JP3913395B2

JP3913395B2 - Method for producing alkaline storage battery

Info

Publication number: JP3913395B2
Application number: JP07051799A
Authority: JP
Inventors: 俊裕赤澤; 幹朗田所; 章史山脇; 洋之田川; 武史吉田
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 1999-03-16
Filing date: 1999-03-16
Publication date: 2007-05-09
Anticipated expiration: 2019-03-16
Also published as: JP2000268847A

Description

【０００１】
【発明の属する技術分野】
本発明はニッケル・水素蓄電池、ニッケル・カドミウム蓄電池などのアルカリ蓄電池に係り、特に、活物質保持体に活物質を塗着した電極の集電構造の改良に関する。
【０００２】
【従来の技術】
従来、ニッケル・水素蓄電池、ニッケル・カドミウム蓄電池などのアルカリ蓄電池に使用されるニッケル電極は、パンチングメタル等の芯体にニッケル粉末を焼結して形成した焼結基板にニッケル塩、カドミウム塩等の溶液を含浸し、アルカリ処理により活物質化するいわゆる焼結式電極が知られている。この焼結式電極は、焼結基板を高多孔度とした場合には機械的強度が弱くなるため、実用的には８０％程度の多孔度とするのが限界であるとともに、パンチングメタル等の芯体を必要とすることから、活物質の充填量が低く、高エネルギー密度の電極を実現する上で問題がある。また、焼結基板の細孔は１０μｍ以下であるので、活物質の充填工程を何度も繰り返す必要がある溶液含浸法や電着含浸法に限定されるため、充填工程が煩雑であるとともに製造コストも高くなるという問題があった。
【０００３】
一方、これらの欠点を改良するために、金属繊維焼結体や発泡ニッケル（ニッケルスポンジ）などの三次元網目状構造をもった金属多孔体（活物質保持体）に活物質スラリーを直接充填した、いわゆる非焼結式電極が主流となってきた。この種の三次元網目状構造をもった金属多孔体は、その多孔度が約９５％と高多孔度であるので、活物質を高密度に充填できる。そのため、高容量の電池が得られるようになるとともに、この種の非焼結式電極は活物質をそのまま金属多孔体に充填するので、面倒な活物質化の処理が必要でなくなり、製造が容易になるという利点がある。
【０００４】
ところで、この種の三次元網目状構造をもった金属多孔体を使用した電極は、一般に高多孔度であることからその強度が弱く、電極から集電を行うためのリード端子を取付けることが困難であった。特に、大電流放電を必要とする場合には、電極群の各電極に略円板状の集電体を固着することが効果的であるが、焼結式電極ではパンチングメタル等の強固な芯体があるため集電体を固着することは容易である。しかしながら、非焼結式電極では三次元網目状構造をもった金属多孔体を用いるため、強固な芯体がなく、略円板状の集電体を固着することが困難である。このため、金属多孔体の一部をプレスする方式、金属多孔体の一部に溶接、溶射、かしめなどにより別の金属を付加する方法、等のように電極の一部に金属の密な部分を得ることにより電極からの集電を行う方法がなされてきた。
【０００５】
上述した電極の一部に金属の密な部分を得る方法の中で現在最も実用的な方法の一つとして、電極の片面の一部に金属板を溶接することにより電極の一部に金属の高密度部分を得て集電用端子取付部とする構造を持つ電極を使用する方法がある。しかしながら、この方法で製造された電極をセパレータを介して対極とともに渦巻状に巻回して渦巻状電極群とすると、短絡不良が多いという問題点があった。
【０００６】
そこで、三次元網目状構造を有する金属多孔体を活物質保持体として用いる電極において、電極の片面の一部に帯状金属板を溶接した後、電極の一部に金属の高密度部分を得て集電用端子取付部とする構造を持つ電極を渦巻状に巻回する場合、溶接した金属板が渦巻の内側、金属多孔体が渦巻の外側となるように巻回して渦巻状電極群とすることが、特許第２７６２５１７号公報において提案された。
【０００７】
この特許第２７６２５１７号公報にて提案された手段によれば、帯状金属板を溶接した金属多孔体が渦巻状に巻回される場合に、縮み方向の力を受けないために金属多孔体が電極群の内側へ凸形に変形しないこと、および金属の弾性により帯状金属板の端縁部が対極側へ凸となる状態が起こりにくいことから短絡不良が防止できるというものである。
【０００８】
【発明が解決しようとする課題】
しかしながら、溶接した金属板が渦巻の内側、金属多孔体が渦巻の外側となるように巻回して渦巻状電極群を形成すると、帯状金属板と活物質充填部との境界部が対極と対向している場合、帯状金属板を溶接している側の面とは反対側の面の金属多孔体（活物質未充填部）が巻回時に亀裂を生じ、この亀裂によってバリ（金属多孔体の骨格が破断されて突出した状態）が発生し、このバリが渦巻の外側に突出するために、セパレータを貫通して対極に接触してショートに至っていた。
【０００９】
また、活物充填部と帯状金属板との境界部にもバリを生じ、このバリによってもショートに至っていた。そして、帯状金属板を金属多孔体（活物質未充填部）に溶接する方法としては、抵抗シーム溶接、超音波シーム溶接等があるが、帯状金属板が平板であると、溶接後、活物質保持体の長手方向に反りが発生し、この反りに起因して巻回時に巻ずれ等の不具合が発生するという問題も生じた。
【００１０】
そこで、本発明は上記問題点を解決するために、三次元網目状構造を有する金属多孔体を活物質保持体として用い、この活物質保持体に帯状金属板を固着して渦巻状に巻回しても内部短絡が生じないアルカリ蓄電池が得られるようにすることを目的としてなされたものである。
【００１３】
【課題を解決するための手段】
上記目的を達成するため、アルカリ蓄電池の製造法は、ニッケル正極の活物質保持体の長手方向端部の活物質除去部分に帯状金属板を固着する固着工程と、活物質除去部分に固着された帯状金属板と活物質充填部との境界部を加圧する加圧工程と、帯状金属板と活物質充填部との境界部が負極と対向するとともに、該帯状金属板が外側になるように巻回する巻回工程とを備えるようにしている。このように、活物質除去部分に帯状金属板が連続的に固着され、帯状金属板が渦巻の外側になるように巻回すると、巻回時に帯状金属板が渦巻の外方に向けて延伸することにより、渦巻の内側になる金属多孔体の活物質除去部分は帯状金属板から剥がれることはない。また、金属多孔体の活物質除去部分は渦巻の内側となるため、金属多孔体の活物質除去部分に外側向きのバリが発生することはない。このため、金属多孔体の活物質除去部分での内部短絡を抑制することが可能となる。さらに帯状金属板を外側に巻回することによって、巻回時の巻ズレも、帯状金属板を内側に巻回する場合に対して良好な結果であった。
【００１４】
そして、帯状金属板は長手方向の一辺のみに不連続な半円形の切欠部を有し、この切欠部を有した側が活物質保持体より外部に向けて突出するように活物質保持体に連続的に固着した後、切欠部を長手方向に切断する切断工程を備えるようにすると、長手方向の一辺のみに不連続な半円形の切欠部を有した帯状金属板は切欠部を有しない帯状金属板よりも破断伸び率が大きくなるため、このような切欠部を有した帯状金属板を活物質保持体に連続的に固着しても活物質保持体に反りを生じることはない。
【００１５】
このため、切欠部を長手方向に切断した後、このような帯状金属板が固着された活物質保持体を渦巻状に巻回しても巻ずれ等の巻回時の不具合を生じることが防止でき、均一な電極群を形成することが可能となる。この結果、この種の電極群の生産性が向上し、生産歩留まりが向上する。そして、帯状金属板の破断伸び率が大きくなって帯状金属板が柔らかくなると、活物質保持体の反りが減少するが、帯状金属板が柔らかくなりすぎると、逆に作業性が低下するため、破断伸び率は１０〜３０％とすることが好ましい。このように破断伸び率を１０〜３０％とするためには、切欠部を有した帯状金属板を熱処理するようにして用いるか、あるいは金属板素材中の炭素量を低減するとよい。
【００１６】
また、帯状金属板を溶接した後、帯状金属板と活物質充填部の境界部を加圧することにより、金属多孔体の活物質除去部分に生じたバリを抑制することが可能になる。また、加圧によってバリを平坦化した後、ポリプロピレン（ＰＰ）製粘着テープあるいはポリプロピレン（ＰＰ）製熱溶着テープ等の耐食性保護材を被覆すると、さらに内部短絡を抑制できるようになる。
【００１７】
【発明の実施の形態】
以下に、本発明の非焼結式電極を用いたアルカリ蓄電池をニッケル−水素蓄電池に適用した場合の一実施の形態を図に基づいて説明する。
なお、図１は発泡ニッケルからなる活物質保持体に活物質を充填した後、活物質除去部分を形成した電極に帯状金属板を溶着した状態を示す正面図であり、図２は活物質保持体に活物質を充填した後、帯状金属板と活物質充填部分との境界部を加圧する状態を示す側面図である。また、図３は図１の電極の帯状金属板をＸ−Ｘ線で切断した状態を示す正面図であり、図４は帯状金属板と活物質充填部分との境界部を加圧した後、この部分に保護材を付加して渦巻状に巻回する状態を示す実施例２の電極群を構成する前の側面図である。図５は比較例１の電極群を構成する前の側面図であり、図６は比較例２の電極群を構成する前の側面図である。
【００１８】
１．帯状金属板の作製
鉄にニッケルメッキを施した帯状金属板１０を用意し、この帯状金属板１０の上部に多数の半円形の切欠部１１，１１を形成した。なお、この帯状金属板１０のビッカース硬度は１２０〜１２５である。この後、還元雰囲気中で６００〜７００℃の温度範囲で約２時間加熱して熱処理を行った。この熱処理により、帯状金属板１０のビッカース硬度は１１０以下に低下して柔らかくなる。また、切欠部１１，１１が形成された帯状金属板１０は熱処理により柔らかくなって、破断伸び率が１０〜３０％と向上する。なお、上述のように、多数の半円形の切欠部１１，１１を形成した後、熱処理して、ビッカース硬度が１１０以下に低下するとともに破断伸び率が１０〜３０％に向上した帯状金属板１０は、後述する溶接時に伸びやすくかつ縮みにくくなる。
【００１９】
２．ニッケル正極板の作製
共沈成分として亜鉛２．５重量％とコバルト１重量％を含有する水酸化ニッケル粉末９０重量部と、水酸化コバルト粉末１０重量部と、酸化亜鉛粉末３重量部との混合粉末に、ヒドロキシプロピルセルロースの０．２重量％水溶液５０重量部を添加混練して活物質スラリーを作製する。
【００２０】
このようにして作製した活物質スラリーを、基体目付が６００ｇ／ｍ²で厚みが約２ｍｍのニッケル発泡体（ニッケルスポンジ）からなる金属多孔体（活物質保持体）２１に充填する。なお、圧延後の活物質充填密度が約２．９ｇ／ｃｃ−ｖｏｉｄとなるように活物質スラリーを充填する。ついで、活物質スラリーを充填した活物質保持体２０を乾燥させた後、厚みが約０．６０ｍｍになるまで圧延した後、所定寸法（例えば、Ｈ（高さ）＝３４．５ｍｍ，Ｗ（幅）＝３００ｍｍ）に切断してニッケル正極板２０を作成する。
【００２１】
ついで、このように活物質スラリーを充填したニッケル正極板２０の長辺側上辺部２２に図示しない超音波ホーンを押し当てて、この上辺部２２に垂直方向に超音波振動を加えて、ニッケル正極板２０の長辺側上辺部２２に充填された活物質を活物質保持体２１より脱落させて活物質除去部分を形成する。なお、超音波ホーンを押し当てて超音波振動を与えることにより、上辺部２２は若干圧縮されて薄肉部となる。
【００２２】
ａ．実施例１
ついで、上述のようにして作製した帯状金属板１０を活物質除去部分に押し当て、抵抗シーム溶接あるいは超音波シーム溶接により、帯状金属板１０を活物質保持体２１の活物質除去部分に連続的に溶着した。この後、図２に示すように、帯状金属板１０と活物質充填部分との境界部に加圧部材２０ａを押しつけて加圧して、活物質除去部分に生じたバリを抑制する。ついで、図１のＸ−Ｘ線に沿って切断して、図３に示すように、帯状金属板１０の半円形の切欠部１１，１１が形成された部分が除去された実施例１のニッケル正極板ａを作製した。
【００２３】
ｂ．実施例２
実施例１と同様に、帯状金属板１０を活物質除去部分に押し当て、抵抗シーム溶接あるいは超音波シーム溶接により、帯状金属板１０を活物質保持体２１の活物質除去部分に連続的に溶着した。この後、図２に示すように、帯状金属板１０と活物質充填部分との境界部に加圧部材２０ａを押しつけて加圧した後、図４に示すように、この境界部にポリプロピレン製の粘着フィルムあるいは熱溶着フィルムを接着あるいは熱溶着して貼着した。これにより、活物質除去部分に生じたバリは完全に抑制されることとなる。ついで、図１のＸ−Ｘ線に沿って切断して、図３に示すように、帯状金属板１０の半円形の切欠部１１，１１が形成された部分が除去された実施例２のニッケル正極板ｂを作製した。
【００２４】
ｃ．比較例１
実施例１と同様に活物質が充填され、かつ活物質除去部分が形成された活物質保持体２１の活物質除去部分に、鉄にニッケルメッキを施した帯状金属板１５を押し当て、抵抗シーム溶接あるいは超音波シーム溶接により、帯状金属板１５を活物質保持体２１の活物質除去部分に連続的に溶着して比較例１のニッケル正極板ｃを作製した。なお、この比較例１のニッケル正極板ｃの帯状金属板１５の幅は上述した帯状金属板１０の幅より短く形成されており、図５に示すように、セパレータ４０を介して負極３０を対向させると帯状金属板１５と活物質充填部分との境界部は対向する負極３０の上端よりも上部に突出している。
【００２５】
ｄ．比較例２
実施例１と同様に、帯状金属板１０を活物質除去部分に押し当て、抵抗シーム溶接あるいは超音波シーム溶接により、帯状金属板１０を活物質保持体２１の活物質除去部分に連続的に溶着した。ついで、図１のＸ−Ｘ線に沿って切断して、図３に示すように、帯状金属板１０の半円形の切欠部１１，１１が形成された部分が除去された比較例２のニッケル正極板ｄを作製した。
【００２６】
３．負極の作製
ミッシュメタル（Ｍｍ：希土類元素の混合物）、ニッケル、コバルト、アルミニウム、およびマンガンを１：３．４：０．８：０．２：０．６の比率で混合し、この混合物をアルゴンガス雰囲気の高周波誘導炉で誘導加熱して合金溶湯となす。この合金溶湯を公知の方法で鋳型に流し込み、冷却して、組成式Ｍｍ_1.0Ｎｉ_3.4Ｃｏ_0.8Ａｌ_0.2Ｍｎ_0.6で表される水素吸蔵合金のインゴットを作製した。
【００２７】
この水素吸蔵合金インゴットを機械的に粗粉砕した後、不活性ガス雰囲気中で平均粒子径が約１００μｍになるまで機械的に粉砕する。このようにして作製した水素吸蔵合金粉末にポリエチレンオキサイド等の結着剤と、適量の水を加えて混合して水素吸蔵合金スラリーを作製する。このスラリーをパンチングメタルからなる活物質保持体の両面に、圧延後の活物質密度が所定量（例えば、５ｇ／ｃｃ）になるように塗着した後、乾燥、圧延を行った後、所定寸法（例えば、幅３４．５ｍｍで長さが３５０ｍｍ）に切断して水素吸蔵合金負極板３０を作製した。
【００２８】
４．ニッケル−水素電池の作製
ａ．実施例１，２
図４（なお、図４は実施例２の場合を示すが、各極板及びセパレータの配置は実施例１も同様である）に示すように、上述のように作製した実施例１のニッケル正極板ａおよび実施例２のニッケル正極板ｂと、上述のように作製した水素吸蔵合金負極板３０とをそれぞれポリプロピレン製不織布からなるセパレータ（厚みが約０．２ｍｍのもの）４０を介して重ね合わせた。このとき、ニッケル正極板ａ，ｂに溶着された帯状金属板１０が渦巻の外側になるように、かつ帯状金属板１０と活物質充填部との境界部が水素吸蔵合金負極板３０と対向するように配置した後、渦巻の最外周がセパレータ４０となるようにして巻回することにより、実施例１および実施例２の渦巻状電極群を作製した。なお、実施例１および実施例２の渦巻状電極群は、帯状金属板１０の端部をセパレータ４０より突出させることにより、帯状金属板１０の端部と正極集電体との溶接を容易にすることができる。
【００２９】
ついで、これらの各渦巻状電極群の負極板３０の端部と図示しない負極集電板とを抵抗溶接するとともに、ニッケル正極板２０の帯状金属板１０の端部と図示しない正極集電板とを抵抗溶接した。この後、有底円筒形の金属外装缶を用意し、各集電板を溶接した各渦巻状電極群をそれぞれの金属外装缶内に挿入し、正極集電板の電解液注液孔より一方の溶接電極を挿入して負極集電板に当接させるとともに金属外装缶の底部に他方の溶接電極を当接して、負極集電板と金属外装缶の底部をスポット溶接した。
【００３０】
一方、正極キャップと蓋体とからなる封口体を用意し、正極集電板の導出部を蓋体の底部に接触させて、蓋体の底部と導出部とを溶接して接続した。この後、金属外装缶内に電解液（例えば、水酸化リチウム（ＬｉＯＨ）と水酸化ナトリウム（ＮａＯＨ）を含有した８Ｎの水酸化カリウム（ＫＯＨ）水溶液）を注入し、封口体を封口ガスケットを介して外装缶の開口部に載置するとともに、この開口部を封口体側にかしめて封口して、公称容量３０００ｍＡＨの実施例１および実施例２の各円筒形ニッケル−水素蓄電池を作製した。
【００３１】
ｂ．比較例１
図５に示すように、上述のように作製した比較例１のニッケル正極板ｃと、上述のように作製した水素吸蔵合金負極板３０とをそれぞれポリプロピレン製不織布からなるセパレータ（厚みが約０．２ｍｍのもの）４０を介して重ね合わせた。このとき、ニッケル正極板ｃに溶着された帯状金属板１５が渦巻の内側になるように配置した後、渦巻の最外周がセパレータ４０となるようにして卷回することにより、比較例１の渦巻状電極群を作製した。ついで、実施例１，２と同様にして電池を構成し、公称容量３０００ｍＡＨの比較例１の円筒形ニッケル−水素蓄電池を作製した。
【００３２】
ｃ．比較例２
図６に示すように、上述のように作製した比較例２のニッケル正極板ｄと、上述のように作製した水素吸蔵合金負極板３０とをそれぞれポリプロピレン製不織布からなるセパレータ（厚みが約０．２ｍｍのもの）４０を介して重ね合わせた。このとき、ニッケル正極板ｄに溶着された帯状金属板１０が渦巻の内側になるように配置した後、渦巻の最外周がセパレータ４０となるようにして卷回することにより、比較例２の渦巻状電極群を作製した。ついで、実施例１，２と同様にして電池を構成し、公称容量３０００ｍＡＨの比較例２の円筒形ニッケル−水素蓄電池を作製した。
【００３３】
５．実験結果
ａ．卷回時の状況
上述のようにして作成した渦巻状電極群をそれぞれ１００個ずつ用意し、これらの各１００個ずつの渦巻状電極群を目視により観察して、正・負極板およびセパレータが所定の位置、所定の幅の範囲内に位置すれば巻ずれは無いと判定し、この範囲を超えると巻ずれが有ると判定して巻ずれ数を測定すると、下記の表１に示すような結果となった。また、上述のようにして作成した渦巻状電極群をそれぞれ１００個ずつ用意し、これらの各１００個ずつの渦巻状電極群の短絡数を測定すると、下記の表１に示すような結果となった。
【００３４】
【表１】

【００３５】
上記表１より明らかなように、実施例１及び実施例２の電極群は比較例１及び比較例２の電極群よりも巻ずれ数が少ないことが分かる。これは、帯状金属板１０の上部に多数の半円形の切欠部１１，１１を形成した後、還元雰囲気中で熱処理を行ってビッカース硬度が１１０以下に低下して柔らかくなるとともに、破断伸び率が１０〜３０％と向上した帯状金属板１０を活物質保持体２１に溶接しているため、活物質保持体２１の反りが減少したことおよび帯状金属板１０が外側になるように巻回することによって巻ずれが低下したためと考えられる。
【００３６】
また、実施例１及び実施例２の電極群は比較例１及び比較例２の電極群よりも短絡数が少ないことが分かる。これは、溶接時に伸びやすくかつ縮みにくくなった帯状金属板１０が外側になるように巻回することによって、帯状金属板１０は渦巻の外方に向けて延伸するため、渦巻の内側になる活物質保持体２１の活物質除去部分２２は帯状金属板１０から剥がれることが減少しためと考えられる。かつ、活物質保持体２１の活物質除去部分２２は渦巻の内側となるため、帯状金属板１０と活物質充填部分の境界部以外となる活物質保持体２１の活物質除去部分２２に外側向きのバリが発生することが減少し、活物質保持体２１の活物質除去部分２２での内部短絡を抑制することができたと考えられる。さらに、帯状金属板１０を溶接した後、帯状金属板１０と活物質充填部の境界部を加圧することによって、活物質保持体２１の活物質除去部分２２に生じたバリを抑制することができたためと考えられる。
【００３７】
一方、実施例１の電極群と実施例２の電極群とを比較すると、実施例２の電極群の方が実施例１の電極群より短絡数が少ないことが分かる。これは、帯状金属板１０を溶接した後、帯状金属板と活物質充填部の境界部を含む位置を加圧した後、ポリプロピレン（ＰＰ）製粘着テープあるいはポリプロピレン（ＰＰ）製熱溶着テープ等の耐食性の保護材を被覆することによって、さらに内部短絡が抑制されたものと考えることができる。
【００３８】
６．破断伸び率およびビッカース硬度と極板の反りとの関係
ついで、帯状金属板１０の破断伸び率およびビッカース硬度と活物質保持体１０の反りとの関係について検討した。
まず、上述した実施例１と同様に半円形の切欠部１１，１１が形成された帯状金属板１０と、半円形の切欠部が形成されていない帯状金属板１６とを用意し、これらの各帯状金属板１０，１６の熱処理温度および熱処理時間を調整して、ビッカース硬度（Ｈｖ）が図８に示されるような値となった各帯状金属板１０，１６を用い、これらの各帯状金属板１０，１６を活物質除去部分に押し当て、抵抗シーム溶接あるいは超音波シーム溶接により、各帯状金属板１０，１６を活物質保持体２１の活物質除去部分に連続的に溶着した。この後に、図７に示すように、活物質保持体２１の一端の下部ｘに定規５０を当てて、活物質保持体２１の他端の下部までの高さｙを測定して反り量（ｍｍ）を求めると、図８に示すような結果となった。なお、反り量（ｍｍ）の上限は巻回時に問題のないレベルである１．０ｍｍとし、０．５ｍｍ以下なら全然問題がなかった。
【００３９】
図８より明らかなように、ビッカース硬度（Ｈｖ）が小さくなるに従って反り量（ｍｍ）が小さくなることが分かる。また、ビッカース硬度（Ｈｖ）が同じであっても、半円形の切欠部１１，１１が形成された帯状金属板（図８においては片側開口有りとしている）１０の方が、半円形の切欠部が形成されていない帯状金属板（図８においては未開口としている）１６よりも反り量（ｍｍ）が小さくなることが分かる。このことから、反り量（ｍｍ）を０．５（ｍｍ）以下にするためには、半円形の切欠部１１，１１が形成された帯状金属板１０を用いるとともに、ビッカース硬度（Ｈｖ）が１１０以下のものを選択して用いる必要がある。このように、反り量（ｍｍ）を０．５（ｍｍ）以下とすることにより、渦巻状電極群とする際の不具合が減少する。
【００４０】
同様に、上述した実施例１と同様に半円形の切欠部１１，１１が形成された帯状金属板１０と、半円形の切欠部が形成されていない帯状金属板１６とを用意し、これらの各帯状金属板１０，１６の熱処理温度および熱処理時間を調整して、破断伸び率（％）が図９に示されるような値となった各帯状金属板１０，１６を用い、これらの各帯状金属板１０，１６を活物質除去部分に押し当て、抵抗シーム溶接あるいは超音波シーム溶接により、各帯状金属板１０，１６を活物質保持体２１の活物質除去部分に連続的に溶着した。この後に、図７に示すように、活物質保持体２１の一端の下部ｘに定規５０を当てて、活物質保持体２１の他端の下部までの高さｙを測定して反り量（ｍｍ）を求めると、図９に示すような結果となった。
【００４１】
図９より明らかなように、破断伸び率（％）が大きくなるに従って反り量（ｍｍ）が小さくなることが分かる。また、破断伸び率（％）が同じであっても、半円形の切欠部１１，１１が形成された帯状金属板（図９においては片側開口有りとしている）１０の方が、半円形の切欠部が形成されていない帯状金属板（図９においては未開口としている）１６よりも反り量（ｍｍ）が小さくなることが分かる。このことから、反り量（ｍｍ）を０．５（ｍｍ）以下にするためには、半円形の切欠部１１，１１が形成された帯状金属板１０を用いるとともに、破断伸び率（％）が１０％以上のものを選択して用いる必要がある。このように、反り量（ｍｍ）を０．５（ｍｍ）以下とすることにより、渦巻状電極群とする際の不具合が減少する。ただし、破断伸び率（％）が３０％より大きくなって柔らかくなりすぎると作業性が低下するため、破断伸び率（％）の上限値は３０％とすることが好ましい。
【図面の簡単な説明】
【図１】発泡ニッケルからなる活物質保持体に活物質を充填した後、活物質除去部分を形成した電極に帯状金属板を溶着した状態を示す正面図である。
【図２】活物質保持体に活物質を充填した後、帯状金属板と活物質充填部分との境界部を加圧する状態を示す側面図である。
【図３】図１の電極の帯状金属板をＸ−Ｘ線で切断した状態を示す正面図である。
【図４】帯状金属板と活物質充填部分との境界部を加圧した後、この部分に保護材を付加して渦巻状に巻回する状態を示す実施例２の電極群を構成する前の側面図である。
【図５】比較例１の電極群を構成する前の側面図である。
【図６】比較例２の電極群を構成する前の側面図である。
【図７】活物質保持体の反り量を測定する状態を示す図である。
【図８】帯状金属板の破断伸び率と活物質保持体の反り量の関係を示す図である。
【図９】帯状金属板のビッカース硬度と活物質保持体の反り量の関係を示す図である。
【符号の説明】
１０，１５，１６…帯状金属板、１１…半円形の切欠部、２０…ニッケル正極板、２１…活物質保持体、２２…活物質除去部分、３０…負極板、４０…セパレータ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an alkaline storage battery such as a nickel / hydrogen storage battery or a nickel / cadmium storage battery, and more particularly to an improvement in a current collecting structure of an electrode in which an active material is coated on an active material holder.
[0002]
[Prior art]
Conventionally, nickel electrodes used in alkaline storage batteries such as nickel / hydrogen storage batteries and nickel / cadmium storage batteries are made by sintering nickel powder on a core body of punching metal or the like on a sintered substrate formed of nickel salt, cadmium salt, etc. A so-called sintered electrode that is impregnated with a solution and made into an active material by alkali treatment is known. Since this sintered electrode has a low mechanical strength when the sintered substrate has a high porosity, it is practically limited to a porosity of about 80%, and a punching metal, etc. Since the core is required, there is a problem in realizing an electrode with a low active material filling amount and a high energy density. In addition, since the pores of the sintered substrate are 10 μm or less, it is limited to solution impregnation methods and electrodeposition impregnation methods that require the active material filling process to be repeated many times. There was a problem of high costs.
[0003]
On the other hand, in order to improve these drawbacks, the active material slurry is directly filled into a metal porous body (active material holding body) having a three-dimensional network structure such as a metal fiber sintered body or nickel foam (nickel sponge). So-called non-sintered electrodes have become mainstream. Since this kind of porous metal body having a three-dimensional network structure has a high porosity of about 95%, the active material can be filled with high density. Therefore, a high-capacity battery can be obtained, and this type of non-sintered electrode fills the metal porous body with the active material as it is, which eliminates the need for troublesome active material treatment and facilitates manufacture. There is an advantage of becoming.
[0004]
By the way, an electrode using a metal porous body having this kind of three-dimensional network structure is generally low in strength because of its high porosity, and it is difficult to attach a lead terminal for collecting current from the electrode. Met. In particular, when a large current discharge is required, it is effective to fix a substantially disc-shaped current collector to each electrode of the electrode group. However, a sintered core has a strong core such as punching metal. Since there is a body, it is easy to fix the current collector. However, since the non-sintered electrode uses a porous metal body having a three-dimensional network structure, there is no strong core, and it is difficult to fix a substantially disc-shaped current collector. For this reason, a metal dense part on a part of the electrode, such as a method of pressing a part of the metal porous body, a method of adding another metal to the part of the metal porous body by welding, spraying, caulking, etc. Thus, a method of collecting current from the electrode has been made.
[0005]
As one of the most practical methods for obtaining a dense metal part in the above-mentioned electrode part, a metal plate is welded to a part of one side of the electrode to weld a metal part to the electrode part. There is a method of using an electrode having a structure in which a high-density portion is obtained and used as a current collecting terminal mounting portion. However, when the electrode manufactured by this method is spirally wound together with a counter electrode via a separator to form a spiral electrode group, there is a problem that there are many short-circuit defects.
[0006]
Therefore, in an electrode using a metal porous body having a three-dimensional network structure as an active material holding body, after welding a band-shaped metal plate to a part of one side of the electrode, a high-density part of the metal is obtained on a part of the electrode. When winding an electrode having a structure as a current collecting terminal mounting portion in a spiral shape, the welded metal plate is wound inside the spiral and the metal porous body is outside the spiral to form a spiral electrode group. Was proposed in Japanese Patent No. 2762517.
[0007]
According to the means proposed in Japanese Patent No. 2762517, when the metal porous body welded with the band-shaped metal plate is wound in a spiral shape, the metal porous body is not subjected to a force in the shrinking direction. A short circuit failure can be prevented because it does not deform into a convex shape inside the group and the edge of the band-shaped metal plate does not easily protrude toward the counter electrode due to the elasticity of the metal.
[0008]
[Problems to be solved by the invention]
However, when the welded metal plate is wound so that the metal porous body is inside the vortex and the metal porous body is outside the vortex to form a spiral electrode group, the boundary between the strip metal plate and the active material filling portion faces the counter electrode. If the metal porous body (active material unfilled part) on the surface opposite to the surface on which the belt-shaped metal plate is welded is cracked during winding, this crack causes burrs (the skeleton of the metal porous body) The burrs protrude to the outside of the spiral, so that the burr penetrates the separator and contacts the counter electrode, resulting in a short circuit.
[0009]
Moreover, a burr | flash generate | occur | produced also in the boundary part of an active material filling part and a strip | belt-shaped metal plate, and it also resulted in the short circuit by this burr | flash. And there are resistance seam welding, ultrasonic seam welding, etc. as a method of welding the strip metal plate to the metal porous body (active material unfilled portion). If the strip metal plate is a flat plate, the active material is welded after welding. A warp occurred in the longitudinal direction of the holding body, and a problem such as a problem of winding deviation occurred during winding due to the warp occurred.
[0010]
Therefore, in order to solve the above problems, the present invention uses a porous metal body having a three-dimensional network structure as an active material holder, and a belt-like metal plate is fixed to the active material holder and wound in a spiral shape. However, it was made for the purpose of obtaining an alkaline storage battery that does not cause an internal short circuit.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, an alkaline storage battery manufacturing method includes an active material at an end portion in a longitudinal direction of an active material holder of a nickel positive electrode. Removal An adhering process for adhering the band-shaped metal plate to the part; A pressurizing step of pressurizing a boundary portion between the band-shaped metal plate fixed to the active material removing portion and the active material filling portion; The boundary part of a strip | belt-shaped metal plate and an active material filling part opposes a negative electrode, and it is provided with the winding process wound so that this strip | belt-shaped metal plate may become an outer side. Thus, the active material Removal When the band-shaped metal plate is continuously fixed to the part and wound so that the band-shaped metal plate is outside the spiral, the band-shaped metal plate extends toward the outside of the spiral during winding, so that the inner side of the spiral Active material of porous metal body Removal The part is not peeled off from the strip metal plate. Moreover, the active material of a metal porous body Removal Because the part is inside the spiral, the active material of the metal porous body Removal There will be no outward burrs in the area. Therefore, the active material of the metal porous body Removal It becomes possible to suppress an internal short circuit at the portion. Furthermore, by winding the belt-shaped metal plate outward, the winding deviation at the time of winding was also a favorable result compared to the case where the belt-shaped metal plate was wound inside.
[0014]
The band-shaped metal plate has a discontinuous semicircular cutout on only one side in the longitudinal direction, and is continuous with the active material holder so that the side having the cutout projects outward from the active material holder. If the cutting step for cutting the cutout portion in the longitudinal direction is provided after the fixing, the strip-shaped metal plate having the semicircular cutout portion that is discontinuous only on one side in the longitudinal direction does not have the cutout portion. Since the elongation at break is larger than that of the plate, even if the band-shaped metal plate having such a notch is continuously fixed to the active material holder, the active material holder is not warped.
[0015]
For this reason, even if the active material holder to which such a band-shaped metal plate is fixed is wound in a spiral shape after the cutout portion is cut in the longitudinal direction, it is possible to prevent problems such as winding slippage from occurring. A uniform electrode group can be formed. As a result, the productivity of this type of electrode group is improved and the production yield is improved. And, when the elongation at break of the band-shaped metal plate is increased and the band-shaped metal plate is softened, the warp of the active material holding body is reduced, but when the band-shaped metal plate is too soft, the workability is reduced, so The elongation is preferably 10 to 30%. Thus, in order to set the elongation at break to 10 to 30%, it is preferable to use the band-shaped metal plate having the notch portion by heat treatment or to reduce the amount of carbon in the metal plate material.
[0016]
Moreover, after welding a strip | belt-shaped metal plate, the active material of a metal porous body is pressurized by pressurizing the boundary part of a strip | belt-shaped metal plate and an active material filling part. Removal Part The resulting burr It becomes possible to suppress. Further, after the burrs are flattened by pressurization, if an anticorrosive protective material such as a polypropylene (PP) adhesive tape or a polypropylene (PP) heat welding tape is coated, the internal short circuit can be further suppressed.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Below, one Embodiment at the time of applying the alkaline storage battery using the non-sintering-type electrode of this invention to a nickel-hydrogen storage battery is described based on figures.
FIG. 1 shows an active material after filling an active material holder made of foamed nickel with an active material. Removal FIG. 2 is a front view showing a state in which a band-shaped metal plate is welded to an electrode in which a portion is formed, and FIG. Quality It is a side view which shows the state which pressurizes the boundary part with a filling part. 3 is a front view showing a state in which the strip metal plate of the electrode of FIG. 1 is cut along the line XX, and FIG. 4 is a strip metal plate and an active material. Quality It is a side view before constituting the electrode group of Example 2 which shows the state which adds a protective material to this part and presses it in a spiral after pressing a boundary part with a filling part. FIG. 5 is a side view before the electrode group of Comparative Example 1 is configured, and FIG. 6 is a side view before the electrode group of Comparative Example 2 is configured.
[0018]
1. Fabrication of strip metal plate
A band-shaped metal plate 10 in which nickel was plated on iron was prepared, and a number of semicircular cutouts 11, 11 were formed on the upper part of the band-shaped metal plate 10. In addition, the Vickers hardness of this strip | belt-shaped metal plate 10 is 120-125. Thereafter, heat treatment was performed by heating for about 2 hours in a temperature range of 600 to 700 ° C. in a reducing atmosphere. By this heat treatment, the Vickers hardness of the band-shaped metal plate 10 is lowered to 110 or less and becomes soft. Moreover, the strip-shaped metal plate 10 in which the notches 11 and 11 are formed is softened by heat treatment, and the elongation at break is improved to 10 to 30%. As described above, after forming a large number of semicircular cutouts 11, 11, heat treatment was performed to reduce the Vickers hardness to 110 or less and improve the elongation at break to 10 to 30%. Is easy to stretch and difficult to shrink during welding, which will be described later.
[0019]
2. Production of nickel positive electrode plate
To a mixed powder of 90 parts by weight of nickel hydroxide powder containing 2.5% by weight of zinc and 1% by weight of cobalt as a coprecipitation component, 10 parts by weight of cobalt hydroxide powder, and 3 parts by weight of zinc oxide powder, hydroxypropyl An active material slurry is prepared by adding and kneading 50 parts by weight of a 0.2% by weight aqueous solution of cellulose.
[0020]
The active material slurry thus prepared has a basis weight of 600 g / m. ² The metal porous body (active material holding body) 21 made of nickel foam (nickel sponge) having a thickness of about 2 mm is filled. The active material slurry is filled so that the active material filling density after rolling is about 2.9 g / cc-void. Next, after the active material holding body 20 filled with the active material slurry is dried, it is rolled until the thickness becomes about 0.60 mm, and then predetermined dimensions (for example, H (height) = 34.5 mm, W (width) ) = 300 mm) to produce the nickel positive electrode plate 20.
[0021]
Next, an ultrasonic horn (not shown) is pressed against the upper side portion 22 of the long side of the nickel positive electrode plate 20 filled with the active material slurry in this way, and ultrasonic vibration is applied to the upper side portion 22 in the vertical direction, thereby producing a nickel positive electrode. The active material filled in the upper side 22 on the long side of the plate 20 is dropped from the active material holder 21 to form an active material removal portion. Note that, by applying ultrasonic vibration by pressing the ultrasonic horn, the upper side portion 22 is slightly compressed into a thin portion.
[0022]
a. Example 1
Next, the band-shaped metal plate 10 produced as described above is pressed against the active material removal portion, and the band-shaped metal plate 10 is continuously applied to the active material removal portion of the active material holding body 21 by resistance seam welding or ultrasonic seam welding. Welded to. Thereafter, as shown in FIG. 2, the pressure member 20a is pressed against the boundary portion between the band-shaped metal plate 10 and the active material filling portion to pressurize the burrs generated in the active material removal portion. Next, the nickel of Example 1 was cut along the line XX in FIG. 1 and the portions where the semicircular cutout portions 11, 11 of the strip-shaped metal plate 10 were formed as shown in FIG. 3 were removed. A positive electrode plate a was produced.
[0023]
b. Example 2
As in Example 1, the belt-like metal plate 10 is pressed against the active material removal portion, and the belt-like metal plate 10 is continuously welded to the active material removal portion of the active material holder 21 by resistance seam welding or ultrasonic seam welding. did. After that, as shown in FIG. 2, the pressing member 20a is pressed against the boundary between the belt-shaped metal plate 10 and the active material filling portion and pressurized, and as shown in FIG. 4, the boundary is made of polypropylene. An adhesive film or a heat-welded film was adhered or heat-welded for pasting. Thereby, the burr | flash produced in the active material removal part will be suppressed completely. Next, the nickel of Example 2 was cut along the line XX in FIG. 1 to remove the portions where the semicircular cutout portions 11, 11 of the strip-shaped metal plate 10 were formed as shown in FIG. 3. A positive electrode plate b was produced.
[0024]
c. Comparative Example 1
In the same manner as in the first embodiment, the active material removing portion of the active material holding body 21 filled with the active material and formed with the active material removing portion is pressed against the band-shaped metal plate 15 obtained by applying nickel plating to iron, and a resistance seam A nickel positive electrode plate c of Comparative Example 1 was prepared by continuously welding the band-shaped metal plate 15 to the active material removing portion of the active material holder 21 by welding or ultrasonic seam welding. In addition, the width of the strip-shaped metal plate 15 of the nickel positive electrode plate c of the comparative example 1 is formed shorter than the width of the strip-shaped metal plate 10 described above, and the negative electrode 30 is opposed via the separator 40 as shown in FIG. If it does so, the boundary part of the strip | belt-shaped metal plate 15 and an active material filling part will protrude above the upper end of the negative electrode 30 which opposes.
[0025]
d. Comparative Example 2
As in Example 1, the belt-like metal plate 10 is pressed against the active material removal portion, and the belt-like metal plate 10 is continuously welded to the active material removal portion of the active material holder 21 by resistance seam welding or ultrasonic seam welding. did. Subsequently, the nickel of Comparative Example 2 was cut along the line XX in FIG. 1 and the portions where the semicircular cutout portions 11, 11 of the strip-shaped metal plate 10 were formed as shown in FIG. 3. A positive electrode plate d was produced.
[0026]
3. Production of negative electrode
Mish metal (Mm: mixture of rare earth elements), nickel, cobalt, aluminum, and manganese were mixed at a ratio of 1: 3.4: 0.8: 0.2: 0.6. Inductively heated in a high frequency induction furnace to make a molten alloy. This molten alloy is poured into a mold by a known method, cooled, and the composition formula Mm _1.0 Ni _3.4 Co _0.8 Al _0.2 Mn _0.6 An ingot of a hydrogen storage alloy represented by
[0027]
The hydrogen storage alloy ingot is mechanically coarsely pulverized and then mechanically pulverized in an inert gas atmosphere until the average particle size becomes about 100 μm. A hydrogen storage alloy slurry is prepared by adding and mixing a binder such as polyethylene oxide and an appropriate amount of water to the hydrogen storage alloy powder thus prepared. After applying this slurry on both surfaces of an active material holder made of punching metal so that the active material density after rolling becomes a predetermined amount (for example, 5 g / cc), drying and rolling, predetermined dimensions are obtained. The hydrogen storage alloy negative electrode plate 30 was produced by cutting into pieces (for example, a width of 34.5 mm and a length of 350 mm).
[0028]
4). Production of nickel-hydrogen battery
a. Examples 1 and 2
As shown in FIG. 4 (FIG. 4 shows the case of Example 2, but the arrangement of each electrode plate and separator is the same as in Example 1), the nickel positive electrode of Example 1 produced as described above The plate a and the nickel positive electrode plate b of Example 2 and the hydrogen storage alloy negative electrode plate 30 produced as described above were overlapped via a separator (thickness of about 0.2 mm) 40 made of polypropylene nonwoven fabric. It was. At this time, the boundary between the strip metal plate 10 and the active material filling portion faces the hydrogen storage alloy negative electrode plate 30 so that the strip metal plate 10 welded to the nickel positive plates a and b is outside the spiral. Then, the spiral electrode group of Example 1 and Example 2 was produced by winding the spiral so that the outermost periphery of the spiral was the separator 40. In addition, the spiral electrode group of Example 1 and Example 2 is ,band By projecting the end of the metal sheet 10 from the separator 40, the end of the metal band 10 and Positive electrode Welding with the current collector can be facilitated.
[0029]
Next, the end of the negative electrode plate 30 of each spiral electrode group and a negative current collector (not shown) are resistance welded, and the end of the strip metal plate 10 of the nickel positive electrode 20 and the positive current collector (not shown) Resistance welded. After this, a bottomed cylindrical metal outer can is prepared, and each spiral electrode group welded to each current collector plate is inserted into each metal outer can, and one side is inserted from the electrolyte injection hole of the positive electrode current collector plate. The welding electrode was inserted and brought into contact with the negative electrode current collector plate, and the other welding electrode was brought into contact with the bottom of the metal outer can, and the bottom of the negative electrode current collector and the metal outer can were spot welded.
[0030]
On the other hand, a sealing body composed of a positive electrode cap and a lid was prepared, the lead-out portion of the positive electrode current collector plate was brought into contact with the bottom of the lid, and the bottom and the lead-out portion of the lid were welded and connected. Thereafter, an electrolytic solution (for example, 8N potassium hydroxide (KOH) aqueous solution containing lithium hydroxide (LiOH) and sodium hydroxide (NaOH)) is injected into the metal outer can, and the sealing body is inserted through the sealing gasket. The cylindrical nickel-metal hydride storage batteries of Examples 1 and 2 having a nominal capacity of 3000 mAH were manufactured by placing the openings on the side of the sealing body and sealing them.
[0031]
b. Comparative Example 1
As shown in FIG. 5, the nickel positive electrode plate c of Comparative Example 1 produced as described above and the hydrogen storage alloy negative electrode plate 30 produced as described above were each made of a polypropylene nonwoven fabric (thickness of about 0.00 mm). 2 mm)). At this time, after arranging the strip-shaped metal plate 15 welded to the nickel positive electrode plate c so as to be inside the spiral, the spiral of Comparative Example 1 is wound by winding the spiral so that the outermost periphery of the spiral is the separator 40. The electrode group was produced. Next, a battery was constructed in the same manner as in Examples 1 and 2, and a cylindrical nickel-hydrogen storage battery of Comparative Example 1 having a nominal capacity of 3000 mAH was produced.
[0032]
c. Comparative Example 2
As shown in FIG. 6, the nickel positive electrode plate d of Comparative Example 2 manufactured as described above and the hydrogen storage alloy negative electrode plate 30 manufactured as described above were each made of a separator made of polypropylene nonwoven fabric (thickness of about 0.00 mm). 2 mm)). At this time, after arranging the strip-shaped metal plate 10 welded to the nickel positive electrode plate d so as to be inside the spiral, it is wound so that the outermost periphery of the spiral is the separator 40, whereby the spiral of Comparative Example 2 is obtained. The electrode group was produced. Next, a battery was constructed in the same manner as in Examples 1 and 2, and a cylindrical nickel-hydrogen storage battery of Comparative Example 2 having a nominal capacity of 3000 mAH was produced.
[0033]
5. Experimental result
a. The situation at the time of winding
Each of the 100 spiral electrode groups prepared as described above is prepared, and each of these 100 spiral electrode groups is visually observed, and the positive and negative electrode plates and the separator are in a predetermined position and a predetermined position. If it was located within the width range, it was determined that there was no winding deviation. If this range was exceeded, it was determined that there was a winding deviation and the number of winding deviations was measured. The results shown in Table 1 below were obtained. In addition, when 100 spiral electrode groups prepared as described above were prepared and the number of short circuits of each of these 100 spiral electrode groups was measured, the results shown in Table 1 below were obtained. It was.
[0034]
[Table 1]

[0035]
As is clear from Table 1 above, it can be seen that the electrode groups of Example 1 and Example 2 have fewer winding deviations than the electrode groups of Comparative Example 1 and Comparative Example 2. This is because, after forming a large number of semicircular cutouts 11, 11 on the upper part of the band-shaped metal plate 10, heat treatment is performed in a reducing atmosphere to reduce the Vickers hardness to 110 or less and soften, and the elongation at break Since the strip-shaped metal plate 10 improved to 10 to 30% is welded to the active material holding body 21, the warpage of the active material holding body 21 is reduced and the strip-shaped metal plate 10 is wound so as to be on the outside. This is considered to be due to the decrease in winding deviation.
[0036]
It can also be seen that the electrode groups of Example 1 and Example 2 have fewer short circuits than the electrode groups of Comparative Example 1 and Comparative Example 2. This is because the band-shaped metal plate 10 is stretched toward the outer side of the spiral by winding the band-shaped metal plate 10 which is easily stretched and difficult to shrink during the welding, so that the active is located inside the spiral. Active material of substance holder 21 Removal The portion 22 is less peeled off from the strip metal plate 10 This is probably because of this. And the active material of the active material holder 21 Removal Since the portion 22 is inside the spiral, the active material of the active material holding body 21 other than the boundary portion between the band-shaped metal plate 10 and the active material filling portion. Removal The occurrence of outward burrs in the portion 22 is reduced, and the active material of the active material holder 21 is reduced. Removal Internal short circuit at the part 22 can be suppressed It is thought. Furthermore, after welding the strip-shaped metal plate 10, the active material of the active material holding body 21 is pressurized by pressurizing the boundary between the strip-shaped metal plate 10 and the active material filling portion.

Removal

Part 22 The burr that occurred in It is thought that it was possible to suppress.
[0037]
On the other hand, comparing the electrode group of Example 1 and the electrode group of Example 2, it can be seen that the electrode group of Example 2 has a smaller number of short circuits than the electrode group of Example 1. This is because, after welding the belt-shaped metal plate 10, after pressurizing a position including the boundary between the belt-shaped metal plate and the active material filling portion, a polypropylene (PP) adhesive tape or a polypropylene (PP) heat welding tape, etc. It can be considered that the internal short circuit is further suppressed by coating the corrosion-resistant protective material.
[0038]
6). Relationship between elongation at break and Vickers hardness and electrode plate warpage
Next, the relationship between the elongation at break and the Vickers hardness of the band-shaped metal plate 10 and the warp of the active material holder 10 was examined.
First, in the same manner as in the first embodiment, the band-shaped metal plate 10 having the semicircular cutouts 11 and 11 formed thereon, Half As shown in FIG. 8, the Vickers hardness (Hv) is prepared by preparing a band-shaped metal plate 16 having no circular notch and adjusting the heat treatment temperature and heat treatment time of each of the

band metal plates

10 and 16. Using the

strip metal plates

10 and 16 having different values, the

strip metal plates

10 and 16 are pressed against the active material removal portion, and the

strip metal plates

10 and 16 are formed by resistance seam welding or ultrasonic seam welding. Was continuously welded to the active material removal portion of the active material holder 21. Thereafter, as shown in FIG. 7, a ruler 50 is applied to the lower part x of one end of the active material holding body 21, the height y to the lower part of the other end of the active material holding body 21 is measured, and the warpage amount (mm ) Was obtained as shown in FIG. The upper limit of the warping amount (mm) was 1.0 mm, which is a level that causes no problem during winding, and there was no problem if it was 0.5 mm or less.
[0039]
As is apparent from FIG. 8, the warpage (mm) decreases as the Vickers hardness (Hv) decreases. Further, even if the Vickers hardness (Hv) is the same, the band-shaped metal plate (having one side opening in FIG. 8) on which the semicircular cutouts 11 and 11 are formed is more semicircular cutout. It can be seen that the amount of warpage (mm) is smaller than that of the band-shaped metal plate 16 in which no is formed (which is not opened in FIG. 8). From this, in order to make the amount of warpage (mm) 0.5 (mm) or less, the band-shaped metal plate 10 on which the semicircular cutouts 11 and 11 are formed is used, and the Vickers hardness (Hv) is 110. The following must be selected and used. Thus, the defect at the time of setting it as a spiral electrode group reduces by making curvature amount (mm) into 0.5 (mm) or less.
[0040]
Similarly, in the same manner as in Example 1 described above, the belt-like metal plate 10 in which the semicircular cutouts 11 and 11 are formed, Half FIG. 9 shows the elongation at break (%) by preparing a strip-shaped metal plate 16 having no circular notch and adjusting the heat treatment temperature and heat treatment time of each of the

strip metal plates

10 and 16. Using the respective

strip metal plates

10 and 16 having such values, the respective

strip metal plates

10 and 16 are pressed against the active material removal portion, and the respective

strip metal plates

10 and 16 are subjected to resistance seam welding or ultrasonic seam welding. 16 was continuously welded to the active material removal portion of the active material holder 21. Thereafter, as shown in FIG. 7, a ruler 50 is applied to the lower part x of one end of the active material holding body 21, the height y to the lower part of the other end of the active material holding body 21 is measured, and the warpage amount (mm ) Was obtained as shown in FIG.
[0041]
As can be seen from FIG. 9, the warpage (mm) decreases as the elongation at break (%) increases. Further, even when the elongation at break (%) is the same, the strip-shaped metal plate (having one side opening in FIG. 9) in which the semicircular cutouts 11 and 11 are formed is more semicircular. It can be seen that the amount of warpage (mm) is smaller than that of the band-shaped metal plate 16 in which no part is formed (which is not opened in FIG. 9). From this, in order to set the warpage amount (mm) to 0.5 (mm) or less, the strip-shaped metal plate 10 in which the semicircular cutout portions 11 and 11 are formed is used, and the elongation at break (%) is high. It is necessary to select and use 10% or more. Thus, the defect at the time of setting it as a spiral electrode group reduces by making curvature amount (mm) into 0.5 (mm) or less. However, if the elongation at break (%) is larger than 30% and becomes too soft, the workability deteriorates, so the upper limit of the elongation at break (%) is preferably 30%.
[Brief description of the drawings]
FIG. 1 After an active material is filled in an active material holder made of nickel foam, the active material Removal It is a front view which shows the state which welded the strip | belt-shaped metal plate to the electrode which formed the part.
FIG. 2 After filling an active material into an active material holder, a strip metal plate and an active material Quality It is a side view which shows the state which pressurizes the boundary part with a filling part.
3 is a front view showing a state in which the strip-shaped metal plate of the electrode of FIG. 1 is cut along the line XX. FIG.
[Fig.4] Strip metal plate and life Quality It is a side view before constituting the electrode group of Example 2 which shows the state which adds a protective material to this part and presses it in a spiral after pressing a boundary part with a filling part.
FIG. 5 is a side view before the electrode group of Comparative Example 1 is configured.
6 is a side view before the electrode group of Comparative Example 2 is configured. FIG.
FIG. 7 is a diagram showing a state in which the amount of warpage of an active material holder is measured.
FIG. 8 is a graph showing the relationship between the elongation at break of the belt-shaped metal plate and the amount of warpage of the active material holder.
FIG. 9 is a diagram showing the relationship between the Vickers hardness of the belt-shaped metal plate and the amount of warpage of the active material holder.
[Explanation of symbols]
DESCRIPTION OF

SYMBOLS

10,15,16 ... Strip | belt-shaped metal plate, 11 ... Semicircular notch part, 20 ... Nickel positive electrode plate, 21 ... Active material holding body, 22 ... Active material Removal Part, 30 ... negative electrode plate, 40 ... separator

Claims

An active material holder made of a porous metal body having a three-dimensional network structure is filled with a positive electrode active material mainly composed of nickel hydroxide to form a non-sintered nickel positive electrode, and then the nickel positive electrode and the negative electrode are separated from each other. A method for producing an alkaline storage battery in which an electrode group is formed by winding through
An adhering step of adhering a band-shaped metal plate to an active material removing portion at a longitudinal end portion of the active material holder of the nickel positive electrode;
A pressurizing step of pressurizing a boundary portion between the band-shaped metal plate fixed to the active material removal portion and the active material filling portion;
A manufacturing process for an alkaline storage battery, comprising: a winding step in which a boundary portion between the strip metal plate and the active material filling portion faces the negative electrode and the strip metal plate is wound outside. Method.

The band-shaped metal plate has a discontinuous circular cutout on only one side in the longitudinal direction, and is continuous to the active material holder so that the side having the cutout projects outward from the active material holder. The method for producing an alkaline storage battery according to claim 1 , further comprising a cutting step of cutting the notched portion in a longitudinal direction after the fixing.

3. The method for producing an alkaline storage battery according to claim 1 , wherein the elongation at break of the strip-shaped metal plate having the discontinuous circular cutout is 10 to 30%. 4.

The method for producing an alkaline storage battery according to any one of claims 1 to 3 , further comprising a step of adding a corrosion-resistant protective material to a boundary portion between the band-shaped metal plate and the active material filling portion.

The method for producing an alkaline storage battery according to any one of claims 1 to 4 , wherein the band-shaped metal plate is selected from materials having a Vickers hardness of 110 or less.