JP4090167B2

JP4090167B2 - Storage battery and manufacturing method thereof

Info

Publication number: JP4090167B2
Application number: JP33405899A
Authority: JP
Inventors: 和洋北岡; 勇治後藤; 隆明池町
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 1999-11-25
Filing date: 1999-11-25
Publication date: 2008-05-28
Anticipated expiration: 2019-11-25
Also published as: JP2001155710A

Description

【０００１】
【発明の属する技術分野】
本発明は、一方極の端子を兼ねる開口部を備えた電池ケースと、この開口部を密封する他方極の端子を兼ねる封口体と、電池ケース内に収容される正・負極の少なくとも一方の端部に集電体が接続された電極体とを備えた蓄電池およびその製造方法に係り、特に、正・負極の少なくとも一方に接続された集電体と封口体とを接続するリード部の集電構造およびその溶接方法の改良に関するものである。
【０００２】
【従来の技術】
一般に、ニッケル−水素化物蓄電池、ニッケル−カドミウム蓄電池などのアルカリ蓄電池は、正極および負極の間にセパレータを介在させ、これらを渦巻状に巻回した後、正極あるいは負極の端部に集電体を接続して電極体を形成し、この電極体を金属製電池ケースに収納して集電体から延伸するリード部を封口体に溶接した後、封口体を電池ケースの開口部に絶縁ガスケットを介在させて装着することにより密閉して構成されている。
【０００３】
このようなアルカリ蓄電池が電動工具や電気自動車などの高率で充放電を行う用途に使用される場合、電池構成の中でも特に、集電体と封口体の間を接続するリード部での電気抵抗が電池特性に大きな影響を与える。即ち、リード部での電気抵抗が大きい場合、大電流で放電を行うと、リード部での電気抵抗に起因する大きな電圧降下が生じて電池電圧が低下するという問題を生じた。そこで、特許第２７６２５９９号公報において、集電部品を複数枚にしてリード部を構成したり、集電部品の厚みを厚くするようにしてリード部での電気抵抗を低減することが提案されるようになった。
【０００４】
【発明が解決しようとする課題】
ところで、リード部を構成する集電部品を複数にした場合、部品点数が多くなるとともに、リード部に柔軟性がないことから、封口体との溶接が困難になり、かつ封口体を電池ケースの開口部にかしめて密閉する際に、リード部を折り曲げることが困難になり、生産性が劣るという問題を生じた。また、リード部を構成する集電部品の厚みを厚くすると、抵抗溶接するための溶接電流に無効な電流が多くなって、封口体との溶接性が悪くなるとともに、封口体を電池ケースの開口部にかしめて密閉する際に、リード部を折り曲げることが困難になり、生産性が劣るという問題も生じた。
【０００５】
一方、封口体にリード部を溶接する場合、集電体から垂直に立ち上がったリード部に封口体を隣接させ、リード部の側面に溶接電極を押し当てて封口体にリード部を抵抗溶接した後、リード部を折り曲げて封口体を電池ケースの開口部に装着し、開口部の端部をかしめて密封するようにしている。一般的に、厚みが厚くて短いリード部を用いた方が、その比抵抗が小さくなって電池内部抵抗が低下する。
【０００６】
しかしながら、上述したように、リード部を封口体に溶接した後、封口体を電池ケースの開口部に装着するためには、長めに形成されたリード部を用い、封口時に、このリード部を屈曲させるようにして封口体を電池ケースの開口部に装着する必要がある。このため、リード部の長さは少なくとも電極体の半径以上の長さが必要であるとともに、リード部を屈曲させるようにするためには、薄くて長いリード部を用いなくてはならず、その比抵抗が大きくなって電池内部抵抗が大きくなるという問題を生じた。
【０００７】
一般的に、集電部品の抵抗はその長さに比例して断面積に反比例するため、集電部品の抵抗を低減させるためには断面積を大きくする必要がある。しかしながら、集電部品としては、通常、板状体が用いられる。板状体を集電部品として用いた場合、円筒状電池にあってはその最大幅は電池の直径が限度となり、集電部品の最大断面積には限界があり、集電部品の抵抗値を低減させるのには限界があった。
【０００８】
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、断面積が大きく、かつ長さが短くても確実に封口体と集電体を溶接できる集電部品を用いて、高率放電性能に優れた蓄電池を得ることを第１の目的とする。また、このような集電部品を用いて封口体と集電体を確実に溶接できる溶接方法を提供することを第２の目的とする。
【０００９】
【課題を解決するための手段】
上記第１の目的を達成するため、本発明の蓄電池は、封口体と集電体とは長さ方向の中央部が内方に向けて凹んで鼓状となされた円筒体から構成されたリード部により固着接続されている。このような円筒体から構成されたリード部を用いることにより、リード部の断面積（円筒体の円周の長さ×円筒体の基材厚み）が大きくなるとともに、リード部の長さも短くできるため、リード部での抵抗が低減する。この結果、内部抵抗が低減し、かつ高い出力特性を有する蓄電池が得られるようになる。
【００１０】
リード部が長さ方向の中央部が内方に向けて凹んで鼓状となされた円筒体から構成されていると、板状体よりなるリード部の幅よりも円筒体の円周の長さの方が長くなるため、このリード部が必要とする断面積を容易に確保することができるようになって、円筒体の基材の厚みを板状体よりなるリード部の厚みよりも薄くすることが可能となる。このため、封口体あるいは集電体との溶接も容易になり、かつ、中央部が内方に向けて凹んだ鼓状に形成されているので、封口体を電池ケースの開口部にかしめて封口する作業も容易となって、この種の蓄電池の製造が容易になる。
【００１１】
そして、この種のリード部と封口体下面あるいは集電体の上面とは抵抗溶接により固着接続されるため、リード部は溶接電極を配置しやすい形状、構造にする必要がある。このため、本発明のリードにおいては、円筒体の上下端部に幅広部と幅狭部とが交互に形成された鍔部を備えるとともに、上端鍔部の幅広部と下端鍔部の幅狭部とが空間を隔てて互に重なり合い、かつ上端鍔部の幅狭部と下端鍔部の幅広部とが空間を隔てて互に重なり合うように配置されている。
これにより鍔部の幅広部は封口体下面あるいは集電体の上面との溶接部となり、鍔部の幅狭部の外周部に溶接電極を配置することが可能となる。このため、円筒体の下端鍔部の幅広部と集電体との溶接あるい円筒体の上端鍔部の幅広部と封口体下面との溶接作業が容易となり、この種の蓄電池の製造が容易になるとともに作業性も向上する。
【００１２】
また、リード部と封口体下面あるいは集電体の上面とを抵抗溶接により強固に固着接続するためには、溶接部に溶接電流が集中するようにする必要があるが、上端鍔部の幅広部の上面あるいは下端鍔部の幅広部の下面に小突起が形成されていると、これらの小突起に溶接電流が集中するようになって、リード部と封口体下面あるいは集電体の上面とが抵抗溶接により強固に固着接続されるようになる。
【００１３】
また、上記第２の目的を達成するため、本発明の蓄電池の製造方法は、長さ方向の中央部が内方に向けて凹んで鼓状となされた円筒体から構成されたリード部を集電体の上面あるいは封口体の下面のいずれか一方に溶接する第１溶接工程と、電池ケース内に電解液を注入する電解液注入工程と、電池ケースの開口部に封口体を配置する配置工程と、封口体を電池ケースの開口部に密封する密閉工程と、電池ケースと封口体との間に電流を流してリード部を封口体の下面あるいは集電体の上面のいずれか一方に溶接する第２溶接工程とを備えるようにしている。
【００１４】
このように、長さ方向の中央部が内方に向けて凹んで鼓状となされた円筒体から構成されたリード部を集電体の上面あるいは封口体の下面のいずれか一方に溶接する第１溶接工程の後、電池ケース内に電解液を注入し、封口体で電池ケースの開口部を密封した後、電池ケースと封口体との間に電圧を印加すると、封口体→リード部→集電体→正・負極→電池ケースの経路、あるいはその逆の経路で電流が流れ（第２溶接工程）るようになるため、リード部を封口体の下面あるいは集電体の上面のいずれか一方に溶接することができるようになる。
【００１５】
この場合、封口体とリード部との間およびリード部と集電体との間が密着していないと溶融した金属が飛散する現象が生じて、所謂「溶接ちり」が発生して、これが電池短絡の原因の１つとなる。このため、密閉工程において封口体を押圧して内方に向けて凹んで鼓状となされた円筒体の長さ方向の中央部を中心にして押しつぶすようにして、封口体とリード部との間およびリード部と集電体との間を密着させる必要がある。
【００１６】
また、本発明の蓄電池の製造方法は、長さ方向の中央部が内方に向けて凹んで鼓状となされた円筒体から構成されたリード部を集電体の上面あるいは封口体の下面のいずれか一方に溶接する第１溶接工程と、電池ケース内に電解液を注入する電解液注入工程と、封口体とリード部あるいはリード部と集電体とが接触した状態となるように電池ケースの開口部に封口体を配置する配置工程と、電池ケースと封口体との間に電流を流してリード部を封口体の下面あるいは集電体の上面のいずれか一方に溶接する第２溶接工程と、封口体を電池ケースの開口部に密封する密閉工程とを備えるようにしている。
【００１７】
このように、第２溶接工程の後、封口体を電池ケースの開口部に密封する密閉工程を行うようにしても、第２溶接工程において、電池ケースと封口体との間に電圧を印加すると、封口体とリード部あるいはリード部と集電体とが接触した状態となっているので、封口体→リード部→集電体→正・負極→電池ケースの経路、あるいはその逆の経路で電流が流れるようになって、リード部を封口体の下面あるいは集電体の上面のいずれか一方に溶接することができるようになる。この後、密閉工程において封口体を電池ケースの開口部に密封すれば、電池を形成することができるようになる。
【００１８】
この場合、封口体とリード部との間およびリード部と集電体との間が密着していないと溶融した金属が飛散する現象が生じて、電池短絡が発生するため、第２溶接工程において封口体を押圧して内方に向けて凹んで鼓状となされた円筒体の長さ方向の中央部を中心にして押しつぶすようにするとともに、電池ケースと封口体との間に電流を流すようにして、封口体とリード部との間およびリード部と集電体との間を密着させる必要がある。
【００１９】
そして、円筒体の上下端部に幅広部と幅狭部とが交互に形成された鍔部を備えるとともに、円筒体の上端鍔部の幅広部と下端鍔部の幅狭部とが空間を隔てて互に重なり合い、かつ円筒体の上端鍔部の幅狭部と下端鍔部の幅広部とが空間を隔てて互に重なり合うように配置されており、上端鍔部の幅狭部の外周部に溶接電極を配置して、下端鍔部の幅広部と集電体の上面とを溶接するか、あるいは下端鍔部の幅狭部の外周部に溶接電極を配置して、上端鍔部の幅広部と封口体の下面とを溶接するようにすると、円筒体の上端鍔部の幅狭部の外周部に溶接電極を配置することが可能となるため、円筒体の下端鍔部の幅広部と集電体とを溶接する際の作業が容易となり、この種の蓄電池の製造が容易になるとともに作業性も向上する。
【００２０】
また、上述した第２溶接においてリード部と封口体下面あるいは集電体の上面とを強固に固着接続するためには、溶接部に溶接電流が集中するようにする必要がある。このため、上端鍔部の幅広部の上面あるいは下端鍔部の幅広部の下面の少なくとも一方に小突起を形成して、該小突起に溶接電流を集中させる必要がある。
【００２１】
【発明の実施の形態】
以下に、本発明をニッケル−水素蓄電池に適用した場合の実施の形態を図に基づいて説明する。なお、図１は本発明のリード部を構成する円筒体を正極集電体と封口体に溶接した状態を示す断面図である。また、図２は電極体を電池ケースに挿入して円筒体と封口体とを溶接する状態を示す断面図である。さらに、図３は電極体の正極集電体の上部に円筒体を溶接した状態の要部を示す図であり、図３（ａ）はその上面図を示し、図３（ｂ）は側面図を示し、図３（ｃ）は図３（ａ）のＡ−Ａ断面を示す断面図である。図４は比較例のリード部を構成する板状体を正極集電体と封口体に溶接した状態を示す断面図である。
【００２２】
１．電極体
本実施形態のニッケル−水素蓄電池はニッケル正極板１１と水素吸蔵合金負極板１２とを備えている。ニッケル正極板１１は、パンチングメタルからなる極板芯体の表面にニッケル焼結多孔体を形成した後、化学含浸法により水酸化ニッケルを主体とする活物質をニッケル焼結多孔体内に充填して作製されている。一方、水素吸蔵合金負極板１２は、パンチングメタルからなる極板芯体の表面に水素吸蔵合金から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作製されている。
【００２３】
これらのニッケル正極板１１と水素吸蔵合金負極板１２との間にセパレータ１３を介在させて渦巻状に巻回して渦巻状電極群を作製した。この渦巻状電極群の上端面には、ニッケル正極板１１の極板芯体であるパンチングメタルの端部１１ａが露出し、また、下端面には水素吸蔵合金負極板１２の極板芯体であるパンチングメタルの端部１２ａが露出している。そして、この渦巻状電極群の上端面に露出する正極芯体に多数の開口１４ａ，１４ａ・・・と注液用開口１４ｂ（図３（ａ）参照）を有する円板状の正極集電体１４を溶接するとともに、下端面に露出する負極芯体に多数の開口（図示せず）を有する円板状の負極集電体１５を溶接して、渦巻状電極体１０を作製した。
【００２４】
２．リード部
ついで、正極集電体１４と封口体１７とを導電接続するリード部となる円筒体２０を用意する。この円筒体２０は、長さ方向の中央部が内方に向けて凹んで鼓状となされた本体部２１と、この本体部２１の上下端に形成された鍔部２２，２３とから構成される。上端鍔部２２には幅広部２２ａと幅狭部２２ｂが交互に形成されており、下端鍔部２３には幅広部２３ａと幅狭部２３ｂが交互に形成されている。
そして、上端鍔部２２の幅広部２２ａと下端鍔部２３の幅狭部２３ｂとが空間を隔てて互に重なり合い、かつ上端鍔部２２の幅狭部２２ｂと下端鍔部２３の幅広部２３ａとが空間を隔てて互に重なり合うように配置されている。また、上端鍔部２２の幅広部２２ａの上面には小突起２２ｃが形成されている。なお、円筒体２０の周壁の厚みは０．３ｍｍで、最小内径は１４．８ｍｍで、最大外径は１９．２ｍｍとなるように形成されている。
【００２５】
３．ニッケル−水素蓄電池
（１）実施例１
ニッケル−水素蓄電池を組み立てるに際しては、まず、上述した円筒体２０を正極集電体１４の上に載置した後、上端鍔部の幅狭部２２ｂの外周部に溶接電極（図示せず）を配置して、下端鍔部の幅広部２３ａと集電体１４とをスポット溶接した。この後、円筒体２０を正極集電体１４に溶接した電極体１０を鉄にニッケルメッキを施した有底筒状の電池ケース（底面の外面は負極外部端子となる）１６内に収納した。
【００２６】
ついで、電池ケース１６の上部内周側に防振リング１８を挿入し、電池ケース１６の外周側に溝入れ加工を施して防振リング１８の上端部に凹部１６ａを形成した。この後、電池ケース１６内に３０質量％の水酸化カリウム（ＫＯＨ）水溶液からなる電解液を注入した。ついで、この電池ケース１６の開口部の上部に、封口体１７の底面が円筒体２０の上端鍔部２２と接触するように配置した。なお、封口体１７は、底面に円形状の下方突出部を形成してなる蓋体１７ａと、正極キャップ（正極外部端子）１７ｂと、これら蓋体１７ａおよび正極キャップ１７ｂ間に介在されるスプリング１７ｃと弁板１７ｄからなる弁体を備えており、蓋体１７ａの中央にはガス抜き孔が形成されている。
【００２７】
上述のように封口体１７を配置した後、正極キャップ（正極外部端子）１７ａの上面に一方の溶接電極Ｗ１を配置するとともに、電池ケース１６の底面（負極外部端子）の下面に他方の溶接電極Ｗ２を配置した。この後、これらの一対の溶接電極Ｗ１，Ｗ２間に２×１０⁶Ｎ／ｍ²の圧力を加えながら、これらの溶接電極Ｗ１，Ｗ２間に電池の放電方向に２４Ｖの電圧を印加し、３ＫＡの電流を約１５ｍｓｅｃの時間流す通電処理を施した。この通電処理により、封口体１７の底面と円筒体２０の上端鍔部２２の幅広部２２ａに形成された小突起２２ｃとの接触部に電流が集中して、この小突起２２ｃと封口体１７の底面とが溶接されて、溶接部が形成された。これと同時に負極集電体１５の下面と電池ケース１６の底面（負極外部端子）の上面との接触部が溶接されて溶接部が形成された。
【００２８】
ついで、封口体１７の周縁に絶縁ガスケット１９を嵌着させ、プレス機を用いて封口体１７に加圧力を加えて、絶縁ガスケット１９の下端が凹部１６ａの位置になるまで封口体１７を電池ケース１６内に押し込んだ。この後、電池ケース１６の開口端縁を内方にかしめて電池を封口して、公称容量６．５Ａｈの円筒形ニッケル−水素蓄電池を作製した。なお、この封口時の加圧力により、円筒体２０の本体部２１は凹んだ中央部を中心にして押しつぶされた。このようにして作製された実施例１のニッケル−水素蓄電池を電池Ａとした。
【００２９】
（２）実施例２
まず、上述した円筒体２０を正極集電体１４の上に載置した後、上端鍔部２２の幅狭部２２ｂの外周部に溶接電極（図示せず）を配置して、下端鍔部２３の幅広部２３ａと集電体１４とをスポット溶接した。この後、円筒体２０を正極集電体１４に溶接した電極体１０を鉄にニッケルメッキを施した有底筒状の電池ケース（底面の外面は負極外部端子となる）１６内に収納した。
【００３０】
ついで、電池ケース１６の上部内周側に防振リング１８を挿入し、電池ケース１６の外周側に溝入れ加工を施して防振リング１８の上端部に凹部１６ａを形成した。この後、電池ケース１６内に３０質量％の水酸化カリウム（ＫＯＨ）水溶液からなる電解液を注入した。ついで、この電池ケース１６の開口部の上部に、封口体１７の底面が円筒体２０の上端鍔部２２と接触するように配置した。なお、封口体１７は上述した実施例１の封口体１７と同様の構成となっている。
【００３１】
ついで、封口体１７の周縁に絶縁ガスケット１９を嵌着させ、プレス機を用いて封口体１７に加圧力を加えて、絶縁ガスケット１９の下端が凹部１６ａの位置になるまで封口体１７を電池ケース１６内に押し込んだ。この後、電池ケース１６の開口端縁を内方にかしめて電池を封口した。なお、この封口時の加圧力により、円筒体２０の本体部２１は内方に凹んだ中央部を中心にして押しつぶされた。ついで、正極キャップ（正極外部端子）１７ａの上面に一方の溶接電極Ｗ１を配置するとともに、電池ケース１６の底面（負極外部端子）の下面に他方の溶接電極Ｗ２を配置した。
【００３２】
この後、これらの一対の溶接電極Ｗ１，Ｗ２間に２×１０⁶Ｎ／ｍ²の圧力を加えながら、これらの溶接電極Ｗ１，Ｗ２間に電池の放電方向に２４Ｖの電圧を印加し、３ＫＡの電流を約１５ｍｓｅｃの時間流す通電処理を施した。この通電処理により、封口体１７の底面と円筒体２０の上端鍔部２２の幅広部２２ａに形成された小突起２２ｃとの接触部に電流が集中して、この小突起２２ｃと封口体１７の底面とが溶接されて、溶接部が形成された。これと同時に負極集電体１５の下面と電池ケース１６の底面（負極外部端子）の上面との接触部が溶接されて溶接部が形成された。これにより、公称容量６．５Ａｈの円筒形ニッケル−水素蓄電池を作製し、実施例２の電池Ｂとした。
【００３３】
（３）比較例
図４に示すように、上述した実施例１と同様に作製した渦巻状電極群の上端面に露出する正極芯体に多数の開口を有するとともに、その一部からリード部１４ｂが延伸した円板状の正極集電体１４ａを溶接した。一方、渦巻状電極群の下端面に露出する負極芯体に多数の開口を有する円板状の負極集電体１５を溶接して、渦巻状電極体を作製した。この電極体を電池ケース１６内に収納し、負極集電体１５をこの電池ケース２０の内底面にスポット溶接（なお、図４においては、巻状電極体の中心部に溶接電極を挿入するための空間が存在しないように見えるが、図４は模式的に示す図であって、実際には溶接電極を挿入するための空間は存在する）した。この後、電池ケース１６の上部内周側に防振リング１８を挿入し、電池ケース１６の外周側に溝入れ加工を施して防振リング１８の上端部に凹部１６ａを形成した。
【００３４】
ついで、正極集電体１４ａから延伸したリード部１４ｂを垂直に折り曲げた後、このリード部１４ｂの端部を封口体１７の底面に抵抗溶接した。ついで、電池ケース１６内に３０質量％の水酸化カリウム（ＫＯＨ）水溶液からなる電解液を注入した後、リード部１４ｂを折り曲げて、その周縁に絶縁ガスケット１９を嵌着させた封口体１７を電池ケース１６の開口部に配置した。ついで、電池ケース１６の開口端縁を内方にかしめて電池を封口し、公称容量６．５Ａｈの円筒形ニッケル−水素蓄電池を作製した。このようにして作製された比較例のニッケル−水素蓄電池を電池Ｘとした。
【００３５】
４．電池特性試験
（１）活性化
上述のようにして作製した実施例１，２の電池Ａ，Ｂおよび比較例の電池Ｘを用いて、室温（周囲温度２５℃）で、６５０ｍＡ（０．１Ｃ）の電流値で８時間充電した後、１時間休止させ、その後、１３００ｍＡ（０．２Ｃ）の電流値で電池電圧が０．８Ｖになるまで放電させるという充放電サイクルを行い、この充放電サイクルを１０回繰り返して電池の活性化を行った。
【００３６】
（２）Ｖ−Ｉ特性試験
ついで、上述のように活性化した実施例１，２の電池Ａ，Ｂおよび比較例の電池Ｘを用いて、室温（周囲温度２５℃）で、１３００ｍＡ（２Ｃ）の電流値で電池電圧が０．８Ｖになるまで放電させた状態の電池を１３００ｍＡ（０．２Ｃ）の電流値で３時間充電した。１時間休止させた後、２５Ａの電流値で３０秒間放電させ、放電開始から１０秒後の電池電圧を測定した。
ついで、放電させた容量分の電力を充電した後、同様に、５０Ａ，７０Ａ，１００Ａの電流値で３０秒間放電させ、放電開始から１０秒後の電池電圧をそれぞれ測定した。このようにして得られた放電開始から１０秒後の電池電圧を縦軸とし、各電流値を横軸としてＶ−Ｉ直線（Ｖ−Ｉ特性）を求めると、図５に示すような結果となった。
【００３７】
図５から明らかなように、比較例の電池ＸのＶ−Ｉ直線の傾きが大きいのに対して、実施例１，２の電池Ａ，ＢのＶ−Ｉ直線の傾きは小さいことが分かる。このことから、実施例１，２の電池Ａ，Ｂの作動電圧はいずれも高く、電池内部抵抗が低いことが分かる。これは、実施例１，２の電池Ａ，Ｂは、リード部となる円筒体２０は集電方向の断面積が大きく、かつ集電方向の長さ（高さ）が短いために、リード部での内部抵抗が低減し、高い出力特性が得られたものと考えられる。また、リード部での内部抵抗が低いことから電圧降下も低減して、作動電圧も高くなったと考えられる。
【００３８】
なお、上述した実施例においては、正極キャップ（正極外部端子）１７ａと電池ケース１６の底面（負極外部端子）との間に電池の放電方向に２４Ｖの電圧を印加し、３ＫＡの電流を約１５ｍｓｅｃ間流して溶接するようにしたが、電池に印加する電流の方向には相関性はなく、電池の放電方向であっても充電方向であっても同様の結果が得られた。また、印加する電流値については、電池のサイズには関係なく、３００Ａ以上で同様の効果が得られた。なお、電池ケースと封口体との間に流す溶接電流の電源としては、直流または交流電源を使用することができる。
【００３９】
但し、極端に過大な電流を印加した場合には、短時間の印加であっても、円筒体２０が溶断し、この溶断する電流値は円筒体２０の材質および形状により上限値は変化するので、電流値は、３００Ａ以上で鼓状筒体２０が溶断しない値とする必要がある。さらに、印加時間については、０.２５ｍｓｅｃ以上であれば同様の効果が得られるが、１秒もの長い時間に渡って印加すれば、円筒体２０が溶断するため好ましくない。
【００４０】
また、上述した実施の形態においては、正極集電体１４側に円筒体２０を溶接した後、正極外部端子（正極キャップ）１７ａと負極外部端子（電池ケース１６の底面）との間に電流を流して、円筒体２０と封口体１７とを溶接するようにしたが、封口体１７と円筒体２０とを溶接した後、正極外部端子（正極キャップ）１７ａと負極外部端子（電池ケース１６の底面）との間に電流を流して、正極集電体１４と円筒体２０とを溶接するようにしても、同様な効果が期待できる。この場合、円筒体２０の下端鍔部２３の幅広部２３ａの下面に小突起を設けるようにする必要がある。
【００４１】
また、上述した実施の形態においては、正極外部端子（正極キャップ）と負極外部端子（電池ケースの底面）との間に電流を流して、封口体と集電体とを溶接するとともに負極集電体と電池ケースの内底面との溶接も同時に行うようにした例について説明したが、負極集電体と電池ケースの内底面とをスポット溶接した後、正極外部端子（正極キャップ）と負極外部端子（電池ケースの底面）との間に電流を流して、封口体と集電体とを溶接するようにしてもよい。
この場合、渦巻状電極体１０の中心部には溶接電極挿入用の空間部を設ける必要があり、この空間部は渦巻状電極群を形成する際の巻芯跡空間により形成するようにすればよい。
【００４２】
さらに、上述した実施の形態においては、封口体を正極端子とし、電池ケースを負極端子とした例について説明したが、封口体を負極端子とし、電池ケースを正極端子としてもよい。この場合、正極集電体は電池ケースの内底面に溶接され、封口体の底面は円筒体２０を介して負極集電体に溶接されることとなる。
さらにまた、上述した実施の形態においては、本発明をニッケル−水素蓄電池に適用する例について説明したが、本発明はニッケル−水素蓄電池に限らず、ニッケル−カドミウム蓄電池等の他の蓄電池にも適用できることは明らかである。
【図面の簡単な説明】
【図１】本発明のリード部を構成する円筒体を正極集電体と封口体に溶接した状態を示す断面図である。
【図２】電極体を電池ケースに挿入して円筒体と封口体とを溶接する状態を示す断面図である。
【図３】電極体の正極集電体の上部に円筒体を溶接した状態の要部を示す図であり、図３（ａ）はその上面図を示し、図３（ｂ）は側面図を示し、図３（ｃ）は図３（ａ）のＡ−Ａ断面を示す断面図である。
【図４】従来例（比較例）の蓄電池を示し、リード部が封口体に溶接された状態を示す断面図である。
【図５】各電池の電圧（Ｖ）−電流（Ｉ）特性を示す図である。
【符号の説明】
１０…電極体、１１…正極板、１２…負極板、１３…セパレータ、１４…正極集電体、１５…負極集電体、１６…電池ケース（負極外部端子）、１６ａ…溝部、１７…封口体、１７ａ…蓋体、１７ｂ…正極キャップ（正極外部端子）、１８…防振リング、１９…絶縁ガスケット、２０…円筒体（リード部）、２１…本体部、２２，２３…鍔部，２２ａ，２３ａ…幅広部、２２ｂ，２３ｂ…幅狭部、Ｗ１，Ｗ２…溶接電極[0001]
BACKGROUND OF THE INVENTION
The present invention provides a battery case having an opening that also serves as a terminal of one electrode, a sealing body that also serves as a terminal of the other electrode that seals the opening, and at least one end of positive and negative electrodes accommodated in the battery case In particular, the present invention relates to a storage battery including an electrode body having a current collector connected to a portion thereof, and a method for manufacturing the same, and in particular, to a current collector of a lead portion that connects a current collector connected to at least one of positive and negative electrodes and a sealing body The present invention relates to an improvement in the structure and the welding method.
[0002]
[Prior art]
In general, alkaline storage batteries such as nickel-hydride storage batteries and nickel-cadmium storage batteries interpose a separator between a positive electrode and a negative electrode, wind them in a spiral shape, and then attach a current collector to the end of the positive electrode or the negative electrode. Connected to form an electrode body, this electrode body is housed in a metal battery case, the lead part extending from the current collector is welded to the sealing body, and then the sealing body is interposed in the opening of the battery case It is configured to be hermetically sealed by mounting.
[0003]
When such alkaline storage batteries are used for applications such as electric tools and electric vehicles that charge and discharge at a high rate, electrical resistance at the lead portion connecting between the current collector and the sealing body, particularly among battery configurations. Greatly affects battery characteristics. That is, when the electrical resistance at the lead portion is large, discharging with a large current causes a problem that a large voltage drop due to the electrical resistance at the lead portion occurs and the battery voltage decreases. Therefore, in Japanese Patent No. 2762599, it is proposed to configure the lead part by using a plurality of current collecting parts, or to reduce the electrical resistance at the lead part by increasing the thickness of the current collecting part. Became.
[0004]
[Problems to be solved by the invention]
By the way, when a plurality of current collecting parts constituting the lead part are used, the number of parts is increased and the lead part is not flexible, so that it is difficult to weld the seal part and the seal part is attached to the battery case. When sealing by caulking to the opening, it becomes difficult to bend the lead portion, resulting in poor productivity. In addition, if the thickness of the current collecting parts constituting the lead portion is increased, the current that is ineffective for the welding current for resistance welding is increased, the weldability with the sealing body is deteriorated, and the sealing body is opened to the battery case. When caulking to the part and sealing, it becomes difficult to bend the lead part, resulting in a problem of poor productivity.
[0005]
On the other hand, when welding the lead part to the sealing body, after the sealing body is adjacent to the lead part rising vertically from the current collector and the welding electrode is pressed against the side surface of the lead part, the lead part is resistance-welded to the sealing body The lead portion is bent to attach the sealing body to the opening portion of the battery case, and the end portion of the opening portion is crimped to be sealed. In general, the use of a thick lead lead portion has a lower specific resistance and a lower battery internal resistance.
[0006]
However, as described above, after welding the lead portion to the sealing body, in order to attach the sealing body to the opening of the battery case, a long lead portion is used, and the lead portion is bent at the time of sealing. Thus, it is necessary to attach the sealing body to the opening of the battery case. Therefore, the length of the lead portion needs to be at least the radius of the electrode body, and in order to bend the lead portion, a thin and long lead portion must be used. A problem arises that the specific resistance increases and the internal resistance of the battery increases.
[0007]
Generally, the resistance of the current collecting component is in proportion to its length and inversely proportional to the cross-sectional area. Therefore, in order to reduce the resistance of the current collecting component, it is necessary to increase the cross-sectional area. However, a plate-like body is usually used as the current collecting component. When a plate-like body is used as a current collector component, the maximum width of a cylindrical battery is limited by the battery diameter, the maximum cross-sectional area of the current collector component is limited, and the resistance value of the current collector component is limited. There was a limit to the reduction.
[0008]
Therefore, the present invention was made to solve the above problems, using a current collector that can weld the sealing body and the current collector reliably even if the cross-sectional area is large and the length is short, It is a first object to obtain a storage battery excellent in high rate discharge performance. It is a second object of the present invention to provide a welding method capable of reliably welding the sealing body and the current collector using such current collector parts.
[0009]
[Means for Solving the Problems]
In order to achieve the first object, a storage battery according to the present invention is a lead comprising a sealing body and a current collector formed of a cylindrical body in which a central portion in a length direction is recessed inward to form a drum shape. The parts are fixedly connected. By using a lead portion made up of such a cylindrical body, together with the cross-sectional area of the lead portion (circumference of the base thickness length × circular cylinder of the circular cylinder) increases, the length of the lead portion Since it can be shortened, the resistance at the lead portion is reduced. As a result, a storage battery having reduced internal resistance and high output characteristics can be obtained.
[0010]
When the lead part is composed of a cylindrical body whose central part in the lengthwise direction is recessed inward to form a drum shape, the circumferential length of the cylindrical body rather than the width of the lead part made of a plate-like body Therefore, the cross-sectional area required for the lead portion can be easily secured, and the thickness of the base material of the cylindrical body is made thinner than the thickness of the lead portion made of a plate-like body. It becomes possible. For this reason, welding with the sealing body or the current collector is facilitated, and since the central part is formed in a drum shape recessed inward , the sealing body is crimped to the opening of the battery case. This makes it easier to manufacture this type of storage battery.
[0011]
Since this type of lead portion and the lower surface of the sealing body or the upper surface of the current collector are fixedly connected by resistance welding, the lead portion needs to have a shape and structure in which a welding electrode can be easily disposed. For this reason, in the lead of the present invention, the upper and lower end portions of the cylindrical body are provided with flange portions in which wide portions and narrow portions are alternately formed, and the wide portion of the upper end flange portion and the narrow portion of the lower end flange portion. Are arranged so as to overlap each other across a space, and the narrow portion of the upper end collar and the wide portion of the lower end collar overlap each other across the space.
As a result, the wide portion of the flange becomes a welded portion with the lower surface of the sealing body or the upper surface of the current collector, and the welding electrode can be disposed on the outer peripheral portion of the narrow portion of the flange. For this reason, welding of the wide part of the lower end collar part of the cylindrical body and the current collector or welding of the wide part of the upper end collar part of the cylindrical body and the lower surface of the sealing body is facilitated, and this type of storage battery can be easily manufactured. As a result, workability is improved.
[0012]
In addition, in order to firmly connect the lead part and the lower surface of the sealing body or the upper surface of the current collector by resistance welding, it is necessary to concentrate the welding current on the welded part. If small protrusions are formed on the upper surface of the upper surface or the lower surface of the wide portion of the lower end flange, the welding current concentrates on these small protrusions, and the lead portion and the lower surface of the sealing body or the upper surface of the current collector are It is firmly connected by resistance welding.
[0013]
In order to achieve the second object, a method of manufacturing a storage battery according to the present invention includes a lead portion composed of a cylindrical body whose central portion in the length direction is recessed inwardly to form a drum shape. A first welding step of welding to either the upper surface of the electric body or the lower surface of the sealing body, an electrolyte injection step of injecting an electrolytic solution into the battery case, and an arrangement step of disposing the sealing body in the opening of the battery case And a sealing step for sealing the sealing body to the opening of the battery case, and a current is passed between the battery case and the sealing body to weld the lead part to either the lower surface of the sealing body or the upper surface of the current collector. A second welding step.
[0014]
In this way, the lead portion composed of the cylindrical body whose longitudinal central portion is recessed inwardly to form a drum shape is welded to either the upper surface of the current collector or the lower surface of the sealing body. 1 After the welding process, the electrolyte is injected into the battery case, the opening of the battery case is sealed with the sealing body, and then a voltage is applied between the battery case and the sealing body. Since the current flows through the path of the electric body → positive / negative electrode → battery case or vice versa (second welding process), the lead portion is either one of the lower surface of the sealing body or the upper surface of the current collector. Can be welded to.
[0015]
In this case, if the sealing body and the lead portion and the lead portion and the current collector are not in close contact with each other, a phenomenon that the molten metal is scattered occurs, so-called “welding dust” occurs, which is the battery. One of the causes of a short circuit. For this reason, in the sealing process, the sealing body is pressed around the central portion in the length direction of the cylindrical body that is recessed inwardly to form a drum shape. In addition, it is necessary to bring the lead portion and the current collector into close contact with each other.
[0016]
Further, in the method for producing a storage battery according to the present invention, the lead portion formed of a cylindrical body having a drum shape with a central portion in the length direction recessed inward is formed on the upper surface of the current collector or the lower surface of the sealing body. A battery case so that a sealing body and a lead part or a lead part and a current collector are in contact with each other, a first welding process for welding to either one, an electrolyte injection process for injecting an electrolyte into the battery case And a second welding step of welding a lead portion to either the lower surface of the sealing body or the upper surface of the current collector by passing an electric current between the battery case and the sealing body. And a sealing step for sealing the sealing body to the opening of the battery case.
[0017]
In this way, even if a sealing step for sealing the sealing body to the opening of the battery case is performed after the second welding step, a voltage is applied between the battery case and the sealing body in the second welding step. Since the sealing body and the lead part or the lead part and the current collector are in contact with each other, the current flows through the sealing body, the lead part, the current collector, the positive / negative electrode, the battery case path, or the reverse path. Then, the lead portion can be welded to either the lower surface of the sealing body or the upper surface of the current collector. Thereafter, if the sealing body is sealed in the opening of the battery case in the sealing step, the battery can be formed.
[0018]
In this case, if the gap between the sealing body and the lead portion and between the lead portion and the current collector are not in close contact with each other, a phenomenon that the molten metal scatters occurs and a battery short circuit occurs. The sealing body is pressed and dented inward so as to be crushed around the central part in the length direction of the cylindrical body , and a current flows between the battery case and the sealing body. Thus, it is necessary to make contact between the sealing body and the lead portion and between the lead portion and the current collector.
[0019]
Then, the wide portion and the narrow portion is provided with a flange portion formed alternately at the upper and lower ends of the cylindrical body, and the narrow portion of the wide portion of the upper flange portion of the cylindrical body and the lower flange portion is a space therebetween mutually overlap, and a wide portion of the narrow portion of the upper flange portion of the cylindrical body and the lower flange portion is disposed so as to overlap each other with a space, the outer peripheral portion of the narrow portion of the upper flange portion Te Place the welding electrode and weld the wide part of the lower end collar part to the upper surface of the current collector, or arrange the welding electrode on the outer periphery of the narrow part of the lower end collar part and place the wide part of the upper end collar part and when so welding the lower surface of the sealing member, it becomes possible to arrange the welding electrodes on the outer periphery of the narrow portion of the upper flange portion of the cylindrical body, and the wide portion of the lower flange portion of the cylindrical body collecting The work at the time of welding the electric body is facilitated, the manufacture of this type of storage battery is facilitated, and the workability is improved.
[0020]
Further, in order to firmly fix and connect the lead portion and the lower surface of the sealing body or the upper surface of the current collector in the second welding described above, it is necessary to concentrate the welding current on the welded portion. For this reason, it is necessary to form small protrusions on at least one of the upper surface of the wide portion of the upper end flange or the lower surface of the wide portion of the lower end flange, and concentrate the welding current on the small protrusion.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Below, an embodiment at the time of applying the present invention to a nickel-hydrogen storage battery is described based on figures. FIG. 1 is a cross-sectional view showing a state in which a cylindrical body constituting the lead portion of the present invention is welded to a positive electrode current collector and a sealing body. FIG. 2 is a cross-sectional view showing a state where the electrode body is inserted into the battery case and the cylindrical body and the sealing body are welded. Further, FIG. 3 is a view showing a main part in a state where a cylindrical body is welded to the upper part of the positive electrode current collector of the electrode body, FIG. 3 (a) is a top view thereof, and FIG. FIG. 3C is a cross-sectional view taken along the line AA of FIG. FIG. 4 is a cross-sectional view showing a state in which the plate-like body constituting the lead portion of the comparative example is welded to the positive electrode current collector and the sealing body.
[0022]
1. Electrode Body The nickel-hydrogen storage battery of this embodiment includes a nickel positive electrode plate 11 and a hydrogen storage alloy negative electrode plate 12. The nickel positive electrode plate 11 is formed by forming a nickel sintered porous body on the surface of an electrode plate core made of punching metal, and then filling the nickel sintered porous body with an active material mainly composed of nickel hydroxide by a chemical impregnation method. Have been made. On the other hand, the hydrogen storage alloy negative electrode plate 12 is prepared by filling the surface of an electrode plate core made of punching metal with a paste-like negative electrode active material made of hydrogen storage alloy, drying, and rolling to a predetermined thickness. Has been.
[0023]
A separator 13 was interposed between the nickel positive electrode plate 11 and the hydrogen storage alloy negative electrode plate 12, and a spiral electrode group was prepared by winding the separator 13 in a spiral shape. An end portion 11a of a punching metal that is an electrode plate core body of the nickel positive electrode plate 11 is exposed at the upper end surface of the spiral electrode group, and an electrode plate core body of the hydrogen storage alloy negative electrode plate 12 is exposed at the lower end surface. An end portion 12a of a punching metal is exposed. The positive electrode core exposed at the upper end surface of the spiral electrode group has a large number of openings 14a, 14a,... And a liquid injection opening 14b (see FIG. 3A), and is a disk-shaped positive current collector. 14 was welded, and a disk-shaped negative electrode current collector 15 having a large number of openings (not shown) was welded to the negative electrode core exposed at the lower end surface to produce a spiral electrode body 10.
[0024]
2. Lead Part Next, a cylindrical body 20 serving as a lead part for conductively connecting the positive electrode current collector 14 and the sealing body 17 is prepared. The cylindrical body 20 is composed of a body portion 21 having a drum shape with a central portion in the length direction being recessed inward, and flanges 22 and 23 formed on the upper and lower ends of the body portion 21. The Wide width portions 22 a and narrow portions 22 b are alternately formed on the upper end flange portion 22, and wide portions 23 a and narrow portions 23 b are alternately formed on the lower end flange portion 23.
And the wide part 22a of the upper end collar part 22 and the narrow part 23b of the lower end collar part 23 overlap each other across a space, and the narrow part 22b of the upper end collar part 22 and the wide part 23a of the lower end collar part 23 Are arranged so as to overlap each other across a space. A small protrusion 22 c is formed on the upper surface of the wide portion 22 a of the upper end flange portion 22. The cylindrical body 20 has a peripheral wall thickness of 0.3 mm, a minimum inner diameter of 14.8 mm, and a maximum outer diameter of 19.2 mm.
[0025]
3. Nickel-hydrogen storage battery (1) Example 1
When assembling the nickel-hydrogen storage battery, first, the cylindrical body 20 described above is placed on the positive electrode current collector 14, and then a welding electrode (not shown) is provided on the outer peripheral portion of the narrow portion 22b of the upper end collar. It arrange | positioned and the wide part 23a of the lower end collar part and the collector 14 were spot-welded. Thereafter, the electrode body 10 in which the cylindrical body 20 was welded to the positive electrode current collector 14 was housed in a bottomed cylindrical battery case 16 in which iron was nickel-plated (the outer surface of the bottom surface serves as a negative electrode external terminal).
[0026]
Next, a vibration isolating ring 18 was inserted into the upper inner peripheral side of the battery case 16, and a groove was formed on the outer peripheral side of the battery case 16 to form a recess 16 a at the upper end of the vibration isolating ring 18. Thereafter, an electrolytic solution made of a 30% by mass potassium hydroxide (KOH) aqueous solution was injected into the battery case 16. Next, the bottom surface of the sealing body 17 was arranged on the upper part of the opening of the battery case 16 so as to contact the upper end flange 22 of the cylindrical body 20. The sealing body 17 includes a lid body 17a formed with a circular downward projecting portion on the bottom surface, a positive electrode cap (positive electrode external terminal) 17b, and a spring 17c interposed between the lid body 17a and the positive electrode cap 17b. And a valve plate 17d. A gas vent hole is formed in the center of the lid 17a.
[0027]
After the sealing body 17 is disposed as described above, one welding electrode W1 is disposed on the upper surface of the positive electrode cap (positive electrode external terminal) 17a, and the other welding electrode is disposed on the lower surface of the bottom surface (negative electrode external terminal) of the battery case 16. W2 was placed. Thereafter, while applying a pressure of 2 × 10 ⁶ N / m ² between the pair of welding electrodes W1 and W2, a voltage of 24V is applied between the welding electrodes W1 and W2 in the discharge direction of the battery, and 3KA Was applied for about 15 msec. By this energization process, current concentrates on the contact portion between the bottom surface of the sealing body 17 and the small protrusion 22c formed on the wide portion 22a of the upper end flange portion 22 of the cylindrical body 20, and the small protrusion 22c and the sealing body 17 The bottom surface was welded to form a weld. At the same time, the contact portion between the lower surface of the negative electrode current collector 15 and the upper surface of the bottom surface (negative electrode external terminal) of the battery case 16 was welded to form a welded portion.
[0028]
Next, an insulating gasket 19 is fitted on the periphery of the sealing body 17, and a pressure is applied to the sealing body 17 using a press machine, and the sealing body 17 is placed in the battery case until the lower end of the insulating gasket 19 is positioned at the recess 16a. 16 was pushed into. Thereafter, the opening edge of the battery case 16 was crimped inward to seal the battery, and a cylindrical nickel-hydrogen storage battery having a nominal capacity of 6.5 Ah was produced. Note that the main body 21 of the cylindrical body 20 was crushed around the recessed central portion by the applied pressure at the time of sealing. The nickel-hydrogen storage battery of Example 1 produced in this way was designated as battery A.
[0029]
(2) Example 2
First, after the cylindrical body 20 described above is placed on the positive electrode current collector 14, a welding electrode (not shown) is disposed on the outer peripheral portion of the narrow portion 22b of the upper end flange 22, and the lower end flange 23 is disposed. The wide portion 23a and the current collector 14 were spot welded. Thereafter, the electrode body 10 in which the cylindrical body 20 was welded to the positive electrode current collector 14 was housed in a bottomed cylindrical battery case 16 in which iron was nickel-plated (the outer surface of the bottom surface serves as a negative electrode external terminal).
[0030]
Next, a vibration isolating ring 18 was inserted into the upper inner peripheral side of the battery case 16, and a groove was formed on the outer peripheral side of the battery case 16 to form a recess 16 a at the upper end of the vibration isolating ring 18. Thereafter, an electrolytic solution made of a 30% by mass potassium hydroxide (KOH) aqueous solution was injected into the battery case 16. Next, the bottom surface of the sealing body 17 was arranged on the upper part of the opening of the battery case 16 so as to contact the upper end flange 22 of the cylindrical body 20. The sealing body 17 has the same configuration as the sealing body 17 of the first embodiment described above.
[0031]
Next, an insulating gasket 19 is fitted on the periphery of the sealing body 17, and a pressure is applied to the sealing body 17 using a press machine, and the sealing body 17 is placed in the battery case until the lower end of the insulating gasket 19 is positioned at the recess 16a. 16 was pushed into. Thereafter, the opening edge of the battery case 16 was crimped inward to seal the battery. Note that the main body portion 21 of the cylindrical body 20 was crushed around the central portion recessed inward by the applied pressure at the time of sealing. Next, one welding electrode W1 was arranged on the upper surface of the positive electrode cap (positive electrode external terminal) 17a, and the other welding electrode W2 was arranged on the lower surface of the bottom surface (negative electrode external terminal) of the battery case 16.
[0032]
Thereafter, while applying a pressure of 2 × 10 ⁶ N / m ² between the pair of welding electrodes W1 and W2, a voltage of 24V is applied between the welding electrodes W1 and W2 in the discharge direction of the battery, and 3KA Was applied for about 15 msec. By this energization process, current concentrates on the contact portion between the bottom surface of the sealing body 17 and the small protrusion 22c formed on the wide portion 22a of the upper end flange portion 22 of the cylindrical body 20, and the small protrusion 22c and the sealing body 17 The bottom surface was welded to form a weld. At the same time, the contact portion between the lower surface of the negative electrode current collector 15 and the upper surface of the bottom surface (negative electrode external terminal) of the battery case 16 was welded to form a welded portion. Thereby, a cylindrical nickel-hydrogen storage battery having a nominal capacity of 6.5 Ah was produced, and battery B of Example 2 was obtained.
[0033]
(3) Comparative Example As shown in FIG. 4, the positive electrode core exposed on the upper end surface of the spiral electrode group produced in the same manner as in Example 1 described above has a large number of openings, and leads 14b from a part thereof. The disk-shaped positive electrode current collector 14a with a stretched line was welded. On the other hand, a disc-shaped negative electrode current collector 15 having a large number of openings was welded to the negative electrode core exposed at the lower end surface of the spiral electrode group to produce a spiral electrode body. This electrode body is accommodated in the battery case 16, and the negative electrode current collector 15 is spot welded to the inner bottom surface of the battery case 20 (in FIG. 4, the welding electrode is inserted into the center of the wound electrode body). 4 does not exist, but FIG. 4 is a diagram schematically showing that there is actually a space for inserting a welding electrode). Thereafter, the vibration isolating ring 18 was inserted into the upper inner peripheral side of the battery case 16, and grooving was performed on the outer peripheral side of the battery case 16 to form a recess 16 a at the upper end portion of the vibration isolating ring 18.
[0034]
Next, after the lead portion 14 b extended from the positive electrode current collector 14 a was bent vertically, the end portion of the lead portion 14 b was resistance welded to the bottom surface of the sealing body 17. Next, after injecting an electrolytic solution made of a 30 mass% potassium hydroxide (KOH) aqueous solution into the battery case 16, the lead part 14b is bent, and the sealing body 17 having the insulating gasket 19 fitted on the periphery thereof is formed into the battery. Arranged in the opening of the case 16. Subsequently, the opening edge of the battery case 16 was crimped inward to seal the battery, and a cylindrical nickel-hydrogen storage battery having a nominal capacity of 6.5 Ah was produced. The nickel-hydrogen storage battery of the comparative example produced in this way was designated as battery X.
[0035]
4). Battery Characteristic Test (1) Activation Using the batteries A and B of Examples 1 and 2 and the battery X of Comparative Example produced as described above, 650 mA (0.1 C) at room temperature (ambient temperature 25 ° C.) The battery was charged for 8 hours at a current value of 1 hour, paused for 1 hour, and then discharged at a current value of 1300 mA (0.2 C) until the battery voltage reached 0.8 V. This charge / discharge cycle was The battery was activated 10 times repeatedly.
[0036]
(2) VI characteristic test Next, using the batteries A and B of Examples 1 and 2 activated as described above and the battery X of Comparative Example, 1300 mA (2C) at room temperature (ambient temperature 25 ° C.) The battery was discharged at a current value of 1300 mA (0.2 C) for 3 hours at a current value of 1300 mA (0.2 C). After resting for 1 hour, the battery was discharged for 30 seconds at a current value of 25 A, and the battery voltage 10 seconds after the start of discharge was measured.
Then, after charging the power for the discharged capacity, similarly, the battery was discharged at current values of 50A, 70A, and 100A for 30 seconds, and the battery voltage 10 seconds after the start of discharge was measured. When the VI voltage (VI characteristics) is obtained with the vertical axis representing the battery voltage 10 seconds after the start of discharge thus obtained and the horizontal axis representing each current value, the results shown in FIG. became.
[0037]
As can be seen from FIG. 5, the slope of the V-I straight line of the batteries A and B of Examples 1 and 2 is small while the slope of the V-I straight line of the battery X of the comparative example is large. From this, it can be seen that the operating voltages of the batteries A and B of Examples 1 and 2 are both high and the battery internal resistance is low. In the batteries A and B of Examples 1 and 2, the cylindrical body 20 serving as the lead portion has a large cross-sectional area in the current collecting direction and a short length (height) in the current collecting direction. It is considered that the internal resistance at the point was reduced and high output characteristics were obtained. Further, since the internal resistance at the lead portion is low, the voltage drop is also reduced, and the operating voltage is considered to be high.
[0038]
In the embodiment described above, a voltage of 24 V is applied in the battery discharge direction between the positive electrode cap (positive electrode external terminal) 17a and the bottom surface (negative electrode external terminal) of the battery case 16, and a current of 3 KA is applied for about 15 msec. Although welding was performed while flowing, there was no correlation in the direction of the current applied to the battery, and similar results were obtained regardless of whether the battery was discharged or charged. In addition, regarding the applied current value, the same effect was obtained at 300 A or more regardless of the size of the battery. Note that a direct current or an alternating current power source can be used as a power source for welding current flowing between the battery case and the sealing body.
[0039]
However, when an extremely excessive current is applied, the cylindrical body 20 is melted even when applied for a short time, and the upper limit value of the current value to be melted varies depending on the material and shape of the cylindrical body 20. The current value must be a value that is 300 A or more and that the hourglass tube 20 does not melt. Furthermore, if the application time is 0.25 msec or more, the same effect can be obtained. However, if the application time is as long as 1 second, the cylindrical body 20 is melted, which is not preferable.
[0040]
In the above-described embodiment, after the cylindrical body 20 is welded to the positive electrode current collector 14 side, a current is applied between the positive electrode external terminal (positive electrode cap) 17a and the negative electrode external terminal (bottom surface of the battery case 16). The cylindrical body 20 and the sealing body 17 are welded to each other, but after the sealing body 17 and the cylindrical body 20 are welded, the positive electrode external terminal (positive electrode cap) 17a and the negative electrode external terminal (the bottom surface of the battery case 16). A similar effect can be expected even when a current is passed between the positive electrode current collector 14 and the cylindrical body 20. In this case, it is necessary to provide a small protrusion on the lower surface of the wide portion 23 a of the lower end flange 23 of the cylindrical body 20.
[0041]
In the above-described embodiment, a current is passed between the positive electrode external terminal (positive electrode cap) and the negative electrode external terminal (bottom surface of the battery case) to weld the sealing body and the current collector and to collect the negative electrode current collector. The example in which the body and the inner bottom surface of the battery case are welded at the same time has been described. After spot welding the negative electrode current collector and the inner bottom surface of the battery case, the positive electrode external terminal (positive electrode cap) and the negative electrode external terminal The sealing member and the current collector may be welded by passing an electric current between them (the bottom surface of the battery case).
In this case, it is necessary to provide a space for inserting a welding electrode at the center of the spiral electrode body 10, and this space is formed by a core trace space when forming the spiral electrode group. Good.
[0042]
Further, in the above-described embodiment, the example in which the sealing body is the positive electrode terminal and the battery case is the negative electrode terminal has been described. However, the sealing body may be the negative electrode terminal and the battery case may be the positive electrode terminal. In this case, the positive electrode current collector is welded to the inner bottom surface of the battery case, and the bottom surface of the sealing body is welded to the negative electrode current collector through the cylindrical body 20.
Furthermore, in the above-described embodiment, an example in which the present invention is applied to a nickel-hydrogen storage battery has been described. However, the present invention is not limited to a nickel-hydrogen storage battery, but may be applied to other storage batteries such as a nickel-cadmium storage battery. Obviously we can do it.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a state in which a cylindrical body constituting a lead portion of the present invention is welded to a positive electrode current collector and a sealing body.
FIG. 2 is a cross-sectional view showing a state in which an electrode body is inserted into a battery case and a cylindrical body and a sealing body are welded.
FIG. 3 is a view showing a main part in a state where a cylindrical body is welded to the upper part of a positive electrode current collector of an electrode body, FIG. 3 (a) shows a top view thereof, and FIG. 3 (b) shows a side view thereof. FIG. 3C is a cross-sectional view showing the AA cross section of FIG.
FIG. 4 is a cross-sectional view showing a storage battery of a conventional example (comparative example), in which a lead part is welded to a sealing body.
FIG. 5 is a diagram showing voltage (V) -current (I) characteristics of each battery.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Electrode body, 11 ... Positive electrode plate, 12 ... Negative electrode plate, 13 ... Separator, 14 ... Positive electrode collector, 15 ... Negative electrode collector, 16 ... Battery case (negative electrode external terminal), 16a ... Groove part, 17 ... Sealing Body, 17a ... Lid, 17b ... Positive electrode cap (positive electrode external terminal), 18 ... Anti-vibration ring, 19 ... Insulating gasket, 20 ... Cylindrical body (lead part), 21 ... Body part, 22, 23 ... Gutter part, 22a , 23a ... Wide part, 22b, 23b ... Narrow part, W1, W2 ... Welding electrode

Claims

Meanwhile a battery case having an opening serving as a pole of terminals, and a sealing body serving as a terminal of the other electrode to seal said opening, collecting at least one end of the positive and negative electrode housed in the battery case A storage battery comprising an electrode body to which an electric body is connected,
The storage battery is characterized in that the sealing body and the current collector are fixedly connected to each other by a lead portion composed of a cylindrical body having a central portion in the length direction that is recessed inward to form a drum shape .

The upper and lower ends of the cylindrical body are provided with ridges in which wide portions and narrow portions are alternately formed, and the wide portions of the upper end ridges and the narrow portions of the lower end ridges overlap each other across a space. The storage battery according to claim 1, wherein the narrow portion of the upper end collar and the wide portion of the lower end collar overlap each other with a space therebetween.

3. The storage battery according to claim 2, wherein a small protrusion is formed on at least one of an upper surface of the wide portion of the upper end flange portion or a lower surface of the wide portion of the lower end flange portion.

The storage battery according to claim 3, wherein the small protrusion is fixedly connected to a lower surface of the sealing body or an upper surface of the current collector.

It said cylindrical body storage battery according to any one of claims 1 to 4, characterized in that they are crushed and pressed around the central portion of its length.

In a battery case having an opening that also serves as a terminal of one electrode, an electrode body in which a current collector is connected to at least one of the positive and negative electrodes is accommodated, and then the opening serves as a terminal of the other electrode A method of manufacturing a storage battery formed by sealing with a sealing body,
1st welding which welds the lead part comprised from the cylindrical body by which the center part of the length direction was dented inwardly, and was made into the drum shape to either the upper surface of the said electrical power collector, or the lower surface of the said sealing body Process,
An electrolyte injection step of injecting an electrolyte into the battery case;
An arrangement step of arranging the sealing body in the opening of the battery case;
A sealing step of sealing the sealing body in the opening of the battery case;
A second welding step in which a current is passed between the battery case and the sealing body to weld the lead portion to either the lower surface of the sealing body or the upper surface of the current collector. A method for manufacturing a storage battery.

The method for manufacturing a storage battery according to claim 6, wherein, in the sealing step, the sealing body is pressed and crushed around a central portion in a length direction of the cylindrical body .

In a battery case having an opening that also serves as a terminal of one electrode, an electrode body in which a current collector is connected to at least one of the positive and negative electrodes is accommodated, and then the opening serves as a terminal of the other electrode A method of manufacturing a storage battery formed by sealing with a sealing body,
1st welding which welds the lead part comprised from the cylindrical body by which the center part of the length direction was dented inwardly, and was made into the drum shape to either the upper surface of the said electrical power collector, or the lower surface of the said sealing body Process,
An electrolyte injection step of injecting an electrolyte into the battery case;
An arranging step of arranging the sealing body in the opening of the battery case so that the sealing body and the lead portion or the lead portion and the current collector are in contact with each other;
A second welding step in which a current is passed between the battery case and the sealing body to weld the lead portion to either the lower surface of the sealing body or the upper surface of the current collector;
A method for producing a storage battery, comprising: a sealing step of sealing the sealing body in an opening of the battery case.

The method for manufacturing a storage battery according to claim 8, wherein in the second welding step, the sealing body is pressed and crushed around a central portion in a length direction of the cylindrical body .

While having an eaves portion in which wide portions and narrow portions are alternately formed on the upper and lower ends of the cylindrical body ,
And the wide portion of the width narrow portion of the wide end and the lower flange portion of the upper flange portion of the drum-shaped cylindrical body overlap each other with a space, and the narrow part of the upper flange portion of the cylindrical body and the lower flange portion Are arranged so as to overlap each other across a space,
A welding electrode is arranged on the outer peripheral portion of the narrow portion of the upper end flange, and the wide portion of the lower end flange and the upper surface of the current collector are welded, or the outer peripheral portion of the narrow portion of the lower end flange The method for manufacturing a storage battery according to any one of claims 6 to 9, wherein a welding electrode is disposed on the wide end of the upper end flange and the lower surface of the sealing body is welded. .

A small protrusion is formed on at least one of the upper surface of the wide portion of the upper end flange or the lower surface of the wide portion of the lower end flange, and a welding current is concentrated on the small protrusion so that the small protrusion and the lower surface of the sealing body or The method for manufacturing a storage battery according to claim 10, wherein the small protrusion and the upper surface of the current collector are welded.