JP4326121B2

JP4326121B2 - Alkaline storage battery

Info

Publication number: JP4326121B2
Application number: JP2000173695A
Authority: JP
Inventors: 正夫武江; 功祐里口; 誠越智
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 2000-06-09
Filing date: 2000-06-09
Publication date: 2009-09-02
Anticipated expiration: 2020-06-09
Also published as: JP2001351673A

Description

【０００１】
【発明の属する技術分野】
本発明は、ニッケル−水素蓄電池やニッケル−カドミウム蓄電池などのアルカリ蓄電池に係り、特に、これらのアルカリ蓄電池に用いられる正極板と負極板とセパレータとからなる電極群の構造に関する。
【０００２】
【従来の技術】
ニッケル・水素蓄電池をはじめとするアルカリ蓄電池は、近年の市場拡大に伴って、電動工具、アシスト自転車、電気自動車等への用途が拡大し、大型化、高容量化、高出力化への需要、要望が高まった。
このような背景にあって、この種のアルカリ蓄電池において、種々の高出力化の検討が行われた。例えば、図４に示すように、電極群４０の上部に正極板４１に接続された正極集電体４４を溶接し、電極群４０の下部に負極板４２に接続された負極集電体４５を溶接するとともに、正極集電体４４を図示しない封口体の下部に溶接し、負極集電体４５を図示しない電池缶の内底部に溶接する構造が採用されるようになった。
【０００３】
ところで、電極群４０の上部に正極板４１に接続された正極集電体４４を溶接し、電極群４０の下部に負極板４２に接続された負極集電体４５を溶接する場合、正極板４１の端部と負極板４２の端部が同位置にあると、正極板４１と負極集電体４５あるいは負極板４２と正極集電体４４とが接触して、内部短絡を生じる恐れがある。このため、負極集電体４５と正極板４１との接触による短絡あるいは正極集電体４４と負極板４２との接触による短絡を防止する目的で、正極板４１に対して負極板４２を下側にずらして配置する構造となっている。
【０００４】
【発明が解決しようとする課題】
ところが、この種のアルカリ蓄電池に用いられる水酸化ニッケルを主正極活物質とする正極板は、充放電サイクルの進行に伴って水酸化ニッケルが高次化して膨潤し、膨潤した活物質が正極板よりせり出すようになるという現象を生じる。そして、上述のように正極板４１に対して負極板４２を下側にずらして配置すると、電極群４０の下部では負極板４２の一部に正極板４１と対向しない部分４２ｂが存在することとなる。
【０００５】
この結果、この負極板４２の正極板４１に対向しない部分４２ｂと正極板４１の下端部４１ｃとの間（図４の符号Ｚを参照）で充放電反応（この充放電反応を以下では回り込み反応という）が生じて、正極板４１の下端部４１ｃは活物質の膨潤によってせり出しを生じるという現象を生じた。
正極板４１の下端部４１ｃでの活物質の膨潤によってせり出しを生じると、やがては正極活物質の脱落によって、容量低下を引き起こしたり、場合によっては、負極集電体４５との短絡を引き起こすという問題を生じた。
【０００６】
そこで、本発明は上記問題点を解決するためになされたものであって、正極板に対して負極板をずらして配置しても、正極板が回り込み反応を起こさないような構造として、正極活物質の脱落による容量低下を防止するとともに、負極集電体との短絡を防止して、高容量で長寿命のアルカリ蓄電池が得られるようにすることを目的とするものである。
【０００７】
【課題を解決するための手段】
上記目的を達成するため、本発明のアルカリ蓄電池は、正極活物質が充填された正極板と負極活物質が充填された負極板とこれらを隔離するセパレータとからなる電極群を備え、電極群の下部に負極板に接続された負極集電体を備えている。そして、この電極群は正極板上部および負極板下部で正極板と負極板とが互いに対向しないようにずらして配置されており、正極板上部の負極板と対向しない部分には正極活物質が充填されている。そして、負極板下部の正極板と対向しない部分には負極活物質が充填されていないか、負極活物質が充填されている場合は当該負極活物質の表面に耐アルカリ性の保護膜が備えられているか、耐アルカリ性の樹脂が塗布されていて、正極板との充放電反応が阻害されるようにしている。
【０００８】
このように、負極板下部の正極板と対向しない部分には負極活物質が充填されていないと、正極板の下端部が回り込み反応を起こさないような構造となるため、正極活物質の脱落による容量低下が防止できて、負極集電体との短絡を防止することが可能となり、高容量で長寿命のアルカリ蓄電池が得られるようになる。
【０００９】
そして、負極板下部の正極板と対向しない部分に負極活物質が充填されている場合は当該負極活物質の表面に耐アルカリ性の保護膜が備えられているか、耐アルカリ性の樹脂が塗布されていると、保護膜あるいは塗布された樹脂は充放電反応を阻害するように作用するため、正極板の下端部が回り込み反応を起こすことが防止できるようになる。
【００１０】
【発明の実施の形態】
ついで、本発明の一実施の形態を図１〜図４に基づいて以下に説明する。なお、図１は本発明の実施例１の電極群の要部の一部を模式的に示す断面図であり、図２は本発明の実施例２の電極群の要部の一部を模式的に示す断面図であり、図３は本発明の実施例３の電極群の要部の一部を模式的に示す断面図であり、図４は比較例の電極群の要部の一部を模式的に示す断面図である。また、本発明は以下の実施の形態に限定されるものではなく、その要旨を変更しない範囲で適宜変更して実施することができる。
【００１１】
１．ニッケル正極板の作製
水酸化ニッケル粉末を９０質量部と、水酸化コバルト粉末を１０質量部と、酸化亜鉛粉末を３質量部とを添加混合した混合粉末に、結着剤としてのヒドロキシプロピルセルロース０．２質量％水溶液を５０質量部を添加混合して正極活物質スラリーを作製した。この正極活物質スラリーをニッケル発泡体（多孔度が約９５％で、目付が約６００ｇ／ｍ²のもの）からなる発泡ニッケル基板１１ａ，２１ａ，３１ａ，４１ａの空孔内にそれぞれ充填した後、乾燥させた。この後、所定の厚みにロール圧延した後、所定の形状に切断してニッケル正極板１１，２１，３１，４１をそれぞれ作製した。
【００１２】
なお、各ニッケル正極板１１，２１，３１，４１においては、発泡ニッケル基板１１ａ，２１ａ，３１ａ，４１ａの上部に充填された正極活物質を欠き落として、該部分を圧縮して高密度化した後、この高密度化した部分にニッケル箔（具体的には上端から約０．５ｍｍ幅）が溶着されており、後述する各正極集電体１４，２４，３４，４４との溶接部１１ｂ，２１ｂ，３１ｂ，４１ｂがそれぞれ形成されている。
【００１３】
２．水素吸蔵合金粉末の作製
ミツシュメタル（Ｍｍ：Ｌａ，Ｃｅ，Ｎｄ，Ｐｒ等の希土類元素を主成分とする化合物）と、ニッケルと、コバルトと、アルミニウムと、マンガンとを元素比で１．０：３．２：１．０：０．２：０．６に秤量して混合し、これをるつぼに入れて高周波溶解炉で溶融した後、冷却して、Ｍｍ_l.0Ｎｉ_3.2Ｃｏ_l.0Ａ１_0.2Ｍｎ_O.6の組成式で表される水素吸蔵合金を作製した。ついで、得られた水素吸蔵合金の鋳塊（インゴット）を、予め粗粉砕した後、不活性ガス中で平均粒径が約５０μｍになるように機械的に粉砕した。
【００１４】
３．水素吸蔵合金負極板の作製
（１）実施例１
ついで、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０．５質量％水溶液を１０質量部だけ添加混合して負極活物質スラリーを作製した。このように作製した負極活物質スラリーをパンチングメタル１２ａの両面に塗着し、乾燥した後、所定の厚みにロール圧延し、所定の形状に切断した。ついで、切断された極板の下端から約１．５ｍｍ幅の負極活物質を欠き落としてパンチングメタル１２ａの露出部１２ｂを形成して、実施例１の水素吸蔵合金負極板１２を作製した。なお、露出部１２ｂの下端部分（下端から約０．５ｍｍ幅の部分）１２ｃは後述する負極集電体１５との溶接部となる。
【００１５】
（２）実施例２
実施例１と同様に作製した負極活物質スラリーをパンチングメタル２２ａの両面に塗着し、乾燥した後、所定の厚みにロール圧延し、所定の形状に切断した。ついで、切断された極板の下端から約０．５ｍｍ幅だけ負極活物質を欠き落としてパンチングメタル２２ａの露出部２２ｃを形成した。ついで、露出部２２ｃの上端から上方に約１．０ｍｍ幅の耐アルカリ性のポリプロピレン製テープ（ＰＰテープ）２２ｂを負極活物質上に貼り付けて、充放電反応の阻害部を形成して、実施例２の水素吸蔵合金負極板２２を作製した。なお、パンチングメタル２２ａの露出部２２ｃ（約０．５ｍｍ幅の部分）は後述する負極集電体２５との溶接部となる。
【００１６】
（３）実施例３
実施例１と同様に作製した負極活物質スラリーをパンチングメタル３２ａの両面に塗着し、乾燥した後、所定の厚みにロール圧延し、所定の形状に切断した。ついで、切断された極板の下端から約０．５ｍｍ幅だけ負極活物質を欠き落としてパンチングメタル３２ａの露出部３２ｃを形成した。ついで、露出部３２ｃの上端から上方に約１．０ｍｍ幅だけに約８．０質量％のフッ素樹脂液（例えば、ＰＴＦＥ液）を塗布して、充放電反応の阻害部となるフッ素樹脂塗布部３２ｂを形成した後、乾燥させて実施例３の水素吸蔵合金負極板３２を作製した。なお、パンチングメタル３２ａの露出部３２ｃ（約０．５ｍｍ幅の部分）は後述する負極集電体３５との溶接部となる。
【００１７】
（４）比較例
実施例１と同様に作製した負極活物質スラリーをパンチングメタル４２ａの両面に塗着し、乾燥した後、所定の厚みにロール圧延し、所定の形状に切断した。ついで、切断された極板の下端から約０．５ｍｍ幅の負極活物質を欠き落としてパンチングメタル４２ａの露出部４２ｃを形成し、比較例の水素吸蔵合金負極板４２を作製した。なお、パンチングメタル４２ａの露出部４２ｃ（約０．５ｍｍ幅の部分）は後述する負極集電体４５との溶接部となる。
【００１８】
４．ニッケル−水素蓄電池の作製
（１）実施例１
上述のように作製したニッケル正極板１１と水素吸蔵合金負極板１２を用い、これらのニッケル正極板１１と水素吸蔵合金負極板１２が正極集電体１４および負極集電体１５の溶接時に短絡を生じないように、高さ方向に約１．５ｍｍだけずらすようにして配置した後、ポリオレフィン製不織布（例えば、ポリプロピレンおよびポリエチレンを主成分とし、厚みが約０．１５ｍｍで、目付が約６０ｇ／ｍ²のもの）からなるセパレータ１３を介して渦巻状に巻回して、渦巻状電極群１０を作製した。
【００１９】
ついで、正極板１１の溶接部１１ｂに正極集電体１４を溶接するとともに、負極板１２のパンチングメタル１２ａの露出部１２ｂの下端部分１２ｃに負極集電体１５を溶接して電極体とした後、この電極体を図示しない負極端子を兼ねる有底円筒形の金属外装缶（ＡＡサイズ）内に挿入した。ついで、負極集電体１５を金属外装缶の内底部に溶接するとともに、正極集電体１４を正極端子を兼ねる封口体に溶接した後、電解液（水酸化ナトリウム及び水酸化リチウムを含む水酸化カリウムを主体とした７ｍｏｌ／ｌのアルカリ水溶液）を金属外装缶内に注入した。ついで、封口体を絶縁ガスケットを介して金属外装缶の開口部に載置し、金属外装缶の開口を封口体側にかしめることにより開口部を封ロして、公称容量が１２００ｍＡｈの実施例１のニッケル−水素蓄電池Ａを作製した。
【００２０】
（２）実施例２
上述のように作製したニッケル正極板２１と水素吸蔵合金負極板２２を用い、これらのニッケル正極板２１と水素吸蔵合金負極板２２が正極集電体２４および負極集電体２５の溶接時に短絡を生じないように、高さ方向に約１．５ｍｍだけずらすようにして配置した後、ポリオレフィン製不織布（例えば、ポリプロピレンおよびポリエチレンを主成分とし、厚みが約０．１５ｍｍで、目付が約６０ｇ／ｍ２のもの）からなるセパレータ２３を介して渦巻状に巻回して、渦巻状電極群２０を作製した。
【００２１】
ついで、に正極板２１の溶接部２１ｂに正極集電体２４を溶接するとともに、負極板２２のパンチングメタル２２ａの露出部２２ｃに負極集電体２５を溶接して電極体とした後、この電極体を実施例１と同様に、金属外装缶（ＡＡサイズ）内に挿入し、負極集電体２５を金属外装缶の内底部に溶接するとともに、正極集電体２４を封口体に溶接した後、電解液を注入し、封口体を絶縁ガスケットを介して金属外装缶の開口部に載置し、金属外装缶の開口を封口体側にかしめることにより開口部を封ロして、公称容量が１２００ｍＡｈの実施例２のニッケル−水素蓄電池Ｂを作製した。
【００２２】
（３）実施例３
上述のように作製したニッケル正極板３１と水素吸蔵合金負極板３２を用い、これらのニッケル正極板３１と水素吸蔵合金負極板３２が正極集電体３４および負極集電体３５の溶接時に短絡を生じないように、高さ方向に約１．５ｍｍだけずらすようにして配置した後、ポリオレフィン製不織布（例えば、ポリプロピレンおよびポリエチレンを主成分とし、厚みが約０．１５ｍｍで、目付が約６０ｇ／ｍ２のもの）からなるセパレータ３３を介して渦巻状に巻回して、渦巻状電極群３０を作製した。
【００２３】
ついで、正極板３１の溶接部３１ｂに正極集電体３４を溶接するとともに、負極板３２のパンチングメタル３２ａの露出部３２ｃに負極集電体３５を溶接して電極体とした後、この電極体を実施例１と同様に、金属外装缶（ＡＡサイズ）内に挿入し、負極集電体３５を金属外装缶の内底部に溶接するとともに、正極集電体３４を封口体に溶接した後、電解液を注入し、封口体を絶縁ガスケットを介して金属外装缶の開口部に載置し、金属外装缶の開口を封口体側にかしめることにより開口部を封ロして、公称容量が１２００ｍＡｈの実施例３のニッケル−水素蓄電池Ｃを作製した。
【００２４】
（４）比較例
上述のように作製したニッケル正極板４１と水素吸蔵合金負極板４２を用い、これらのニッケル正極板４１と水素吸蔵合金負極板４２が正極集電体４４および負極集電体４５の溶接時に短絡を生じないように、高さ方向に約１．５ｍｍだけずらすようにして配置した後、ポリオレフィン製不織布（例えば、ポリプロピレンおよびポリエチレンを主成分とし、厚みが約０．１５ｍｍで、目付が約６０ｇ／ｍ２のもの）からなるセパレータ４３を介して渦巻状に巻回して、渦巻状電極群４０を作製した。
【００２５】
ついで、正極板４１の溶接部４１ｂに正極集電体４４を溶接するとともに、負極板４２のパンチングメタル４２ａの露出部４２ｃに負極集電体４５を溶接して電極体とした後、この電極体を実施例１と同様に、金属外装缶（ＡＡサイズ）内に挿入し、負極集電体４５を金属外装缶の内底部に溶接するとともに、正極集電体４４を封口体に溶接した後、電解液を注入し、封口体を絶縁ガスケットを介して金属外装缶の開口部に載置し、金属外装缶の開口を封口体側にかしめることにより開口部を封ロして、公称容量が１２００ｍＡｈの比較例のニッケル−水素蓄電池Ｘを作製した。
【００２６】
５．試験
（１）活性化処理
ついで、上述のようにして作製した各ニッケル−水素蓄電池Ａ，Ｂ，Ｃ，Ｘを用いて、室温（約２５℃）で１２０ｍＡ（０．１Ｃ）の充電電流で１６時間充電した後に１時間休止させ、その後、２４０ｍＡ（０．２Ｃ）の放電電流で放電終止電圧が１．０Ｖになるまで放電させた後に、１時間休止させるという充放電サイクルを３サイクル繰り返して、各ニッケル−水素蓄電池Ａ，Ｂ，Ｃ，Ｘを活性化した。
【００２７】
（２）充放電サイクル試験
ついで、上述のようにして活性化した各ニッケル−水素蓄電池Ａ，Ｘを用いて、室温（約２５℃）で、１．２Ａ（１Ｃ）の充電々流で充電を行い、充電末期の電池電圧のピーク値を記憶し、これを基準として一定値（１０ｍＶ）だけ電圧が低下した時点で充電を終了し、１時間休止した後、１．２Ａ（１Ｃ）の放電電流で電池電圧が１．０Ｖになるまで放電させ、１時間休止するという−ΔＶサイクル試験を行い、各充放電サイクル毎の放電容量を求めると、図５に示すような結果が得られた。
【００２８】
図５から明らかなように、負極板４２の正極板４１と対向しない部分４２ｂに負極活物質が充填されている比較例の電池Ｘは、数１０サイクル経過後に数％の容量低下が生じ、約３００サイクル経過した時点では初期容量の９０％程度の放電容量となり、３００サイクル以降での容量低下が顕著となり、約５５０サイクルで寿命（初期容量の６０％）となっていることが分かる。
一方、負極板１２の正極板１１と対向しない部分にパンチングメタル１２ａの露出部（負極活物質が充填されていない部分）１２ｂが形成された実施例１の電池Ａは、３００サイクル付近までは安定して初期容量が維持され、その後に放電容量が徐々に低下し、約７００サイクルで寿命となって、比較例の電池Ｘよりも充放電サイクル特性が優れていることが分かる。
【００２９】
ここで、寿命後の各ニッケル−水素蓄電池Ａ，Ｘを解体して調査した結果、比較例の電池Ｘは、電極群４０の正極板４１の下端部４１ｃで活物質が下側にせり出しており、また、外装缶の内底部に正極板４１から脱落した活物質が滞留していることが確認できた。一方、実施例１の電池Ａの正極板１１には下端部１１ｃに活物質のせり出しは見られず、外装缶の内底部にも脱落した活物質がほとんど認められなかった。
【００３０】
これらの事実を勘案すると、比較例の電池Ｘにおいては、負極板４２の正極板４１と対向しない部分４２ｂにも負極活物質が存在するため、正極板４１の下端部４１ｃに回り込み反応が生じて、正極活物質が膨潤して正極板４１の下端部４１ｃから下方にせり出し、この正極活物質がせり出した部分が大きくなって、やがては正極板４１から脱落して、充放電初期から容量が低下したと考えられる。一方、実施例１の電池Ａにおいては、負極板１２の正極板１１と対向しない部分（パンチングメタル１２ａの露出部１２ｂ）には負極活物質が存在しないため、正極板１１の下端部１１ｃでの回り込み反応が抑制されて、活物質のせり出しおよび脱落が抑制されたと考えられる。
【００３１】
（３）高率充放電サイクル試験
ついで、上述のようにして活性化した各ニッケル−水素蓄電池Ｂ，Ｃ，Ｘを用いて、室温（約２５℃）で、２．４Ａ（２Ｃ）の充電々流で高率充電を行い、充電末期の電池電圧のピーク値を記憶し、これを基準として一定値（５ｍＶ）だけ電圧が低下した時点で充電を終了し、１時間休止した後、４．８Ａ（４Ｃ）の放電電流で電池電圧が１．０Ｖになるまで高率放電させ、１時間休止するという−ΔＶサイクル試験を行い、各充放電サイクル毎の放電容量を求めると、図６に示すような結果が得られた。
【００３２】
図６から明らかなように、負極板４２の正極板４１と対向しない部分４２ｂに負極活物質が充填されている比較例の電池Ｘは、充放電の初期から徐々に容量低下が生じ、約２００サイクル経過した時点では初期容量の約８５％程度まで低下し、その後に全く充放電できなくなった。また、寿命（初期容量の６０％）に至った比較例の電池Ｘの開放電圧を測定すると０Ｖとなっていた。
一方、負極板２２の正極板２１と対向しない部分にＰＰテープ２２ｂを貼り付けた実施例２の電池Ｂ、および正極板３１と対向しない部分にフッ素樹脂塗布部３２ｂを形成した実施例３の電池Ｃは、共に２００サイクル付近までは安定して初期容量が維持され、その後に容量低下が徐々に始まり、いずれも約５００サイクルで寿命となっていることが分かる。
【００３３】
ここで、寿命に至った比較例の電池Ｘを解体して調査した結果、電極群４０の正極板４１の下端部４１ｃより下方にせり出した活物質と外装缶の内底部に脱落して滞留した活物質とが接触しているとともに、滞留した活物質が負極集電体４５に接触して、正極板４１と負極板４２とが短絡していることが確認できた。一方、実施例２の電池Ｂの正極板２１および実施例３の電池Ｃの正極板３１には活物質のせり出しは見られず、外装缶の内底部にも脱落した活物質がほとんど認められなかった。
【００３４】
これは、高率充放電試験は通常の充放電試験に比べて充放電電流が大きいために、正極活物質のせり出しおよび脱落への影響が大きくなったものと考えられ、その影響が大きい場合には短絡までに至ったと考えられる。一方、負極板２２の正極板２１と対向しない部分に、ＰＰテープ２２ｂを貼り付けた電池Ｂおよびフッ素樹脂塗布部３２ｂを形成した電池Ｃにおいては、正極板２１の下端部２１ｃあるいは正極板３１の下端部３１ｃでの回り込み反応が抑制されて、活物質のせり出しおよび脱落が抑制されたものと考えられる。
【００３５】
上述したように、本発明においては、負極板１２の正極板１１と対向しない部分（パンチングメタル１２ａの露出部１２ｂ）に負極活物質が充填されていないか、あるいは負極板２２（３２）の正極板２１（３１）と対向しない部分に、ＰＰテープ２２ｂを貼り付けたり、フッ素樹脂塗布部３２ｂを形成して充放電反応を阻害しているため、正極板１１（２１，３１）の下端部１１ｃ（２１ｃ，３１ｃ）での回り込み反応が起こらないような構造となり、正極活物質の脱落による容量低下が防止できて、負極集電体１５（２５，３５）との短絡を防止することが可能となって、高容量で、長寿命のアルカリ蓄電池が得られるようになる。
【００３６】
なお、上述した実施形態においては、発泡ニッケルに正極活物質を充填した正極板を用いる例について説明したが、ニッケルメッシュなどの基材に正極活物質を充填した正極板、あるいはパンチングメタル、エキスパンドメタル等の芯材に正極活物質を塗着した正極板を用いるようにしてもよい。
また、上述した実施形態においては、パンチングメタルに負極活物質を塗着した負極板を用いる例について説明したが、エキスパンドメタル等の芯材に負極活物質を塗着した負極板、あるいは発泡ニッケルやニッケルメッシュ等の基材に負極活物質を充填した負極板を用いるようにしてもよい。
さらに、上述した実施形態においては、本発明をニッケル−水素蓄電池に適用する例について説明したが、本発明のアルカリ蓄電池として、ニッケル−カドミウム蓄電池に適用してもほぼ同様である。
【図面の簡単な説明】
【図１】本発明の実施例１の電極群の要部の一部を模式的に示す断面図である。
【図２】本発明の実施例２の電極群の要部の一部を模式的に示す断面図である。
【図３】本発明の実施例３の電極群の要部の一部を模式的に示す断面図である。
【図４】従来例（比較例）の電極群の要部の一部を模式的に示す断面図である。
【図５】充放電サイクルに対する放電容量の関係を示す図である。
【図６】高率充放電サイクルに対する放電容量の関係を示す図である。
【符号の説明】
１０，２０，３０，４０…電極群、１１，２１，３１，４１…正極板、１１ａ，２１ａ，３１ａ，４１ａ…発泡ニッケル基板（多孔性基板）、１１ｂ，２１ｂ，３１ｂ，４１ｂ…正極集電体との溶接部、１１ｃ，２１ｃ，３１ｃ，４１ｃ…正極板の下端部、１２，２２，３２，４２…負極板、１２ａ，２２ａ，３２ａ，４２ａ…パンチングメタル（多孔性基板）、１３，２３，３３，４３…セパレータ、１４，２４，３４，４４…正極集電体、１５，２５，３５，４５…負極集電体、１２ｂ…パンチングメタルの露出部（活物質が充填されていない部分）、２２ｂ…ポリプロピレン製テープ、３２ｂ…フッ素樹脂塗布部、４２ｂ…負極板の正極板に対向しない部分[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 a structure of an electrode group including a positive electrode plate, a negative electrode plate, and a separator used in these alkaline storage batteries.
[0002]
[Prior art]
Alkaline storage batteries such as nickel-hydrogen storage batteries have been used in power tools, assist bicycles, electric vehicles, etc. as the market has expanded in recent years, and demand for larger size, higher capacity, higher output, The demand increased.
Against this background, various kinds of high output have been studied for this type of alkaline storage battery. For example, as shown in FIG. 4, a positive electrode current collector 44 connected to the positive electrode plate 41 is welded to the upper part of the electrode group 40, and a negative electrode current collector 45 connected to the negative electrode plate 42 is attached to the lower part of the electrode group 40. In addition to welding, a structure in which the positive electrode current collector 44 is welded to a lower portion of a sealing body (not shown) and the negative electrode current collector 45 is welded to an inner bottom portion of a battery can (not shown) has been adopted.
[0003]
By the way, when the positive electrode current collector 44 connected to the positive electrode plate 41 is welded to the upper part of the electrode group 40 and the negative electrode current collector 45 connected to the negative electrode plate 42 is welded to the lower part of the electrode group 40, If the end of the negative electrode 42 and the end of the negative electrode plate 42 are in the same position, the positive electrode plate 41 and the negative electrode current collector 45 or the negative electrode plate 42 and the positive electrode current collector 44 may come into contact with each other, thereby causing an internal short circuit. Therefore, for the purpose of preventing a short circuit due to contact between the negative electrode current collector 45 and the positive electrode plate 41 or a short circuit due to contact between the positive electrode current collector 44 and the negative electrode plate 42, the negative electrode plate 42 is placed below the positive electrode plate 41. It has a structure that is shifted and arranged.
[0004]
[Problems to be solved by the invention]
However, the positive electrode plate using nickel hydroxide as the main positive electrode active material used in this type of alkaline storage battery has a higher level of nickel hydroxide and swells as the charge / discharge cycle progresses. This causes a phenomenon of becoming more protruding. When the negative electrode plate 42 is shifted downward with respect to the positive electrode plate 41 as described above, a portion 42 b that does not face the positive electrode plate 41 exists in a part of the negative electrode plate 42 below the electrode group 40. Become.
[0005]
As a result, a charge / discharge reaction (this charge / discharge reaction is referred to as a wraparound reaction below) between the portion 42b of the negative electrode plate 42 that does not oppose the positive electrode plate 41 and the lower end portion 41c of the positive electrode plate 41 (see symbol Z in FIG. 4). And the lower end portion 41c of the positive electrode plate 41 is caused to protrude due to swelling of the active material.
When protrusion occurs due to the swelling of the active material at the lower end portion 41c of the positive electrode plate 41, the capacity of the positive electrode active material may eventually drop, resulting in a decrease in capacity or, in some cases, a short circuit with the negative electrode current collector 45. Produced.
[0006]
Accordingly, the present invention has been made to solve the above-described problems, and has a structure in which the positive electrode plate does not cause a wraparound reaction even when the negative electrode plate is shifted from the positive electrode plate. An object of the present invention is to prevent a decrease in capacity due to dropping of a substance and to prevent a short circuit with a negative electrode current collector so that a high-capacity and long-life alkaline storage battery can be obtained.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an alkaline storage battery of the present invention comprises an electrode group consisting of a positive electrode plate filled with a positive electrode active material, a negative electrode plate filled with a negative electrode active material, and a separator separating them . A negative electrode current collector connected to the negative electrode plate is provided at the bottom. Then, the electrode group are staggered such that the positive and negative electrode plates in the positive electrode plate upper and the negative electrode plate bottom do not face each other, the positive electrode active material is filled in the negative electrode plate not facing the portion of the positive electrode plate upper Has been. Then, either the negative electrode active material in the positive electrode plate not facing the portion of the lower negative electrode plate are not filled, with a protective film on the surface in alkali resistance of the negative electrode active material is provided in the case where the anode active material is filled Or an alkali-resistant resin is applied so that the charge / discharge reaction with the positive electrode plate is inhibited.
[0008]
Thus, when the negative electrode active material in the positive electrode plate not facing the portion of the lower negative electrode plate are not filled, since a structure such as the lower end portion of the positive electrode plate does not cause wraparound reaction, by falling of the positive electrode active material The capacity can be prevented from decreasing, and a short circuit with the negative electrode current collector can be prevented, so that an alkaline storage battery having a high capacity and a long life can be obtained.
[0009]
Then, either the protective film on the surface in alkali resistance of the anode active material is provided, the alkali resistance of the resin that has been applied if the anode active material is filled in the positive electrode plate not facing the portion of the lower negative electrode plate Since the protective film or the applied resin acts to inhibit the charge / discharge reaction, the lower end portion of the positive electrode plate can be prevented from wrapping around and causing a reaction .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described below with reference to FIGS. 1 is a cross-sectional view schematically showing a part of the main part of the electrode group of Example 1 of the present invention, and FIG. 2 is a schematic part of the main part of the electrode group of Example 2 of the present invention. FIG. 3 is a sectional view schematically showing a part of the main part of the electrode group of Example 3 of the present invention, and FIG. 4 is a part of the main part of the electrode group of the comparative example. It is sectional drawing which shows this typically. Further, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within a range not changing the gist thereof.
[0011]
1. Preparation of Nickel Positive Electrode Plate Hydroxypropylcellulose 0 as a binder to a mixed powder obtained by adding 90 parts by mass of nickel hydroxide powder, 10 parts by mass of cobalt hydroxide powder, and 3 parts by mass of zinc oxide powder. A positive electrode active material slurry was prepared by adding and mixing 50 parts by mass of a 2 mass% aqueous solution. After filling this positive electrode active material slurry into the pores of the foamed nickel substrates 11a, 21a, 31a, 41a made of nickel foam (having a porosity of about 95% and a basis weight of about 600 g / m ² ), Dried. Then, after rolling to predetermined thickness, it cut | disconnected to the predetermined shape and produced the nickel positive electrode plates 11, 21, 31, and 41, respectively.
[0012]
In each of the nickel positive plates 11, 21, 31, and 41, the positive electrode active material filled in the upper portions of the foamed nickel substrates 11a, 21a, 31a, and 41a is cut off, and the portions are compressed and densified. Thereafter, a nickel foil (specifically, about 0.5 mm width from the upper end) is welded to the densified portion, and a welded portion 11b with each of the positive electrode current collectors 14, 24, 34, 44 described later, 21b, 31b, and 41b are formed, respectively.
[0013]
2. Preparation of hydrogen storage alloy powder 1.0: 3 in an element ratio of Mitsmetal (Mm: a compound mainly composed of rare earth elements such as La, Ce, Nd, and Pr), nickel, cobalt, aluminum, and manganese. .2: 1.0: 0.2: 0.6 were weighed and mixed, placed in a crucible, melted in a high-frequency melting furnace, cooled, and then cooled to Mm _1.0 Ni _3.2 Co _1.0 A1. A hydrogen storage alloy represented by a composition formula of _0.2 Mn _O.6 was produced. Subsequently, the obtained ingot of the hydrogen storage alloy was coarsely pulverized in advance, and then mechanically pulverized in an inert gas so that the average particle diameter was about 50 μm.
[0014]
3. Preparation of hydrogen storage alloy negative electrode plate (1) Example 1
Next, 10 parts by mass of a 0.5% by weight aqueous solution of polyethylene oxide as a binder was added to and mixed with the pulverized hydrogen storage alloy powder to prepare a negative electrode active material slurry. The negative electrode active material slurry thus produced was applied to both sides of the punching metal 12a, dried, and then roll-rolled to a predetermined thickness and cut into a predetermined shape. Next, a negative electrode active material having a width of about 1.5 mm was cut off from the lower end of the cut electrode plate to form an exposed portion 12b of the punching metal 12a, and the hydrogen storage alloy negative electrode plate 12 of Example 1 was produced. Note that a lower end portion (a portion having a width of about 0.5 mm from the lower end) 12c of the exposed portion 12b is a welded portion to the negative electrode current collector 15 described later.
[0015]
(2) Example 2
The negative electrode active material slurry produced in the same manner as in Example 1 was applied to both sides of the punching metal 22a, dried, roll-rolled to a predetermined thickness, and cut into a predetermined shape. Subsequently, the exposed portion 22c of the punching metal 22a was formed by cutting off the negative electrode active material by a width of about 0.5 mm from the lower end of the cut electrode plate. Next, an alkali-resistant polypropylene tape (PP tape) 22b having a width of about 1.0 mm is pasted on the negative electrode active material upward from the upper end of the exposed portion 22c to form a charge / discharge reaction inhibiting portion. 2 hydrogen storage alloy negative electrode plate 22 was produced. The exposed portion 22c (a portion having a width of about 0.5 mm) of the punching metal 22a is a welded portion with the negative electrode current collector 25 described later.
[0016]
(3) Example 3
The negative electrode active material slurry produced in the same manner as in Example 1 was applied to both sides of the punching metal 32a, dried, and then roll-rolled to a predetermined thickness and cut into a predetermined shape. Subsequently, the exposed portion 32c of the punching metal 32a was formed by removing the negative electrode active material by a width of about 0.5 mm from the lower end of the cut electrode plate. Next, a fluororesin application portion that serves as an inhibition portion of the charge / discharge reaction is applied by applying an approximately 8.0 mass% fluororesin liquid (for example, PTFE solution) only to a width of about 1.0 mm upward from the upper end of the exposed portion 32c. After forming 32b, it was made to dry and the hydrogen storage alloy negative electrode plate 32 of Example 3 was produced. The exposed portion 32c (a portion having a width of about 0.5 mm) of the punching metal 32a serves as a welded portion with the negative electrode current collector 35 described later.
[0017]
(4) Comparative Example A negative electrode active material slurry produced in the same manner as in Example 1 was applied to both sides of the punching metal 42a, dried, and then roll-rolled to a predetermined thickness and cut into a predetermined shape. Next, an exposed portion 42c of the punching metal 42a was formed by cutting off the negative electrode active material having a width of about 0.5 mm from the lower end of the cut electrode plate, and a hydrogen storage alloy negative electrode plate 42 of a comparative example was produced. The exposed portion 42c (a portion having a width of about 0.5 mm) of the punching metal 42a becomes a welded portion with a negative electrode current collector 45 described later.
[0018]
4). Preparation of nickel-hydrogen storage battery (1) Example 1
Using the nickel positive electrode plate 11 and the hydrogen storage alloy negative electrode plate 12 produced as described above, the nickel positive electrode plate 11 and the hydrogen storage alloy negative electrode plate 12 are short-circuited when the positive electrode current collector 14 and the negative electrode current collector 15 are welded. After being arranged so as to be shifted by about 1.5 mm in the height direction so as not to occur, a polyolefin non-woven fabric (for example, having polypropylene and polyethylene as main components, a thickness of about 0.15 mm, and a basis weight of about 60 g / m) ² ) to form a spiral electrode group 10 by spirally winding the separator.
[0019]
Next, the positive electrode current collector 14 is welded to the welded portion 11b of the positive electrode plate 11, and the negative electrode current collector 15 is welded to the lower end portion 12c of the exposed portion 12b of the punching metal 12a of the negative electrode plate 12 to obtain an electrode body. The electrode body was inserted into a bottomed cylindrical metal outer can (AA size) that also served as a negative electrode terminal (not shown). Next, the negative electrode current collector 15 is welded to the inner bottom portion of the metal outer can, and the positive electrode current collector 14 is welded to a sealing body that also serves as a positive electrode terminal, and then an electrolyte solution (hydroxide containing sodium hydroxide and lithium hydroxide). 7 mol / l alkaline aqueous solution mainly composed of potassium) was injected into the metal outer can. Next, the sealing body is placed on the opening of the metal outer can through an insulating gasket, and the opening of the metal outer can is caulked toward the sealing body to seal the opening, and the nominal capacity is 1200 mAh. Nickel-hydrogen storage battery A was prepared.
[0020]
(2) Example 2
Using the nickel positive electrode plate 21 and the hydrogen storage alloy negative electrode plate 22 produced as described above, the nickel positive electrode plate 21 and the hydrogen storage alloy negative electrode plate 22 are short-circuited when the positive electrode current collector 24 and the negative electrode current collector 25 are welded. After being arranged so as to be shifted by about 1.5 mm in the height direction so as not to occur, a non-woven fabric made of polyolefin (for example, polypropylene and polyethylene as main components, a thickness of about 0.15 mm, and a basis weight of about 60 g / m 2) The spiral electrode group 20 was produced by spirally winding it through a separator 23 made of
[0021]
Next, the positive electrode current collector 24 is welded to the welded portion 21b of the positive electrode plate 21, and the negative electrode current collector 25 is welded to the exposed portion 22c of the punching metal 22a of the negative electrode plate 22 to form an electrode body. After the body was inserted into the metal outer can (AA size) as in Example 1, the negative electrode current collector 25 was welded to the inner bottom of the metal outer can, and the positive electrode current collector 24 was welded to the sealing body The electrolyte is injected, the sealing body is placed on the opening of the metal outer can through the insulating gasket, and the opening of the metal outer can is caulked toward the sealing body to seal the opening, so that the nominal capacity is A nickel-hydrogen storage battery B of Example 2 with 1200 mAh was produced.
[0022]
(3) Example 3
Using the nickel positive electrode plate 31 and the hydrogen storage alloy negative electrode plate 32 produced as described above, the nickel positive electrode plate 31 and the hydrogen storage alloy negative electrode plate 32 are short-circuited when the positive electrode current collector 34 and the negative electrode current collector 35 are welded. After being arranged so as to be shifted by about 1.5 mm in the height direction so as not to occur, a non-woven fabric made of polyolefin (for example, polypropylene and polyethylene as main components, a thickness of about 0.15 mm, and a basis weight of about 60 g / m 2) A spiral electrode group 30 was produced by spirally winding the separator 33.
[0023]
Next, the positive electrode current collector 34 is welded to the welded portion 31b of the positive electrode plate 31, and the negative electrode current collector 35 is welded to the exposed portion 32c of the punching metal 32a of the negative electrode plate 32 to obtain an electrode body. In the same manner as in Example 1, after being inserted into a metal outer can (AA size) and welding the negative electrode current collector 35 to the inner bottom of the metal outer can, and welding the positive electrode current collector 34 to the sealing body, The electrolyte is injected, the sealing body is placed on the opening of the metal outer can through an insulating gasket, and the opening is sealed by caulking the opening of the metal outer can toward the sealing body, so that the nominal capacity is 1200 mAh. A nickel-hydrogen storage battery C of Example 3 was prepared.
[0024]
(4) Comparative Example Using the nickel positive electrode plate 41 and the hydrogen storage alloy negative electrode plate 42 produced as described above, the nickel positive electrode plate 41 and the hydrogen storage alloy negative electrode plate 42 are formed as the positive electrode current collector 44 and the negative electrode current collector 45. In order not to cause a short circuit during welding, a polyolefin non-woven fabric (for example, polypropylene and polyethylene as main components, with a thickness of about 0.15 mm and a basis weight of about 1.5 mm is disposed. Is spirally wound through a separator 43 made of about 60 g / m 2) to produce a spiral electrode group 40.
[0025]
Next, the positive electrode current collector 44 is welded to the welded portion 41b of the positive electrode plate 41, and the negative electrode current collector 45 is welded to the exposed portion 42c of the punching metal 42a of the negative electrode plate 42 to form an electrode body. In the same manner as in Example 1, after being inserted into a metal outer can (AA size) and welding the negative electrode current collector 45 to the inner bottom of the metal outer can, and welding the positive electrode current collector 44 to the sealing body, The electrolyte is injected, the sealing body is placed on the opening of the metal outer can through an insulating gasket, and the opening is sealed by caulking the opening of the metal outer can toward the sealing body, so that the nominal capacity is 1200 mAh. The nickel-hydrogen storage battery X of the comparative example was prepared.
[0026]
5. Test (1) Activation Treatment Next, using each of the nickel-hydrogen batteries A, B, C, and X produced as described above, a charge current of 120 mA (0.1 C) at room temperature (about 25 ° C.) 16 After charging for 1 hour, the battery is paused for 1 hour, and then discharged at 240 mA (0.2 C) until the end-of-discharge voltage reaches 1.0 V, and then repeated for 3 cycles of charge / discharge cycles of resting for 1 hour, Each nickel-hydrogen storage battery A, B, C, X was activated.
[0027]
(2) Charging / discharging cycle test Next, using the nickel-hydrogen storage batteries A and X activated as described above, charging was performed at a room temperature (about 25 ° C.) with a charging current of 1.2 A (1 C). And the peak value of the battery voltage at the end of charging is stored, and when the voltage drops by a constant value (10 mV) with reference to this, charging is terminated, and after resting for 1 hour, the discharge current of 1.2 A (1 C) The battery was discharged until the battery voltage reached 1.0 V, and a −ΔV cycle test was performed in which the battery was paused for 1 hour, and the discharge capacity for each charge / discharge cycle was determined. The result shown in FIG. 5 was obtained.
[0028]
As is apparent from FIG. 5, the battery X of the comparative example in which the portion 42b of the negative electrode plate 42 not facing the positive electrode plate 41 is filled with the negative electrode active material has a capacity drop of several percent after several tens of cycles. When 300 cycles have elapsed, the discharge capacity is about 90% of the initial capacity, and the capacity decrease after 300 cycles becomes remarkable, and it can be seen that the life (60% of the initial capacity) is reached at about 550 cycles.
On the other hand, the battery A of Example 1 in which the exposed portion (the portion not filled with the negative electrode active material) 12b of the punching metal 12a is formed in the portion of the negative electrode plate 12 that does not face the positive electrode plate 11 is stable up to about 300 cycles. Thus, the initial capacity is maintained, after which the discharge capacity gradually decreases, and the life is reached in about 700 cycles, indicating that the charge / discharge cycle characteristics are superior to the battery X of the comparative example.
[0029]
Here, as a result of disassembling and investigating each of the nickel-hydrogen storage batteries A and X after the life, in the battery X of the comparative example, the active material protrudes downward at the lower end portion 41c of the positive electrode plate 41 of the electrode group 40. In addition, it was confirmed that the active material dropped from the positive electrode plate 41 was retained in the inner bottom portion of the outer can. On the other hand, in the positive electrode plate 11 of the battery A of Example 1, no protruding active material was observed at the lower end portion 11c, and almost no active material dropped off at the inner bottom of the outer can.
[0030]
Considering these facts, in the battery X of the comparative example, since the negative electrode active material is also present in the portion 42b of the negative electrode plate 42 that does not face the positive electrode plate 41, a wraparound reaction occurs in the lower end portion 41c of the positive electrode plate 41. The positive electrode active material swells and protrudes downward from the lower end portion 41c of the positive electrode plate 41, and the portion where the positive electrode active material protrudes increases, eventually falling off from the positive electrode plate 41 and the capacity decreasing from the beginning of charge and discharge. It is thought that. On the other hand, in the battery A of Example 1, since the negative electrode active material does not exist in the portion of the negative electrode plate 12 that does not face the positive electrode plate 11 (exposed portion 12b of the punching metal 12a), the lower end portion 11c of the positive electrode plate 11 It is considered that the wraparound reaction was suppressed and the protrusion and dropping of the active material were suppressed.
[0031]
(3) High-rate charge / discharge cycle test Next, 2.4 A (2 C) is charged at room temperature (about 25 ° C.) using the nickel-hydrogen storage batteries B, C, and X activated as described above. The battery is charged at a high rate, and the peak value of the battery voltage at the end of charging is memorized. When the voltage drops by a constant value (5 mV) with reference to this, charging is terminated, and after suspending for 1 hour, 4.8 A When the discharge capacity of each charge / discharge cycle is determined by performing a -ΔV cycle test in which a high-rate discharge is performed until the battery voltage reaches 1.0 V with the discharge current of (4C) and the discharge is stopped for 1 hour, the discharge capacity for each charge / discharge cycle is obtained as shown in FIG. Results were obtained.
[0032]
As is clear from FIG. 6, in the battery X of the comparative example in which the portion 42b of the negative electrode plate 42 not facing the positive electrode plate 41 is filled with the negative electrode active material, the capacity is gradually reduced from the initial stage of charge / discharge. At the time when the cycle passed, the capacity dropped to about 85% of the initial capacity, and after that, charging / discharging was impossible at all. Moreover, when the open circuit voltage of the battery X of the comparative example which reached the lifetime (60% of the initial capacity) was measured, it was 0V.
On the other hand, the battery B of Example 2 in which the PP tape 22b was pasted on the portion of the negative electrode plate 22 not facing the positive electrode plate 21, and the battery of Example 3 in which the fluororesin coating portion 32b was formed on the portion not facing the positive electrode plate 31. It can be seen that the initial capacity of C is stably maintained up to around 200 cycles, and thereafter, the capacity starts gradually decreasing, and both have a lifetime of about 500 cycles.
[0033]
Here, as a result of disassembling and investigating the battery X of the comparative example that reached the end of life, the active material protruding downward from the lower end portion 41c of the positive electrode plate 41 of the electrode group 40 and the inner bottom portion of the outer can dropped and stayed. While the active material was in contact, it was confirmed that the staying active material was in contact with the negative electrode current collector 45 and the positive electrode plate 41 and the negative electrode plate 42 were short-circuited. On the other hand, no positive active material was seen on the positive electrode plate 21 of the battery B of Example 2 and the positive electrode plate 31 of the battery C of Example 3, and almost no fallen active material was observed at the inner bottom of the outer can. It was.
[0034]
This is because the charge / discharge current of the high rate charge / discharge test is larger than that of the normal charge / discharge test. Is thought to have led to a short circuit. On the other hand, in the battery B in which the PP tape 22b is attached to the portion of the negative electrode plate 22 that does not face the positive electrode plate 21 and in the battery C in which the fluororesin coating portion 32b is formed, the lower end portion 21c of the positive electrode plate 21 or the positive electrode plate 31 It is considered that the wraparound reaction at the lower end 31c is suppressed, and the protrusion and dropping of the active material are suppressed.
[0035]
As described above, in the present invention, the portion of the negative electrode plate 12 not facing the positive electrode plate 11 (exposed portion 12b of the punching metal 12a) is not filled with the negative electrode active material, or the positive electrode of the negative electrode plate 22 (32). Since the PP tape 22b is affixed to the portion not facing the plate 21 (31) or the fluororesin coating portion 32b is formed to inhibit the charge / discharge reaction, the lower end portion 11c of the positive electrode plate 11 (21, 31). (21c, 31c) has a structure that does not cause a wraparound reaction, can prevent a decrease in capacity due to the dropout of the positive electrode active material, and can prevent a short circuit with the negative electrode current collector 15 (25, 35). Thus, a high-capacity and long-life alkaline storage battery can be obtained.
[0036]
In the embodiment described above, an example in which a positive electrode plate in which foamed nickel is filled with a positive electrode active material has been described. However, a positive electrode plate in which a base material such as a nickel mesh is filled with a positive electrode active material, punching metal, or expanded metal. A positive electrode plate in which a positive electrode active material is coated on a core material such as the above may be used.
In the embodiment described above, an example of using a negative electrode plate in which a negative electrode active material is applied to punching metal has been described. However, a negative electrode plate in which a negative electrode active material is applied to a core material such as expanded metal, or nickel foam or You may make it use the negative electrode plate which filled base materials, such as a nickel mesh, with the negative electrode active material.
Furthermore, in the above-described embodiment, an example in which the present invention is applied to a nickel-hydrogen storage battery has been described. However, even if the present invention is applied to a nickel-cadmium storage battery, the alkaline storage battery is substantially the same.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing a part of an essential part of an electrode group of Example 1 of the present invention.
FIG. 2 is a cross-sectional view schematically showing a part of an essential part of an electrode group of Example 2 of the present invention.
FIG. 3 is a cross-sectional view schematically showing a part of an essential part of an electrode group of Example 3 of the present invention.
FIG. 4 is a cross-sectional view schematically showing a part of the main part of an electrode group of a conventional example (comparative example).
FIG. 5 is a diagram showing a relationship of a discharge capacity with respect to a charge / discharge cycle.
FIG. 6 is a diagram showing a relationship of discharge capacity with respect to a high rate charge / discharge cycle.
[Explanation of symbols]
10, 20, 30, 40 ... electrode group, 11, 21, 31, 41 ... positive electrode plate, 11a, 21a, 31a, 41a ... nickel foam substrate (porous substrate), 11b, 21b, 31b, 41b ... positive electrode current collector 11c, 21c, 31c, 41c ... lower end of positive plate, 12, 22, 32, 42 ... negative plate, 12a, 22a, 32a, 42a ... punching metal (porous substrate), 13, 23 , 33, 43 ... separator, 14, 24, 34, 44 ... positive electrode current collector, 15, 25, 35, 45 ... negative electrode current collector, 12b ... exposed portion of punching metal (portion not filled with active material) , 22b ... polypropylene tape, 32b ... fluororesin coating part, 42b ... part of the negative electrode plate not facing the positive electrode plate

Claims

A positive electrode plate in which a porous substrate is filled with a positive electrode active material mainly composed of nickel hydroxide, a negative electrode plate in which the porous substrate is filled with a negative electrode active material, and a separator for separating them are provided. And an alkaline storage battery comprising a negative electrode current collector connected to the negative electrode plate at the bottom of the electrode group,
The electrode group is arranged so that the positive electrode plate and the negative electrode plate are not opposed to each other at the upper part of the positive electrode plate and the lower part of the negative electrode plate ,
Wherein the positive electrode plate and the negative electrode plate not facing the portion of the top and the cathode active material is filled, wherein the negative electrode plate The negative electrode active material in the positive electrode plate not facing the portion of the lower has not been filled Alkaline storage battery.

A positive electrode plate in which a porous substrate is filled with a positive electrode active material mainly composed of nickel hydroxide, a negative electrode plate in which the porous substrate is filled with a negative electrode active material, and a separator for separating them are provided. And an alkaline storage battery comprising a negative electrode current collector connected to the negative electrode plate at the bottom of the electrode group,
The electrode group is arranged so that the positive electrode plate and the negative electrode plate are not opposed to each other at the upper part of the positive electrode plate and the lower part of the negative electrode plate ,
A portion of the upper portion of the positive electrode plate that does not face the negative electrode plate is filled with a positive electrode active material, and a portion of the lower portion of the negative electrode plate that does not face the positive electrode plate is filled with a negative electrode active material. An alkaline storage battery characterized in that an alkali-resistant protective film is provided on the surface of a substance to inhibit a charge / discharge reaction with the positive electrode plate.

A positive electrode plate in which a porous substrate is filled with a positive electrode active material mainly composed of nickel hydroxide, a negative electrode plate in which the porous substrate is filled with a negative electrode active material, and a separator for separating them are provided. And an alkaline storage battery comprising a negative electrode current collector connected to the negative electrode plate at the bottom of the electrode group,
The electrode group is arranged so that the positive electrode plate and the negative electrode plate are not opposed to each other at the upper part of the positive electrode plate and the lower part of the negative electrode plate ,
A portion of the upper portion of the positive electrode plate that does not face the negative electrode plate is filled with a positive electrode active material, and a portion of the lower portion of the negative electrode plate that does not face the positive electrode plate is filled with a negative electrode active material. An alkaline storage battery, wherein a surface of a substance is coated with an alkali-resistant resin to inhibit a charge / discharge reaction with the positive electrode plate.