JP3883728B2

JP3883728B2 - Cylindrical storage battery

Info

Publication number: JP3883728B2
Application number: JP04641099A
Authority: JP
Inventors: 和洋北岡
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 1999-02-24
Filing date: 1999-02-24
Publication date: 2007-02-21
Anticipated expiration: 2019-02-24
Also published as: JP2000251867A

Description

【０００１】
【発明の属する技術分野】
本発明はニッケル・水素蓄電池、ニッケル・カドミウム蓄電池、リチウムイオン蓄電池などの正極板および負極板をセパレータを介して渦巻状に巻回した渦巻状電極体を備えた円筒型蓄電池に係り、特に、渦巻状電極体と集電体および集電体と外部端子との導電接続に関する。
【０００２】
【従来の技術】
従来、ニッケル・カドミウム蓄電池、ニッケル・水素蓄電池、リチウムイオン蓄電池などの円筒型蓄電池においては、正極板と負極板とをセパレータを介して渦巻状に巻回して渦巻状電極体とする。そして、このように形成した渦巻状電極体の負極板の芯体を負極集電体に溶接するとともに、渦巻状電極体の正極板の芯体を正極集電体に溶接した後、この渦巻状電極体を負極端子を兼ねる金属製円筒状外装缶に挿入し、負極集電体を金属製外装缶の底部に溶接するとともに、正極集電体より延出する集電リード部を正極端子を兼ねる封口体の底部に溶接して構成するにしていた。
【０００３】
あるいは、渦巻状電極体を負極端子を兼ねる金属製円筒状外装缶に挿入し、渦巻状電極体の負極板の芯体を金属製外装缶の底部に接触させるとともに、負極板の芯体より延出する集電タブを金属製外装缶の底部に溶接する。一方、渦巻状電極体の正極板の芯体を正極集電体に溶接し、正極集電体より延出する集電リード部を正極端子を兼ねる封口体の底部に溶接して構成するのが一般的である。
このように渦巻状電極体の負極板の芯体を金属製外装缶の底部に電気的に接続するとともに、渦巻状電極体の正極板の芯体を正極集電体に溶接すると、正極板から正極端子（封口体）までの電流分布、および負極板から負極端子（金属製外装缶）までの電流分布が均一になるため、高率放電特性が向上した蓄電池が得られるようになる。
【０００４】
【発明が解決しようとする課題】
ところで、上述したような円筒型蓄電池を数十アンペア〜数百アンペアの大電流で充放電する場合にあっては、上述した接続部での抵抗に起因する電圧降下が生じて作動電圧が低下し、高電圧が得られないという問題を生じた。
ここで、正・負極の一方の集電体は、渦巻状電極体の一方の極板端部に溶接される集電部（本体部）と封口体の下面に溶接される集電リード部から構成されるが、この集電リード部は本体部により集電された電流が集中するため、この部分の抵抗値が大きいと電圧降下も大きくなる。
【０００５】
そこで、集電リード部の抵抗値を低減させるために集電リード部の厚みを厚くすることが考えらるが、集電リード部と本体部とは一体的に形成されているため、集電リード部の厚みを厚くすると必然的に本体部の厚みも厚くする必要が生じる。しかしながら、本体部の厚みを厚くすると、本体部と渦巻状電極体とを抵抗溶接する際に無効な溶接電流が本体部自体に多く流れて、渦巻状電極体と本体部とを溶接する溶接点に流れる有効な溶接電流が減少し、溶接性が損なわれるという問題を生じた。
このため、特許第２７６２５９９号公報において、本体部の厚みをそのままにして集電リード部の抵抗値を低減させるために複数枚の集電リード部を設けるようすることが提案された。
【０００６】
しかしながら、特許第２７６２５９９号公報において提案された方法にあっては、部品点数が増加するとともに、集電リード部と封口体との溶接が複雑で溶接作業が煩雑になるという問題を生じた。また、従来の集電体にあっては、集電リード部と本体部とが一体的に形成されているため、集電リード部は本体部の端部側に位置するように形成されている。
【０００７】
このため、この集電体が渦巻状電極体に溶接されると、集電リード部は本体部の中心から隔たった位置に存在するため、渦巻状電極体から均一に電気エネルギーを取り出すことができにくくなる。さらに、集電リード部の抵抗値を低減させるために集電リード部の幅を広げれば広げるほど、逆に本体部の面積が減少するため、本体部での集電性が低下するという問題も生じた。
そこで、本発明は上記問題点を解決するためになされたものであって、集電体全体の集電性を損なわずに集電リード部の内部抵抗を低減し、かつ部品点数が少なくて安価な集電体を得て、電圧降下が少ない蓄電池が得られるようにすることを目的とする。
【０００８】
【課題を解決するための手段】
このため、本発明は円筒型蓄電池に用いられる両集電体の少なくとも一方は、２つの略半円形の本体部と、これらの本体部を連結するとともに該本体部と同一厚みで略長方形状で前記本体部と一体的に形成された集電リード部とからなる集電体基材から形成されていて、集電リード部は略半円形の両本体部との境界部で谷折りされるとともに当該集電リード部の中心部で山折りされて該本体部から起立するように折りたたまれて形成されており、集電リード部が折りたたまれたことにより略半円形の両本体部は互いに向き合って略円形状に形成されており、略円形状になされた本体部から起立するように形成された集電リード部が封口体の下面に溶接されている。
【０００９】
このように、両集電体の少なくとも一方は、２つの略半円形の本体部と、これらの本体部を連結するとともに該本体部と同一厚みで略長方形状で前記本体部と一体的に形成された集電リード部とからなる集電体基材から形成されていて、集電リード部は略半円形の両本体部との境界部で谷折りされるとともに当該集電リード部の中心部で山折りされて該本体部から起立するように折りたたまれて形成されていると、集電リード部の厚みは本体部に対して２倍の厚みとなる。このため、本体部と渦巻状電極体との溶接性を損なうことなく、集電リード部の内部抵抗を１／２に減少させることが可能となる。この結果、集電リード部での電圧降下が減少して、高率放電特性および作動電圧が向上した円筒型蓄電池が得られるようになる。
【００１０】
また、集電リード部は前記略半円形の両本体部との境界部で谷折りされ、その中心部で山折りと谷折りが繰り返されて該本体部から起立するように折りたたまれて形成されていると、集電リード部の厚みは本体部に対して４倍の厚みとなる。このため、本体部と極板群との溶接性を損なうことなく、集電リード部の内部抵抗を１／４に減少させることが可能となる。この結果、集電リード部での電圧降下がさらに減少して、高率放電特性および作動電圧がさらに向上した円筒型蓄電池が得られるようになる。
【００１１】
そして、略円形状になされた本体部から起立するように形成された集電リード部が渦巻状電極体の略直径上に位置するように形成されていると、極板群全体から均一に集電できるようになって、大電流充放電時の極板内での電位の偏在を低減し、電極反応の不均一化を軽減して、高率放電特性および作動電圧がさらに向上した円筒型蓄電池が得られるようになる。また、渦巻状電極体の略直径上の位置に集電リード部を配置するようにすると、集電リード部の幅を最大限に広げることが可能となるため、さらに内部抵抗が低減した集電リード部となる。このように集電リード部の幅を最大限に広げても、集電部は渦巻状電極体の略全面に存在するため、集電部の面積が減少することもない。
【００１２】
また、集電リード部が折りたたまれたことにより略半円形の両本体部が互いに向き合って略円形状になるように形成された両本体部が渦巻状電極体の上部に配置された際に同渦巻状電極体の中心部に一致する位置に所定寸法の開口が形成されるように、両本体部あるいは同両本体部と集電リード部との境界部には所定寸法の開口が設けられていると、集電リード部が渦巻電極体の中心上に位置していても、集電リード部を倒すだけで中心位置の開口を確保できるようになる。このため、他方の集電体を外装缶の底部内面に溶接する際に渦巻電極体の中心に溶接電極を容易に挿入できるようになり、この種の円筒型蓄電池の製造が容易になる。
【００１３】
そして、略円形状になされた本体部から起立するように形成された集電リード部の１面の封口体下面に接続固定される部位に突起部や開口を配設したり、あるいは起立するように形成された集電リード部の１面の封口体下面に溶接される部位に同集電リード部より延出するタブを配設するようにすると、突起部や開口の対向部やタブに溶接電流が集中して流れるようになるため、集電リード部と封口体との溶接性が向上する。
【００１４】
【発明の実施の形態】
以下に、本発明の円筒型蓄電池をニッケル・水素蓄電池に適用した場合の一実施の形態を図１〜図１０に基づいて説明する。なお、図１は本発明の第１実施例の集電体の折り曲げ加工前の状態を示す図であり、図２は図１の集電体を折り曲げ加工した状態を示す図であり、図２（ａ）は上面図であり、図２（ｂ）は正面図であり、図２（ｃ）は図２（ａ）の右側側面図である。また、図３は図２の集電体を渦巻状電極体に溶接した状態を示す斜視図である。また、図４は本発明の第２実施例の集電体を渦巻状電極体に溶接した状態を示す図であり、図４（ａ）は斜視図であり、図４（ｂ）は上面図である。
【００１５】
また、図５は図３及び図４の集電リード部を拡大して示す斜視図であり、図６は本発明の第３実施例の集電体を渦巻状電極体に溶接した状態を示す斜視図であり、図７は本発明の第４実施例の集電体を渦巻状電極体に溶接した状態を示す斜視図であり、図８は本発明の第５実施例の集電体を渦巻状電極体に溶接した状態を示す斜視図である。さらに、図９は比較例（従来例）の集電体を渦巻状電極体に溶接した状態を示す斜視図であり、図１０は放電特性を示す図である。
【００１６】
１．渦巻状電極体の作製
ニッケル発泡体（芯体）に水酸化ニッケルを主成分とするペースト状正極活物質を充填し、乾燥させた後、所定の厚みになるまで圧延してニッケル正極板を作製した。一方、パンチングメタル（芯体）に水素吸蔵合金よりなるペースト状負極活物質を充填し、乾燥させた後、所定の厚みになるまで圧延して水素吸蔵合金負極板を作製した。このようにして作成されたニッケル正極板と、水素吸蔵合金負極板とを、ポリプロピレン製不織布からなるセパレータを介して最外周が負極板となるようにして渦巻状に卷回して渦巻状電極体１０を作製した。
【００１７】
２．ニッケル・水素蓄電池の作製
（１）実施例１
まず、図１に示すように、左右の両側に略半円形状の本体部２１，２１と、これらの本体部２１，２１を連結する略長方形状の集電リード部２２と、これらの本体部２１，２１と集電リード部２２との境界部に所定寸法の開口部２３，２３が形成されるように、所定の厚み（例えば０．３ｍｍ）のニッケル金属板を打ち抜いて正極集電体基材２０ａを作製した。なお、各本体部２１，２１の中央部には溝部２４，２４も同時に打ち抜かれており、この溝部２４，２４を設けることにより、無効な溶接電流を減少させる、即ち、有効な溶接電流を増大させることが可能となる。
【００１８】
ついで、この正極集電体基材２０ａの集電リード部２２の中心部の山折り部２５に沿って山折りするとともに、両本体部２１，２１と集電リード部２２との境界部の谷折り部２６，２６に沿って谷折りする折り曲げ加工を施して、図２に示すような形状の正極集電体２０を作製した。
この折り曲げ加工により、略半円形状の本体部２１，２１は互いに対向して略円形状の本体部が形成されるとともに、この対向部に予め形成された溝部２４，２４の他に新たな溝部２７，２７が形成される。一方、集電リード部２２は本体部２１，２１より垂直に起立するとともに、この垂直に起立した集電リード部２２は略円形状に形成された本体部の直径上に位置することとなる。
【００１９】
ついで、このようにして形成した正極集電体２０を上述した渦巻状電極体１０の上部に載置した後、本体部２１，２１の相対向する箇所に一対の溶接電極を当接させてこれらの溶接電極間に溶接電流を流すことにより、渦巻状電極体１０より若干突出した正極板の芯体と本体部２１，２１との接触部を抵抗溶接して固着した。一方、渦巻状電極体１０の下部に図示しない円板状の負極集電体を載置して、同様に一対の溶接電極を当接させて負極板の芯体と負極集電体との接触部を抵抗溶接して固着した。
【００２０】
ついで、図示しない有底円筒形の金属外装缶を用意し、正極集電体２０を溶接した渦巻状電極体を金属外装缶内に挿入した。この後、正極集電体２０の開口部２３より一方の溶接電極を挿入して図示しない負極集電体に当接させるとともに金属外装缶の底部に他方の溶接電極を当接して、負極集電体と金属外装缶の底部とをスポット溶接した。
【００２１】
一方、正極キャップと蓋体（なお、正極キャップと蓋体との間には圧力弁が配置されている）とからなる図示しない封口体を用意し、正極集電体２０の導電リード部２２を封口体の蓋体底部に接触させて、蓋体底部と導電リード部２２とを溶接して接続した。
なお、集電リード部２２には、図５に示すように突起部２８，２８が形成されており、この突起部２８，２８を集電リード部２２に設けることにより、溶接電流が突起部２８，２８に集中して流れるようになるため、集電リード部２２と封口体下面との溶接性が向上する。
この後、金属外装缶内に３０重量％の水酸化カリウム（ＫＯＨ）水溶液よりなる電解液を注液し、封口体を封口ガスケットを介して外装缶の開口部に載置するとともに、この開口部を封口体側にカシメて封口した。これにより、公称容量６．５ＡＨの実施例１の円筒状ニッケル・水素蓄電池Ａを作製した。
【００２２】
（２）実施例２
図４に示すように、略半円形状の本体部３１ａ，３１ｂ（なお、本体部３１ａの方が本体部３１ｂより大きく形成されている）と、集電リード部３２と、開口３３と、溝部３４，３４と備えるように所定形状に打ち抜かれた正極集電体基材を用意する。
この正極集電体基材を用いて、本体部３１ａ，３１ｂが互いに対向して略円形状の本体部が形成され、新たな溝部３７，３７がこの対向部に形成され、さらに、集電リード部３２が本体部３１ａ，３１ｂより垂直に起立するとともに、この垂直に起立した集電リード部３２が略円形状に形成された本体部の直径上より若干ずれた位置に位置するように折り曲げ加工を施して、正極集電体３０を作製した以外は上述した実施例１と同様にして、公称容量６．５ＡＨの実施例２の円筒状ニッケル・水素蓄電池Ｂを作製した。
【００２３】
なお、集電リード部３２には、図５に示すように突起部３８，３８が形成されており、この突起部３８，３８を集電リード部３２に設けることにより、溶接電流が突起部３８，３８に集中して流れるようになるため、集電リード部３２と封口体下面との溶接性が向上する。
【００２４】
（３）実施例３
図６に示すように、略半円形状の本体部４１，４１と、集電リード部４２と、開口４３と、溝部４４，４４と、開口４８とを備えるように所定形状に打ち抜かれた正極集電体基材を用意する。
この正極集電体基材を用いて、折り曲げ加工により、略半円形状の本体部４１，４１が互いに対向して略円形状の本体部が形成されるとともに、新たな溝部４７，４７がこの対向部に形成され、かつ、集電リード部４２は山折りされた際に本体部４１，４１より垂直に起立するとともに、この垂直に起立した集電リード部４２が略円形状に形成された本体部の直径上に位置するように折り曲げ加工して正極集電体４０を作製した以外は上述した実施例１と同様にして、公称容量６．５ＡＨの実施例３の円筒状ニッケル・水素蓄電池Ｃを作製した。
【００２５】
なお、開口４８は山折りされた際に山折り部の近傍に形成され、この開口４８の反対側を封口体との溶接部とすることにより、溶接部の厚みは集電リード部４２の厚みの１／２となるため、溶接電流が開口４８の反対側に集中して流れるようになって、集電リード部４２と封口体下面との溶接性が向上する。
【００２６】
（４）実施例４
図７に示すように、略半円形状の本体部５１，５１と、集電リード部５２と、開口５３と、溝部５４，５４と、集電リード部５２より延出するタブ５８，５８とを備えるように所定形状に打ち抜かれた正極集電体基材を用意する。
この正極集電体基材を用いて、略半円形状の本体部５１，５１が互いに対向して略円形状の本体部が形成されるとともに、新たな溝部５７，５７がこの対向部に形成され、かつ、本体部５１，５１より垂直に起立するとともに、この垂直に起立した集電リード部５２が略円形状に形成された本体部の直径上に位置するように折り曲げ加工して、正極集電体５０を作製した以外は上述した実施例１と同様にして、公称容量６．５ＡＨの実施例４の円筒状ニッケル・水素蓄電池Ｄを作製した。
【００２７】
なお、集電リード部５２より延出するタブ５８，５８を備え、このタブ５８，５８を封口体との溶接部とすることにより、タブ５８，５８の厚みは集電リード部５２の厚みの１／２となるため、溶接電流がタブ５８，５８に集中して流れるようになって、集電リード部５２と封口体下面との溶接性が向上する。
【００２８】
（５）実施例５
図８に示すように、略半円形状の本体部６１，６１と、上述した実施例１の２倍の長さの集電リード部６２と、開口６３と、溝部６４，６４とを備えるように所定形状に打ち抜かれた正極集電体基材を用意する。
【００２９】
この正極集電体基材を用いて、集電リード部６２の山折り部６５，６５に沿って山折りするとともに、谷折り部６６に沿って谷折りする折り曲げ加工を施し、略半円形状の本体部６１，６１が互いに対向して略円形状の本体部が形成され、かつ新たな溝部６７，６７がこの対向部に形成され、さらに、集電リード部６２が本体部６１，６１より垂直に起立するとともに、この垂直に起立した集電リード部６２が略円形状に形成された本体部の直径上に位置するように折り曲げ加工を施して正極集電体６０を作製した以外は上述した実施例１と同様にして、公称容量６．５ＡＨの実施例５の円筒状ニッケル・水素蓄電池Ｅを作製した。
なお、集電リード部６２には、図５に示すような突起部を備えるようにすると、この突起部に溶接電流が集中して流れるようになるため、集電リード部６２と封口体下面との溶接性が向上する。
【００３０】
（６）比較例
図９に示すように、正極集電体基材に中央に溶接電極挿入用開口７３と溝部７４，７４とを備えるとともに、その周囲に多数の開口７１ａを備えた本体部７１と、この本体部７１の一端から垂直に起立する集電リード部７２とを形成するように打ち抜いて作製した正極集電体７０を用いて、上述した実施例１と同様にして、公称容量６．５ＡＨの比較例の円筒状ニッケル・水素蓄電池Ｆを作製した。
【００３１】
３．ニッケル・水素蓄電池の活性化
上述のように作製した実施例１〜５および比較例のニッケル・水素蓄電池を活性化した後、１．３Ａの充電々流で８時間充電した後、１時間休止させ、その後、６５Ａの放電々流で高率放電を行って、放電時間に対する放電電圧の測定を行うと、下記の図１０に示すような結果となった。
【００３２】
図１０より明らかなように、各実施例１〜５のニッケル・水素蓄電池Ａ，Ｂ，Ｃ，Ｄ，Ｅは比較例のニッケル・水素蓄電池Ｆより放電電圧の低下が少なく、高率放電特性が向上していることが分かる。これは、各集電体２０，３０，４０，５０，６０の集電リード部２２，３２，４２，５２，６２が折り重なって各集電リード部２２，３２，４２，５２，６２の抵抗値が減少したためと考えられる。
【００３３】
以上に詳述したように、本発明のおいては、折り重なって形成され各集電リード部２２，３２，４２，５２，６２が本体部２１，３１，４１，５１，６１から起立した構造となっているため、この種の集電体２０，３０，４０，５０，６０の製造が簡単・容易になるとともに、この種の集電体２０，３０，４０，５０，６０を用いることにより、高率放電特性の優れた円筒型蓄電池が得られるようになる。
【図面の簡単な説明】
【図１】本発明の第１実施例の集電体の加工前の状態を示す図である。
【図２】図１の集電体を折り曲げ加工した状態を示す図である。
【図３】図２の集電体を極板群に溶接した状態を示す斜視図である。
【図４】第２実施例の集電体を極板群に溶接した状態を示す図である。
【図５】図３及び図４の集電リード部に突起を設けた状態を示す図である。
【図６】第３実施例の集電体を極板群に溶接した状態を示す図である。
【図７】第４実施例の集電体を極板群に溶接した状態を示す図である。
【図８】第５実施例の集電体を極板群に溶接した状態を示す図である。
【図９】比較例（従来例）の集電体を極板群に溶接した状態を示す図である。
【図１０】放電特性を示す図である。
【符号の説明】
１０…渦巻状極板群、２０ａ…正極集電体基材、２０…正極集電体、２１…略半円形状本体部、２２…集電リード部、２３…開口、２４…溝部、２５…山折り部、２６…谷折り部、２７…新たな溝部、２８…突起部、３０…正極集電体、３１ａ，３１ｂ…略半円形状本体部、３２…集電リード部、３３…開口、３４…溝部、３７…新たな溝部、３８…突起部、４０…正極集電体、４１…略半円形状本体部、４２…集電リード部、４３…開口、４４…溝部、４７…新たな溝部、４８…開口、５０…正極集電体、５１…略半円形状本体部、５２…集電リード部、５３…開口、５４…溝部、５７…新たな溝部、５８…タブ部、６０…正極集電体、６１…略半円形状本体部、６２…集電リード部、６３…開口、６４…溝部、６５…山折り部、６６…谷折り部、６７…新たな溝部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cylindrical storage battery including a spiral electrode body in which a positive electrode plate and a negative electrode plate such as a nickel / hydrogen storage battery, a nickel / cadmium storage battery, and a lithium ion storage battery are spirally wound through a separator. The present invention relates to a conductive connection between a cylindrical electrode body and a current collector and between the current collector and an external terminal.
[0002]
[Prior art]
Conventionally, in a cylindrical storage battery such as a nickel / cadmium storage battery, a nickel / hydrogen storage battery, or a lithium ion storage battery, a positive electrode plate and a negative electrode plate are spirally wound via a separator to form a spiral electrode body. And after welding the core of the negative electrode plate of the spiral electrode body formed in this way to the negative electrode current collector and welding the core body of the positive electrode plate of the spiral electrode body to the positive electrode current collector, this spiral shape The electrode body is inserted into a metal cylindrical outer can also serving as a negative electrode terminal, and the negative electrode current collector is welded to the bottom of the metal outer can and the current collecting lead portion extending from the positive electrode current collector also serves as the positive electrode terminal It was configured to be welded to the bottom of the sealing body.
[0003]
Alternatively, the spiral electrode body is inserted into a metal cylindrical outer can that also serves as a negative electrode terminal, and the core of the negative electrode plate of the spiral electrode body is brought into contact with the bottom of the metal outer can and extends from the core of the negative electrode plate. Weld the current collecting tab to the bottom of the metal outer can. On the other hand, the core of the positive electrode plate of the spiral electrode body is welded to the positive electrode current collector, and the current collecting lead portion extending from the positive electrode current collector is welded to the bottom of the sealing body that also serves as the positive electrode terminal. It is common.
Thus, while electrically connecting the core of the negative electrode plate of the spiral electrode body to the bottom of the metal outer can, and welding the core of the positive electrode plate of the spiral electrode body to the positive electrode current collector, Since the current distribution from the positive electrode terminal (sealing body) and the current distribution from the negative electrode plate to the negative electrode terminal (metal outer can) are uniform, a storage battery with improved high-rate discharge characteristics can be obtained.
[0004]
[Problems to be solved by the invention]
By the way, when charging / discharging a cylindrical storage battery as described above with a large current of several tens of amperes to several hundreds of amperes, a voltage drop due to the resistance at the above-described connection occurs, resulting in a decrease in operating voltage. As a result, there was a problem that a high voltage could not be obtained.
Here, one of the positive and negative current collectors consists of a current collector part (main body part) welded to one electrode plate end of the spiral electrode body and a current collector lead part welded to the lower surface of the sealing body. Although the current collecting lead portion concentrates the current collected by the main body portion, the voltage drop increases as the resistance value of this portion increases.
[0005]
Therefore, it is conceivable to increase the thickness of the current collecting lead portion in order to reduce the resistance value of the current collecting lead portion. However, since the current collecting lead portion and the main body portion are integrally formed, Increasing the thickness of the lead portion inevitably necessitates increasing the thickness of the main body portion. However, if the thickness of the main body is increased, a lot of invalid welding current flows through the main body itself when resistance welding the main body and the spiral electrode body, and the welding point where the spiral electrode body and the main body are welded. As a result, the effective welding current flowing to the surface decreases and the weldability is impaired.
For this reason, in Japanese Patent No. 2762599, it has been proposed to provide a plurality of current collecting lead portions in order to reduce the resistance value of the current collecting lead portion while keeping the thickness of the main body portion as it is.
[0006]
However, in the method proposed in Japanese Patent No. 2762599, there are problems that the number of parts increases and welding between the current collecting lead portion and the sealing body is complicated and the welding work becomes complicated. Further, in the conventional current collector, the current collecting lead portion and the main body portion are integrally formed, so that the current collecting lead portion is formed so as to be positioned on the end side of the main body portion. .
[0007]
For this reason, when the current collector is welded to the spiral electrode body, the current collector lead portion is present at a position separated from the center of the main body portion, so that electric energy can be uniformly extracted from the spiral electrode body. It becomes difficult. Furthermore, as the width of the current collector lead portion is increased in order to reduce the resistance value of the current collector lead portion, the area of the main body portion is conversely reduced, so that the current collecting performance in the main body portion is lowered. occured.
Therefore, the present invention has been made to solve the above-described problems, and reduces the internal resistance of the current collecting lead portion without impairing the current collecting performance of the current collector as a whole, and has a small number of parts and is inexpensive. An object of the present invention is to obtain a current collector and obtain a storage battery with a small voltage drop.
[0008]
[Means for Solving the Problems]
Therefore, at least one of the present invention both current collector for use in a cylindrical storage battery, and two substantially semi-circular body portion, the same thickness as the main body with connecting the main body portion in a substantially rectangular shape The current collector lead portion is formed of a current collector lead portion formed integrally with the main body portion, and the current collector lead portion is valley-folded at a boundary portion between the substantially semicircular main body portions. The current collector lead part is folded in a mountain at the center part and folded so as to stand up from the main body part, and the two semi-circular main body parts face each other because the current collector lead part is folded. A current collecting lead portion formed so as to stand up from a substantially circular main body portion is welded to the lower surface of the sealing body.
[0009]
Thus, at least one of the two current collector, and two substantially semi-circular body portion, said body portion integrally formed with a substantially rectangular shape in the same thickness as the main body with connecting the body portion The current collector lead portion is formed of a current collector lead portion , and the current collector lead portion is valley-folded at the boundary between the substantially semicircular main body portions and the center portion of the current collector lead portion. The current collecting lead portion is twice as thick as the main body portion when it is folded and formed so as to stand up from the main body portion. For this reason, it becomes possible to reduce the internal resistance of a current collection lead part to 1/2, without impairing the weldability of a main-body part and a spiral electrode body. As a result, a voltage drop at the current collecting lead portion is reduced, and a cylindrical storage battery with improved high rate discharge characteristics and operating voltage can be obtained.
[0010]
The current collecting lead part is folded at the boundary between the substantially semicircular main body parts and is folded so that the mountain fold and the valley fold are repeated at the central part so as to stand up from the main body part. In this case, the thickness of the current collecting lead portion is four times that of the main body portion. For this reason, it becomes possible to reduce the internal resistance of a current collection lead part to 1/4, without impairing the weldability of a main-body part and an electrode group. As a result, the voltage drop at the current collecting lead portion is further reduced, and a cylindrical storage battery having further improved high rate discharge characteristics and operating voltage can be obtained.
[0011]
When the current collecting lead portion formed so as to stand up from the substantially circular main body portion is formed so as to be positioned on the substantially diameter of the spiral electrode body, the current collecting lead portion is uniformly collected from the entire electrode plate group. Cylindrical storage battery with improved high-rate discharge characteristics and operating voltage by reducing the uneven distribution of potential in the electrode plate during large current charge / discharge, reducing non-uniform electrode reaction Can be obtained. Further, if the current collecting lead part is arranged at a position approximately on the diameter of the spiral electrode body, the current collecting lead part can be widened to the maximum, so that the current collecting with a further reduced internal resistance is possible. It becomes the lead part. Thus, even if the width of the current collecting lead portion is maximized, the current collecting portion exists on substantially the entire surface of the spiral electrode body, so that the area of the current collecting portion does not decrease.
[0012]
Further, when the two main body portions formed so that the substantially semicircular main body portions face each other and have a substantially circular shape when the current collecting lead portion is folded are arranged on the upper part of the spiral electrode body. In order to form an opening of a predetermined size at a position coinciding with the center of the spiral electrode body, an opening of a predetermined size is provided at both body parts or a boundary part between the both body parts and the current collecting lead part. In this case, even if the current collecting lead portion is located on the center of the spiral electrode body, it is possible to secure the opening at the center position by simply tilting the current collecting lead portion. For this reason, when welding the other current collector to the bottom inner surface of the outer can, the welding electrode can be easily inserted into the center of the spiral electrode body , and this type of cylindrical storage battery can be easily manufactured.
[0013]
Then, or arranged protrusions and openings in portions which are fixedly connected to the sealing body the lower surface of one side of the current collecting lead portion formed so as to stand up from the main body portion that is made in a substantially circular shape, or to erect If a tab extending from the current collecting lead portion is disposed at a portion to be welded to the bottom surface of the sealing body on one surface of the current collecting lead portion formed on the welding lead portion, it is welded to the protruding portion or the opening facing portion or tab. Since the current flows in a concentrated manner, the weldability between the current collecting lead portion and the sealing body is improved.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Below, one Embodiment at the time of applying the cylindrical storage battery of this invention to a nickel hydride storage battery is described based on FIGS. FIG. 1 is a view showing a state before the current collector is bent according to the first embodiment of the present invention, and FIG. 2 is a view showing a state where the current collector of FIG. 1 is bent. (A) is a top view, FIG.2 (b) is a front view, FIG.2 (c) is a right side view of Fig.2 (a). FIG. 3 is a perspective view showing a state in which the current collector of FIG. 2 is welded to the spiral electrode body. FIG. 4 is a view showing a state in which the current collector of the second embodiment of the present invention is welded to the spiral electrode body, FIG. 4 (a) is a perspective view, and FIG. 4 (b) is a top view. It is.
[0015]
5 is an enlarged perspective view showing the current collecting lead portion of FIGS. 3 and 4, and FIG. 6 shows a state where the current collector of the third embodiment of the present invention is welded to the spiral electrode body. FIG. 7 is a perspective view showing a state in which the current collector of the fourth embodiment of the present invention is welded to the spiral electrode body, and FIG. 8 shows the current collector of the fifth embodiment of the present invention. It is a perspective view which shows the state welded to the spiral electrode body. Further, FIG. 9 is a perspective view showing a state in which a current collector of a comparative example (conventional example) is welded to a spiral electrode body, and FIG. 10 is a diagram showing discharge characteristics.
[0016]
1. Preparation of spiral electrode body A nickel foam (core body) is filled with a paste-like positive electrode active material mainly composed of nickel hydroxide, dried, and then rolled to a predetermined thickness to produce a nickel positive electrode plate. did. On the other hand, a punched metal (core body) was filled with a paste-like negative electrode active material made of a hydrogen storage alloy, dried, and then rolled to a predetermined thickness to prepare a hydrogen storage alloy negative electrode plate. The nickel positive electrode plate thus prepared and the hydrogen storage alloy negative electrode plate are wound in a spiral shape with the outermost periphery being a negative electrode plate via a separator made of polypropylene nonwoven fabric, and the spiral electrode body 10 is wound. Was made.
[0017]
2. Production of nickel-hydrogen storage battery (1) Example 1
First, as shown in FIG. 1, substantially semicircular main body parts 21 and 21 on both the left and right sides, a substantially rectangular current collecting lead part 22 connecting these main body parts 21 and 21, and these main body parts. A positive current collector base is formed by punching a nickel metal plate having a predetermined thickness (for example, 0.3 mm) so that openings 23 and 23 having a predetermined dimension are formed at the boundary between the current collector 21 and the current collector lead 22. A material 20a was produced. In addition, the groove portions 24 and 24 are simultaneously punched in the central portions of the main body portions 21 and 21. By providing the groove portions 24 and 24, the invalid welding current is reduced, that is, the effective welding current is increased. It becomes possible to make it.
[0018]
Next, the positive current collector base material 20 a is folded in a mountain along the mountain fold 25 at the center of the current collecting lead 22, and the valley at the boundary between the main body 21, 21 and the current collecting lead 22. A positive electrode current collector 20 having a shape as shown in FIG. 2 was produced by performing a bending process of valley folding along the folding portions 26 and 26.
By this bending process, the substantially semicircular body parts 21 and 21 are opposed to each other to form a substantially circular body part, and in addition to the groove parts 24 and 24 previously formed in the opposing part, new groove parts are formed. 27, 27 are formed. On the other hand, the current collecting lead part 22 stands vertically from the main body parts 21 and 21, and the current standing lead collecting part 22 standing vertically is positioned on the diameter of the main body part formed in a substantially circular shape.
[0019]
Subsequently, after the positive electrode current collector 20 formed in this way is placed on the upper part of the spiral electrode body 10 described above, a pair of welding electrodes are brought into contact with the opposing portions of the main body portions 21 and 21 so as to contact them. By passing a welding current between the welding electrodes, the contact portion between the core body of the positive electrode plate slightly protruding from the spiral electrode body 10 and the main body portions 21 and 21 was fixed by resistance welding. On the other hand, a disc-shaped negative electrode current collector (not shown) is placed below the spiral electrode body 10, and a pair of welding electrodes are similarly brought into contact with each other to contact the core of the negative electrode plate and the negative electrode current collector. The part was fixed by resistance welding.
[0020]
Next, a bottomed cylindrical metal outer can (not shown) was prepared, and the spiral electrode body welded with the positive electrode current collector 20 was inserted into the metal outer can . Thereafter , one welding electrode is inserted from the opening 23 of the positive electrode current collector 20 and brought into contact with a negative electrode current collector (not shown), and the other welding electrode is brought into contact with the bottom of the metal outer can, The body and the bottom of the metal outer can were spot welded.
[0021]
On the other hand, a sealing body (not shown) composed of a positive electrode cap and a lid (a pressure valve is disposed between the positive electrode cap and the lid) is prepared, and the conductive lead portion 22 of the positive electrode current collector 20 is provided. The lid bottom part and the conductive lead part 22 were welded and connected to the lid bottom part of the sealing body .
As shown in FIG. 5, projections 28, 28 are formed on the current collecting lead portion 22, and by providing the projections 28, 28 on the current collection lead portion 22, the welding current is changed to the projection portion 28. , 28, the weldability between the current collecting lead portion 22 and the lower surface of the sealing body is improved.
Thereafter, an electrolytic solution made of a 30 wt% potassium hydroxide (KOH) aqueous solution is poured into the metal outer can, and the sealing body is placed on the opening of the outer can via the sealing gasket. Was sealed to the side of the sealing body . This produced the cylindrical nickel-hydrogen storage battery A of Example 1 having a nominal capacity of 6.5 AH.
[0022]
(2) Example 2
As shown in FIG. 4, substantially semicircular main body portions 31a and 31b (the main body portion 31a is formed larger than the main body portion 31b), a current collecting lead portion 32, an opening 33, and a groove portion. A positive electrode current collector base material punched into a predetermined shape so as to be provided with 34 and 34 is prepared.
Using this positive electrode current collector base material, the main body portions 31a and 31b are opposed to each other to form a substantially circular main body portion, and new groove portions 37 and 37 are formed in the facing portion. Bending process is performed so that the portion 32 rises vertically from the main body portions 31a and 31b, and the vertically rising current collecting lead portion 32 is located at a position slightly deviated from the diameter of the substantially circular main body portion. The cylindrical nickel-hydrogen storage battery B of Example 2 having a nominal capacity of 6.5 AH was produced in the same manner as in Example 1 described above except that the positive electrode current collector 30 was produced.
[0023]
As shown in FIG. 5, the current collecting lead portion 32 has projections 38, 38. By providing the projection portions 38, 38 on the current collecting lead portion 32, the welding current is increased. , 38, the weldability between the current collecting lead portion 32 and the lower surface of the sealing body is improved.
[0024]
(3) Example 3
As shown in FIG. 6, the positive electrode punched into a predetermined shape so as to include substantially semicircular body portions 41, 41, current collecting lead portions 42, openings 43, grooves 44, 44, and openings 48. A current collector base material is prepared.
By using this positive electrode current collector base material, the substantially semicircular main body portions 41 and 41 are opposed to each other by bending and a substantially circular main body portion is formed. The current collecting lead portion 42 is formed in the facing portion and rises vertically from the main body portions 41 and 41 when the mountain-folded portion is folded, and the current collecting lead portion 42 standing vertically is formed in a substantially circular shape. Cylindrical nickel-hydrogen storage battery of Example 3 with a nominal capacity of 6.5 AH in the same manner as in Example 1 except that the positive electrode current collector 40 was produced by bending so as to be positioned on the diameter of the main body. C was produced.
[0025]
The opening 48 is formed in the vicinity of the mountain fold when the mountain is folded, and the opposite side of the opening 48 is a welded portion with the sealing body, so that the thickness of the welded portion is the thickness of the current collecting lead portion 42. Therefore, the welding current flows in a concentrated manner on the opposite side of the opening 48, and the weldability between the current collecting lead portion 42 and the lower surface of the sealing body is improved.
[0026]
(4) Example 4
As shown in FIG. 7, the substantially semicircular main body portions 51, 51, the current collecting lead portion 52, the opening 53, the groove portions 54, 54, and the tabs 58, 58 extending from the current collecting lead portion 52, A positive electrode current collector base material punched into a predetermined shape is prepared.
Using the positive electrode current collector base material, the substantially semicircular body portions 51 and 51 are opposed to each other to form a substantially circular body portion, and new groove portions 57 and 57 are formed in the facing portion. In addition, the current collector lead portion 52 standing vertically from the main body portions 51, 51 is bent so as to be positioned on the diameter of the main body portion formed in a substantially circular shape. A cylindrical nickel-hydrogen storage battery D of Example 4 having a nominal capacity of 6.5 AH was produced in the same manner as Example 1 described above except that the current collector 50 was produced.
[0027]
The tabs 58 and 58 extending from the current collecting lead portion 52 are provided, and the tabs 58 and 58 are welded to the sealing body, whereby the thickness of the tabs 58 and 58 is equal to the thickness of the current collecting lead portion 52. Therefore, the welding current flows in a concentrated manner on the tabs 58 and 58, and the weldability between the current collecting lead portion 52 and the lower surface of the sealing body is improved.
[0028]
(5) Example 5
As shown in FIG. 8, it is provided with substantially semicircular main body portions 61, 61, a current collecting lead portion 62 having a length twice that of the first embodiment, an opening 63, and groove portions 64, 64. A positive electrode current collector base material punched into a predetermined shape is prepared.
[0029]
Using this positive electrode current collector base material, the folds are folded along the mountain folds 65, 65 of the current collector lead 62, and are folded along the valley fold 66. The main body portions 61 and 61 are opposed to each other to form a substantially circular main body portion, and new groove portions 67 and 67 are formed in the opposite portion. Further, the current collecting lead portion 62 is formed from the main body portions 61 and 61. The positive electrode current collector 60 was manufactured except that the positive electrode current collector 60 was manufactured by being bent so that the current-collecting lead portion 62 standing vertically was positioned on the diameter of the main body portion formed in a substantially circular shape. In the same manner as in Example 1, a cylindrical nickel-hydrogen storage battery E of Example 5 having a nominal capacity of 6.5 AH was produced.
If the current collecting lead part 62 is provided with a protrusion as shown in FIG. 5, the welding current flows in a concentrated manner on this protrusion, so that the current collecting lead part 62 and the bottom surface of the sealing body This improves the weldability.
[0030]
(6) Comparative Example As shown in FIG. 9, the positive electrode current collector base is provided with a welding electrode insertion opening 73 and grooves 74, 74 at the center, and a main body 71 having a large number of openings 71a around it. And a positive electrode current collector 70 produced by punching so as to form a current collecting lead portion 72 standing upright from one end of the main body portion 71 in the same manner as in the first embodiment described above. A cylindrical nickel-hydrogen storage battery F of a comparative example of 5 AH was produced.
[0031]
3. Activation of Nickel / Hydrogen Storage Battery After activating the nickel / hydrogen storage batteries of Examples 1 to 5 and Comparative Example prepared as described above, the battery was charged with 1.3 A charging current for 8 hours and then rested for 1 hour. Thereafter, when a high rate discharge was performed at a discharge current of 65 A and the discharge voltage was measured with respect to the discharge time, the result shown in FIG. 10 was obtained.
[0032]
As is clear from FIG. 10, the nickel-hydrogen storage batteries A, B, C, D, and E of Examples 1 to 5 have a lower discharge voltage than the nickel-hydrogen storage battery F of the comparative example, and have high rate discharge characteristics. It can be seen that it has improved. This is because the current collecting lead portions 22, 32, 42, 52, 62 of the current collectors 20, 30, 40, 50, 60 are folded and the resistance values of the current collecting lead portions 22, 32, 42, 52, 62 are folded. This is thought to be due to the decrease.
[0033]
As described in detail above, in the present invention, the current collecting lead portions 22, 32, 42, 52, 62 are erected from the main body portions 21, 31, 41, 51, 61. Therefore, the manufacture of this type of current collector 20, 30, 40, 50, 60 becomes simple and easy, and by using this type of current collector 20, 30, 40, 50, 60, A cylindrical storage battery having excellent high rate discharge characteristics can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing a state before processing of a current collector according to a first embodiment of the present invention.
2 is a view showing a state where the current collector of FIG. 1 is bent; FIG.
3 is a perspective view showing a state in which the current collector of FIG. 2 is welded to an electrode plate group. FIG.
FIG. 4 is a view showing a state in which a current collector of a second embodiment is welded to an electrode plate group.
5 is a view showing a state in which a protrusion is provided on the current collecting lead portion of FIGS. 3 and 4. FIG.
FIG. 6 is a view showing a state in which a current collector of a third embodiment is welded to an electrode plate group.
FIG. 7 is a view showing a state in which a current collector of a fourth embodiment is welded to an electrode plate group.
FIG. 8 is a view showing a state where a current collector of a fifth embodiment is welded to an electrode plate group.
FIG. 9 is a view showing a state in which a current collector of a comparative example (conventional example) is welded to an electrode plate group.
FIG. 10 is a diagram showing discharge characteristics.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Spiral electrode group, 20a ... Positive electrode collector base material, 20 ... Positive electrode collector, 21 ... Substantially semicircular main-body part, 22 ... Current collection lead part, 23 ... Opening, 24 ... Groove part, 25 ... Mountain fold, 26 ... Valley fold, 27 ... New groove, 28 ... Projection, 30 ... Positive current collector, 31a, 31b ... Substantially semicircular main body, 32 ... Current collector lead, 33 ... Opening, 34 ... Groove portion, 37 ... New groove portion, 38 ... Projection portion, 40 ... Positive current collector, 41 ... Substantially semicircular main body portion, 42 ... Current collecting lead portion, 43 ... Opening, 44 ... Groove portion, 47 ... New Groove part, 48 ... opening, 50 ... positive electrode current collector, 51 ... substantially semicircular main body part, 52 ... current collecting lead part, 53 ... opening, 54 ... groove part, 57 ... new groove part, 58 ... tab part, 60 ... Positive electrode current collector, 61 ... substantially semicircular main body, 62 ... current collector lead, 63 ... opening, 64 ... groove, 65 ... mountain fold, 66 ... valley Ri part, 67 ... a new groove

Claims

A spiral electrode body in which a positive electrode plate and a negative electrode plate are spirally wound via a separator is provided in a metal cylindrical outer can that also serves as an external terminal of one electrode, and the opening of the outer can is interposed through an insulator. A cylindrical storage battery having a sealing body that also serves as an external terminal of the other electrode to be sealed,
One end of the positive electrode plate of the spiral electrode body is connected to a positive electrode current collector, and the other end of the negative electrode plate of the spiral electrode body is connected to a negative electrode current collector ,
Wherein at least one of the two current collector, two substantially semi-circular body portion, these said body portion are integrally formed with condensed in a substantially rectangular shape in the same thickness as the main body with connecting the body portion It is formed from a current collector base material composed of an electric lead part ,
The current collecting lead portion is folded at a boundary portion between the substantially semicircular main body portions and folded at a center portion of the current collecting lead portion so as to stand up from the main body portion. And
The substantially semicircular main body portions are formed in a substantially circular shape so as to face each other by folding the current collecting lead portion,
A cylindrical storage battery, wherein a current collecting lead portion formed so as to stand up from the substantially circular main body portion is welded to a lower surface of the sealing body .

The current collecting lead portion is valley-folded at a boundary portion between the substantially semicircular main body portions, and is formed so that mountain folds and valley folds are repeated at the central portion and folded so as to stand up from the main body portion. cylindrical storage battery according to claim 1, characterized in that it is the form.

The current collecting lead portion formed so as to stand up from the substantially circular main body portion is formed so as to be positioned on a substantially diameter of the spiral electrode body. Item 3. The cylindrical storage battery according to Item 2.

Claim 1, characterized in that the current collecting lead portion formed so as to stand from the generally body portion which is made in a circular shape is formed so as to be positioned offset from the substantially the diameter of the spiral-wound electrode assembly Or the cylindrical storage battery of Claim 2.

When both the main body portions formed so that the substantially semicircular main body portions face each other and become substantially circular due to the current collecting lead portion being folded are disposed on the upper part of the spiral electrode body An opening of a predetermined size is formed at the body portion or a boundary portion between the body portion and the current collecting lead portion so that an opening of a predetermined size is formed at a position coinciding with the central portion of the spiral electrode body. The cylindrical storage battery according to claim 1, wherein the cylindrical storage battery is provided.

The protrusion part is formed in the site | part connected and fixed to the said sealing body lower surface of the current collection lead part formed so that it may stand up from the main-body part made | formed by the said substantially circular shape. Item 6. The cylindrical storage battery according to any one of Items 5.

The opening is formed in the site | part connected and fixed to the lower surface of the said sealing body of the current collection lead part formed so that it may stand up from the main-body part made | formed by the said substantially circular shape. Item 6. The cylindrical storage battery according to any one of Items 5.

The substantially by tabs from the current collecting lead portion extending outwardly is formed at a site connected and fixed to the sealing body lower surface of the formed current collecting lead portion so as to stand up from the main body portion that is made in a circular shape cylindrical storage battery according to any one of claims 1 to 5, characterized in that there.