JP3649909B2

JP3649909B2 - battery

Info

Publication number: JP3649909B2
Application number: JP18722398A
Authority: JP
Inventors: 貴志山口; 隆明池町; 茂人為実; 訓生川
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 1998-07-02
Filing date: 1998-07-02
Publication date: 2005-05-18
Anticipated expiration: 2018-07-02
Also published as: JP2000021384A

Description

【０００１】
【発明の属する技術分野】
本発明は、電極群に集電板を溶着して高率放電特性を向上させた電池に関する。
【０００２】
【従来の技術】
アルカリ電池等に使用される電極板として、焼結式電極と非焼結式電極がある。従来は焼結式電極が主流で多く使用されてきた。この電極は、カルボニルニッケル焼結体にニッケル塩、力ドミウム塩などの溶液を含浸させ、アルカリ処理をして活物質化して製作される。しかし、近年は、コストを低減して、高エネルギー密度にできることから、非焼結式電極が有望となってきた。非焼結式電極は、発泡ニッケルや、ニッケル繊維多孔体などの金属３次元多孔体を基板とし、この基板の空隙に、ペースト状の活物質を直接に充填して製作される。
【０００３】
非焼結式電極は、基板に金属３次元多孔体を使用するので、焼結式電極の基板に使用されるパンチングメタルのように、基板に直接にリード板を溶接して接続できない。金属３次元多孔体はほとんどの部分が空隙で、金属部分がしめる割合が極めて少ないために、リード板を接触させても、接触面積が極めて小さく制限されるからである。
【０００４】
金属３次元多孔体の基板を集電板に接続する技術は、以下の公報に記載される。
(1) 特開昭６３−４５６２号公報
(2) 特開平２−２２０３６５号公報
【０００５】
(1) と (2)の公報には、金属３次元多孔体の基板の端縁に沿って、活物質を充填しない帯状連結部を設け、ここに金属薄板を溶着して、この部分を集電板に接続する構造が記載される。
【０００６】
帯状連結部に金属薄板を溶着している電極板は、セパレータを介して渦巻状に捲回されて電極群となる。この渦巻状の電極群は、図１の分解図で示すように、集電板６を溶着して集電できる。この図に示すように、集電板６を電極群４に溶着する電池は、高率放電特性を向上させて、大電流での放電特性を改善できる。金属薄板を溶着している電極板は、図２の展開図で示すように、帯状連結部７の一部にリード板６Ａを溶着して集電することもできる。しかしながら、図２に示すように、リード板６Ａを溶着して集電する構造の電池は、大電流放電特性を向上させるのが難しい。図１に示すように、帯状連結部となる電極群４の上端縁を、複数部分で集電板６に接続する電池は、電極板に流れる電流分布を均一にできる特長がある。
【０００７】
図３の断面図は、電極群４の上面に集電板６を接続する電池の断面構造を示している。この構造の電池は、集電板６の下面を片方の極板に複数部分で帯状連結部７に接続している。片方の極板を集電板６に接続するために、一方の電極板は他方の電極板よりも上方に突出されている。電極板の突出部は、金属薄板１０を溶着している帯状連結部７である。この構造の電極群は、図４の断面図に示すように、上面に集電板６を押圧して、集電板６に抵抗電気溶接して接続される。
【０００８】
【発明が解決しようとする課題】
以上の構造の電池は、基板の帯状連結部を、集電板に理想的な状態で接続するのが極めて難しい。とくに、帯状連結部の複数部分を、確実に集電板に接続するためには、集電板を相当な圧力で帯状連結部に押圧して、抵抗電気溶接する必要がある。集電板の押圧力を弱くすると、集電板と帯状連結部との連結部分の間の電気抵抗が大きくなって、正常に電気溶接できなくなるからである。電気抵抗が大きな状態で、集電板と帯状連結部とを抵抗電気溶接すると、溶接機は、定電流を流すために、集電板と帯状連結部との間に印加する電圧を高くする。高い電圧が印加されると、集電板と帯状連結部の間でアーク放電するようになって、抵抗が急激に低下し、溶接部分に大電力が供給されて接触部が瞬時に溶解して飛び散る、いわゆる「爆飛」といわれる状態となる。この状態になると、集電板と帯状連結部とは正常に接続できなくなってしまう。
【０００９】
とくに、電池の内部抵抗を小さくするために、集電板の複数部分を帯状連結部に接着する電池は、帯状連結部と集電板とを接続する全ての部分で理想的な状態で連結するのが極めて難しい。帯状連結部の上面と、集電板の下面を完全な平面には加工できないからである。とくに、複数の貫通孔を設けて、貫通孔の周縁に下方に突起を設けて、この突起を帯状連結部に接触させて電気溶接する集電板は、下面を完全な平面状とすることは現実には極めて困難である。
【００１０】
集電板を電極群に強く押圧することで、帯状連結部と集電板とを隙間なく接触できる。したがって、この状態で集電板を帯状連結部に溶着すれば、集電板と帯状連結部とを確実に溶着できる。しかしながら、集電板を帯状連結部に強く押圧して、溶着すると、図５と図６に示すように、帯状連結部７が折れ曲がって、内部ショートの原因となる。折れ曲がった部分がセパレータ３を突き破って、他の端子に接触するからである。とくに、金属薄板１０を溶着している帯状連結部７は、不連続な部分が弱くなって、充填境界で折れ曲がりやすい性質がある。さらに、金属３次元多孔体の基板に活物質を充填している非焼結式電極は、基板の強度が弱く、集電板を強く押圧すると、変形しやすい。
【００１１】
したがって、従来の電池は、集電板を電極群に強く押圧して溶着すると、内部ショートが多くなり、反対に集電板を電極群に押圧する圧力を弱くして溶着すると、集電板と電極群とを低抵抗な状態で溶着できなくなる欠点があった。さらに、電池は、落下された時などに受ける衝撃で、溶着部分が剥離して使用できなくなることがある。とくに、電極群の帯状連結部を、複数部分で集電板に溶着している大電流特性の優れた電池は、細長いリード板を介して電極群を端子に接続している電池に比較すると、衝撃による不良品の発生率が高くなる欠点がある。それは、リード板のように自由に変形して衝撃を吸収する能力が少ないからである。
【００１２】
本発明は、上記のような従来の欠点を解決することを目的に開発されたもので、本発明の重要な目的は、電極群の帯状連結部を、低抵抗な状態で集電板の複数部分に確実に溶着でき、さらに、集電板を溶着する工程における内部ショートが少なく、しかも、耐衝撃特性の優れた電池を提供することにある。
【００１３】
【課題を解決するための手段】
本発明の電池は、前述の目的を達成するために以下の構造を有している。電池は、正極板と負極板とからなる第１極板１と第２極板２を、セパレータ３を介して積層している電極群４と、この電極群４を収納している外装缶５と、第１極板１に電気接続されて、第１極板１を一方の端子に電気的に接続する集電板６とを備える。
【００１４】
第１極板を正極板とする電池は、第２極板を負極板とし、第１極板を負極板とする電池は、第２極板を正極板とする。
【００１５】
第１極板１は、金属３次元多孔体の基板９に活物質を充填している非焼結式電極であって、基板９を露出させている帯状連結部７を有する。この帯状連結部７は、金属３次元多孔体を露出させている帯状連結部７に、金属薄板１０を溶着している。金属薄板１０を溶着している帯状連結部７は、集電板６の複数部分に溶着して電気的に接続している。
【００１６】
さらに、本発明の請求項１の電池は、帯状連結部７に溶着している金属薄板１０の厚さを０．０７ｍｍ以上で第１極板１の厚さの８０％よりも薄くすると共に、ビッカース硬度を５０以上で２５０以下としている。
【００１７】
本発明の電池は、集電板６に、ビッカース硬度を５０以上で２５０以下として、厚さを０．１〜１．５ｍｍとする金属板を使用する。
【００１８】
本発明の電池は、集電板６が外装缶５の内形よりも小さい外形であって、電極群４の端部に対向して配設されている。さらに集電板６は、複数の貫通孔６Ｄを設けている。貫通孔６Ｄは、周縁に、電極群４の帯状連結部７に向かって突出している突起６Ｅを有する。突出している突起６Ｅは、第１極板１の帯状連結部７に複数部分で溶着されている。
【００１９】
本発明の請求項２の電池は、金属３次元多孔体を、発泡ニッケル、又は、ニッケル繊維多孔体とする。
【００２０】
本発明の電池は、金属３次元多孔体の基板９の帯状連結部７をプレスして高密度に圧縮している。
【００２１】
本発明の請求項３の電池は、第１極板１と第２極板２とをセパレータ３を介して積層して渦巻状に捲回してなる渦巻電極を電極群４に使用している。集電板６は、渦巻電極の端部に接近して配設されている円板状である。
【００２２】
【発明の実施の形態】
以下、本発明の実施の形態を図面に基づいて説明する。ただし、以下に示す実施の形態は、本発明の技術思想を具体化するための電池を例示するものであって、本発明は電池を以下のものに特定しない。
【００２３】
さらに、この明細書は、特許請求の範囲を理解しやすいように、実施の形態に示される部材に対応する番号を、「特許請求の範囲の欄」、および「課題を解決するための手段の欄」に示される部材に付記している。ただ、特許請求の範囲に示される部材を、実施の形態の部材に特定するものでは決してない。
【００２４】
図７に示す電池は、封口板１１で気密に密閉された円筒状の外装缶５と、この外装缶５に挿入している電極群４と、電極群４を外装缶５の端子１２に接続する集電板６とを備える。図に示す電池は、外装缶を円筒状としているが、本発明は電池の外装缶を円筒状に特定しない。外装缶は、図示しないが、たとえば、四角筒状ないし楕円筒状とすることもできる。
【００２５】
外装缶５は鉄製で、その表面をニッケルメッキしている。外装缶５の材質は、電池の種類と特性を考慮して最適な金属が選択される。外装缶は、例えば、ステンレス、アルミニウム、アルミニウム合金製とすることもある。金属製の外装缶は、上端の開口部を、封口蓋で気密に密閉している。封口蓋は、外装缶をかしめる構造、あるいは、外装缶と封口蓋の境界をレーザー溶接する等の方法で、気密に固定される。封口板１１は電池の一方の端子１２を固定している。この端子１２は、外装缶に対して絶縁して固定される。
【００２６】
本発明の電池は、非焼結式電極を内蔵する電池、たとえば、ニッケル−水素電池である。ただ、本発明は、電池をニッケル−水素電池に特定しない。電池には、たとえば、ニッケル−カドミウム電池、リチウムイオン電池等とすることもできる。以下、好ましい実施の形態として、ニッケル−水素電池の実施の形態を詳述する。
【００２７】
電極群４は、第１極板１と第２極板２を、セパレータ３を介して捲回している。図に示す電池は、集電板６に接続される第１極板１を正極板とし、第２極板２を負極板としている。ただし、本発明は、第１極板を負極板として、第２極板を正極板とすることもできる。セパレータ３を介して互いに積層された第１極板１と第２極板２は、巻回して渦巻状の電極群４に製作される。渦巻状の電極群４は、円筒状の外装缶５に挿入される。渦巻状の電極群は、両側からプレスして楕円形に変形させて、楕円形の外装缶に挿入することができる。さらに、角筒状の外装缶に挿入される電極群は、板状に裁断された複数枚の第１極板と第２極板とを、セパレータを介して積層して製作される。
【００２８】
セパレータ３は、ポリオレフィン製不織布が使用される。ただ、セパレータ３には、ポリエチレン等の合成樹脂製微多孔膜も使用できる。セパレータ３には、両側に積層される第１極板１と第２極板２を絶縁でき、かつ、電解液を浸透できる全てのシート材が使用できる。
【００２９】
第１極板１は、金属３次元多孔体の基板９に活物質を充填している非焼結式電極である。金属３次元多孔体の基板９は、発泡ニッケル多孔体やニッケル繊維多孔体等である。第１極板１は、これ等の基板９に活物質を充填している。
【００３０】
第１極板１の基板は、図８の展開図に示すように、基板９の上部に帯状連結部７を設け、他の部分は活物質を充填している活物質充填部８としている。帯状連結部７は、活物質を充填せず、あるいは、充填した活物質を除去して基板９を露出させている。基板９は、好ましくは、帯状連結部７でプレスされて高密度に圧縮されている。圧縮された帯状連結部７は、金属薄板を確実に溶着できる特長がある。
【００３１】
帯状連結部７は、集電板６により確実に電気的に接続するために、図９の断面図に示すように、金属薄板１０を固定している。金属薄板１０は、抵抗電気溶接して、あるいは導電性の接着材を介して、帯状連結部７に電気的に接続される状態で接着される。
【００３２】
金属薄板１０の厚さは、０．０７ｍｍ以上で、第１極板１の８０％の厚さよりも薄い。金属薄板１０を０．０７ｍｍよりも薄くすると、帯状連結部を集電板に溶接するときの強度が充分でなくなる。反対に、金属薄板の厚さが第１極板１の８０％よりも厚くなると、第１極板と第２極板とをセパレータを介して積層した状態で、帯状連結部が厚くなって、スペース効率が低下する。金属薄板の厚さは、好ましくは０．０９５〜０．２ｍｍとする。
【００３３】
さらに、金属薄板は、ビッカース硬度を５０以上として、２５０以下とする金属薄板が使用される。金属薄板の硬度が５０以下であると、帯状連結部を集電板に溶着するときの強度が充分でなくなり、また、電池が衝撃を受けたときに、帯状連結部が集電板から離れて、耐衝撃強度が低下する。金属薄板のビッカース硬度が２５０よりも大きくなると、帯状連結部を集電板に溶着するときに、金属薄板がセパレータを突き破って内部ショートしやすく、また、衝撃強度も低下する。したがって、金属薄板には、ビッカース硬度を５０〜２５０とする金属の薄板、好ましくは、ビッカース硬度を１７０〜２００とする金属の薄板、たとえば、ニッケル薄板、リンニッケル薄板、鉄にニッケルメッキをした薄板等を使用する。
【００３４】
図９の第１極板１は、帯状連結部７の第２極板２との対向面に保護テープ１３を付着している。保護テープ１３は、下端縁を充填境界よりも下方まで延長している。帯状連結部７に集電板６を押圧して溶接するときに、充填境界が折れ曲がってセパレータを突き破るのを防止するためである。ここに保護テープ１３を接着している電池は、内部ショートを防止して、集電板６を帯状連結部７に確実に接続できる特長がある。ただ、保護テープを使用しない状態で、帯状連結部を集電板に接続することもできる。
【００３５】
集電板６は、鉄にニッケルメッキをした金属板、あるいは、ニッケル板等の金属板で、図１０に示すように、金属板を外装缶５の内形よりも小さい円板状に切断して、リード板６Ａを突出させたものである。集電板６は、電極群４の両端部で対向するように配設される。図１０に示す集電板６は、電池の外装缶５が円筒形である電池に使用するために円形としているが、本発明の電池は円筒形電池に特定されないので、例えば図示しないが、角形電池には、方形状の集電板を使用することができる。
【００３６】
集電板６は、抵抗電気溶接するときの無効電流を少なくするために、中心孔６Ｂの両側にスリット６Ｃを設けている。さらに、複数の貫通孔６Ｄを開口している。貫通孔６Ｄの周縁には、図１１の拡大断面図に示すように、下方に突出する突起６Ｅを設けている。突起６Ｅは、第１極板１の帯状連結部７に複数部分で溶着して接続される。集電板６のリード板６Ａは、外装缶５の開口部に絶縁して固定される端子１２に接続される。
【００３７】
集電板は、ビッカース硬度を５０以上で２５０以下として、厚さを０．１〜１．５ｍｍとする金属板である。集電板は、ビッカース硬度を５０以下とし、あるいは、厚さを０．１ｍｍ以下としても、また、ビッカース硬度を２５０以上とし、あるいは厚さを１．５ｍｍよりも厚くしても、帯状連結部に確実に溶着できなくなる。
【００３８】
ビッカース硬度を５０以下とし、あるいは厚さを０．１ｍｍ以下とする集電板は、充分な強度がないために、溶接用の電極棒を局部的に押圧して、帯状連結部と集電板との接触部分を確実に溶着できなくなる。集電板が変形してしまうからである。さらに、ビッカース硬度を２５０以上とし、あるいは厚さを１．５ｍｍ以上とする集電板も、溶接用の電極棒を局部的に押圧するときに、帯状連結部と集電板との接触部分を確実に溶着できなくなる。集電板がほとんど変形しないからである。
【００３９】
帯状連結部を集電板に溶着するときには、帯状連結部と集電板の溶着部分において、接触部分を均一な状態で接触させることが大切である。集電板は、溶接用電極棒で局部的に押圧される状態で、全く変形しなくても、また、変形が大きすぎても、溶接部分を均一に接触できなくなる。変形が大きすぎると、溶接用電極棒で押圧される近傍の溶接部分は強く押圧されるが、溶接用電極棒から離れた部分での溶接部分の接触が弱く、あるいは離れてしまう。また、集電板が全く変形しないと、集電板と帯状連結部の突出している溶接部分のみが強く接触して、他の溶接部分は接触しなくなる。このため、全ての溶接部分を均一に接触させて理想的な状態で溶着できなくなる。
【００４０】
さらに、集電板は、ビッカース硬度を２５０以上とし、あるいは厚さを１．５ｍｍ以上とすると、帯状連結部を連結するときに、第１極板と第２極板とがセパレータを突き破って内部ショートする率が高くなって、歩留を低下させる。それは、溶接用電極棒で押圧される集電板の変形が小さくなって、互いに突出する状態で集電板に押圧される帯状連結部が折れ曲がって、セパレータ３を突き破るからである。
【００４１】
さらに、集電板は、ビッカース硬度を５０以下とし、あるいは、厚さを０．１ｍｍ以下としても、また、ビッカース硬度を２５０以上とし、あるいは厚さを１．５ｍｍよりも厚くしても、耐衝撃強度が低下する。ビッカース硬度を５０以下とし、あるいは、厚さを０．１ｍｍ以下とする集電板６は、充分な強度がないために、衝撃を受けたときに帯状連結部との溶着が外れて耐衝撃強度が低下する。また、ビッカース硬度を２５０以上とし、あるいは、１．５ｍｍよりも厚い集電板は、衝撃を受けたときに全く変形しない、いいかえると、緩衝作用がないために、帯状連結部と集電板との溶着部分が外れやすく、耐衝撃強度が低下する。
【００４２】
【実施例】
以下の工程で、ＳＣサイズの円筒型ニッケル−水素電池を試作し、金属薄板の厚さとビッカース硬度、および集電板のビッカース硬度を変更して、それぞれの良品率を測定した。
【００４３】
以下の工程で、ニッケル−水素電池の外装缶に挿入する電極群を製作した。
ａ．第１極板である正極板の製作
(1) 下記の工程で金属多孔体を作製する。
連続気泡のポリウレタンフォームであるスポンジ状の有機多孔体を、導電処理した後、電解槽のメッキ液に浸漬してメッキする。メッキした有機多孔体を、７５０℃の温度で所定時間ばい焼して、有機多孔体の樹脂成分を除去し、さらに、還元雰囲気で焼結して金属多孔体を製作する。この工程で製作された金属多孔体は、目付を約６００ｇ／ｍ^２とし、多孔度を９５％とし、厚みを約２．０ｍｍとする発泡ニッケルである。
【００４４】
(2) 下記のものを混練して、正極の活物質スラリーとする。
水酸化ニッケル粉末…………………………………………９０重量部
（２．５ｗｔ％の亜鉛と、１ｗｔ％のコバルトを共沈成分として含有）
コバルト粉末…………………………………………………１０重量部
酸化亜鉛粉末……………………………………………………３重量部
ヒドロキシプロピルセルロース０．２重量％水溶液……５０重量部
【００４５】
(3) 作製した正極の活物質スラリーを、金属多孔体の空隙に充填した。充填量は、ロール圧延後の活物質密度が約２．９１ｇ／ｃｃ−ｖｏｉｄとなるように調整した。その後、乾燥し、厚みが約０．７０ｍｍとなるように口ール圧延を行った。さらに短冊状に切断し、金属薄板１０を溶接する帯状連結部７に対し、垂直方向の超音波振動を加える超音波剥離等により活物質を除去した。そして図８に示すように、基板９の露出する帯状連結部７のある第１極板１とする。
【００４６】
第１極板は、以下の工程で活物質を製造することもできる。図１２に示すように、活物質を充填する前に、金属多孔体を所定の幅で平行にロール圧延する。ロール圧延の幅は、帯状連結部７の幅の２倍の約５ｍｍとし、圧延後の厚さを０．５ｍｍとする。このように圧延した金属多孔体の基板９に、上記の活物質スラリーを充填して圧延する。その後、図１２の矢印で示す位置で切断して、短冊状の第１極板を作製する。その後、帯状連結部７となる薄く圧延された部分に沿って、圧縮空気を噴射し、あるいはブラシ等を使用して、活物質を除去して基板を露出させる。
【００４７】
(4) 基板９の露出した帯状連結部７に、抵抗電気溶接により金属薄板１０を接着する。帯状連結部７と金属薄板１０との接着には、直径１．５ｍｍの銅を溶接用電極棒として使用し、２ｍｍ間隔で抵抗電気溶接した。金属薄板１０には、ニッケルリボンを使用し、幅１．５ｍｍとした。
【００４８】
金属薄板の厚さとビッカース硬度をパラメータとして、複数の試作電池を作製する。試作電池１〜１３は、金属薄板の厚さを、０．０１〜０．５０ｍｍの範囲で設定している。このとき使用した金属薄板は、幅１．５ｍｍ、ビッカース硬度１５０のニッケルリボンで、また集電板はビッカース硬度１５０、厚さ０．４０ｍｍのニッケルメッキをした鉄を使用した。
【００４９】
さらに、金属薄板のビッカース硬度を３０〜３５０まで変更して、試作電池１４〜２２を作製する。このとき使用した金属薄板は、幅１．５ｍｍ、厚さを０．０７ｍｍとするニッケルリボンであり、また集電板は前記と同じくビッカース硬度１５０、厚さ０．４０ｍｍのニッケルメッキをした鉄を使用した。
【００５０】
ｂ．第２極板である負極板の製作
(1) 水素吸蔵合金の作製と粉砕
ミッシュメタル（Ｌａ、Ｃｅ、Ｎｄ、Ｐｒ等の希土類元素の混合物）と、ニッケルと、コバルトと、アルミニウムと、マンガンを、元素比で１．０：３．４：０．８：０．２：０．６に秤量して混合し、これをルツボに入れて高周波溶解炉で溶融した後冷却し、下記の組成式の水素吸蔵合金電極を作製する。
Ｍｍ_１．０Ｎｉ_３．４Ｃｏ_０．８Ａｌ_０．２Ｍｎ_０．６
そして、得られた水素吸蔵合金の鋳塊を、あらかじめ粗粉砕した後、不活性ガス中で平均粒径が６０μｍとなるように粉砕する。
【００５１】
(2) 水素吸蔵合金スラリーの作製
粉砕した水素吸蔵合金の粉末に、結着剤としてポリエチレンオキサイド粉末を添加し、さらにイオン交換水を添加、混練してスラリーとする。結着剤であるポリエチレンオキサイド粉末の添加量は、水素吸蔵合金に対して１．０重量％とする。
【００５２】
(3) スラリーをパンチングメタルである基板の両面に塗着した。塗着量は、圧延後の活物質密度が５ｇ／ｃｃとなるように調整した。その後、乾燥、圧延を行った後、所定寸法に切断を行い、第２極板である負極板とした。スラリーは、パンチングメタルの下縁に帯状連結部７ができるように、下縁を残して塗着した。また、パンチングメタルの全面にスラリーを塗着した後、乾燥し、下縁の活物質を除去して帯状連結部を設けることもできる。
【００５３】
以上の工程で製作した第１極板と第２極板を、ポリオレフィン製不織布からなるセバレータを介して捲回し渦巻状の電極群とし、渦巻電極を作製した。この渦巻電極の上端端部に突出する金属薄板１０に、集電板を抵抗電気溶接にて溶着する。集電板は、円板状で厚さ０．４０ｍｍのニッケルメッキをした鉄製の板を使用した。この集電板のビッカース硬度は、試作電池のパラメータとして、３０〜３５０で変更して、試作電池２３〜３１を作製した。
【００５４】
以上の方法で作製した第１極板、第２極板を使用して、円筒型のニッケル−水素電池の試作電池を作製した。
【００５５】
［試作電池１〜１３］
試作電池１〜１３は、金属薄板の厚さをパラメータとして、０．０１〜０．５０ｍｍの範囲で設定している。金属薄板として、幅１．５ｍｍ、ビッカース硬度１５０のニッケルリボンを使用し、また集電板としてビッカース硬度１５０、厚さ０．４０ｍｍのニッケルメッキを施した鉄製の板を使用した。
【００５６】
各試作電池の金属薄板１０の厚さは、０．０１〜０．５０ｍｍの範囲で変更して、試作電池を１〜１３まで作製した。０．０１〜０．０７ｍｍまでは０．０２ｍｍ毎に変更し、以後は０．１０ｍｍ〜０．５０ｍｍまで０．０５ｍｍ毎に厚さを変更した。
【００５７】
上記のようにして試作した試作電池１〜１３の、良品率を測定する。ここにおいて、良品率とは電池１００個に対する良品の数を表しており、とくに端子が接続状態にあって使用できるかどうかで判断している。つまり、各試作電池は一つの条件について同じ電池をそれぞれ１００個作製し、そのうちの良品の個数を計数した。
【００５８】
ここでは、良品率として、溶接良品率、組立良品率、衝撃良品率の３つを測定した。溶接良品率とは、電池の作製過程で金属薄板と集電板とを溶着した段階で、次の工程で使用できる率、つまり溶着直後に端子が正常である割合を示す。また、組立不良率とは、正常に溶着できた端子を使用して電池の作製を続行した場合、製造工程終了時において第１極板と第２極板がショートする内部ショートがない率、つまり溶接良品率１００％とした電池の製造直後に端子が正常である割合を示す。さらに、衝撃不良品とは、完成した正常な電池を１ｍの高さから鉄板上に１００回落下させた後に、電池が使用可能な率、つまり正常に組み立てられた電池に衝撃を与えても端子が剥離しない割合を示す。
【００５９】
金属薄板の厚さを０．０１〜０．５０ｍｍとした電池の、溶接良品率、組立良品率、衝撃良品率を測定した結果を表１に示す。
【００６０】
【表１】
金属薄板の厚さを０．０１〜０．５０ｍｍとした場合の溶接良品率、組立良品率、衝撃良品率

【００６１】
表１に示すように、金属薄板の厚さが０．０３ｍｍ以下である試作電池１、２は溶接良品率、衝撃良品率共に極めて悪かった。金属薄板の厚さが０．０５ｍｍである試作電池３で、溶接良品率、衝撃率は８０％となる。さらに金属薄板の厚みが０．０７ｍｍ以上では、溶接良品率、組立良品率、衝撃良品率すべてが極めて良好な結果を示した。また、試作電池１１が示すように、金属薄板の厚さが０．４０ｍｍで、溶接良品率、組立良品率、衝撃良品率はすべて９９％となった。第１極板の厚みは０．５ｍｍであるから、第１極板の厚さの８０％である０．４０ｍｍまで、極めて溶接良品率、組立良品率、衝撃良品率が高いことが判る。しかし、試作電池１２、１３が示すように、金属薄板の厚さが０．４５ｍｍ以上になると、組立良品率が低下した。組立良品率が悪くなった原因は、第１極板と第２極板がショートしたためであった。ショート部分は帯状連結部と活物質充填部との充填境界であり、この部分で基板である発泡ニッケルの骨格が突出した状態となった。
【００６２】
［試作電池１４〜２２］
次に、金属薄板のビッカース硬度をパラメータとする試作電池１４〜２２を作製した。使用した金属薄板は、幅１．５ｍｍ、厚さを０．０７ｍｍとするニッケルリボンであり、また集電板は、前記試作電池１〜１３と同じく、ビッカース硬度１５０、厚さ０．４０ｍｍのニッケルメッキを施した鉄板を使用した。
【００６３】
金属薄板のビッカース硬度は、３０〜３５０の範囲で変更した。ビッカース硬度３０〜７０までは、２０毎に変更し、１００〜３５０までは５０刻みとした。表２に、金属薄板のビッカース硬度を３０〜３５０として試作した試作電池の、良品率を測定した結果を示す。
【００６４】
【表２】
金属薄板のビッカース硬度を３０〜３５０とした場合の溶接良品率、組立良品率、衝撃良品率

【００６５】
表２に示すように、金属薄板のビッカース硬度は、５０〜２５０の範囲で、溶接良品率、組立良品率、衝撃良品率が極めて優れた結果を示した。試作電池１４のビッカース硬度３０では、組立良品率のみ９９％と高いが、溶接良品率、衝撃良品率はそれぞれ８５％、６０％で、若干低下している。またビッカース硬度３００以上の試作電池２１、２２は、溶接良品率は９９％と高いものの、組立良品率と衝撃良品率は若干低下した。したがって、最も良い結果を示すのは、金属薄板のビッカース硬度が５０〜２５０の範囲となる。
【００６６】
［試作電池２３〜３１］
さらに、集電板のビッカース硬度をパラメータとする試作電池２３〜３１を作製した。ここで使用した金属薄板は、幅１．５ｍｍ、厚さ０．０７ｍｍ、ビッカース硬度１５０とするニッケルリボンである。集電板は、厚さ０．４０ｍｍのニッケルメッキを施した鉄板を使用した。
【００６７】
集電板のビッカース硬度は、上記試作電池１４〜２２の金属薄板のビッカース硬度と同じく、３０〜３５０の範囲で変更した。集電板のビッカース硬度を、３０〜７０までは２０刻み、１００〜３５０までは５０刻みとしている。表３に、集電板のビッカース硬度を３０〜３５０として試作した試作電池の、溶接良品率、組立良品率、衝撃良品率を測定した結果を示す。
【００６８】
【表３】
集電板のビッカース硬度を３０〜３５０とした場合の溶接良品率、組立良品率、衝撃良品率

【００６９】
上記表３に示すように、集電板のビッカース硬度についても、前記金属薄板のビッカース硬度の試験と同じく、５０〜２５０の範囲で高い結果を示した。試作電池２３が示す集電板のビッカース硬度３０では、組立良品率は９９％と高いが、溶接良品率８５％、衝撃良品率３０％であった。またビッカース硬度３００では、試作電池３０が示すように、溶接良品率が９０％、組立良品率が８９％となって若干低下する。ビッカース硬度３５０では、さらに溶接良品率、組立良品率、衝撃良品率が低下した。
【００７０】
【発明の効果】
本発明の電池は、電極群と集電板との溶着を確実にして、電気的接続の遮断やショートを防止し、高率放電特性でしかも信頼性の高い電池にできる特長を実現する。それは本発明の電池が、帯状連結部に溶着される金属薄板の厚さとビッカース硬度を最適値として、溶着が確実に行えかつ使用時の耐衝撃性も向上しているからである。特に本発明の電池は、電池の製造工程において、電極群の帯状連結部に十分な強度をもって確実に溶着する厚さを集電板は有している。
また同時に、金属薄板のビッカース硬度を、製造時に必要な変形が十分行える硬度としているので、電池製造時の内部ショート等のトラブルも避けることができ、歩止まりを良くできる特長も実現する。
【００７１】
さらに加えて、適度な緩衝性と十分な強度とを有する本発明の電池は、電池製造後の使用時においても、電池を落としたりぶつけたりした際の衝撃で、電極板と集電板との電気接続が断たれ難い構造として耐衝撃性を向上し、高性能で信頼性の高い電池を提供できる。
【００７２】
また本発明の電池は、金属薄板の溶着された帯状連結部と溶着される集電板のビッカース硬度と厚さとを、十分な強度と製造時の変形が十分行えるバランスを保った最適な範囲とすることで、より確実な溶着を実現している。特に、本発明の電池によって、従来の焼結式電極でなく、非焼結式電極を使用して、コスト低減と高エネルギー密度化とを同時に実現できる優れた電池をさらに便利に使用できる。それは本発明が、高率放電可能な非焼結電極を製造するにおいて、本発明の電池に係る最適な硬度とすることで、集電板と電極群との電気的な接続を強固にでき、製造時および使用時における端子の剥離事故を防止できるからである。
【００７３】
焼結式電極は、パンチングメタル等の基板を使用しているが、非焼結式電極では、発泡ニッケルなどの３次元金属多孔体を基板として使用している。ただ、３次元金属多孔体を基板とする非焼結式極板は、集電板との溶接が難しく、集電性が不十分となることがあり、また衝撃によって端子が剥離するおそれがある。これに対し本発明の電池は、帯状連結部に溶着される金属薄板の厚さを、十分な強度を保持しつつ、省スペースをも維持した最適な範囲に調整している。さらに硬度も、十分に衝撃に耐える程高く、一方で製造時の溶着が十分に行えるよう低く、最適に調整することにより、耐衝撃性を向上している。また本発明の電池は、金属薄板の溶着された帯状連結部と溶着される集電板の硬度を、十分な強度と製造時の変形が十分行えるバランスを保った最適な範囲とすることで、耐衝撃性をより向上している。
【００７４】
さらにまた本発明の電池は、集電板に貫通孔と共に突起を設けており、溶着をさらに容易にかつ確実に行うことができる。このため、低コストおよび高率放電のみならず、信頼性をさらに向上して、安全で便利に使用できる極めて使い勝手の良い電池を提供できる特長が実現される。
【図面の簡単な説明】
【図１】電池に内蔵される電極群の極板に集電板を接続する状態を示す分解斜視図
【図２】リード板を溶着した極板の一例を示す平面図
【図３】従来の電池の一部断面正面図
【図４】電極群に集電板を押圧して接続する状態を示す拡大断面図
【図５】帯状連結部と充填境界が折れ曲がって内部ショートを起こす一例を示す拡大断面図
【図６】帯状連結部と充填境界が折れ曲がって内部ショートを起こす他の一例を示す拡大断面図
【図７】本発明の一実施例の電池の一部断面正面図
【図８】図７に示す電池の第１極板の展開図
【図９】図７に示す電池の電極群の積層構造を示す拡大断面図
【図１０】図７に示す電池の集電板の展開図
【図１１】図１０に示す集電板の拡大断面図
【図１２】第１極板の製造方法の一例を示す平面図
【符号の説明】
１…第１極板
２…第２極板
３…セパレータ
４…電極群
５…外装缶
６…集電板６Ａ…リード板６Ｂ…中心孔
６Ｃ…スリット６Ｄ…貫通孔
６Ｅ…突起
７…帯状連結部
８…活物質充填部
９…基板
１０…金属薄板
１１…封口板
１２…端子
１３…保護テープ[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a battery in which a current collecting plate is welded to an electrode group to improve high rate discharge characteristics.
[0002]
[Prior art]
  As an electrode plate used for an alkaline battery or the like, there are a sintered electrode and a non-sintered electrode. Conventionally, a sintered electrode has been mainly used. This electrode is manufactured by impregnating a carbonyl nickel sintered body with a solution such as a nickel salt or a force dium salt, and performing an alkali treatment to obtain an active material. However, in recent years, non-sintered electrodes have become promising because the cost can be reduced and the energy density can be increased. The non-sintered electrode is manufactured by using a metal three-dimensional porous material such as foamed nickel or a nickel fiber porous material as a substrate, and directly filling a paste-like active material into the space of the substrate.
[0003]
  Since the non-sintered electrode uses a metal three-dimensional porous body for the substrate, the lead plate cannot be directly connected to the substrate by welding as in the punching metal used for the substrate of the sintered electrode. This is because the most part of the metal three-dimensional porous body is a void, and the proportion of the metal part is extremely small. Therefore, even if the lead plate is brought into contact, the contact area is extremely small.
[0004]
  Techniques for connecting a metal three-dimensional porous substrate to a current collector plate are described in the following publications.
  (1)  JP-A 63-4562
  (2)  JP-A-2-220365
[0005]
  (1) When (2)In this publication, there is provided a structure in which a strip-shaped connecting portion not filled with an active material is provided along the edge of the substrate of the metal three-dimensional porous body, a metal thin plate is welded thereto, and this portion is connected to the current collector plate. be written.
[0006]
  The electrode plate in which the metal thin plate is welded to the belt-like connecting portion is wound in a spiral shape via a separator to form an electrode group. As shown in the exploded view of FIG. 1, the spiral electrode group can collect current by welding a current collecting plate 6. As shown in this figure, the battery in which the current collector plate 6 is welded to the electrode group 4 can improve the high-rate discharge characteristics and improve the discharge characteristics at a large current. As shown in the development view of FIG. 2, the electrode plate on which the metal thin plate is welded can also collect current by welding the lead plate 6A to a part of the strip-like connecting portion 7. However, as shown in FIG. 2, it is difficult to improve the large current discharge characteristics of a battery having a structure in which the lead plate 6A is welded to collect current. As shown in FIG. 1, the battery in which the upper end edge of the electrode group 4 serving as a strip-like connecting portion is connected to the current collector plate 6 at a plurality of portions has a feature that the current distribution flowing through the electrode plate can be made uniform.
[0007]
  The cross-sectional view of FIG. 3 shows a cross-sectional structure of a battery in which the current collector plate 6 is connected to the upper surface of the electrode group 4. In the battery having this structure, the lower surface of the current collecting plate 6 is connected to the strip-like connecting portion 7 at one electrode plate at a plurality of portions. In order to connect one electrode plate to the current collector plate 6, one electrode plate protrudes above the other electrode plate. The protruding portion of the electrode plate is a strip-like connecting portion 7 to which the thin metal plate 10 is welded. As shown in the sectional view of FIG. 4, the electrode group having this structure is connected to the current collector plate 6 by resistance electric welding by pressing the current collector plate 6 on the upper surface.
[0008]
[Problems to be solved by the invention]
  In the battery having the above structure, it is extremely difficult to connect the belt-like connecting portion of the substrate to the current collector plate in an ideal state. In particular, in order to reliably connect a plurality of portions of the belt-like connecting portion to the current collector plate, it is necessary to press the current collector plate to the belt-like connecting portion with a considerable pressure and perform resistance electric welding. This is because if the pressing force of the current collector plate is weakened, the electric resistance between the connecting portions of the current collector plate and the belt-like connecting portion increases, and normal electric welding cannot be performed. When the current collector plate and the strip-like connecting portion are resistance-electrically welded in a state where the electric resistance is large, the welding machine increases the voltage applied between the current collector plate and the strip-like connecting portion in order to flow a constant current. When a high voltage is applied, an arc discharge occurs between the current collector plate and the belt-like connecting part, the resistance rapidly decreases, a large power is supplied to the welded part, and the contact part melts instantly. It will be in a state called so-called “exploding”. If it will be in this state, a current collection board and a strip | belt-shaped connection part will no longer be able to connect normally.
[0009]
  In particular, in order to reduce the internal resistance of the battery, a battery in which a plurality of portions of the current collector plate are bonded to the belt-like connecting portion is connected in an ideal state at all portions connecting the belt-like connecting portion and the current collector plate. It is extremely difficult. This is because the upper surface of the belt-like connecting portion and the lower surface of the current collector plate cannot be processed into a perfect plane. In particular, a current collector plate that is provided with a plurality of through-holes and has a protrusion on the periphery of the through-hole and is brought into contact with the belt-like connecting portion to perform electric welding has a completely flat bottom surface. In reality it is extremely difficult.
[0010]
  By strongly pressing the current collector plate against the electrode group, the belt-like connecting portion and the current collector plate can be contacted without a gap. Therefore, if the current collector plate is welded to the belt-like connecting portion in this state, the current collector plate and the belt-like connecting portion can be reliably welded. However, if the current collector plate is pressed strongly against the belt-like connecting portion and welded, as shown in FIGS. 5 and 6, the belt-like connecting portion 7 is bent, causing an internal short circuit. This is because the bent portion breaks through the separator 3 and contacts other terminals. In particular, the band-like connecting portion 7 to which the metal thin plate 10 is welded has a property that the discontinuous portion becomes weak and is easily bent at the filling boundary. Furthermore, the non-sintered electrode in which the active material is filled in the metal three-dimensional porous substrate has a weak substrate strength and is easily deformed when the current collector plate is strongly pressed.
[0011]
  Therefore, when the current battery is strongly pressed and welded to the electrode group, the internal short circuit increases, and conversely, when the pressure to press the current plate to the electrode group is weakened and welded, There was a drawback that the electrode group could not be welded in a low resistance state. Furthermore, the battery may become unusable due to an impact received when it is dropped or the like, with the welded portion peeled off. In particular, the battery with excellent large current characteristics in which the strip-shaped connecting portion of the electrode group is welded to the current collector plate in a plurality of portions is compared to the battery in which the electrode group is connected to the terminal via an elongated lead plate. There is a drawback that the incidence of defective products due to impact is increased. This is because the ability to freely deform and absorb the impact like a lead plate is small.
[0012]
  The present invention was developed for the purpose of solving the above-mentioned conventional drawbacks, and an important object of the present invention is to provide a plurality of current collector plates in a low resistance state with a belt-like connecting portion of an electrode group. An object of the present invention is to provide a battery that can be reliably welded to a portion, has few internal shorts in the step of welding a current collector plate, and has excellent impact resistance.
[0013]
[Means for Solving the Problems]
  The battery of the present invention has the following structure in order to achieve the aforementioned object. The battery includes an electrode group 4 in which a first electrode plate 1 and a second electrode plate 2 composed of a positive electrode plate and a negative electrode plate are laminated via a separator 3, and an outer can 5 in which the electrode group 4 is accommodated. And a current collector plate 6 that is electrically connected to the first electrode plate 1 and electrically connects the first electrode plate 1 to one terminal.
[0014]
  A battery using the first electrode plate as the positive electrode plate uses the second electrode plate as the negative electrode plate, and a battery using the first electrode plate as the negative electrode plate uses the second electrode plate as the positive electrode plate.
[0015]
  The first electrode plate 1 is a non-sintered electrode in which a substrate 9 made of a metal three-dimensional porous material is filled with an active material, and has a strip-like connecting portion 7 exposing the substrate 9. In this strip-shaped connecting portion 7, a metal thin plate 10 is welded to the strip-shaped connecting portion 7 exposing the metal three-dimensional porous body. The belt-like connecting portion 7 to which the metal thin plate 10 is welded is welded to and electrically connected to a plurality of portions of the current collector plate 6.
[0016]
  Further, in the battery of claim 1 of the present invention, the thickness of the thin metal plate 10 welded to the belt-like connecting portion 7 is 0.07 mm or more and thinner than 80% of the thickness of the first electrode plate 1, Vickers hardness is 50 or more and 250 or less.
[0017]
  Main departureAkira DenIn the pond, a metal plate having a Vickers hardness of 50 or more and 250 or less and a thickness of 0.1 to 1.5 mm is used for the current collector plate 6.
[0018]
  Main departureAkira DenThe pond has an outer shape in which the current collector plate 6 is smaller than the inner shape of the outer can 5, and is arranged to face the end of the electrode group 4. Furthermore, the current collector plate 6 is provided with a plurality of through holes 6D. The through-hole 6 </ b> D has a protrusion 6 </ b> E that protrudes toward the band-shaped connecting portion 7 of the electrode group 4 at the periphery. The protruding protrusions 6E are welded to the strip-like connecting portion 7 of the first electrode plate 1 at a plurality of portions.
[0019]
  Of the present inventionClaim 2In the battery, the metal three-dimensional porous body is made of foamed nickel or nickel fiber porous body.
[0020]
  Main departureAkira DenIn the pond, the belt-like connecting portion 7 of the metal three-dimensional porous substrate 9 is pressed and compressed to a high density.
[0021]
  Of the present inventionClaim 3In this battery, a spiral electrode formed by laminating a first electrode plate 1 and a second electrode plate 2 via a separator 3 and winding them in a spiral shape is used for the electrode group 4. The current collecting plate 6 has a disk shape arranged close to the end of the spiral electrode.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a battery for embodying the technical idea of the present invention, and the present invention does not specify the battery as follows.
[0023]
  Further, in this specification, in order to facilitate understanding of the claims, the numbers corresponding to the members shown in the embodiments are referred to as “claim column” and “means for solving the problems”. It is added to the members shown in the column. However, the members shown in the claims are not limited to the members in the embodiments.
[0024]
  The battery shown in FIG. 7 has a cylindrical outer can 5 hermetically sealed with a sealing plate 11, an electrode group 4 inserted in the outer can 5, and the electrode group 4 connected to a terminal 12 of the outer can 5. Current collector plate 6. Although the battery shown in the figure has a cylindrical outer can, the present invention does not specify the cylindrical outer can of the battery. Although the outer can is not shown, it can also be formed in, for example, a rectangular tube shape or an elliptic tube shape.
[0025]
  The outer can 5 is made of iron, and the surface thereof is nickel-plated. As the material of the outer can 5, an optimum metal is selected in consideration of the type and characteristics of the battery. For example, the outer can may be made of stainless steel, aluminum, or an aluminum alloy. In the metal outer can, the opening at the upper end is hermetically sealed with a sealing lid. The sealing lid is hermetically fixed by a structure such as caulking the outer can or by laser welding the boundary between the outer can and the sealing lid. The sealing plate 11 fixes one terminal 12 of the battery. The terminal 12 is insulated and fixed to the outer can.
[0026]
  The battery of the present invention is a battery containing a non-sintered electrode, for example, a nickel-hydrogen battery. However, the present invention does not specify the battery as a nickel-hydrogen battery. The battery can be, for example, a nickel-cadmium battery, a lithium ion battery, or the like. Hereinafter, as a preferred embodiment, an embodiment of a nickel-hydrogen battery will be described in detail.
[0027]
  In the electrode group 4, the first electrode plate 1 and the second electrode plate 2 are wound through a separator 3. In the battery shown in the figure, the first electrode plate 1 connected to the current collector plate 6 is a positive electrode plate, and the second electrode plate 2 is a negative electrode plate. However, in the present invention, the first electrode plate can be a negative electrode plate and the second electrode plate can be a positive electrode plate. The first electrode plate 1 and the second electrode plate 2 stacked on each other via the separator 3 are wound into a spiral electrode group 4. The spiral electrode group 4 is inserted into a cylindrical outer can 5. The spiral electrode group can be pressed from both sides to be deformed into an elliptical shape and inserted into an elliptical outer can. Furthermore, the electrode group inserted into the rectangular tube-shaped outer can is manufactured by laminating a plurality of first electrode plates and second electrode plates cut into a plate shape via a separator.
[0028]
  The separator 3 is a polyolefin nonwoven fabric. However, the separator 3 can also be a microporous membrane made of synthetic resin such as polyethylene. For the separator 3, all sheet materials that can insulate the first electrode plate 1 and the second electrode plate 2 laminated on both sides and can penetrate the electrolytic solution can be used.
[0029]
  The first electrode plate 1 is a non-sintered electrode in which a metal three-dimensional porous substrate 9 is filled with an active material. The metal three-dimensional porous substrate 9 is a foamed nickel porous body, a nickel fiber porous body, or the like. The first electrode plate 1 fills these substrates 9 with an active material.
[0030]
  As shown in the development view of FIG. 8, the substrate of the first electrode plate 1 is provided with a band-like connecting portion 7 on the upper portion of the substrate 9, and the other portion is an active material filling portion 8 filled with an active material. The strip-shaped connecting part 7 does not fill the active material, or removes the filled active material to expose the substrate 9. The substrate 9 is preferably pressed by the belt-like connecting portion 7 and compressed to a high density. The compressed belt-like connecting portion 7 has a feature that the metal thin plate can be reliably welded.
[0031]
  The strip-shaped connecting portion 7 fixes the thin metal plate 10 as shown in the cross-sectional view of FIG. The metal thin plate 10 is bonded in a state where it is electrically connected to the strip-like connecting portion 7 by resistance electric welding or via a conductive adhesive.
[0032]
  The thickness of the metal thin plate 10 is 0.07 mm or more, and is thinner than 80% of the thickness of the first electrode plate 1. If the metal thin plate 10 is thinner than 0.07 mm, the strength when welding the strip-shaped connecting portion to the current collector plate becomes insufficient. On the other hand, when the thickness of the metal thin plate is thicker than 80% of the first electrode plate 1, the band-shaped connecting portion becomes thick with the first electrode plate and the second electrode plate laminated via the separator, Space efficiency is reduced. The thickness of the metal thin plate is preferably 0.095 to 0.2 mm.
[0033]
  Further, as the metal thin plate, a metal thin plate having a Vickers hardness of 50 or more and 250 or less is used. When the hardness of the metal thin plate is 50 or less, the strength when welding the strip-shaped connecting portion to the current collector plate is insufficient, and when the battery is impacted, the strip-shaped connecting portion is separated from the current collector plate. , Impact strength decreases. When the Vickers hardness of the metal thin plate is greater than 250, the metal thin plate easily breaks through the separator when the strip-shaped connecting portion is welded to the current collector plate, and the impact strength is also reduced. Therefore, the metal thin plate is a metal thin plate having a Vickers hardness of 50 to 250, preferably a metal thin plate having a Vickers hardness of 170 to 200, such as a nickel thin plate, a phosphorous nickel thin plate, or a thin plate obtained by plating iron on nickel. Etc.
[0034]
  In the first electrode plate 1 of FIG. 9, a protective tape 13 is attached to the surface of the belt-like connecting portion 7 facing the second electrode plate 2. The protective tape 13 extends the lower end edge below the filling boundary. This is to prevent the filling boundary from being bent and breaking through the separator when the current collector plate 6 is pressed and welded to the belt-like connecting portion 7. The battery to which the protective tape 13 is bonded has the advantage that the current collector plate 6 can be reliably connected to the belt-like connecting portion 7 by preventing an internal short circuit. However, the strip-shaped connecting portion can be connected to the current collector plate without using the protective tape.
[0035]
  The current collector plate 6 is a metal plate obtained by plating nickel on iron, or a metal plate such as a nickel plate, and is cut into a disk shape smaller than the inner shape of the outer can 5 as shown in FIG. The lead plate 6A is projected. The current collector plate 6 is disposed so as to be opposed at both ends of the electrode group 4. The current collector plate 6 shown in FIG. 10 has a circular shape for use in a battery in which the battery outer can 5 is cylindrical, but the battery of the present invention is not specified as a cylindrical battery. A rectangular current collector plate can be used for the battery.
[0036]
  The current collector plate 6 is provided with slits 6C on both sides of the center hole 6B in order to reduce reactive current when resistance electric welding is performed. Further, a plurality of through holes 6D are opened. As shown in the enlarged sectional view of FIG. 11, a protrusion 6E protruding downward is provided on the periphery of the through hole 6D. The protrusion 6E is welded and connected to the belt-like connecting portion 7 of the first electrode plate 1 at a plurality of portions. The lead plate 6 </ b> A of the current collector plate 6 is connected to a terminal 12 that is insulated and fixed to the opening of the outer can 5.
[0037]
  The current collector plate is a metal plate having a Vickers hardness of 50 to 250 and a thickness of 0.1 to 1.5 mm. Even if the current collector plate has a Vickers hardness of 50 or less, a thickness of 0.1 mm or less, a Vickers hardness of 250 or more, or a thickness of more than 1.5 mm, Can not be welded reliably.
[0038]
  The current collector plate having a Vickers hardness of 50 or less or a thickness of 0.1 mm or less does not have sufficient strength, so the electrode rod for welding is locally pressed to form a belt-like connecting portion and a current collector plate It is impossible to reliably weld the contact part with. This is because the current collector plate is deformed. Furthermore, the current collector plate having a Vickers hardness of 250 or more or a thickness of 1.5 mm or more also has a contact portion between the belt-like connecting portion and the current collector plate when the electrode rod for welding is locally pressed. It becomes impossible to weld reliably. This is because the current collector plate hardly deforms.
[0039]
  When welding the strip-shaped connecting portion to the current collector plate, it is important to bring the contact portion into contact in a uniform state at the welded portion between the strip-shaped connecting portion and the current collector plate. The current collector plate is locally pressed by the welding electrode rod, and even if it is not deformed at all or if the deformation is too large, the welded portion cannot be contacted uniformly. If the deformation is too large, the welding portion in the vicinity pressed by the welding electrode rod is strongly pressed, but the contact of the welding portion at a portion away from the welding electrode rod is weak or separated. Further, if the current collector plate is not deformed at all, only the welded portion protruding from the current collector plate and the belt-like connecting portion comes into strong contact and the other welded portions do not come into contact. For this reason, it becomes impossible to weld in an ideal state by bringing all the welded portions into uniform contact.
[0040]
  Furthermore, when the collector plate has a Vickers hardness of 250 or more, or a thickness of 1.5 mm or more, the first electrode plate and the second electrode plate break through the separator when connecting the belt-like connecting portions. The rate of shorting increases and yield decreases. This is because the deformation of the current collector plate pressed by the welding electrode rod is reduced, and the belt-like connecting portions pressed against the current collector plate in a state of protruding from each other are bent to break through the separator 3.
[0041]
  Furthermore, the current collector plate has a Vickers hardness of 50 or less, a thickness of 0.1 mm or less, a Vickers hardness of 250 or more, or a thickness of more than 1.5 mm. Impact strength decreases. The current collector plate 6 having a Vickers hardness of 50 or less or a thickness of 0.1 mm or less does not have sufficient strength. Decreases. Further, a current collector plate having a Vickers hardness of 250 or more or thicker than 1.5 mm does not deform at all when subjected to an impact. In other words, since there is no buffering action, The welded part of this is easily detached, and the impact strength is reduced.
[0042]
【Example】
  In the following steps, SC-sized cylindrical nickel-hydrogen batteries were prototyped, and the thickness and Vickers hardness of the metal thin plate and the Vickers hardness of the current collector plate were changed, and the yield rate of each product was measured.
[0043]
  In the following process, an electrode group to be inserted into the outer can of the nickel-hydrogen battery was manufactured.
a. Production of positive electrode plate as first electrode plate
(1) A porous metal body is produced by the following process.
  A sponge-like organic porous body, which is an open-cell polyurethane foam, is subjected to a conductive treatment, and is then immersed in a plating solution in an electrolytic bath for plating. The plated organic porous body is roasted at a temperature of 750 ° C. for a predetermined time to remove the resin component of the organic porous body, and further sintered in a reducing atmosphere to produce a metal porous body. The metal porous body manufactured in this process has a basis weight of about 600 g / m.²And foamed nickel having a porosity of 95% and a thickness of about 2.0 mm.
[0044]
(2) Knead the following to make a positive electrode active material slurry.
    Nickel hydroxide powder ………………………………………… 90 parts by weight
    (Contains 2.5wt% zinc and 1wt% cobalt as coprecipitation components)
    Cobalt powder ………………………………………………… 10 parts by weight
    Zinc oxide powder ……………………………… 3 parts by weight
    Hydroxypropylcellulose 0.2% by weight aqueous solution 50 parts by weight
[0045]
(3) The positive electrode active material slurry thus prepared was filled in the voids of the metal porous body. The filling amount was adjusted so that the active material density after roll rolling was about 2.91 g / cc-void. Thereafter, it was dried and round-rolled so as to have a thickness of about 0.70 mm. Furthermore, the active material was removed by ultrasonic stripping or the like that applies ultrasonic vibration in the vertical direction to the strip-shaped connecting portion 7 that was cut into strips and welded to the metal thin plate 10. And as shown in FIG. 8, it is set as the 1st electrode plate 1 with the strip | belt-shaped connection part 7 which the board | substrate 9 exposes.
[0046]
  The first electrode plate can also produce an active material by the following steps. As shown in FIG. 12, before filling the active material, the metal porous body is rolled in parallel with a predetermined width. The width of the roll rolling is about 5 mm, which is twice the width of the belt-like connecting portion 7, and the thickness after rolling is 0.5 mm. The metal porous substrate 9 rolled in this way is filled with the above active material slurry and rolled. Then, it cut | disconnects in the position shown by the arrow of FIG. 12, and produces a strip-shaped 1st electrode plate. After that, along the thinly rolled portion that becomes the belt-like connecting portion 7, compressed air is sprayed or a brush or the like is used to remove the active material and expose the substrate.
[0047]
(4) The thin metal plate 10 is bonded to the exposed strip-like connecting portion 7 of the substrate 9 by resistance electric welding. For bonding the band-shaped connecting portion 7 and the metal thin plate 10, copper having a diameter of 1.5 mm was used as a welding electrode rod, and resistance electric welding was performed at intervals of 2 mm. The metal thin plate 10 was made of a nickel ribbon and had a width of 1.5 mm.
[0048]
  A plurality of prototype batteries are manufactured using the thickness of the metal sheet and the Vickers hardness as parameters. In the prototype batteries 1 to 13, the thickness of the thin metal plate is set in the range of 0.01 to 0.50 mm. The metal thin plate used at this time was a nickel ribbon with a width of 1.5 mm and a Vickers hardness of 150, and the current collector plate was nickel-plated iron with a Vickers hardness of 150 and a thickness of 0.40 mm.
[0049]
  Furthermore, the Vickers hardness of the metal thin plate is changed from 30 to 350, and prototype batteries 14 to 22 are produced. The metal thin plate used at this time was a nickel ribbon having a width of 1.5 mm and a thickness of 0.07 mm, and the current collector plate was made of nickel-plated iron with a Vickers hardness of 150 and a thickness of 0.40 mm as described above. used.
[0050]
b. Production of negative electrode plate as second electrode plate
(1) Preparation and grinding of hydrogen storage alloy
  Misch metal (mixture of rare earth elements such as La, Ce, Nd, Pr, etc.), nickel, cobalt, aluminum, and manganese in an element ratio of 1.0: 3.4: 0.8: 0.2: Weigh and mix to 0.6, put in a crucible, melt in a high-frequency melting furnace, and then cool to produce a hydrogen storage alloy electrode having the following composition formula.
          Mm_1.0Ni_3.4Co_0.8Al_0.2Mn_0.6
  The obtained hydrogen storage alloy ingot is then coarsely pulverized in advance and then pulverized in an inert gas so that the average particle size becomes 60 μm.
[0051]
(2) Preparation of hydrogen storage alloy slurry
  Polyethylene oxide powder is added as a binder to the pulverized hydrogen storage alloy powder, and ion exchange water is further added and kneaded to form a slurry. The addition amount of the polyethylene oxide powder as the binder is 1.0% by weight with respect to the hydrogen storage alloy.
[0052]
(3) The slurry was applied to both sides of a substrate that was a punching metal. The coating amount was adjusted so that the active material density after rolling was 5 g / cc. Then, after drying and rolling, it cut | disconnected to the predetermined dimension, and was set as the negative electrode plate which is a 2nd electrode plate. The slurry was applied leaving the lower edge so that the band-like connecting portion 7 was formed at the lower edge of the punching metal. Moreover, after apply | coating a slurry to the whole surface of a punching metal, it can also dry and can remove the active material of a lower edge, and can provide a strip | belt-shaped connection part.
[0053]
  The first electrode plate and the second electrode plate manufactured in the above steps were wound through a separator made of a polyolefin nonwoven fabric to form a spiral electrode group, and a spiral electrode was manufactured. A current collector plate is welded to the thin metal plate 10 protruding from the upper end of the spiral electrode by resistance electric welding. The current collector plate was a disc-shaped iron plate plated with nickel having a thickness of 0.40 mm. Vickers hardness of the current collector plate was changed from 30 to 350 as parameters of the prototype battery, and prototype batteries 23 to 31 were produced.
[0054]
  Using the first electrode plate and the second electrode plate manufactured by the above method, a prototype battery of a cylindrical nickel-hydrogen battery was manufactured.
[0055]
[Prototype batteries 1-13]
  The prototype batteries 1 to 13 are set in the range of 0.01 to 0.50 mm with the thickness of the metal thin plate as a parameter. A nickel ribbon having a width of 1.5 mm and a Vickers hardness of 150 was used as the metal thin plate, and a nickel-plated iron plate having a Vickers hardness of 150 and a thickness of 0.40 mm was used as the current collector plate.
[0056]
  The thickness of the metal thin plate 10 of each prototype battery was changed within a range of 0.01 to 0.50 mm, and prototype batteries 1 to 13 were produced. The thickness was changed every 0.02 mm from 0.01 to 0.07 mm, and thereafter the thickness was changed every 0.05 mm from 0.10 mm to 0.50 mm.
[0057]
  The non-defective product ratio of the prototype batteries 1 to 13 manufactured as described above is measured. Here, the non-defective product rate represents the number of non-defective products with respect to 100 batteries, and is determined particularly by whether or not the terminals are in a connected state. That is, for each prototype battery, 100 identical batteries were produced under one condition, and the number of non-defective products was counted.
[0058]
  Here, as the non-defective product rate, three of the weld good product rate, the assembly good product rate, and the impact good product rate were measured. The welding good product rate indicates a rate at which the metal thin plate and the current collector plate are welded in the battery manufacturing process and can be used in the next step, that is, a rate at which the terminals are normal immediately after welding. The assembly failure rate is the rate at which there is no internal short-circuit between the first electrode plate and the second electrode plate at the end of the manufacturing process when the production of the battery is continued using the terminals that have been successfully welded. The rate at which the terminals are normal immediately after the production of the battery with a weld good rate of 100% is shown. Furthermore, an impact defective product is a terminal that can be used even after impacting a normally assembled battery after the completed normal battery is dropped 100 times from a height of 1 m onto an iron plate 100 times. Indicates the rate at which does not peel.
[0059]
  Table 1 shows the results of measuring the welding good product rate, the assembly good product rate, and the impact good product rate of the batteries having a metal sheet thickness of 0.01 to 0.50 mm.
[0060]
[Table 1]
  Good weld rate, good assembly rate, good impact rate when the thickness of the metal sheet is 0.01 to 0.50 mm.

[0061]
As shown in Table 1, the

prototype batteries

1 and 2 in which the thickness of the metal thin plate was 0.03 mm or less were extremely poor in both the welding good product rate and the impact good product rate. The prototype battery 3 having a metal thin plate thickness of 0.05 mm has a good weld rate and an impact rate of 80%. Furthermore, when the thickness of the thin metal plate was 0.07 mm or more, all of the welding good product rate, the assembly good product rate, and the impact good product rate showed extremely good results. Moreover, as the prototype battery 11 showed, the thickness of the metal thin plate was 0.40 mm, and the welding good product rate, the assembly good product rate, and the impact good product rate were all 99%. Since the thickness of the first electrode plate is 0.5 mm, it can be seen that the welding good product rate, the assembly good product rate, and the impact good product rate are extremely high up to 0.40 mm which is 80% of the thickness of the first electrode plate. However, as the

prototype batteries

12 and 13 show, when the thickness of the metal thin plate is 0.45 mm or more, the assembly non-defective rate is lowered. The reason why the assembly good product rate deteriorated was that the first electrode plate and the second electrode plate were short-circuited. The short part is a filling boundary between the belt-like connecting part and the active material filling part, and the framework of the foamed nickel, which is the substrate, protrudes at this part.
[0062]
[Prototype batteries 14-22]
  Next, prototype batteries 14 to 22 having the Vickers hardness of the metal thin plate as a parameter were produced. The metal thin plate used was a nickel ribbon having a width of 1.5 mm and a thickness of 0.07 mm, and the current collector plate was nickel having a Vickers hardness of 150 and a thickness of 0.40 mm, similar to the prototype batteries 1-13. A plated iron plate was used.
[0063]
  The Vickers hardness of the metal thin plate was changed in the range of 30 to 350. Vickers hardness of 30 to 70 was changed every 20 and 100 to 350 was set to 50 increments. Table 2 shows the result of measuring the non-defective product rate of the prototype battery which was prototyped with the metal thin plate having a Vickers hardness of 30 to 350.
[0064]
[Table 2]
  Good weld rate, good assembly rate, good impact rate when the Vickers hardness of the metal sheet is 30 to 350

[0065]
  As shown in Table 2, the Vickers hardness of the thin metal plate was in the range of 50 to 250, and the results showed that the welding good product rate, the assembly good product rate, and the impact good product rate were extremely excellent. With the Vickers hardness 30 of the prototype battery 14, only the assembly good product rate is as high as 99%, but the weld good product rate and the impact good product rate are 85% and 60%, respectively, which are slightly lower. In addition, the prototype batteries 21 and 22 having a Vickers hardness of 300 or more had a high welding good product rate of 99%, but the assembly good product rate and the impact good product rate were slightly decreased. Therefore, the best results are obtained when the Vickers hardness of the metal sheet is in the range of 50 to 250.
[0066]
[Prototype batteries 23 to 31]
  Further, prototype batteries 23 to 31 using Vickers hardness of the current collector as a parameter were produced. The thin metal plate used here is a nickel ribbon having a width of 1.5 mm, a thickness of 0.07 mm, and a Vickers hardness of 150. As the current collector plate, an iron plate having a nickel plating thickness of 0.40 mm was used.
[0067]
  The Vickers hardness of the current collector plate was changed in the range of 30 to 350, similar to the Vickers hardness of the metal thin plates of the prototype batteries 14 to 22 described above. The current collector plate has a Vickers hardness of 20 increments from 30 to 70 and 50 increments from 100 to 350. Table 3 shows the results of measuring the welding good product rate, the assembly good product rate, and the impact good product rate of the prototype battery prototyped with the current collector plate having a Vickers hardness of 30 to 350.
[0068]
[Table 3]
  Good weld rate, good assembly rate, good impact rate when current collector plate has Vickers hardness of 30-350

[0069]
  As shown in Table 3 above, the Vickers hardness of the current collector plate also showed high results in the range of 50 to 250, similar to the Vickers hardness test of the metal thin plate. At the Vickers hardness 30 of the current collector plate shown by the prototype battery 23, the assembly good product rate was as high as 99%, but the weld good product rate was 85% and the impact good product rate was 30%. Further, at the Vickers hardness of 300, as shown in the prototype battery 30, the welding good product rate is 90% and the assembly good product rate is 89%, which is slightly decreased. At a Vickers hardness of 350, the welding good product rate, assembly good product rate, and impact good product rate were further reduced.
[0070]
【The invention's effect】
  The battery of the present invention ensures the welding between the electrode group and the current collector plate, prevents the electrical connection from being interrupted or short-circuited, and realizes the characteristics that can provide a battery with high rate discharge characteristics and high reliability. This is because the battery of the present invention can be reliably welded and the impact resistance during use is improved with the optimum values of the thickness and Vickers hardness of the metal thin plate to be welded to the belt-like connecting portion. In particular, in the battery manufacturing process of the present invention, the current collector plate has a thickness that can be surely welded with sufficient strength to the belt-like connecting portion of the electrode group in the battery manufacturing process.
At the same time, the Vickers hardness of the thin metal plate is set so that the deformation necessary for manufacturing can be sufficiently performed, so that troubles such as an internal short circuit during battery manufacturing can be avoided and the yield can be improved.
[0071]
  In addition, the battery of the present invention having an appropriate buffer property and sufficient strength can be used between the electrode plate and the current collector plate due to an impact when the battery is dropped or bumped even during use after the battery is manufactured. As a structure in which the electrical connection is not easily broken, the impact resistance is improved, and a high-performance and highly reliable battery can be provided.
[0072]
  In addition, the battery of the present invention has an optimum range in which the balance between the Vickers hardness and the thickness of the belt-like connecting portion to which the metal thin plate is welded and the current collector plate to be welded is sufficiently strong and sufficiently deformed at the time of manufacture. By doing so, more reliable welding is realized. In particular, with the battery of the present invention, an excellent battery that can simultaneously realize cost reduction and high energy density using a non-sintered electrode instead of a conventional sintered electrode can be used more conveniently. That is, when the present invention produces a non-sintered electrode capable of high rate discharge, by making the hardness suitable for the battery of the present invention, the electrical connection between the current collector plate and the electrode group can be strengthened, This is because a terminal peeling accident at the time of manufacture and use can be prevented.
[0073]
  The sintered electrode uses a substrate such as punching metal, but the non-sintered electrode uses a three-dimensional metal porous body such as foamed nickel as the substrate. However, a non-sintered electrode plate using a three-dimensional metal porous body as a substrate is difficult to weld to the current collector plate, current collection may be insufficient, and the terminal may be peeled off by impact. . On the other hand, in the battery of the present invention, the thickness of the metal thin plate welded to the belt-like connecting portion is adjusted to an optimal range that maintains sufficient space while maintaining sufficient strength. Furthermore, the hardness is sufficiently high to withstand impacts, and on the other hand, the hardness is low so that welding during production can be sufficiently performed. In addition, the battery of the present invention has the hardness of the current collector plate to be welded to the belt-like connecting portion to which the thin metal plate is welded, within an optimum range that maintains a sufficient strength and a balance that can be sufficiently deformed during production. Improves impact resistance more.
[0074]
  Furthermore, the present inventionPower ofThe pond is provided with a protrusion on the current collector plate along with the through hole, so that welding can be performed more easily and reliably. For this reason, not only low cost and high rate discharge, but also the feature of further improving the reliability and providing an extremely easy-to-use battery that can be used safely and conveniently is realized.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a state in which a current collector plate is connected to an electrode plate of an electrode group built in a battery.
FIG. 2 is a plan view showing an example of an electrode plate on which a lead plate is welded.
FIG. 3 is a partially sectional front view of a conventional battery.
FIG. 4 is an enlarged cross-sectional view showing a state in which a current collector plate is pressed and connected to an electrode group
FIG. 5 is an enlarged cross-sectional view showing an example in which a belt-like connecting portion and a filling boundary are bent to cause an internal short circuit.
FIG. 6 is an enlarged cross-sectional view showing another example in which the belt-like connecting portion and the filling boundary are bent to cause an internal short circuit.
FIG. 7 is a partially sectional front view of a battery according to an embodiment of the present invention.
8 is a development view of the first electrode plate of the battery shown in FIG.
9 is an enlarged cross-sectional view showing a laminated structure of the electrode group of the battery shown in FIG.
10 is a development view of the current collector plate of the battery shown in FIG.
11 is an enlarged sectional view of the current collector plate shown in FIG.
FIG. 12 is a plan view showing an example of a method for producing the first electrode plate.
[Explanation of symbols]
    1 ... 1st plate
    2 ... Second plate
    3 ... Separator
    4 ... Electrode group
    5 ... Exterior can
    6 ... Current collector plate 6A ... Lead plate 6B ... Center hole
                          6C ... Slit 6D ... Through hole
                          6E ... Projection
    7 ... Strip-shaped connecting part
    8 ... Active material filling part
    9 ... Board
  10 ... Metal sheet
  11 ... Sealing plate
  12 ... Terminal
  13 ... Protective tape

Claims

An electrode group (4) in which a first electrode plate (1) and a second electrode plate (2) composed of a positive electrode plate and a negative electrode plate are stacked via a separator (3), and this electrode group (4) are stored. And a current collector plate (6) electrically connected to the first electrode plate (1) and electrically connecting the first electrode plate (1) to one terminal,
The first electrode plate (1) is a non-sintered electrode in which a substrate (9) made of a metal three-dimensional porous material is filled with an active material, and a strip-shaped connecting portion (7) exposing the substrate (9). The thin metal plate (10) is welded to the belt-like connecting portion (7) from which the substrate (9) is exposed, and the thin metal plate (10) welded belt-like connecting portion (7) is collected. In a battery that is welded and electrically connected to a plurality of portions of the plate (6),
The metal thin plate (10) welded to the belt-like connecting portion (7) has a thickness of 0.07 mm or more and thinner than 80% of the first electrode plate (1), and a Vickers hardness of 50 or more. 250 or less ,
Furthermore, the current collector plate (6) is a metal plate having a Vickers hardness of 50 to 250 and a thickness of 0.1 to 1.5 mm. The current collector plate (6) is an outer can (5) The outer shape of the electrode group (4) is opposed to the end of the electrode group (4) , has a plurality of through holes (6D) , and has a plurality of through holes (6D) at the periphery of the through holes (6D) . And a projection (6E) projecting toward the strip-shaped connecting portion (7) of the electrode group (4) , and this projection (6E) is formed in a plurality of portions on the strip-shaped connecting portion (7) of the first electrode plate (1) Welded with
A battery characterized in that a metal three-dimensional porous substrate is pressed at a belt-like connecting portion (7) and compressed to a high density.

The battery according to claim 1, wherein the metal three-dimensional porous body is foamed nickel or nickel fiber porous body.

The electrode group (4) is a spiral electrode formed by laminating a first electrode plate (1) and a second electrode plate (2) through a separator (3) and winding them in a spiral shape. The battery according to claim 1, wherein the battery is in the shape of a disk arranged close to the end of the spiral electrode.