JP3829086B2

JP3829086B2 - Non-aqueous electrolyte battery and manufacturing method thereof

Info

Publication number: JP3829086B2
Application number: JP2001346060A
Authority: JP
Inventors: 順哉西森; 喜治小柿; 貴敏尾崎; 靖平川
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2001-11-12
Filing date: 2001-11-12
Publication date: 2006-10-04
Anticipated expiration: 2021-11-12
Also published as: JP2003151527A

Description

【０００１】
【発明の属する技術分野】
本発明は、小型でありながらも大容量を有する密閉形電池であるリチウムイオン二次電池などの非水電解液（有機溶媒系電解液）電池およびその製造方法に関するものである。
【０００２】
【従来の技術】
近年では、ＡＶ機器あるいはパソコンや携帯形通信機器などの電気機器のポータブル化やコードレス化が急速に促進されている。これらの電気機器の駆動用電源としては、従来においてニッケルカドミウム電池やニッケル水素電池が主に用いられていたが、近年では、特に、急速充電が可能でエネルギ密度が高く、高い安全性を有するリチウムイオン二次電池に代表される非水電解液二次電池が主流になりつつある。この非水電解液二次電池では、高エネルギ密度や負荷特性に優れた密閉型とし、さらに、機器の薄型化に適し、且つスペース効果の高い角形とすることが促進されている。
【０００３】
ところで、近年では、非水電解液二次電池に対し単位体積当たりの電池容量の一層の向上を図る要望が高い。そこで、従来では、単位体積当たりの電池容量の向上を目的として、正，負極板の芯材（一般に正極板はアルミニウム製芯材、負極板には、銅製の芯材がそれぞれ用いられている）を可及的に薄くして、その正，負極板の芯材に正，負極集電用の各リードを抵抗溶接などで接続する手段を採用することが検討されている。
【０００４】
【発明が解決しようとする課題】
一般に、抵抗溶接に際しては、溶接対象物の双方の厚さに大きな差がないことが好ましく、上述のように正，負極板の各々の芯材を薄くするのに対応して正，負極集電用の各リードの厚みを薄くすることは可能である。しかしながら、正極集電用リードまたは負極集電用リードにおける芯材との溶接部とは反対側の端部を溶接する封口板は、電池内圧の上昇に対し所定の耐圧性能を有してことが必要であることから、芯材に対し数倍の厚みに設定せざるおえない。そのため、図６（ａ）に示すように、電極群１の芯材（図示せず）に一端を接続した厚みの薄いリード２の他端部をこのリード２の数倍の厚みを有する封口板３に一対の抵抗溶接電極４Ａ，４Ｂを用いて抵抗溶接した場合には、この溶接時に厚みの薄いリード２が封口板３よりも先に溶けるので、同図（ｂ）に示すように、溶接部周辺に亀裂７が入ったり、あるいはスパークして穴が開いたりし、溶接の接合強度および機械的強度が低下するだけでなく、電池としたときの充放電時の内部抵抗が増大してしまうという問題が生じる。
【０００５】
そこで、本発明は、上記従来の課題に鑑みてなされたもので、集電用リードと封口板などとの接合強度や機械的強度の低下を招くことなしに単位体積当たりの電池容量の向上を図ることができる構成を備えた非水電解液電池およびその製造方法を提供することを目的とするものである。
【０００６】
【課題を解決するための手段】
上記目的を達成するために、本発明に係る非水電解液電池は、電極群と電解液とを収容して一方の電極を兼ねる電池ケースと、前記電池ケースに対しこれの開口部を封止して電気的に接続された封口板と、前記封口板に絶縁ガスケットを介し絶縁状態に配設されて他方の電極となる電極ターミナルと、前記電極群の正，負の両極板の各芯材に各々の一端部がそれぞれ接合されて前記電極群から取り出され、各々の他端部が前記封口板および前記電極ターミナルのうちの一方または他方にそれぞれ抵抗溶接にて接合された正極集電用リードおよび負極集電用リードとを備え、前記正，負の両極板の各々の芯材の厚みは８〜２０μｍに設定され、前記正極集電用リードおよび負極集電用リードは、厚みが５０μｍ以下に設定されている薄肉短冊状のリード片部の他端部に、前記リード片部よりも大きな厚みに形成された接続部を有していることを特徴としている。
【０００７】
この非水電解液電池では、正、負極集電用リードのリード片部の他端部に大きな厚みの接続部を備えているので、上記リード片部の厚みを５０μｍ以下に可及的に薄く設定しても、接続部を介して厚みの大きな封口板などに対し亀裂や穿孔などの不具合が生じることなく抵抗溶接にて接合することができ、十分な接合強度や機械的強度を確保できる。この効果を得ながらも、正、負極集電用リードの各リード片部は、上述のように厚みを５０μｍ以下に可及的に薄くできるので、正，負極板の各芯材の厚みを８〜２０μｍに、正、負極集電用リードの各々のリード片部の厚みを５０μｍ以下に薄くして単位体積当たりの電池容量の向上を図ることができる。
【０００９】
この構成によれば、正，負極板の全体の厚みが従来の極板と同様になるように設定した場合、芯材の厚みを薄くした分だけ単位体積当たりの電池容量の増大を図ることができる。また、正，負極板は正、負極集電用リードの各々のリード片部の一端部を芯材の巻き始め端または巻き終わり端に接合して渦巻状に巻回されるので、リード片部の厚みを薄くした分だけ電極群における渦巻状の中央部分が薄くなるから、従来と同様の外形を有する電極群を構成する場合に渦巻状の中央部分が薄くなった分だけ巻回数を増やすことができ、これによっても単位体積当たりの電池容量を一層向上させることができる。
【００１０】
また、上記発明における正極集電用リードおよび負極集電用リードは、リード片部の他端部に接続部を一体に有する形状に金型成形または／およびトリミング加工によって形成されたものであることが好ましい。この構成によれば、リードを生産性良く大量生産できる。
【００１１】
一方、上記発明における正極集電用リードおよび負極集電用リードは、薄肉短冊状のリード片部の他端部を折り畳みまたは渦巻状に巻回したのちに、加圧加工を施すことによる圧潰手段で接続部が形成されたものとすることもできる。この構成によれば、例えば金属箔を単なる薄肉短冊状に切断するだけでリード片部を形成でき、そのリード片部の端部に折曲および加圧の加工を施すだけで接続部を形成できるから、特に、加工性に優れたアルミニウムを素材とする場合には、接続部を容易に形成することができ、やはり生産性良く大量生産できる。
【００１２】
また、上記発明における正極集電用リードおよび負極集電用リードは、薄肉短冊状のリード片部の他端部に前記リード片部よりも厚みの大きな接続部を貼着して形成することもできる。この構成によれば、例えば金属箔を単なる薄肉短冊状に切断して形成したリード片部の端部に、厚みの大きな接続部を接着手段などによって取り付けることにより形成できるので、金型による成形加工や折曲および加圧の加工などが不要となるので、所要の形状を有するものを安価に大量生産できる。
【００１３】
本発明の非水電解液電池の製造方法は、正極集電用リードおよび負極集電用リードにおける薄肉短冊状に形成されたリード片部の一端部が正極板および負極板の各芯材に接合された電極群を電池ケース内に収納する工程と、前記正極集電用リードの前記リード片部の他端部にこれよりも大きな厚みに形成された接続部をアルミニウム製の封口板に接合するとともに、前記負極集電用リードの前記リード片部の他端部にこれよりも大きな厚みに形成された接続部を、前記封口板に絶縁状態で配設された負極ターミナルに接合する工程と、前記封口板を前記電池ケースの開口部に嵌合して接合することによって前記電池ケースを封口する工程と、前記封口板の注液孔から電解液を前記電池ケース内に注入したのちに、前記注液孔を封栓する工程とを有していることを特徴としている。
【００１４】
この非水電解液電池の製造方法では、アルミニウム製の正極集電用リードのリード片部の他端に設けた厚みの大きい接続部を同一素材のアルミニウム製の封口板に溶接により接合し、例えばニッケル製の負極集電用リードのリード片部の他端に設けた厚みの大きい接続部を、絶縁ガスケットにより封口板に絶縁して配設した負極ターミナルに接合するので、本発明の非水電解液電池を不具合の発生を防止しながら生産性良く製造することができる。
【００１５】
上記発明の製造方法において、負極板の銅製の芯材における少なくとも負極集電用リードの接合箇所に表面処理を施して粗面化し、この粗面化した前記芯材の箇所に前記負極集電用リードのリード片部の一端部を抵抗溶接して接合することが好ましい。これにより、例えば、ニッケル製の負極集電用リードは、銅製の負極側芯材に抵抗溶接することが可能となる。すなわち、負極集電用リードと負極側芯材とを接触させたときには、負極側芯材の表面の粗面化によって接触抵抗が上がるから、抵抗溶接によって支障なく接合することができ、非水電解液電池をコストダウンしながらも生産性良く大量生産することが可能となる。
【００１６】
【発明の実施の形態】
以下、本発明の好ましい実施の形態について図面を参照しながら説明する。図１は本発明の一実施の形態に係る非水電解液電池を示す縦断面図、図２はその非水電解液電池の分解斜視図である。これらの図において、アルミニウム製の有底角筒状の電池ケース８内には、正極板、負極板およびセパレータを渦巻状に巻回して横断面形状を長円形とした電極群９が収納されている。
【００１７】
アルミニウム製の正極集電用リード１０およびニッケル製の負極集電用リード１１は、図２に明示するように、薄肉短冊状となった正極側および負極側リード片部１５，１６の各々の他端部に、大きな厚みに設定された溶接用の正極側接続部１２および負極側接続部１３がそれぞれ一体形成された形状を有している。正極側および負極側リード片部１５，１６の各々の一端側（図の下端側）は、それぞれ正極板および負極板の各々の芯材に溶接されて電極群９から取り出されている。正極板および負極板は、単位体積当たりの電池容量の向上を図るために、その厚みを可及的に薄く設定されているが、これについての詳細は後述する。正極集電用リード１０および負極集電用リード１１の各々のリード片部１５，１６は、上述の芯材の厚みを薄くしたのに対応して薄いを厚みに設定されている。
【００１８】
上記正極集電用リード１０および負極集電用リード１１の他端部はそれぞれ枠体１４の挿通孔１４ａ，１４ｂに挿通されたのち、それらの他端の正極側接続部１２は平板状のアルミニウム製封口板１７に、負極側接続部１３は負極端子板１８にそれぞれ溶接されている。この溶接としては、抵抗溶接、レーザー溶接または超音波溶接の何れかを採用できるが、この実施の形態では抵抗溶接を行う。
【００１９】
上記枠体１４は電池ケース８の開口部近傍箇所に嵌着され、封口板１７は、枠体１４上に載置して支持された状態で電池ケース８にレーザー溶接されて、電池ケース８の開口部を封口している。封口板１７の中央部の凹所１９には上部絶縁ガスケット２０が嵌め入れられており、ニッケルめっきされた鉄製のリベットからなる負極ターミナル２１は、上部絶縁ガスケット２０を介在して封口板１７に対し絶縁された状態で上部絶縁ガスケット２０および封口板１７の各々の挿通孔に挿通されている。この負極ターミナル２１における上記上部絶縁ガスケット２０および封口板１７をそれぞれ挿通した下部は、さらに下部絶縁ガスケット２２および上記負極端子板１８の各々の取付孔２２ａ，１８ａにそれぞれ挿通されたのち、下端部をかしめ加工されている。これにより、負極端子板１８は、下部絶縁ガスケット２２を介して封口板１７に対し電気絶縁され、且つ上記かしめ加工部を介して負極ターミナル２１に電気的接続状態で取り付けられている。
【００２０】
組み立てに際して、封口板１７は、負極ターミナル２１によって上部絶縁ガスケット２０、下部絶縁ガスケット２２および負極端子板１８が取り付けられた状態で電池ケース８の開口部に嵌入して溶接される。そののち、電池ケース８内には、封口板１７の注液孔１７ａを通じて電解液（図示せず）が注入される。注液孔１７ａは、電解液の注入後に封栓２３で閉塞される。
【００２１】
また、封口板１７には、注液口１７ａとは反対側の箇所に安全弁用孔部１７ｂが形成されている。図１に示すように、安全弁用孔部１７ｂは、封口板１７の下面にクラッド工法で設けられたアルミニウム箔膜２４で閉塞されており、この樹脂膜２４における安全弁用孔部１７ｂを塞いでいる部分は、電池内圧の上昇時に破断してガスを外部に放出するための安全弁２４ａを構成している。一方、電池ケース８の底壁下面には正極ターミナル２７が溶接されている。したがって、この非水電解液電池は、電池ケース８が正極で、リベットからなる負極ターミナル２１が負極となる。
【００２２】
図３（ａ）は、正極集電用リード１０または負極集電用リード１１の各々のリード片部１５，１６の一端部を正極板２８または負極板２９の正極側芯材３０または負極側芯材３１に接続した状態を示す斜視図である。正極板２８はアルミニウムからなる正極側芯材３０の両面に正極活物質３２を塗着して構成され、負極板２９は銅からなる負極側芯材３１の両面に負極活物質３３を塗着して構成されている。すなわち、正極板２８および負極板２９は、形成素材が異なるだけで、共に同一構成であり、リード１０，１１との接続形態も同様であるので、同図には正負両方の符号を付してある。
【００２３】
この実施の形態では、正，負極板２８，２９の各々の芯材３０，３１が８〜２０μｍ以下の可及的に小さい厚みｔ１に形成されている。これに伴って、正、負極側集電用リード１０，１１の各々の薄肉短冊状のリード片部１５，１６の厚みｔ２は、５０μｍ以下に極めて薄く設定されており、このリード片部１５，１６の他端部に厚みｔ３の大きな接続部１２，１３が一体に形成されている。なお、芯材３０，３１とこれの両側の活物質３２，３３を含む極板２８，２９全体の厚みｔは１２０〜１８０μｍである。
【００２４】
これに対し従来の非水電解液電池の極板は、比較のために同図（ｂ）に示すように、芯材３０，３１の厚みＴ１が３０μｍ程度であり、それに伴ってリード２の厚みＴ２は１００μｍ程度に設定されている。なお、芯材３０，３１とこれの両側の活物質３２，３３を含む極板全体の厚みｔは、上記実施の形態と同様に１４０〜１９０μｍ程度である。
【００２５】
したがって、上記実施の形態では、正，負極板２８，２９の全体の厚みｔが従来の極板と同様になるように設定した場合、芯材３０，３１の厚みｔ１が薄くなった分だけ単位体積当たりの電池容量の増大を図ることができる。また、正，負極板２８，２９は正、負極集電用リード１０，１１の各々のリード片部１５，１６の一端部を芯材３０，３１の巻き始め端に溶接して渦巻状に巻回されるので、リード片部１５，１６の厚みｔ２が従来の１００μｍから５０μｍと薄くなった分だけ電極群９における渦巻状の中央部分が薄くなるから、従来と同様の外形を有する電極群９を構成する場合に渦巻状の中央部分が薄くなった分だけ巻回数を増やすことができ、これによっても単位体積当たりの電池容量が約２％程度向上する。
【００２６】
上記実施の形態の非水電解液電池では、正，負極側芯材３０，３１および正、負極集電用リード１０，１１の各々のリード片部１５，１６の厚みｔ１，ｔ２を薄くして単位体積当たりの電池容量の向上を図りながらも、厚みｔ２が薄いリード片部１５，１６と封口板１７および負極端子板１８との溶接部分には、十分な接合強度や機械的強度を確保できる。すなわち、図３に明示するように、正，負極集電用リード１０，１１は、一端側が芯材３０，３１に溶接により接続されたリード片部１５，１６の他端部に厚みｔ３の大きな正，負極側接続部１２，１３が一体形成された形状を有しているので、正，負極側接続部１２，１３の厚みｔ３は溶接対象の封口板１７または負極端子板１８の厚みに適合するよう設定できるから、不具合が発生することなく溶接することができる。この点について、図４を参照しながら詳述する。
【００２７】
図４（ａ）は、正極集電用リード１０を封口板１７に抵抗溶接する状態を示した縦断面図である。電池ケース８内に収納した電極群９から枠体１４の挿通孔１４ａを通じて取り出した正極集電用リード１０は、これの他端部の正極側溶接部１２が封口板１７に対し一対の抵抗溶接電極４Ａ，４Ｂを用いて抵抗溶接することにより、同図（ｂ）に示すように、正極側溶接部１２が封口板１７に接合される。このとき、正極側接続部１２は、封口板１７と略同じ厚みに設定されているので、封口板１７とほぼ同時に溶けて高い接合強度で接合され、その接合部の周辺に亀裂が生じたり、孔が開いたりするといった不具合が生じることがないので、高い機械的強度を確保できる。なお、同図に符号のみ示しているように、負極集電用リード１１の負極側接続部１３の負極端子板１８への接続は、上述した正極集電用リード１０と同様に支障なく抵抗溶接することにより行える。
【００２８】
ところで、上記正極集電用リード１０は、非水電解液に対して優れた耐腐食性を有して取扱い易いアルミニウムを素材として形成され、負極集電用リード１１はニッケルを素材として形成されている。一方、上述したように、正極側芯材３０アルミニウムで形成され、負極側芯材３１は銅により形成されている。したがって、正極集電用リード１０と正極側芯材３０とは、同一素材であることから、容易に抵抗溶接によって接合できる。これに対し、ニッケル製の負極集電用リード１１は、銅製の負極側芯材３１に対しレーザー溶接または超音波溶接によって接合することになる。ところが、レーザー溶接または超音波溶接は何れも大掛かりな装置を必要とし、特に超音波溶接では、超音波を照射するホーンの磨耗が激しいために、このホーンを早期に交換する必要があり、大量生産に問題がある。
【００２９】
そこで、上記実施の形態では、負極側芯材３１における少なくとも負極集電用リード１１の溶接箇所が、表面処理を施すことによって表面が粗面化されている。これにより、負極集電用リード１１と負極側芯材３１とは、粗面化によって接触抵抗が上がるから、抵抗溶接によって支障なく接合することができ、上記実施の形態の非水電解液電池をコストダウンしながらも生産性良く大量生産することが可能となる。
【００３０】
図５（ａ）〜（ｅ）は、上記実施の形態の非水電解液電池に好適に用いることができる種類の異なる正極集電用または負極集電用のリード１０，１１を示したものであり、これらは正極集電用および負極集電用の双方に用いることができるが、いま、正極集電用リード１０として説明する。（ａ）の正極集電用リード１０は、金型を用いた成形加工により、正極側リード片部１５の端部に矩形状の正極側接続部１２を一体に有した形状に形成されたものであり、生産性良く大量生産できる。
【００３１】
（ｂ）の正極集電用リード１０は、（ａ）のものと同様に金型を用いた成形加工によって形成したのちに、正極側接続部１２における薄肉短冊状部のリード片部との境界部分にトリミング加工を施してテーパー面３４を形成したものである。この正極集電用リード１０では、（ａ）のものと同様に生産性良く大量生産できる効果を得られるのに加えて、組立時においてリード片部１５を折曲させる際に接続部１２とリード片部１５との境界部分に生じ易い切断や亀裂をテーパー面３４によって確実に防止できる利点がある。
【００３２】
（ｃ）の正極集電用リード１０は、薄肉短冊状のリード片部１５の端部を交互に反対方向に折り畳むようにして重ね合わせたのちに、この重ね合わせ部を加圧加工により圧潰することによって接続部１２を形成したものである。（ｄ）の正極集電用リード１０は、薄肉短冊状のリード片部の端部を渦巻状に巻き込んで重ね合わせたのちに、この重ね合わせ部を加圧加工により圧潰することによって接続部１２を形成したものである。この（Ｃ），（ｄ）の各正極用集電リード１０は、例えば金属箔を単なる薄肉短冊状に切断するだけでリード片部１５を形成でき、そのリード片部１５の端部に折曲および加圧の加工を施すだけで接続部１２を形成でき、特に、この正極用集電リード１０は加工性に優れたアルミニウムを素材とするので、接続部１２を容易に形成することができ、やはり生産性良く大量生産できる。
【００３３】
（ｅ）の正極集電用リード１０は、例えば金属箔を単なる薄肉短冊状に切断して形成したリード片部１５の端部に、矩形状の接続部１２を接着手段などによって取り付けるものであり、金型による成形加工や折曲および加圧の加工が不要となるので、やはり所要の形状を有するものを生産性良く大量生産できる。
【００３４】
【発明の効果】
以上のように本発明の非水電解液電池によれば、正、負極集電用リードのリード片部の他端部に大きな厚みの溶接用の接続部を備えた構成としたので、上記リード片部の厚みを可及的に薄く設定しても、接続部を介して厚みの大きな封口板などに対し亀裂や穿孔などの不具合が生じることなく抵抗溶接にて接合することができ、十分な接合強度や機械的強度を確保できる。この効果を得ながらも、正、負極集電用リードの各リード片部は、上述のように厚みを可及的に薄くできるので、正，負極板の各芯材および正、負極集電用リードの各々のリード片部の厚みを共に薄くして単位体積当たりの電池容量の向上を図ることができる。
【００３５】
また、本発明の非水電解液電池の製造方法によれば、アルミニウム製の正極集電用リードのリード片部の他端に設けた厚みの大きい接続部を同一素材のアルミニウム製の封口板に溶接により接合し、ニッケル製の負極集電用リードのリード片部の他端に設けた厚みの大きい接続部を、絶縁ガスケットにより封口板に絶縁して配設した負極ターミナルに溶接により接合するので、本発明の非水電解液電池を不具合の発生を防止しながら生産性良く製造することができる。
【図面の簡単な説明】
【図１】本発明の一実施の形態に係る非水電解液電池を示す縦断面図。
【図２】同上の非水電解液電池を示す分解斜視図。
【図３】（ａ）は同上の非水電解液電池におけるリードを極板の芯材に接続した状態を示す斜視図、（ｂ）は比較のために示した従来の非水電解液電池におけるリードを極板の芯材に接続した状態を示す斜視図。
【図４】（ａ）は同上の非水電解液電池の製造過程における正極集電用リードを封口板に抵抗溶接する状態を示す縦断面図、（ｂ）は組み立て後の切断側面図。
【図５】（ａ）〜（ｅ）はそれぞれ同上の非水電解液電池における種類の異なる正，負極集電用リードをそれぞれ示す斜視図または分解斜視図。
【図６】（ａ），（ｂ）は従来の非水電解液電池の製造過程を示す一部の縦断面図および側面図。
【符号の説明】
９電極群
８電池ケース
１０正極集電用リード
１１負極集電用リード
１２正極側接続部
１３負極側接続部
１５正極側リード片部
１６負極側リード片部
１７封口板
２０上部絶縁ガスケット（絶縁ガスケット）
２１負極ターミナル（電極ターミナル）
２８正極板
２９負極板
３０正極側芯材
３１負極側芯材
ｔ１芯材の厚み
ｔ２リードの厚み[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-aqueous electrolyte (organic solvent-based electrolyte) battery such as a lithium ion secondary battery that is a sealed battery having a small capacity but a large capacity, and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, portable and cordless electronic devices such as AV devices or personal computers and portable communication devices have been rapidly promoted. Conventionally, nickel cadmium batteries and nickel metal hydride batteries have been mainly used as power sources for driving these electric devices. However, in recent years, lithium batteries that can be rapidly charged, have high energy density, and are highly safe. Non-aqueous electrolyte secondary batteries represented by ion secondary batteries are becoming mainstream. In this non-aqueous electrolyte secondary battery, it is promoted to be a sealed type excellent in high energy density and load characteristics, and to be a square shape suitable for thinning of the device and having a high space effect.
[0003]
By the way, in recent years, there is a high demand for non-aqueous electrolyte secondary batteries to further improve battery capacity per unit volume. Therefore, conventionally, for the purpose of improving the battery capacity per unit volume, the core material of the positive and negative electrode plates (generally, the positive electrode plate is made of an aluminum core material and the negative electrode plate is made of a copper core material). It is considered to adopt a means for connecting the positive and negative current collecting leads to the core material of the positive and negative electrode plates by resistance welding or the like.
[0004]
[Problems to be solved by the invention]
In general, in resistance welding, it is preferable that there is no significant difference between the thicknesses of both of the objects to be welded. As described above, the positive and negative current collectors correspond to the thinning of the cores of the positive and negative electrodes. It is possible to reduce the thickness of each lead. However, the sealing plate that welds the end of the positive electrode current collecting lead or the negative electrode current collecting lead opposite to the welded portion with the core member may have a predetermined pressure resistance performance against an increase in battery internal pressure. Since it is necessary, it must be set several times as thick as the core material. Therefore, as shown in FIG. 6A, the other end portion of the thin lead 2 whose one end is connected to the core material (not shown) of the electrode group 1 is a sealing plate having a thickness several times that of the lead 2. 3, when the resistance welding is performed using the pair of resistance welding electrodes 4A and 4B, the thin lead 2 is melted before the sealing plate 3 at the time of welding, so that welding is performed as shown in FIG. Cracks are generated in the periphery of the part, or a hole is formed by sparking, so that not only the welding joint strength and mechanical strength are reduced, but also the internal resistance during charging and discharging of the battery is increased. The problem arises.
[0005]
Therefore, the present invention has been made in view of the above-described conventional problems, and it is possible to improve the battery capacity per unit volume without causing a decrease in bonding strength or mechanical strength between the current collecting lead and the sealing plate. An object of the present invention is to provide a non-aqueous electrolyte battery having a configuration that can be achieved and a method for manufacturing the same.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a nonaqueous electrolyte battery according to the present invention includes a battery case containing an electrode group and an electrolyte and serving as one electrode, and an opening for the battery case sealed. A sealing plate electrically connected to each other, an electrode terminal which is disposed in an insulating state on the sealing plate via an insulating gasket and serves as the other electrode, and each core material of the positive and negative bipolar plates of the electrode group 1 is connected to one end of each of the sealing plate and the electrode terminal by resistance welding , and one end of each is joined to the electrode group. And a negative electrode current collecting lead, the thickness of each of the positive and negative bipolar plates is set to 8 to 20 μm, and the positive electrode current collecting lead and the negative electrode current collecting lead have a thickness of 50 μm or less. Thin strip-shaped set to The lead piece portion has a connection portion formed at a thickness larger than that of the lead piece portion at the other end portion.
[0007]
In this non-aqueous electrolyte battery, since the connecting portion having a large thickness is provided at the other end portion of the lead piece portion of the positive and negative electrode current collecting leads, the thickness of the lead piece portion is made as thin as 50 μm or less. Even if it sets, it can join by resistance welding, without producing troubles, such as a crack and a piercing | piercing, with respect to a sealing plate with a large thickness etc. via a connection part, and can ensure sufficient joining strength and mechanical strength. While obtain this effect, positive, the lead piece of the negative electrode current collecting lead, since the thickness as described above can be below as much as possible thin 50 [mu] m, positive, the thickness of the core members of the negative electrode plate 8 The battery capacity per unit volume can be improved by reducing the thickness of each lead piece of the positive and negative current collecting leads to ˜20 μm to 50 μm or less .
[0009]
According to this configuration, when the total thickness of the positive and negative electrode plates is set to be the same as that of the conventional electrode plate, the battery capacity per unit volume can be increased by the thickness of the core material. it can. The positive and negative electrode plates are wound in a spiral shape by joining one end of each lead piece of the positive and negative current collecting leads to the winding start end or winding end of the core member. Since the spiral central part of the electrode group becomes thinner as the thickness of the electrode becomes thinner, when forming an electrode group having the same external shape as before, the number of turns is increased by the amount of the thinner spiral central part. As a result, the battery capacity per unit volume can be further improved.
[0010]
Further, the positive electrode current collecting lead and the negative electrode current collecting lead in the above invention are formed by molding or / and trimming into a shape integrally having a connection portion at the other end portion of the lead piece portion. Is preferred. According to this configuration, the leads can be mass-produced with high productivity.
[0011]
On the other hand, the positive electrode current collecting lead and the negative electrode current collecting lead in the above invention are a crushing means by applying pressure processing after the other end portion of the thin strip-like lead piece portion is folded or spirally wound. It can also be assumed that a connection portion is formed. According to this configuration, for example, a lead piece can be formed simply by cutting a metal foil into a thin strip shape, and a connecting portion can be formed simply by bending and pressing the end of the lead piece. Therefore, in particular, when aluminum having excellent workability is used as a material, the connecting portion can be easily formed, and mass production can be performed with high productivity.
[0012]
In addition, the positive electrode current collecting lead and the negative electrode current collecting lead in the above invention may be formed by attaching a connecting portion having a thickness larger than that of the lead piece portion to the other end portion of the thin strip-like lead piece portion. it can. According to this configuration, for example, a metal foil can be formed by attaching a thick connecting portion to the end portion of a lead piece portion formed by cutting a thin strip into a thin strip shape by means of an adhesive or the like. No need for bending, pressing and pressing, etc., so that a product having a required shape can be mass-produced at low cost.
[0013]
In the method for producing a non-aqueous electrolyte battery according to the present invention, one end of a lead strip portion formed in a thin strip shape in the positive electrode current collecting lead and the negative electrode current collecting lead is bonded to each core material of the positive electrode plate and the negative electrode plate. A step of housing the formed electrode group in the battery case, and joining a connecting portion formed at a thickness larger than the other end portion of the lead piece portion of the positive electrode current collecting lead to an aluminum sealing plate A step of joining a connecting portion formed at a thickness larger than the other end of the lead piece portion of the negative electrode current collecting lead to a negative electrode terminal disposed in an insulating state on the sealing plate; The step of sealing the battery case by fitting and joining the sealing plate to the opening of the battery case, and after injecting the electrolyte into the battery case from the injection hole of the sealing plate, The process of sealing the injection hole It is characterized by having.
[0014]
In this non-aqueous electrolyte battery manufacturing method, a thick connecting portion provided at the other end of the lead piece portion of the aluminum positive electrode current collecting lead is joined to an aluminum sealing plate made of the same material by welding, for example, Since the thick connecting portion provided at the other end of the lead piece portion of the nickel negative electrode current collecting lead is joined to the negative electrode terminal that is insulated from the sealing plate by the insulating gasket, the non-aqueous electrolysis of the present invention The liquid battery can be manufactured with good productivity while preventing the occurrence of defects.
[0015]
In the manufacturing method of the above invention, at least a joint portion of the negative electrode current collecting lead in the copper core material of the negative electrode plate is subjected to surface treatment to be roughened, and the roughened core material portion is used for collecting the negative electrode current. It is preferable to join one end of the lead piece of the lead by resistance welding. Thereby, for example, the negative electrode current collecting lead made of nickel can be resistance-welded to the negative electrode core material made of copper. That is, when the negative electrode current collecting lead and the negative electrode side core material are brought into contact with each other, the contact resistance increases due to the roughening of the surface of the negative electrode side core material. It is possible to mass-produce liquid batteries with high productivity while reducing costs.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a nonaqueous electrolyte battery according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view of the nonaqueous electrolyte battery. In these figures, an electrode group 9 having an oval cross-sectional shape is housed in a battery case 8 made of aluminum with a bottomed rectangular tube by winding a positive electrode plate, a negative electrode plate and a separator in a spiral shape. Yes.
[0017]
The positive electrode current collecting lead 10 made of aluminum and the negative electrode current collecting lead 11 made of nickel, as clearly shown in FIG. 2, are each of the positive electrode side and negative electrode side lead piece portions 15 and 16 each having a thin strip shape. The positive electrode side connection portion 12 and the negative electrode side connection portion 13 for welding, which are set to a large thickness, are integrally formed at the end portions. One end side (lower end side in the figure) of each of the positive electrode side and negative electrode side lead pieces 15 and 16 is welded to the core material of each of the positive electrode plate and the negative electrode plate and taken out from the electrode group 9. In order to improve the battery capacity per unit volume, the positive electrode plate and the negative electrode plate are set as thin as possible. Details of this will be described later. The lead piece portions 15 and 16 of each of the positive electrode current collecting lead 10 and the negative electrode current collecting lead 11 are set to have a thin thickness corresponding to the above-described reduction in the thickness of the core material.
[0018]
After the other end portions of the positive electrode current collecting lead 10 and the negative electrode current collecting lead 11 are inserted into the insertion holes 14a and 14b of the frame body 14, respectively, the positive electrode side connecting portion 12 at the other end is formed of flat aluminum. The negative electrode side connecting portion 13 is welded to the negative electrode terminal plate 18 and the sealing plate 17. As this welding, any one of resistance welding, laser welding, and ultrasonic welding can be employed. In this embodiment, resistance welding is performed.
[0019]
The frame body 14 is fitted in the vicinity of the opening of the battery case 8, and the sealing plate 17 is laser-welded to the battery case 8 while being supported on the frame body 14. The opening is sealed. An upper insulating gasket 20 is fitted in the recess 19 at the center of the sealing plate 17, and the negative electrode terminal 21 made of nickel-plated iron rivets is connected to the sealing plate 17 via the upper insulating gasket 20. The insulating gasket 20 is inserted into the insertion holes of the upper insulating gasket 20 and the sealing plate 17 in an insulated state. The lower portion of the negative terminal 21 through which the upper insulating gasket 20 and the sealing plate 17 are inserted is further inserted into the mounting holes 22a and 18a of the lower insulating gasket 22 and the negative terminal plate 18, respectively. It is caulked. Thus, the negative electrode terminal plate 18 is electrically insulated from the sealing plate 17 via the lower insulating gasket 22 and is attached to the negative electrode terminal 21 via the caulking portion in an electrically connected state.
[0020]
During assembly, the sealing plate 17 is fitted and welded to the opening of the battery case 8 with the upper insulating gasket 20, the lower insulating gasket 22, and the negative terminal plate 18 attached by the negative terminal 21. Thereafter, an electrolytic solution (not shown) is injected into the battery case 8 through the injection hole 17 a of the sealing plate 17. The liquid injection hole 17a is closed with a sealing plug 23 after the electrolyte solution is injected.
[0021]
The sealing plate 17 is formed with a safety valve hole 17b at a location opposite to the liquid injection port 17a. As shown in FIG. 1, the safety valve hole 17 b is closed by an aluminum foil film 24 provided by a cladding method on the lower surface of the sealing plate 17, and the safety valve hole 17 b in the resin film 24 is blocked. The portion constitutes a safety valve 24a for breaking and releasing gas to the outside when the battery internal pressure increases. On the other hand, a positive terminal 27 is welded to the bottom surface of the bottom wall of the battery case 8. Therefore, in this nonaqueous electrolyte battery, the battery case 8 is the positive electrode and the negative terminal 21 made of rivets is the negative electrode.
[0022]
FIG. 3A shows one end portion of each of the lead piece portions 15 and 16 of the positive electrode current collecting lead 10 or the negative electrode current collecting lead 11 as the positive electrode side core material 30 or the negative electrode side core of the positive electrode plate 28 or the negative electrode plate 29. It is a perspective view which shows the state connected to the material 31. FIG. The positive electrode plate 28 is configured by applying a positive electrode active material 32 on both surfaces of a positive electrode side core material 30 made of aluminum, and the negative electrode plate 29 is formed by applying a negative electrode active material 33 on both surfaces of a negative electrode side core material 31 made of copper. Configured. That is, the positive electrode plate 28 and the negative electrode plate 29 have the same configuration except for the formation material, and the connection form with the leads 10 and 11 is also the same. is there.
[0023]
In this embodiment, the core members 30 and 31 of the positive and negative electrode plates 28 and 29 are formed to have a thickness t1 as small as possible of 8 to 20 μm or less. Accordingly, the thickness t2 of the thin strip-like lead pieces 15 and 16 of each of the positive and negative current collecting leads 10 and 11 is set to be very thin to 50 μm or less. The connecting portions 12 and 13 having a large thickness t3 are integrally formed at the other end portion of 16. The total thickness t of the electrode plates 28 and 29 including the core materials 30 and 31 and the active materials 32 and 33 on both sides thereof is 120 to 180 μm.
[0024]
On the other hand, the electrode plate of the conventional non-aqueous electrolyte battery has a thickness T1 of the core materials 30 and 31 of about 30 μm as shown in FIG. T2 is set to about 100 μm. In addition, the thickness t of the whole electrode plate including the core materials 30 and 31 and the active materials 32 and 33 on both sides thereof is about 140 to 190 μm as in the above embodiment.
[0025]
Therefore, in the above embodiment, when the total thickness t of the positive and negative electrode plates 28 and 29 is set to be the same as that of the conventional electrode plate, the unit corresponding to the thickness t1 of the core members 30 and 31 is reduced. The battery capacity per volume can be increased. The positive and negative electrode plates 28 and 29 are wound in a spiral shape by welding one end of each of the lead pieces 15 and 16 of the positive and negative current collecting leads 10 and 11 to the winding start ends of the core members 30 and 31. Since the lead strips 15 and 16 are thinned, the spiral central portion of the electrode group 9 becomes thinner by the thickness of the lead pieces 15 and 16 from 50 μm to 100 μm. The number of turns can be increased as much as the spiral central portion becomes thinner, and this also improves the battery capacity per unit volume by about 2%.
[0026]
In the non-aqueous electrolyte battery of the above embodiment, the thicknesses t1 and t2 of the lead pieces 15 and 16 of the positive and negative electrode side core members 30 and 31 and the positive and negative electrode current collecting leads 10 and 11 are reduced. While improving the battery capacity per unit volume, sufficient bonding strength and mechanical strength can be secured at the welded portion between the lead piece portions 15 and 16 having a small thickness t2 and the sealing plate 17 and the negative electrode terminal plate 18. . That is, as clearly shown in FIG. 3, the positive and negative current collecting leads 10 and 11 have a large thickness t3 at the other end portions of the lead piece portions 15 and 16 whose one ends are connected to the core members 30 and 31 by welding. Since the positive and negative electrode side connecting portions 12 and 13 are integrally formed, the thickness t3 of the positive and negative electrode side connecting portions 12 and 13 matches the thickness of the sealing plate 17 or the negative electrode terminal plate 18 to be welded. Therefore, welding can be performed without causing any trouble. This point will be described in detail with reference to FIG.
[0027]
FIG. 4A is a longitudinal sectional view showing a state in which the positive electrode current collecting lead 10 is resistance-welded to the sealing plate 17. The positive electrode current collecting lead 10 taken out from the electrode group 9 housed in the battery case 8 through the insertion hole 14 a of the frame body 14 has a positive electrode side welding portion 12 at the other end thereof paired with the sealing plate 17 by a pair of resistance welding. By resistance welding using the electrodes 4A and 4B, the positive electrode side welded portion 12 is joined to the sealing plate 17 as shown in FIG. At this time, since the positive electrode side connecting portion 12 is set to have substantially the same thickness as the sealing plate 17, it melts almost simultaneously with the sealing plate 17 and is bonded with high bonding strength, and a crack is generated around the bonding portion, Since there is no problem such as opening of holes, high mechanical strength can be ensured. Note that, as indicated by only the reference numeral in the figure, the negative electrode current collecting lead 11 is connected to the negative electrode terminal plate 18 of the negative electrode side connecting portion 13 by resistance welding similarly to the positive electrode current collecting lead 10 described above. You can do that.
[0028]
By the way, the positive electrode current collecting lead 10 is made of aluminum which has excellent corrosion resistance against non-aqueous electrolyte and is easy to handle, and the negative electrode current collecting lead 11 is made of nickel. Yes. On the other hand, as described above, the positive electrode side core material 30 is formed of aluminum, and the negative electrode side core material 31 is formed of copper. Therefore, since the positive electrode current collecting lead 10 and the positive electrode side core member 30 are the same material, they can be easily joined by resistance welding. On the other hand, the negative electrode current collecting lead 11 made of nickel is joined to the negative electrode side core material 31 made of copper by laser welding or ultrasonic welding. However, both laser welding and ultrasonic welding require large-scale equipment. Especially in ultrasonic welding, since the horn that irradiates ultrasonic waves is heavily worn, it is necessary to replace this horn early and mass production There is a problem.
[0029]
Therefore, in the above embodiment, the surface of the negative electrode side core material 31 at least where the negative electrode current collecting lead 11 is welded is subjected to surface treatment so that the surface is roughened. As a result, the negative electrode current collecting lead 11 and the negative electrode side core material 31 have a contact resistance that is increased by roughening, and can be joined without any problem by resistance welding. The nonaqueous electrolyte battery of the above embodiment is It is possible to mass-produce with good productivity while reducing costs.
[0030]
5 (a) to 5 (e) show different types of positive and negative current collecting leads 10 and 11 that can be suitably used in the non-aqueous electrolyte battery of the above embodiment. These can be used for both positive electrode current collection and negative electrode current collection, but will now be described as a positive electrode current collection lead 10. (A) The positive electrode current collecting lead 10 is formed into a shape integrally having a rectangular positive electrode side connection portion 12 at an end portion of the positive electrode side lead piece portion 15 by molding using a mold. It can be mass-produced with high productivity.
[0031]
The positive electrode current collecting lead 10 in (b) is formed by molding using a mold in the same manner as in (a), and then the boundary between the thin strip-shaped portion in the positive electrode side connecting portion 12 and the lead piece portion. The tapered surface 34 is formed by trimming the portion. In the positive electrode current collecting lead 10, in addition to obtaining the effect of mass production with high productivity as in the case of (a), the connecting portion 12 and the lead when the lead piece portion 15 is bent during assembly. There exists an advantage which can prevent reliably the cutting | disconnection and crack which are easy to occur in the boundary part with the piece part 15 by the taper surface 34. FIG.
[0032]
(C) The positive electrode current collecting lead 10 is overlapped by alternately folding the end portions of the thin strip-like lead piece portions 15 in opposite directions, and then crushing the overlapped portion by pressure processing. Thus, the connecting portion 12 is formed. The positive current collecting lead 10 in (d) is obtained by winding the end portions of the thin strip-shaped lead piece portions in a spiral shape and then superimposing them, and then crushing the overlapped portion by pressure processing to connect the connecting portion 12. Is formed. Each of the positive electrode current collecting leads 10 of (C) and (d) can form a lead piece portion 15 by simply cutting a metal foil into a thin strip shape, for example, and bends at the end of the lead piece portion 15. In addition, the connecting portion 12 can be formed simply by applying pressure processing, and in particular, since the positive electrode current collecting lead 10 is made of aluminum having excellent workability, the connecting portion 12 can be easily formed. It can be mass-produced with good productivity.
[0033]
The positive electrode current collecting lead 10 in (e) is one in which, for example, a rectangular connecting portion 12 is attached to an end portion of a lead piece portion 15 formed by cutting a metal foil into a simple thin strip shape by an adhesive means or the like. In addition, since there is no need to perform molding processing, bending and pressurizing processing using a mold, it is possible to mass-produce a product having a required shape with high productivity.
[0034]
【The invention's effect】
As described above, according to the nonaqueous electrolyte battery of the present invention, the lead is provided with a connecting portion for welding having a large thickness at the other end of the lead piece of the positive and negative current collecting leads. Even if the thickness of one part is set as thin as possible, it can be joined by resistance welding to the sealing plate with a large thickness through the connecting part without causing defects such as cracks and perforations. Bonding strength and mechanical strength can be secured. While obtaining this effect, the lead piece portions of the positive and negative current collecting leads can be made as thin as possible as described above. It is possible to improve the battery capacity per unit volume by reducing the thickness of each lead piece portion of the lead.
[0035]
Further, according to the method for producing a non-aqueous electrolyte battery of the present invention, the thick connecting portion provided at the other end of the lead piece portion of the aluminum positive electrode current collecting lead is formed on the aluminum sealing plate made of the same material. Joined by welding, the thick connecting part provided at the other end of the lead piece of the nickel negative electrode current collecting lead is joined by welding to the negative electrode terminal that is insulated from the sealing plate by an insulating gasket. The non-aqueous electrolyte battery of the present invention can be manufactured with good productivity while preventing the occurrence of problems.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a nonaqueous electrolyte battery according to an embodiment of the present invention.
FIG. 2 is an exploded perspective view showing the same nonaqueous electrolyte battery.
FIG. 3A is a perspective view showing a state in which the lead in the above nonaqueous electrolyte battery is connected to the core of the electrode plate, and FIG. 3B is a conventional nonaqueous electrolyte battery shown for comparison. The perspective view which shows the state which connected the lead | read | reed to the core material of the electrode plate.
4A is a longitudinal sectional view showing a state in which the positive electrode current collecting lead is resistance-welded to the sealing plate in the manufacturing process of the nonaqueous electrolyte battery, and FIG. 4B is a cut side view after assembly.
FIGS. 5A to 5E are a perspective view or an exploded perspective view showing positive and negative current collecting leads of different types in the nonaqueous electrolyte battery of the same.
6A and 6B are a partial longitudinal sectional view and a side view showing a manufacturing process of a conventional non-aqueous electrolyte battery.
[Explanation of symbols]
9 Electrode group 8 Battery case 10 Positive electrode current collecting lead 11 Negative electrode current collecting lead 12 Positive electrode side connecting portion 13 Negative electrode side connecting portion 15 Positive electrode side lead piece portion 16 Negative electrode side lead piece portion 17 Sealing plate 20 Upper insulating gasket (insulating gasket) )
21 Negative terminal (electrode terminal)
28 Positive electrode plate 29 Negative electrode plate 30 Positive electrode side core material 31 Negative electrode side core material t1 Core material thickness t2 Lead thickness

Claims

A battery case that houses an electrode group and an electrolyte and serves as one electrode;
A sealing plate electrically sealed by sealing the opening of the battery case;
An electrode terminal which is disposed in an insulating state via an insulating gasket on the sealing plate and becomes the other electrode;
One end of each of the positive and negative bipolar plates of the electrode group is joined to each other and taken out from the electrode group, and the other end is one or the other of the sealing plate and the electrode terminal. Each having a positive current collecting lead and a negative current collecting lead joined by resistance welding ,
The thickness of each of the positive and negative bipolar plates is set to 8 to 20 μm,
The positive electrode current collecting lead and the negative electrode current collecting lead are connected to the other end portion of the thin strip-shaped lead piece portion whose thickness is set to 50 μm or less, and is formed to have a larger thickness than the lead piece portion. A nonaqueous electrolyte battery characterized by comprising:

Positive current collector lead and the negative electrode current collecting lead is No placement claim 1 Symbol the connecting portion to the other end of the lead piece and is formed by molding and / or trimming the shape integrally having Non-aqueous electrolyte battery.

The positive current collecting lead and the negative current collecting lead are formed by connecting the other end of the thin strip-shaped lead piece part by folding or spiraling, and then applying pressure processing to form the connection part. non-aqueous electrolyte battery according to claim 1 Symbol placement was one in which the.

Positive current collector lead and the negative electrode current collecting lead is claim 1 Symbol mounting the other end portion of the thin strip-like lead piece portion than the lead piece is formed by sticking a large connection of thickness Non-aqueous electrolyte battery.

A step of accommodating in the battery case an electrode group in which one end portion of the lead strip portion formed in a thin strip shape in the positive electrode current collecting lead and the negative electrode current collecting lead is bonded to each core material of the positive electrode plate and the negative electrode plate; ,
A connecting portion formed to a thickness larger than the other end of the lead piece portion of the positive electrode current collecting lead is welded to an aluminum sealing plate, and the lead of the negative electrode current collecting lead is joined. A step of joining a connecting portion formed on the other end of the one piece with a thickness larger than this to a negative electrode terminal disposed in an insulating state on the sealing plate;
Fitting the sealing plate into the opening of the battery case and sealing the battery case;
And a step of sealing the liquid injection hole after injecting the electrolyte from the liquid injection hole of the sealing plate into the battery case.

A surface treatment is applied to at least a joining portion of the negative electrode current collecting lead in the copper core material of the negative electrode plate to roughen the surface, and one end of the lead piece portion of the negative current collecting lead is provided on the roughened core material portion. nonaqueous electrolyte manufacturing method of battery according to claim 5 Symbol placement was to join the parts resistance welding to.