive member. The prismatic non-aqueous electrolyte battery according to claim 1 , comprising: