JP4235805B2

JP4235805B2 - Cylindrical nickel metal hydride storage battery and battery module using the same

Info

Publication number: JP4235805B2
Application number: JP2003192397A
Authority: JP
Inventors: 隆伊藤; 俊樹田中; 知徳岸本; 禎弘片山
Original assignee: GS Yuasa Corp
Current assignee: GS Yuasa Corp
Priority date: 2003-07-04
Filing date: 2003-07-04
Publication date: 2009-03-11
Anticipated expiration: 2023-07-04
Also published as: JP2005026163A

Description

【０００１】
【発明の属する利用分野】
本発明は、捲回式極板群を備える円筒形ニッケル水素蓄電池および該ニッケル水素蓄電池を複数個シリーズ接続した電池モジュールに関するものである。
【０００２】
【従来の技術】
正極にニッケル電極を、負極に水素吸蔵合金電極を用いた密閉形ニッケル水素蓄電池は、充放電サイクル性能、耐過充電性、耐過放電性に優れているなど、長期使用に耐え、取り扱いが簡便であるところから用途が拡大しつつある。中でもハイブリッド電気自動車（HEV）用電源としての適正が高く該用途の需要拡大が見込まれている。
【０００３】
HEV用電源には１４０〜２８０Ｖの電圧と最大で１５〜３０ｋｗの負荷を満たす出力、３〜４Ａｈの放電容量が要求される。また、HEVの走行性能を確保するために電源である電池に対して小形で軽量であることが要求され、重量エネルギー密度Ｗｈ／ｋｇを例にとれば７５０ｗｈ／ｋｇ以上であることが望ましいとされる。また、４５Ｗｈ／ｋｇ以上のエネルギー密度を有することが望ましいとされる。
【０００４】
前記HEV用電源に要求される電圧、最大負荷を満たすため、従来の２８０Ｖ系のHEVの電源には容量が約８Ａｈの単一サイズの円筒形ニッケル水素蓄電池（以下複数の円筒形蓄電池を組み合わせた電池モジュールや複数の電池モジュールを組み合わせた組電池との区別を明確にする意味で単電池と記述する）約２４０個をシリーズに接続した組電池が適用されている。通常６個の単電池を接続リングを介してシリーズに接続して電圧が７．２Ｖの電池モジュールを構成し（例えば特許文献１参照）、該電池モジュールを４０本シリーズに接続して全体としての組電池を構成している。
【０００５】
【特許文献１】
特開平１０−１０６５３３号公報（図１、図３）
【０００６】
前記従来からHEV用電源に適用されている単一サイズの単電池においては、厚さが０．５〜０．６ｍｍ、短辺の長さが約５１ｍｍ、長辺と短辺の長さの比が約１１の矩形状の正極板を適用している。該従来から適用されている単一サイズの単電池を適用した組電池は、HEV用電源としては出力特性が低いという欠点があった。
【０００７】
前記のように、HEV用電源には例えば前記のように容量が３〜４Ａｈあれば十分なのに対して、従来の単一サイズの円筒形単電池を適用した組電池は、電池の容量が約８Ａｈと大過剰であり、容量を大きくした分電池の占める容積や重量が大きくなるので好ましいことでは無いが、HEV用電源に要求される最大負荷（出力）を満足させるためには組電池を構成する単電池や電池モジュールを減らすことが困難であった。このような事情から、電池の小形軽量化を図るために、単電池の出力特性（Ｗ／ｋｇやＷ／ｌ）を向上させることが求められていた。
【０００８】
HEV用電源としての電池モジュールは、一般的に水平に装着される。従って電池モジュールにはその自重による曲げの負荷（力）が加わる。また、HEVの走行中には振動や発信、停止時の加速に伴う曲げの力が加わる。前記従来の電池モジュールにおいては、単電池の重量が大きいことと単電池の高さ（長さ）が大きくて単電池と単電池を接続している接続部分の間隔が大きいために単電池間の接続部分に加わる負荷（力）が大きく、大きな負荷が加わったときに損傷を受ける虞があり、負荷（力）を軽減することが求められていた。
【０００９】
【発明が解決しようとする課題】
本発明は、前記従来のHEV用電源としてのニッケル水素蓄電池の持つ欠点に鑑みなされたものであって、単電池およびそれを用いた電池モジュールの出力特性を向上させ、かつ電池モジュールに加わる負荷（力）の軽減を図ろうとするものである。
【００１０】
【課題を解決するための手段】
本発明に係る単電池は、金属性基板に活物質を担持させた矩形状の正極板および負極板を備え、正極板の一方の長辺に正極基板端部を露出させ、負極板の一方の長辺に負極基板端部を露出させ、前記正極板と負極板の間にセパレータを配置し、一方の長辺側に前記正極基板端部、他方の長辺側に負極基板端部を突出させた積層体を捲回した捲回式極板群の前記正極基板端部の端面に正極集電端子を、負極基板端部の端面に負極集電端子を接合した円筒形アルカリ蓄電池において、前記正極板の長辺の長さ（Ｄ）と短辺の長さ（Ｃ）の比（Ｄ／Ｃ）を１６〜２４とし、前記正極板の短辺の長さが３０ｍｍ〜４５ｍｍであることおよび容量が４〜７Ａｈであることを特徴とする単電池である。本発明によれば、優れた出力特性を有し、高率で充電したときの充電受け入れ性も良好な単電池および電池モジュールを提供することができる。
【００１１】
本発明においては、前記単電池において矩形状の正極板の短辺の長さが３０〜４５ｍｍである。この構成を備えることにより、高率放電特性に優れ、高率で充電した時の充電受け入れ特性の優れたニッケル水素蓄電池とすることができる。
【００１２】
本発明においては、前記単電池の容量が、４〜７Ａｈである。この構成を備えることにより、高率放電特性の優れた単電池を得ることができ、該単電池を適用することにより、電池モジュールおよび組電池の小形軽量化を図ることができる。
【００１３】
本発明においては、前記単電池の肩高さ（Ａ）と直径（Ｂ）の比（Ａ／Ｂ）を１．１〜１．５とすることが好ましい。この構成を備えることにより、電池モジュールの小形化を図ると共に電池モジュールに加わる負荷（力）の軽減を図ることができる。
【００１４】
【発明の実施の形態】
図１は、本発明に係る円筒形ニッケル水素蓄電池の捲回式極板群１０の構成を示す斜視図である。捲回式極板群１０は、矩形状正極板１１と負極板１２の間にセパレータ１３を置いて積層し、該積層体をロール状に捲回したものである。正極板１１の一方の長辺には正極基板端部を１４を露出させ、負極板１２の一方の長辺には負極基板端部を１５を露出させ、正極基板端部と負極基板端部を矩形状積層体の対向する長辺に位置するように配置した積層体を捲回することによって捲回式極板群の一方の捲回端面（図では上）に正極基板端部１４を他方の捲回端面（図では下側）に負極基板端部１５を突出させた捲回式極板群とする。
【００１５】
図２は、前記図１に示した捲回式極板群１０を備えた本発明に係る円筒形ニッケル水素蓄電池の内部構造を模式的に示す図である。前記捲回式極板群１０の一方の捲回端面に突出させた正極基板端部１４の端面に円板状の正極集電端子１６を、他方の捲回端面に突出させた負極基板端部１５の端面には円板状の負極集電端子１７をそれぞれシリーズスポット溶接により接合してある。正極集電端子１６と金属製封口蓋２とは金属製リード板１８により接続する。前記金属製封口板２にはキャップ３が接合され両者が一体となって正極端子を構成している。負極集電端子１７の中心部分は負極端子を兼ねる金属製電槽５の底壁内面に接合されている。図２の６、７は電池内の圧力が異常に上昇したときに内部に溜まったガスを外に排出するための透孔、８は透孔６を塞ぐように配置されたゴム製弁体である。
【００１６】
また、HEVの電源用電池の場合、大電流での充放電を繰り返すので、強制的に空冷を行なったとしても通電時に発生する熱が電池に蓄積するために電池温度が上昇する。例えば既に実用化されている直径が３２〜３４ｍｍの単一サイズの単電池で構成した組電池を実際にHEVに搭載して動作させた時に動作前に比べて電池温度が２０℃から３０℃も上昇する。ニッケル水素蓄電池の場合、電池温度が６０〜７０℃を超えると充電効率の低下を招く他、放電性能や耐久性に悪影響を及ぼすので好ましくない。円筒形ニッケル水素蓄電池においては、経験上電池の直径が大きくなるにつれ熱が蓄積し温度が上昇する。ことに、単電池の直径が４０ｍｍを超えると極端に電池の放熱機能が低下し電池温度の上昇が顕著になる。そのためHEVの電源のように高率で放電したり、充電したりする用途には直径が４０ｍｍ未満の単電池を適用することが好ましい。また、単電池の直径が２０ｍｍ以下の場合には活物質充填量が小さくて容量が低下すると共に出力特性も低下するので好ましくない。
【００１７】
また、本発明に係る単電池の正極板は、水酸化ニッケルを主成分とする活物質粉末をペースト状とし、多孔質基板に担持させた非焼結式の極板であって、その厚さは０．２〜０．５ｍｍの範囲にあることが好ましく、０．３〜０．４ｍｍの範囲にあることがさらに好ましい。極板厚さを０．５ｍｍより大きくすると、容量を大きくできるメリットがあるものの出力特性が低下するので高出力特性を持ったニッケル水素蓄電池を達成しようとする本発明にとっては好ましくない。また。極板厚さを０．２ｍｍより小さくすると、極板の見かけの作用面積を大きくすることができるが、活物質充填量が減少するために放電容量が低下する他に出力特性の低下も招くので好ましくない。
【００１８】
本発明に係る正極板１１は、図３に示すように矩形状であって、基板に水酸化ニッケルを主成分とする活物質粉末を担持させた部分１９と一方の長辺に設けた基板端部が露出した部分１４からなる。該正極板１１の長辺の長さＤと短辺の長さＣの比（Ｄ／Ｃ）を１６〜２３の範囲に設定することにより高出力密度を達成する。Ｄ／Ｃを１６〜２１の範囲に設定すると、さらに優れた出力密度が得られるので好ましい。
【００１９】
また、正極板１１は、図３に示すように矩形状であって、短辺の長さＣを３０〜４５ｍｍに設定することが好ましく、３５〜４５ｍｍに設定することがさらに好ましい。このような構成とすることによって従来電池に比べて優れた出力特性を持つ単電池および電池モジュールを提供することができる。
【００２０】
図４に示すように、本発明係る電池モジュール３０は、前記円筒形ニッケル水素蓄電池１を複数個、それぞれの電池の円筒の中心が直線をなすように並べてシリーズに接続したものである。隣り合う電池同士および正極のエンド端子３３とこれに隣接する電池の間にはドーナツ状絶縁板３２を配置し、隣合う電池同士および正極のエンド端子３３とこれに隣接する電池の正極端子、負極エンド端子３４とこれに隣接する電池の負極端子は、金属製接続リング３１により接続されている。
【００２１】
図５は、本発明に係る電池モジュール３０を構成する円筒形ニッケル水素蓄電池１および正極エンド端子３３、負極エンド端子３４の接続構造を模式的に示した図である。金属製接続リングの一端は、一方の蓄電池正極端子（図２の金属製蓋２）に接合され、他端は隣の電池の負極端子（図２の電槽４）に接合されている。正極エンド端子、負極エンド端子は、それぞれ接続リングを介して隣接する蓄電池の正極端子、負極端子に接続されている。
【００２２】
図６は、図４、図５に示した電池モジュール３０を構成する円筒形ニッケル水素蓄電池１の外形を示す図である。３は正極端子を兼ねるキャップ、４は負極端子を兼ねる電槽である。従来用いられていた単一サイズの単電池においては図で示した肩高さ（Ａ）と直径（Ｂ）の大きさの比（Ａ／Ｂ）が１．８〜１．９と大きい値であった。これに対して、本発明に係る電池モジュールを構成する円筒形ニッケル水素蓄電池の場合、電池の肩高さ（Ａ）と直径（Ｂ）の大きさの比（Ａ／Ｂ）が１．１〜１．５の範囲にあることが好ましく、１．２〜１．５の範囲にあることがさらに好ましい。Ａ／Ｂを１．５以下とすることによって、電池モジュールの単電池間の接続部分に加わる振動や曲げの負荷（力）を軽減することができ、また、Ａ／Ｂを１．１以上とすることによって単電池の出力特性において優れた特性を確保することができる。
【００２３】
【実施例】
以下に一実施例により本発明の詳細を説明する。なお、単電池の形状等は以下に示した例に限定されるものではない。
（単電池の作製）
（実施例１）
金属換算でＺｎ３．７重量％、Ｃｏ１．２重量％を固溶させた水酸化ニッケルを主成分とする芯層の表面に水酸化コバルトの被覆層を形成させた平均粒径１０μｍの粉末を用意した。該粉末に占める前記被覆層の比率を７重量％とした。該粉末１００ｇを、温度６０℃、濃度１０重量％の水酸化ナトリウム水溶液中に投入して撹拌しながら次亜塩素酸ナトリウム溶液４５ｍｌを加えて酸化処理をした。酸化処理後の粉末に温度８０℃、濃度３０重量％の水酸化ナトリウム水溶液２０ｇを加えて撹拌しながら同温度に２時間維持したのち水洗、乾燥した。得られた粉末に含まれる遷移金属元素（ＮｉとＣｏ）の平均酸化数を測定したところ、２．１５の値が得られた。該粉末を正極（ニッケル電極）用の活物質粉末とした。
【００２４】
前記正極活物質粉末にカルボキシメチルセルロース（ＣＭＣ）の水溶液を添加混練してペースト状とした。なお前記ペーストに含まれる活物質粉末とＣＭＣの比率を重量比で９９．５：０．５とした。該ペーストを厚さ０．９ｍｍ、坪量４５０ｇ／ｍ²の発泡ニッケル製の正極基板に充填した。８０℃の雰囲気中に放置して乾燥した後プレス加工を施して厚さを０．４ｍｍの極板とした。該極板を短辺の長さが４５ｍｍ、長辺の長さが７２０ｍｍの矩形（Ｄ／Ｃ≒１６）となるように裁断した。一方の長辺に１ｍｍの幅で活物質を取り去り、基板の長辺端部に基板露出部を形成し、活物質充填部分の短辺の長さを４４ｍｍ、長辺の長さを７２０ｍｍとした。前記基板露出部をプレスしてその厚さを０．０５ｍｍとし、該基板露出部全面にスポット溶接により幅１ｍｍ、厚さ０．３ｍｍのニッケル製フープを接合して正極板とした。活物質充填量から正極板の容量は７．０Ａｈと算定された。
【００２５】
平均粒径３０μｍ、ＭｍＮｉ_3.6Ｃｏ_0.6Ａｌ_0.3Ｍｎ_0.35（Ｍｍはミッシュメタルを表す）で表される組成の水素吸蔵合金粉末とＳＢＲ（スチレンブタジエン共重合体）のエマルジョンを乾燥基準の重量比で９９．３：０．７の比率で混合し、ペースト状にした。該ペーストを開口径１．０ｍｍ、開孔率４５％で表面にニッケルメッキを施した厚さが０．０５ｍｍの鋼板製の穿孔鋼板からなる負極基板の両面にコートした後、８０℃の雰囲気中に放置して乾燥した後プレス加工を施して厚さを０．３ｍｍの極板とした。該極板を短辺の長さが４５ｍｍ、長辺の長さが８００ｍｍの矩形に裁断した。一方の長辺に１ｍｍの幅で両面の活物質を取り去り、負極基板露出部分を設け、水素吸蔵合金粉末塗工部分の短辺の長さが４４ｍｍ、長辺の長さが８００ｍｍの負極板とした。該負極板の活物質粉末（水素吸蔵合金粉末）充填量から算定される負極板の容量は１１．２Ａｈと算定された。
【００２６】
公知の方法でスルフォン化処理を施すことによって親水性を付与した厚さ０．１１ｍｍ、坪量５５ｇのポリプロピレン不織布製の帯状セパレータを用意した。前記１枚の正極板の両面にセパレータを重ね、さらに１枚の負極板を重ねて矩形の積層体を構成した。該積層体の一方の長辺に正極基板端部を突出させ、他方の長辺に負極基板端部を突出させた。該積層体を直径３．５ｍｍの棒状芯体を巻芯とした正極板が内側になるように捲回し、直径が３０ｍｍの捲回式極板群を得た。
【００２７】
前記捲回式極板群の一方の捲回端面に突出させた正極基板の端面に厚さ０．２ｍｍ、外形２９ｍｍ、内径４ｍｍのドーナツ状正極集電端子を接合した。正極集電端子に厚さ０．３ｍｍ、幅２．５ｍｍのニッケルフープ製の正極リード板を接合した。捲回式極板群の他方の捲回端面に突出させた負極基板の端面に厚さ０．２ｍｍ、外形２９．５ｍｍの円板状負極集電端子を接合した。
【００２８】
集電端子を取り付けた極板群をニッケルメッキを施した鋼板製の円筒形電槽内に収納した後、前記負極集電端子の中心部分を電槽の内定面に接合し、前記正極リード板にガス排出弁、キャップおよびガスケットを取り付けた金属製封口板を接合した。６．８モルの水酸化カリウムと０．８モルの水酸化リチウムを含むアルカリ電解液を所定量注入し、所定の方法で封口して総高５４ｍｍ、肩高さ（Ａ）５０ｍｍ、直径（Ｂ）３２．５ｍｍ、Ａ／Ｂが１．５の単電池を作製した。該単電池を実施例１とする。
【００２９】
（実施例２）
前記実施例１において正極板の短辺の長さが４２ｍｍ、長辺の長さが７２０ｍｍの矩形（Ｄ／Ｃ≒１７）となるように裁断した。一方の長辺に１ｍｍの幅で活物質を取り去り、基板の長辺端部に基板露出部を形成し、活物質充填部分の短辺の長さを４１ｍｍ、長辺の長さを７２０ｍｍとした。また、負極板を短辺の長さが４２ｍｍ、長辺の長さが８００ｍｍの矩形に裁断した。一方の長辺に１ｍｍの幅で両面の活物質を取り去り、負極基板露出部分を設け、水素吸蔵合金粉末塗工部分の短辺の長さが４１ｍｍ、長辺の長さが８００ｍｍの負極板とした。その他は実施例１と同じとした。正極板の容量は６．５Ａｈ、負極板の容量は１０．４Ａｈと算定された。作製し単電池は総高５１ｍｍ、肩高さ４７（Ａ）ｍｍ、直径（Ｂ）３２．５ｍｍ、Ａ／Ｂが１．４であった。該単電池を実施例２とする。
【００３０】
（実施例３）
前記実施例１において正極板の短辺の長さが３８ｍｍ、長辺の長さが７２０ｍｍの矩形（Ｄ／Ｃ≒１９）となるように裁断した。一方の長辺に１ｍｍの幅で活物質を取り去り、基板の長辺端部に基板露出部を形成し、活物質充填部分の短辺の長さを３７ｍｍ、長辺の長さを７２０ｍｍとした。また、負極板を短辺の長さが３８ｍｍ、長辺の長さが８００ｍｍの矩形に裁断した。一方の長辺に１ｍｍの幅で両面の活物質を取り去り、負極基板露出部分を設け、水素吸蔵合金粉末塗工部分の短辺の長さが３７ｍｍ、長辺の長さが８００ｍｍの負極板とした。その他は実施例１と同じとした。正極板の容量は５．８Ａｈ、負極板の容量は９．３Ａｈと算定された。作製した単電池は総高４７ｍｍ、肩高さ（Ａ）４３ｍｍ、直径（Ｂ）３２．５ｍｍ、Ａ／Ｂが１．３であった。該単電池を実施例３とする。
【００３１】
（実施例４）
前記実施例１において正極板の短辺の長さが３５ｍｍ、長辺の長さが７２０ｍｍの矩形（Ｄ／Ｃ≒２１）となるように裁断した。一方の長辺に１ｍｍの幅で活物質を取り去り、基板の長辺端部に基板露出部を形成し、活物質充填部分の短辺の長さを３４ｍｍ、長辺の長さを７２０ｍｍとした。また、負極板を短辺の長さが３５ｍｍ、長辺の長さが８００ｍｍの矩形に裁断した。一方の長辺に１ｍｍの幅で両面の活物質を取り去り、負極基板露出部分を設け、水素吸蔵合金粉末塗工部分の短辺の長さが３４ｍｍ、長辺の長さが８００ｍｍの負極板とした。その他は実施例１と同じとした。正極板の容量は４．８Ａｈ、負極板の容量は７．８Ａｈと算定された。作製した単電池は総高４４ｍｍ、肩高さ（Ａ）４０ｍｍ、直径（Ｂ）３２．５ｍｍ、Ａ／Ｂが１．２であった。該単電池を実施例４とする。
【００３２】
（実施例５）
前記実施例１において正極板の短辺の長さが３０ｍｍ、長辺の長さが７２０ｍｍの矩形（Ｄ／Ｃ≒２４）となるように裁断した。一方の長辺に１ｍｍの幅で活物質を取り去り、基板の長辺端部に基板露出部を形成し、活物質充填部分の短辺の長さを２９ｍｍ、長辺の長さを７２０ｍｍとした。また、負極板を短辺の長さが３０ｍｍ、長辺の長さが８００ｍｍの矩形に裁断した。一方の長辺に１ｍｍの幅で両面の活物質を取り去り、負極基板露出部分を設け、水素吸蔵合金粉末塗工部分の短辺の長さが２９ｍｍ、長辺の長さが８００ｍｍの負極板とした。その他は実施例１と同じとした。正極板の容量は４．０Ａｈ、負極板の容量は６．４Ａｈと算定された。作製した単電池は総高３９ｍｍ、肩高さ（Ａ）３５ｍｍ、直径（Ｂ）３２．５ｍｍ、Ａ／Ｂが１．１であった。該単電池を実施例５とする。
【００３３】
（比較例１）
前記実施例１において正極板の短辺の長さが２７ｍｍ、長辺の長さが７２０ｍｍの矩形（Ｄ／Ｃ≒２８）となるように裁断した。一方の長辺に１ｍｍの幅で活物質を取り去り、基板の長辺端部に基板露出部を形成し、活物質充填部分の短辺の長さを２６ｍｍ、長辺の長さを７２０ｍｍとした。また、負極板を短辺の長さが２７ｍｍ、長辺の長さが８００ｍｍの矩形に裁断した。一方の長辺に１ｍｍの幅で両面の活物質を取り去り、負極基板露出部分を設け、水素吸蔵合金粉末塗工部分の短辺の長さが２６ｍｍ、長辺の長さが８００ｍｍの負極板とした。その他は実施例１と同じとした。正極板の容量は３．０Ａｈ、負極板の容量は４．８Ａｈと算定された。作製した単電池は総高３４ｍｍ、肩高さ（Ａ）３２ｍｍ、直径（Ｂ）３２．５ｍｍ、Ａ／Ｂが１．０であった。該単電池を比較例１とする。
【００３４】
（比較例２）
前記実施例１において正極板の短辺の長さが４８ｍｍ、長辺の長さが７２０ｍｍの矩形（Ｄ／Ｃ≒１５）となるように裁断した。一方の長辺に１ｍｍの幅で活物質を取り去り、基板の長辺端部に基板露出部を形成し、活物質充填部分の短辺の長さを４７ｍｍ、長辺の長さを７２０ｍｍとした。また、負極板を短辺の長さが４８ｍｍ、長辺の長さが８００ｍｍの矩形に裁断した。一方の長辺に１ｍｍの幅で両面の活物質を取り去り、負極基板露出部分を設け、水素吸蔵合金粉末塗工部分の短辺の長さが４７ｍｍ、長辺の長さが８００ｍｍの負極板とした。その他は実施例１と同じとした。正極板の容量は７．５Ａｈ、負極板の容量は１２．０Ａｈと算定された。作製した単電池は総高５７ｍｍ、肩高さ（Ａ）５３ｍｍ、直径（Ｂ）３２．５ｍｍ、Ａ／Ｂが１．６であった。該単電池を比較例２とする。
【００３５】
（比較例３）
前記実施例１において正極板の短辺の長さが６４ｍｍ、長辺の長さが７２０ｍｍの矩形（Ｄ／Ｃ≒１１）となるように裁断した。一方の長辺に１ｍｍの幅で活物質を取り去り、基板の長辺端部に基板露出部を形成し、活物質充填部分の短辺の長さを６３ｍｍ、長辺の長さを７２０ｍｍとした。また、負極板を短辺の長さが６４ｍｍ、長辺の長さが８００ｍｍの矩形に裁断した。一方の長辺に１ｍｍの幅で両面の活物質を取り去り、負極基板露出部分を設け、水素吸蔵合金粉末塗工部分の短辺の長さが６３ｍｍ、長辺の長さが８００ｍｍの負極板とした。その他は実施例１と同じとした。正極板の容量は１０．０Ａｈ、負極板の容量は１６．０Ａｈと算定された。作製した単電池は総高７３ｍｍ、肩高さ（Ａ）６９ｍｍ、直径（Ｂ）３２．５ｍｍ、Ａ／Ｂが２．１であった。該単電池を実施例３とする。
【００３６】
（比較例４）
実施例１に適用したニッケル極用ペーストを厚さ１．６ｍｍ、坪量４５０ｇ／ｍ²の発泡ニッケル製の正極基板に充填した。８０℃の雰囲気中に放置して乾燥した後プレス加工を施して厚さを０．６ｍｍの極板とした。該極板を短辺の長さが５１ｍｍ、長辺の長さが５６０ｍｍの矩形（Ｄ／Ｃ≒１１）となるように裁断した。一方の長辺に１ｍｍの幅で活物質を取り去り、基板の長辺端部に基板露出部を形成し、活物質充填部分の短辺の長さを５０ｍｍ、長辺の長さを５６０ｍｍとした。前記基板露出部をプレスしてその厚さを０．０５ｍｍとし、該基板露出部全面にスポット溶接により幅１ｍｍ、厚さ０．３ｍｍのニッケル製フープを接合して正極板とした。活物質充填量から正極板の容量は８．２Ａｈと算定された。
【００３７】
実施例１に適用した水素吸蔵合金電極用ペーストを開口径１．０ｍｍ、開孔率４５％で表面にニッケルメッキを施した厚さが０．０５ｍｍの鋼板製の穿孔鋼板からなる負極基板の両面にコートした後、８０℃の雰囲気中に放置して乾燥した後プレス加工を施して厚さを０．４５ｍｍの極板とした。該極板を短辺の長さが５１ｍｍ、長辺の長さが６４０ｍｍの矩形に裁断した。一方の長辺に１ｍｍの幅で両面の活物質を取り去り、負極基板露出部分を設け、水素吸蔵合金粉末塗工部分の短辺の長さが５０ｍｍ、長辺の長さが６４０ｍｍの負極板とした。該負極板の活物質粉末（水素吸蔵合金粉末）充填量から算定される負極板の容量は１３．１Ａｈと算定された。作製した単電池は総高６０ｍｍ、肩高さ（Ａ）５６ｍｍ、直径（Ｂ）３２．５ｍｍ、Ａ／Ｂが１．８であった。該電池を実施例３とする。
【００３８】
（化成）
前記実施例１〜実施例５、比較例１〜比較例４に係る単電池を、２０℃の雰囲気で１５時間エージングした後、０．０５ＩｔＡの電流で２０時間充電後、さらに０．１ＩｔＡの電流で６時間充電した後０．１ＩｔＡの電流で終止電圧を１．０として放電した。続く２〜１０サイクル目は、０．１ＩｔＡの電流で１２時間充電した後０．２ＩｔＡの電流で終止電圧を１．０として放電した。
（放電容量の評価）
化成済みの単電池を、２０℃の雰囲気で０．２ＩｔＡの電流で６時間充電した後、同じ電流で終止電圧１．０Vまで放電した時に得られた放電容量を測定し、この値をもって、該蓄電池の放電容量とした。
（エネルギー密度）
単電池を前記２０℃の雰囲気で０．２ＩｔＡで放電したときの平均放電電圧（Ｖ）と放電容量（Ａｈ）をその電池の持つエネルギー（Ｗｈ）とし、該エネルギーをその電池の重量（ｋｇ）で徐した値をその電池のエネルギー密度（Ｗｈ／ｋｇ）とした。
【００３９】
（出力特性の評価）
完全充電状態にある単電池を２０℃の雰囲気において０．２ＩｔＡの電流で２．５時間放電した後、放電電流１ＩｔＡで１１秒間放電した。同様の操作を放電電流２ＩｔＡ刻みで３ＩｔＡ〜１０ＩｔＡの範囲において実施した（但し、放電電圧が０．５ｖを下回ったときには直ちに放電をうち切った）。Ｘ軸を放電電流、Ｙ軸を放電開始後１０秒目の放電電圧（以下単に１０秒目電圧と記述する）として測定結果をプロットして１０秒目電圧と放電電流の関係を示す曲線を作成し、該曲線から１０秒目電圧が０．８Ｖになる時の放電電流値（Ａ）を求めた。該放電電流値に０．８Ｖを乗じた値をその電池の出力（Ｗ）とし、該出力（Ｗ）を電池の重量（ｋｇ）で徐した値をその電池の出力密度（Ｗ／ｋｇ）とした。
結果を表１に示す。
【００４０】
【表１】

【００４１】
表１に示すように本発明に係る実施例は、出力密度において比較例を上回っており、比較例に比べて、組電池の重量を低減できることを示している。また、実施例の中で最も小形の電池である実施例５においても単電池の出力が７５Ｗであり、該単電池２００本を適用して組電池を構成すれば、前記HEV用電源に要求される最大負荷時の出力１５ｋｗを満足させることができる。これに対して、比較例１は出力が小さく同負荷を満足させるためには２４６本以上の単電池を必要とする。
【００４２】
他方比較例２〜比較例４の場合は、出力は満足しているものの容量が大過剰であり、容量を大きくした分、電池の重量および容積が大きくなる欠点がある。実施例１〜実施例３、比較例２比較例３と比較すると、正極の短辺長さを大きくして単電池の容量が大きくなるに従いその出力（Ｗ）は増大するが、増大幅は次第に小さくなり実施例１，比較例２、比較例３の差は小さく出力が飽和する傾向にあることが分かる。これに対して、正極の短辺長さを大きくする（Ｄ／Ｃを小さくする）に従って、電池の重量、容積は増大し続けるので電池の出力密度（Ｗ／ｋｇ、Ｗ／ｌ）は低下する。図７は、上記実施例、比較例の試験結果のうち出力密度とＤ／Ｃの関係をグラフ化した結果を示す図である。該図から分かるように、Ｄ／Ｃを１６〜２４とすると本発明の狙いとする７５０Ｗ／ｋｇ以上の高い出力密度が得られることが分かる。さらに、Ｄ／Ｃを１６〜２１とすると、８００Ｗ／ｋｇを超える極めて高い出力密度が得られので好ましい。
【００４３】
表１の実施例１〜実施例５の結果に示すように、矩形状正極板の短辺の長さを３０〜４５ｍｍ、さらに好ましくは３５〜４５ｍｍち設定することによって、比較例に比べて高い出力密度を有する単電池を得ることが出来、該単電池を適用すれば出力密度の高い電池モジュールおよび組電池を得ることができる。
【００４４】
比較例４は、従来の単一サイズの単電池と同様、正極板の厚さを０．６ｍｍ（実施例および比較例１〜比較例３の正極板の厚さは０．４ｍｍ）とし、正極板の短辺の長さを５１ｍｍとした例であるが、エネルギ密度（Ｗｈ／ｋｇ）は高いものの出力密度（Ｗ／ｋｇ）が低い欠点がある。
【００４５】
図８は、上記実施例、比較例の試験結果のうち出力密度と単電池容量の関係をグラフ化した結果を示す図である。該図から分かるように、単電池容量を４〜７Ａｈとすると７５０Ｗ／ｋｇ以上の高い出力密度が得られ好ましい。単電池容量を５〜７Ａｈとするとほぼ８００Ｗ／ｋｇを超える高い出力密度が得られさらに好ましい。
【００４６】
図９は、上記実施例、比較例の試験結果のうちエネルギー密度と単電池容量の関係をグラフ化した結果を示す図である。該図から分かるように、Ｄ／Ｃが２４以下であれば４５Ｗｈ／ｋｇを超えるエネルギー密度が得られ、Ｄ／Ｃが２１以下であれば５０Ｗｈ／ｋｇを超えるエネルギー密度が得られる。従って、優れた出力特性とエネルギー密度の両方を兼ね備える単電池とするには、Ｄ／Ｃを１６〜２４とするのが好ましく、１６〜２１とするのがさらに好ましい。
【００４７】
（電池モジュールの作製）
前記実施例１〜実施例６および比較例１〜比較例３に記載した単電池を図４に示したように６個直線状に並べてシリーズに接続し、電圧が７．２Ｖ系の電池モジュールとした。なお隣合う電池同士の接続には、ニッケルメッキを施した厚みが０．２ｍｍの鋼板製であって、図５に示した断面形状を有する接続リングを用い、接続リングの一端を隣合う電池のうち一方の電池の金属製封口板にスポット溶接により等間隔で４点接合し、他端を他方の電池の電槽の側面にスポット溶接により等間隔で４点接合した。また、電池モジュールの両端には図４に示したように正極エンド端子および負極エンド端子を取り付けた。該電池モジュールを、その作製に適用した円単電池の区分に対応させ、それぞれ実施例１〜実施例５、比較例１〜比較例４とした。
【００４８】
（電池モジュールの荷重耐性評価）
前記電池モジュールの両端を支える位置に配置した、２つの支点の上に電池モジュールを水平にさし渡し、モジュールの中央に吊りひもを介して５ｋｇの重りを吊し、電池モジュールの接続に破損が発生するか否かを調べた。
結果を表２に示す。
【００４９】
【表２】

【００５０】
表２に示したように、比較例の場合比較例１を除き、比較例２〜比較例４は耐荷重性が劣る。実施例および比較例１の場合は比較例２〜比較例４に比べて単電池の自重が小さく、かつ、単電池の長さが小さくて接続部分の間隔が小さいために、該接続部分に加わる付加（力）が軽減されたために耐荷重性が高いものと考えられる。このように、電池モジュールの耐荷重性を高めるには単電池の肩高さと直径の大きさの比（Ａ／Ｂ）が１．５以下とすることが好ましい。実施例や比較例１の場合、水平に装着した時のたわみも小さく振動や加速に対する信頼性が高い。但し、比較例１は、耐荷重性には優れるが前記表１の結果に示した通り、出力がおよび小さく、出力密度も低い欠点がある。また、表１に示した如く、実施例１〜実施例４において８００Ｗ／Ｋｇを超える優れた出力特性が得られるところから、本発明に係る電池モジュールを構成する単電池のＡ／Ｂを、１．１〜１．５にすることが好ましく、１．２〜１．５にすることがさらに好ましいことが分かる。
【００５１】
表では省略したが、従来の単一サイズの単電池６個で構成した比較例４の電池モジュールの重量が１１００ｇであるのに対して、実施例２の電池モジュールの重量は８００ｇであり、比較例４に比べて実施例２の方が約２７％重量が軽減され、また、比較例４の電池モジュールの容積が２８７ｍｌであるのに対して、実施例２の電池モジュールの容積は２４２ｍｌで容積が１６％小さくなった。さらにＷ／ｌにおいても比較例４の電池モジュールが２７０Ｗ／ｌであるのに対して実施例２が４６０Ｗ／ｌと顕著に向上した。このように、本発明に係る電池モジュールは単電池の出力特性（Ｗ／ｋｇ、Ｗ／ｌ）を向上させたことにより電池の重量および容積の軽減に顕著な効果を発揮する。
【００５２】
なお、本明細書においては詳細を省略したが、本発明に係る円筒形ニッケル水素蓄電池およびそれを適用して構成した電池モジュールならびに組電池は、従来電池に比べ高率で充電したときの充電受け入れ性能においても優れていることが分かった。
【発明の効果】
【００５３】
本発明によれば、高出力密度を有する円筒形ニッケル水素蓄電池（単電位）を得ることができる。また、該単電池を適用することによって、高出力を要求される電池モジュールや該電池モジュールで構成される組電池の小形軽量化を図ることができる。
【００５４】
本発明によれば、円筒形ニッケル水素蓄電池を複数個直線状に接続した電池モジュールであって、振動や曲げ等の外部から加わる力に対して強い電池モジュールを得ることができる。
【図面の簡単な説明】
【図１】本発明に係る極板群の斜視図である。
【図２】本発明に係るニッケル水素蓄電池の内部の構造を模式的に示す断面図である。
【図３】本発明に係るニッケル水素蓄電池の正極板の形状を示す平面図である。
【図４】本発明に係る電池モジュールの外観を模式的に示す斜視図である。
【図５】本発明に係る電池モジュールの構成を模式的に示す図である。
【図６】本発明に係る円筒形ニッケル水素蓄電池の外観を示す正面図である。
【図７】円筒形ニッケル水素蓄電池の出力密度とＤ／Ｃの関係を示すグラフである。
【図８】円筒形ニッケル水素蓄電池の出力密度と電池容量の関係を示すグラフである。
【図９】円筒形ニッケル水素蓄電池のエネルギー密度とＤ／Ｃの関係を示すグラフである。
【符号の説明】
１円筒形ニッケル水素蓄電池
１０捲回式極板群
１１正極板
１２負極板
１３セパレータ
１４正極基板露出部
１５負極基板露出部
３０電池モジュール
３１接続リング
３２絶縁リング[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cylindrical nickel-metal hydride storage battery having a wound electrode group and a battery module in which a plurality of the nickel-metal hydride storage batteries are connected in series.
[0002]
[Prior art]
Sealed nickel-metal hydride storage batteries using a nickel electrode for the positive electrode and a hydrogen storage alloy electrode for the negative electrode have excellent charge / discharge cycle performance, overcharge resistance, and overdischarge resistance. Therefore, the use is expanding. Above all, it is highly suitable as a power source for a hybrid electric vehicle (HEV), and demand for the application is expected to increase.
[0003]
The HEV power supply is required to have a voltage of 140 to 280 V, an output satisfying a maximum load of 15 to 30 kw, and a discharge capacity of 3 to 4 Ah. In addition, in order to ensure the running performance of HEV, the battery as a power source is required to be small and light, and if the weight energy density Wh / kg is taken as an example, it is considered to be 750 wh / kg or more. The Further, it is desirable to have an energy density of 45 Wh / kg or more.
[0004]
In order to satisfy the voltage and maximum load required for the HEV power source, the conventional 280V HEV power source has a single-size cylindrical nickel-metal hydride storage battery (hereinafter, a plurality of cylindrical storage batteries combined) with a capacity of about 8 Ah. An assembled battery in which about 240 batteries are connected in series is applied (which is referred to as a single cell in the sense of clarifying the distinction from a battery module or an assembled battery in which a plurality of battery modules are combined). Usually, six cell cells are connected to a series via a connection ring to form a battery module with a voltage of 7.2 V (see, for example, Patent Document 1), and the battery modules are connected to a series of 40 batteries as a whole. An assembled battery is configured.
[0005]
[Patent Document 1]
JP-A-10-106533 (FIGS. 1 and 3)
[0006]
In the single-size unit cell conventionally applied to the HEV power source, the thickness is 0.5 to 0.6 mm, the short side is about 51 mm, and the ratio of the long side to the short side is Applies a positive electrode plate having a rectangular shape of about 11. The battery pack to which the single size single cell applied from the past is applied has a drawback that the output characteristic is low as a power source for HEV.
[0007]
As described above, for example, a capacity of 3 to 4 Ah is sufficient for a power source for HEV as described above, whereas an assembled battery using a conventional single-sized cylindrical unit cell has a battery capacity of about 8 Ah. However, it is not preferable because the volume and weight of the battery increases as the capacity is increased. However, in order to satisfy the maximum load (output) required for the HEV power supply, an assembled battery is configured. It was difficult to reduce the number of cells and battery modules. Under such circumstances, in order to reduce the size and weight of the battery, it has been required to improve the output characteristics (W / kg and W / l) of the single cell.
[0008]
Battery modules as HEV power supplies are generally mounted horizontally. Therefore, a bending load (force) due to its own weight is applied to the battery module. In addition, during the HEV traveling, vibration, transmission, and bending force accompanying acceleration when stopped are applied. In the conventional battery module, since the weight of the unit cell is large and the height (length) of the unit cell is large, and the interval between the connection parts connecting the unit cell and the unit cell is large, The load (force) applied to the connection portion is large, and there is a risk of damage when a large load is applied, and there has been a demand for reducing the load (force).
[0009]
[Problems to be solved by the invention]
The present invention has been made in view of the drawbacks of the nickel-metal hydride storage battery as the conventional HEV power source, and improves the output characteristics of the unit cell and the battery module using the same, and the load applied to the battery module ( Power).
[0010]
[Means for Solving the Problems]
The unit cell according to the present invention includes a rectangular positive electrode plate and a negative electrode plate each having an active material supported on a metallic substrate, the end of the positive electrode substrate is exposed on one long side of the positive electrode plate, and one of the negative electrode plates is exposed. A laminate in which a negative electrode substrate end is exposed on the long side, a separator is disposed between the positive electrode plate and the negative electrode plate, and the positive substrate end is protruded on one long side and a negative substrate end is protruded on the other long side In a cylindrical alkaline storage battery in which a positive electrode current collector terminal is joined to an end face of the positive electrode substrate end portion and a negative electrode current collector terminal is joined to an end face of the negative electrode substrate end portion of the wound electrode group in which the body is wound, The ratio of long side length (D) to short side length (C) (D / C) is 16-24 The length of the short side of the positive electrode plate is 30 mm to 45 mm and the capacity is 4 to 7 Ah. It is a single battery characterized by. According to the present invention, it is possible to provide a unit cell and a battery module that have excellent output characteristics and good charge acceptability when charged at a high rate.
[0011]
In the present invention, the length of the short side of the rectangular positive electrode plate in the unit cell. But 30-45mm Is . By having this configuration The nickel-metal hydride storage battery having excellent high-rate discharge characteristics and excellent charge acceptance characteristics when charged at a high rate can be obtained.
[0012]
In the present invention, the capacity of the unit cell is 4 to 7 Ah. The By having this configuration In addition, a single battery excellent in high rate discharge characteristics can be obtained, and by applying the single battery, the battery module and the assembled battery can be reduced in size and weight.
[0013]
In the present invention In front The ratio (A / B) of shoulder height (A) to diameter (B) of the cell is 1.1 to 1.5. Preferably . By having this configuration Thus, the battery module can be reduced in size and the load (force) applied to the battery module can be reduced.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a perspective view showing the configuration of a wound electrode group 10 of a cylindrical nickel-metal hydride storage battery according to the present invention. The wound electrode plate group 10 is formed by laminating a separator 13 between a rectangular positive electrode plate 11 and a negative electrode plate 12 and winding the laminate in a roll shape. Positive electrode substrate end 14 is exposed on one long side of positive electrode plate 11, negative electrode substrate end 15 is exposed on one long side of negative electrode plate 12, and positive electrode substrate end and negative electrode substrate end are exposed. By winding the laminated body disposed so as to be located on the opposite long sides of the rectangular laminated body, the positive electrode substrate end portion 14 is placed on the other winding end surface (upper in the drawing) of the wound electrode plate group. The wound electrode plate group has a negative electrode substrate end 15 projecting from a wound end surface (lower side in the figure).
[0015]
FIG. 2 is a diagram schematically showing the internal structure of the cylindrical nickel-metal hydride storage battery according to the present invention provided with the wound electrode group 10 shown in FIG. A negative electrode substrate end portion in which a disk-like positive electrode current collecting terminal 16 is protruded from the end surface of the positive electrode substrate end portion 14 protruded from one winding end surface of the wound electrode group 10 and is protruded from the other winding end surface. A disc-shaped negative electrode current collecting terminal 17 is joined to each end face 15 by series spot welding. The positive electrode current collecting terminal 16 and the metal sealing lid 2 are connected by a metal lead plate 18. A cap 3 is joined to the metal sealing plate 2 and both are integrated to constitute a positive electrode terminal. The central portion of the negative electrode current collecting terminal 17 is joined to the inner surface of the bottom wall of the metal battery case 5 that also serves as the negative electrode terminal. 2 and 6 in FIG. 2 are through holes for discharging the gas accumulated inside when the pressure in the battery rises abnormally, and 8 is a rubber valve element arranged so as to close the through hole 6. is there.
[0016]
In the case of a battery for HEV power supply, since charging and discharging with a large current are repeated, even if forced air cooling is performed, the battery temperature rises because heat generated during energization is accumulated in the battery. For example, when an assembled battery composed of single-sized cells having a diameter of 32 to 34 mm, which has already been put into practical use, is actually mounted on a HEV and operated, the battery temperature is 20 ° C. to 30 ° C. compared to before operation. To rise. In the case of a nickel metal hydride storage battery, if the battery temperature exceeds 60 to 70 ° C., the charging efficiency is lowered and the discharge performance and durability are adversely affected. In a cylindrical nickel metal hydride storage battery, experience shows that heat accumulates and the temperature increases as the diameter of the battery increases. In particular, when the diameter of the unit cell exceeds 40 mm, the heat dissipation function of the battery is extremely lowered and the battery temperature rises significantly. Therefore, it is preferable to apply a unit cell having a diameter of less than 40 mm for the purpose of discharging or charging at a high rate like a HEV power source. Further, when the diameter of the unit cell is 20 mm or less, the active material filling amount is small, the capacity is lowered, and the output characteristics are also lowered.
[0017]
The positive electrode plate of the unit cell according to the present invention is a non-sintered electrode plate in which an active material powder mainly composed of nickel hydroxide is pasted and supported on a porous substrate, and the thickness thereof is Is preferably in the range of 0.2 to 0.5 mm, and more preferably in the range of 0.3 to 0.4 mm. If the electrode plate thickness is larger than 0.5 mm, there is a merit that the capacity can be increased, but the output characteristics are deteriorated. Therefore, it is not preferable for the present invention to achieve a nickel hydride storage battery having high output characteristics. Also. If the electrode plate thickness is smaller than 0.2 mm, the apparent working area of the electrode plate can be increased. However, since the active material filling amount is reduced, the discharge capacity is reduced and the output characteristics are also reduced. It is not preferable.
[0018]
The positive electrode plate 11 according to the present invention has a rectangular shape as shown in FIG. 3, and includes a portion 19 in which an active material powder mainly composed of nickel hydroxide is supported on a substrate and a substrate end provided on one long side. The portion consists of an exposed portion 14. High power density is achieved by setting the ratio (D / C) of the long side length D to the short side length C of the positive electrode plate 11 in the range of 16-23. It is preferable to set D / C in the range of 16 to 21 because a further excellent output density can be obtained.
[0019]
Further, the positive electrode plate 11 has a rectangular shape as shown in FIG. 3, and the short side length C is preferably set to 30 to 45 mm, and more preferably set to 35 to 45 mm. By adopting such a configuration, it is possible to provide a unit cell and a battery module having output characteristics superior to those of conventional batteries.
[0020]
As shown in FIG. 4, a battery module 30 according to the present invention includes a plurality of the cylindrical nickel-metal hydride batteries 1 arranged in series so that the centers of the cylinders of each battery form a straight line and connected in series. Between the adjacent batteries and the positive end terminal 33 and the battery adjacent thereto, a donut-shaped insulating plate 32 is arranged, and the adjacent batteries and the positive end terminal 33 and the positive terminal and negative electrode of the adjacent battery are arranged. The end terminal 34 and the negative electrode terminal of the battery adjacent thereto are connected by a metal connection ring 31.
[0021]
FIG. 5 is a diagram schematically showing a connection structure of the cylindrical nickel-metal hydride storage battery 1, the positive electrode end terminal 33, and the negative electrode end terminal 34 constituting the battery module 30 according to the present invention. One end of the metal connection ring is joined to one storage battery positive terminal (metal lid 2 in FIG. 2), and the other end is joined to the negative terminal (battery 4 in FIG. 2) of the adjacent battery. The positive electrode end terminal and the negative electrode end terminal are respectively connected to the positive electrode terminal and the negative electrode terminal of the adjacent storage battery via a connection ring.
[0022]
FIG. 6 is a view showing an outer shape of the cylindrical nickel-metal hydride storage battery 1 constituting the battery module 30 shown in FIGS. 4 and 5. 3 is a cap also serving as a positive electrode terminal, and 4 is a battery case also serving as a negative electrode terminal. In a single-size unit cell conventionally used, the ratio (A / B) between the shoulder height (A) and the diameter (B) shown in the figure is as large as 1.8 to 1.9. there were. On the other hand, in the case of the cylindrical nickel metal hydride storage battery constituting the battery module according to the present invention, the ratio (A / B) of the shoulder height (A) and the diameter (B) of the battery is 1.1 to It is preferably in the range of 1.5, and more preferably in the range of 1.2 to 1.5. By setting A / B to 1.5 or less, vibration or bending load (force) applied to the connection part between the single cells of the battery module can be reduced, and A / B is 1.1 or more. By doing so, it is possible to ensure excellent characteristics in the output characteristics of the unit cell.
[0023]
【Example】
The details of the present invention will be described below by way of an example. In addition, the shape of a single cell etc. are not limited to the example shown below.
(Production of single cell)
Example 1
Prepared a powder with an average particle size of 10 μm, in which a coating layer of cobalt hydroxide is formed on the surface of a core layer mainly composed of nickel hydroxide in which 3.7% by weight of Zn and 1.2% by weight of Co are dissolved as metal. did. The ratio of the coating layer in the powder was 7% by weight. 100 g of the powder was put into a sodium hydroxide aqueous solution having a temperature of 60 ° C. and a concentration of 10% by weight, and 45 ml of sodium hypochlorite solution was added with stirring to oxidize the powder. To the powder after the oxidation treatment, 20 g of an aqueous sodium hydroxide solution having a temperature of 80 ° C. and a concentration of 30% by weight was added and maintained at the same temperature for 2 hours with stirring, then washed with water and dried. When the average oxidation number of the transition metal elements (Ni and Co) contained in the obtained powder was measured, a value of 2.15 was obtained. The powder was used as an active material powder for a positive electrode (nickel electrode).
[0024]
An aqueous solution of carboxymethyl cellulose (CMC) was added to the positive electrode active material powder and kneaded to obtain a paste. The weight ratio of the active material powder and CMC contained in the paste was 99.5: 0.5. The paste has a thickness of 0.9 mm and a basis weight of 450 g / m. ² The positive electrode substrate made of nickel foam was filled. After being left to dry in an atmosphere at 80 ° C., press working was performed to obtain an electrode plate having a thickness of 0.4 mm. The electrode plate was cut into a rectangle (D / C≈16) having a short side length of 45 mm and a long side length of 720 mm. The active material was removed with a width of 1 mm on one long side, a substrate exposed portion was formed at the end of the long side of the substrate, the short side length of the active material filling portion was 44 mm, and the long side length was 720 mm. . The substrate exposed portion was pressed to a thickness of 0.05 mm, and a nickel hoop having a width of 1 mm and a thickness of 0.3 mm was joined to the entire surface of the substrate exposed portion by spot welding to obtain a positive electrode plate. From the active material filling amount, the capacity of the positive electrode plate was calculated to be 7.0 Ah.
[0025]
Average particle size 30μm, MmNi _3.6 Co _0.6 Al _0.3 Mn _0.35 (Mm represents Misch metal) A hydrogen storage alloy powder having a composition represented by an emulsion of SBR (styrene butadiene copolymer) is mixed at a weight ratio of 99.3: 0.7 on a dry basis to obtain a paste. I made it. After coating the paste on both sides of a negative electrode substrate made of a perforated steel plate made of a steel plate having an opening diameter of 1.0 mm and an aperture ratio of 45% and nickel-plated on the surface and having a thickness of 0.05 mm, in an atmosphere at 80 ° C. After being left to dry, it was pressed to obtain an electrode plate having a thickness of 0.3 mm. The electrode plate was cut into a rectangle having a short side length of 45 mm and a long side length of 800 mm. Remove the active material on both sides with a width of 1 mm on one long side, provide a negative electrode substrate exposed portion, and a negative electrode plate with a hydrogen storage alloy powder coating portion with a short side length of 44 mm and a long side length of 800 mm did. The capacity of the negative electrode plate calculated from the active material powder (hydrogen storage alloy powder) filling amount of the negative electrode plate was calculated to be 11.2 Ah.
[0026]
A strip-shaped separator made of a polypropylene nonwoven fabric having a thickness of 0.11 mm and a basis weight of 55 g was prepared by applying a sulfonation treatment by a known method. A separator was stacked on both surfaces of the single positive electrode plate, and a negative electrode plate was further stacked to form a rectangular laminate. The positive electrode substrate end was protruded from one long side of the laminate, and the negative substrate end was protruded from the other long side. The laminate was wound so that a positive electrode plate having a rod-shaped core body having a diameter of 3.5 mm as a core was inside, and a wound electrode group having a diameter of 30 mm was obtained.
[0027]
A donut-shaped positive electrode current collector terminal having a thickness of 0.2 mm, an outer shape of 29 mm, and an inner diameter of 4 mm was joined to the end surface of the positive electrode substrate that protruded from one wound end surface of the wound electrode plate group. A positive electrode lead plate made of nickel hoop having a thickness of 0.3 mm and a width of 2.5 mm was joined to the positive electrode current collecting terminal. A disc-shaped negative electrode current collector terminal having a thickness of 0.2 mm and an outer shape of 29.5 mm was joined to the end surface of the negative electrode substrate projected from the other wound end surface of the wound electrode plate group.
[0028]
After the electrode plate group with the current collector terminal attached is housed in a nickel-plated steel plate cylindrical battery case, the central portion of the negative current collector terminal is joined to the inner surface of the battery case, and the positive electrode lead plate A metal sealing plate fitted with a gas discharge valve, a cap and a gasket was joined to the plate. A predetermined amount of an alkaline electrolyte containing 6.8 moles of potassium hydroxide and 0.8 moles of lithium hydroxide is injected and sealed by a predetermined method, and the total height is 54 mm, shoulder height (A) is 50 mm, diameter (B ) A single cell with 32.5 mm and A / B of 1.5 was produced. This single cell is referred to as Example 1.
[0029]
(Example 2)
In Example 1, the positive electrode plate was cut so as to be a rectangle (D / C≈17) having a short side length of 42 mm and a long side length of 720 mm. The active material was removed with a width of 1 mm on one long side, a substrate exposed portion was formed at the end of the long side of the substrate, the short side length of the active material filling portion was 41 mm, and the long side length was 720 mm. . The negative electrode plate was cut into a rectangle having a short side length of 42 mm and a long side length of 800 mm. Remove the active material on both sides with a width of 1 mm on one long side, provide a negative electrode substrate exposed portion, and a negative electrode plate with a short side length of 41 mm and a long side length of 800 mm of the hydrogen storage alloy powder coating portion did. Others were the same as in Example 1. The capacity of the positive electrode plate was calculated to be 6.5 Ah, and the capacity of the negative electrode plate was calculated to be 10.4 Ah. The produced single cell had a total height of 51 mm, a shoulder height of 47 (A) mm, a diameter (B) of 32.5 mm, and an A / B of 1.4. This single cell is referred to as Example 2.
[0030]
(Example 3)
In Example 1, the positive electrode plate was cut into a rectangle (D / C≈19) having a short side length of 38 mm and a long side length of 720 mm. The active material was removed with a width of 1 mm on one long side, a substrate exposed portion was formed at the end of the long side of the substrate, the short side length of the active material filling portion was 37 mm, and the long side length was 720 mm. . The negative electrode plate was cut into a rectangle having a short side length of 38 mm and a long side length of 800 mm. Remove the active material on both sides with a width of 1 mm on one long side, provide a negative electrode substrate exposed portion, and a negative electrode plate with a hydrogen storage alloy powder coating portion with a short side length of 37 mm and a long side length of 800 mm did. Others were the same as in Example 1. The capacity of the positive electrode plate was calculated to be 5.8 Ah, and the capacity of the negative electrode plate was calculated to be 9.3 Ah. The produced single cell had a total height of 47 mm, a shoulder height (A) of 43 mm, a diameter (B) of 32.5 mm, and an A / B of 1.3. This single cell is referred to as Example 3.
[0031]
(Example 4)
In Example 1, the positive electrode plate was cut so as to be a rectangle (D / C≈21) having a short side length of 35 mm and a long side length of 720 mm. The active material was removed with a width of 1 mm on one long side, a substrate exposed portion was formed at the end of the long side of the substrate, the short side length of the active material filling portion was 34 mm, and the long side length was 720 mm. . Further, the negative electrode plate was cut into a rectangle having a short side length of 35 mm and a long side length of 800 mm. Remove the active material on both sides with a width of 1 mm on one long side, provide a negative electrode substrate exposed portion, and a negative electrode plate with a hydrogen storage alloy powder coating portion with a short side length of 34 mm and a long side length of 800 mm did. Others were the same as in Example 1. The capacity of the positive electrode plate was calculated to be 4.8 Ah, and the capacity of the negative electrode plate was calculated to be 7.8 Ah. The produced single cell had a total height of 44 mm, a shoulder height (A) of 40 mm, a diameter (B) of 32.5 mm, and an A / B of 1.2. This single cell is referred to as Example 4.
[0032]
(Example 5)
In Example 1, the positive electrode plate was cut into a rectangle (D / C≈24) having a short side length of 30 mm and a long side length of 720 mm. The active material was removed with a width of 1 mm on one long side, a substrate exposed portion was formed at the end of the long side of the substrate, the short side length of the active material filling portion was 29 mm, and the long side length was 720 mm. . Further, the negative electrode plate was cut into a rectangle having a short side length of 30 mm and a long side length of 800 mm. Remove the active material on both sides with a width of 1 mm on one long side, provide a negative electrode substrate exposed portion, and a negative electrode plate with a short side length of 29 mm and a long side length of 800 mm of the hydrogen storage alloy powder coating portion did. Others were the same as in Example 1. The capacity of the positive electrode plate was calculated to be 4.0 Ah, and the capacity of the negative electrode plate was calculated to be 6.4 Ah. The produced single cell had a total height of 39 mm, a shoulder height (A) of 35 mm, a diameter (B) of 32.5 mm, and an A / B of 1.1. This single cell is referred to as Example 5.
[0033]
(Comparative Example 1)
In Example 1, the positive electrode plate was cut into a rectangle (D / C≈28) having a short side length of 27 mm and a long side length of 720 mm. The active material was removed with a width of 1 mm on one long side, a substrate exposed portion was formed at the end of the long side of the substrate, the short side length of the active material filling portion was 26 mm, and the long side length was 720 mm. . The negative electrode plate was cut into a rectangle having a short side length of 27 mm and a long side length of 800 mm. Remove the active material on both sides with a width of 1 mm on one long side, provide a negative electrode substrate exposed portion, and a negative electrode plate with a hydrogen storage alloy powder coating portion with a short side length of 26 mm and a long side length of 800 mm did. Others were the same as in Example 1. The capacity of the positive electrode plate was calculated to be 3.0 Ah, and the capacity of the negative electrode plate was calculated to be 4.8 Ah. The produced single cell had a total height of 34 mm, a shoulder height (A) of 32 mm, a diameter (B) of 32.5 mm, and an A / B of 1.0. This single cell is referred to as Comparative Example 1.
[0034]
(Comparative Example 2)
In Example 1, the positive electrode plate was cut so as to be a rectangle (D / C≈15) having a short side length of 48 mm and a long side length of 720 mm. The active material was removed with a width of 1 mm on one long side, a substrate exposed portion was formed at the end of the long side of the substrate, the short side length of the active material filling portion was 47 mm, and the long side length was 720 mm. . The negative electrode plate was cut into a rectangle with a short side length of 48 mm and a long side length of 800 mm. Remove the active material on both sides with a width of 1 mm on one long side, provide a negative electrode substrate exposed portion, and a negative electrode plate with a short side length of 47 mm and a long side length of 800 mm of the hydrogen storage alloy powder coating portion did. Others were the same as in Example 1. The capacity of the positive electrode plate was calculated to be 7.5 Ah, and the capacity of the negative electrode plate was calculated to be 12.0 Ah. The produced single cell had a total height of 57 mm, a shoulder height (A) of 53 mm, a diameter (B) of 32.5 mm, and an A / B of 1.6. This single cell is referred to as Comparative Example 2.
[0035]
(Comparative Example 3)
In Example 1, the positive electrode plate was cut into a rectangle (D / C≈11) having a short side length of 64 mm and a long side length of 720 mm. The active material was removed with a width of 1 mm on one long side, a substrate exposed portion was formed at the end of the long side of the substrate, the short side length of the active material filling portion was 63 mm, and the long side length was 720 mm. . The negative electrode plate was cut into a rectangle having a short side length of 64 mm and a long side length of 800 mm. Remove the active material on both sides with a width of 1 mm on one long side, provide a negative electrode substrate exposed portion, and a negative electrode plate with a short side length of 63 mm and a long side length of 800 mm of the hydrogen storage alloy powder coating portion did. Others were the same as in Example 1. The capacity of the positive electrode plate was calculated to be 10.0 Ah, and the capacity of the negative electrode plate was calculated to be 16.0 Ah. The produced single cell had a total height of 73 mm, a shoulder height (A) of 69 mm, a diameter (B) of 32.5 mm, and an A / B of 2.1. This single cell is referred to as Example 3.
[0036]
(Comparative Example 4)
The nickel electrode paste applied to Example 1 is 1.6 mm thick and has a basis weight of 450 g / m. ² The positive electrode substrate made of nickel foam was filled. After being left to dry in an atmosphere at 80 ° C., press working was performed to obtain an electrode plate having a thickness of 0.6 mm. The electrode plate was cut into a rectangle (D / C≈11) having a short side length of 51 mm and a long side length of 560 mm. The active material was removed with a width of 1 mm on one long side, a substrate exposed portion was formed at the end of the long side of the substrate, the short side length of the active material filling portion was 50 mm, and the long side length was 560 mm. . The substrate exposed portion was pressed to a thickness of 0.05 mm, and a nickel hoop having a width of 1 mm and a thickness of 0.3 mm was joined to the entire surface of the substrate exposed portion by spot welding to obtain a positive electrode plate. From the active material filling amount, the capacity of the positive electrode plate was calculated to be 8.2 Ah.
[0037]
Both surfaces of a negative electrode substrate made of a perforated steel plate made of a steel plate having a thickness of 0.05 mm, the surface of which is nickel plated on the surface of the paste for a hydrogen storage alloy electrode applied to Example 1 with an opening diameter of 1.0 mm and a porosity of 45% After being coated, it was left to stand in an atmosphere of 80 ° C. and dried, and then pressed to obtain an electrode plate having a thickness of 0.45 mm. The electrode plate was cut into a rectangle having a short side length of 51 mm and a long side length of 640 mm. Remove the active material on both sides with a width of 1 mm on one long side, provide a negative electrode substrate exposed part, and a negative electrode plate with a short side length of 50 mm and a long side length of 640 mm of the hydrogen storage alloy powder coating part did. The capacity of the negative electrode plate calculated from the active material powder (hydrogen storage alloy powder) filling amount of the negative electrode plate was calculated to be 13.1 Ah. The produced single cell had a total height of 60 mm, a shoulder height (A) of 56 mm, a diameter (B) of 32.5 mm, and an A / B of 1.8. This battery is referred to as Example 3.
[0038]
(Chemical formation)
The cells according to Examples 1 to 5 and Comparative Examples 1 to 4 were aged in an atmosphere of 20 ° C. for 15 hours, charged with a current of 0.05 ItA for 20 hours, and further a current of 0.1 ItA. Then, the battery was discharged at a current of 0.1 ItA with a final voltage of 1.0. In the subsequent 2nd to 10th cycles, the battery was charged with a current of 0.1 ItA for 12 hours and then discharged with a current of 0.2 ItA and a final voltage of 1.0.
(Evaluation of discharge capacity)
After the formed unit cell was charged for 6 hours at a current of 0.2 ItA in an atmosphere of 20 ° C., the discharge capacity obtained when discharging to the end voltage of 1.0 V with the same current was measured. The discharge capacity of the storage battery was used.
(Energy density)
The average discharge voltage (V) and discharge capacity (Ah) when a single battery is discharged at 0.2 ItA in the atmosphere of 20 ° C. are defined as the energy (Wh) of the battery, and the energy is the weight (kg) of the battery. The energy density (Wh / kg) of the battery was taken as the value gradually decelerated.
[0039]
(Evaluation of output characteristics)
The unit cell in a fully charged state was discharged at a current of 0.2 ItA for 2.5 hours in an atmosphere at 20 ° C., and then discharged for 11 seconds at a discharge current of 1 ItA. The same operation was carried out in the range of 3 ItA to 10 ItA in increments of 2 ItA of discharge current (however, the discharge was cut off immediately when the discharge voltage fell below 0.5 V). Plot the measurement results with the X axis as the discharge current and the Y axis as the discharge voltage 10 seconds after the start of discharge (hereinafter simply referred to as the 10th voltage) to create a curve showing the relationship between the 10th voltage and the discharge current The discharge current value (A) when the voltage at the 10th second was 0.8 V was determined from the curve. A value obtained by multiplying the discharge current value by 0.8V is the output (W) of the battery, and a value obtained by gradually grading the output (W) by the weight (kg) of the battery is the output density (W / kg) of the battery. did.
The results are shown in Table 1.
[0040]
[Table 1]

[0041]
As shown in Table 1, the example according to the present invention exceeds the comparative example in terms of power density, and indicates that the weight of the assembled battery can be reduced as compared with the comparative example. Also, in Example 5, which is the smallest battery in the examples, the output of the unit cell is 75 W, and if an assembled battery is configured by applying the 200 unit cells, it is required for the HEV power source. An output of 15 kW at the maximum load can be satisfied. On the other hand, Comparative Example 1 has a small output and requires 246 or more single cells to satisfy the same load.
[0042]
On the other hand, Comparative Examples 2 to 4 are satisfactory in output but have a large excess of capacity, and there is a drawback that the weight and volume of the battery are increased by increasing the capacity. Examples 1 to 3 and Comparative Example 2 Compared with Comparative Example 3, the output (W) increases as the short side length of the positive electrode is increased and the capacity of the unit cell is increased, but the increase width is gradually increased. It can be seen that the difference between Example 1, Comparative Example 2, and Comparative Example 3 is small and the output tends to be saturated. On the other hand, as the short side length of the positive electrode is increased (D / C is decreased), the battery weight and volume continue to increase, so the battery output density (W / kg, W / l) decreases. . FIG. 7 is a graph showing the results of graphing the relationship between the output density and D / C among the test results of the above-described examples and comparative examples. As can be seen from the figure, when D / C is 16 to 24, a high output density of 750 W / kg or more, which is the target of the present invention, can be obtained. Furthermore, it is preferable that D / C is 16 to 21 because an extremely high power density exceeding 800 W / kg can be obtained.
[0043]
As shown in the results of Example 1 to Example 5 in Table 1, the length of the short side of the rectangular positive plate is set to 30 to 45 mm, more preferably 35 to 45 mm, which is higher than the comparative example. A single battery having an output density can be obtained, and a battery module and an assembled battery having a high output density can be obtained by applying the single battery.
[0044]
In Comparative Example 4, the thickness of the positive electrode plate is 0.6 mm (the thickness of the positive electrode plate in Examples and Comparative Examples 1 to 3 is 0.4 mm), as in the case of a conventional single-size unit cell. This is an example in which the length of the short side of the plate is 51 mm, but the energy density (Wh / kg) is high but the output density (W / kg) is low.
[0045]
FIG. 8 is a graph showing the result of graphing the relationship between the output density and the unit cell capacity among the test results of the examples and comparative examples. As can be seen from the figure, when the unit cell capacity is 4 to 7 Ah, a high output density of 750 W / kg or more is preferably obtained. When the cell capacity is 5 to 7 Ah, a high output density exceeding 800 W / kg is obtained, which is more preferable.
[0046]
FIG. 9 is a graph showing the relationship between the energy density and the unit cell capacity among the test results of the examples and comparative examples. As can be seen from the figure, when D / C is 24 or less, an energy density exceeding 45 Wh / kg is obtained, and when D / C is 21 or less, an energy density exceeding 50 Wh / kg is obtained. Therefore, in order to obtain a unit cell having both excellent output characteristics and energy density, the D / C is preferably 16 to 24, and more preferably 16 to 21.
[0047]
(Production of battery module)
As shown in FIG. 4, six unit cells described in Examples 1 to 6 and Comparative Examples 1 to 3 are arranged in a straight line and connected to a series, and the voltage is 7.2V. did. For connection between adjacent batteries, a nickel-plated steel plate having a thickness of 0.2 mm and having a cross-sectional shape shown in FIG. 5 is used, and one end of the connection ring is connected to the adjacent battery. Of these, four points were joined at equal intervals to the metal sealing plate of one battery by spot welding, and the other end was joined to the side surface of the battery case of the other battery at four points at equal intervals by spot welding. Further, a positive end terminal and a negative end terminal were attached to both ends of the battery module as shown in FIG. This battery module was made to correspond to the classification of the single cell applied to its production, and it was set as Example 1 to Example 5 and Comparative Example 1 to Comparative Example 4, respectively.
[0048]
(Battery module load resistance evaluation)
The battery module is horizontally placed on two fulcrums arranged at positions supporting both ends of the battery module, and a weight of 5 kg is suspended through a hanging string in the center of the module, and the connection of the battery module is damaged. It was examined whether it occurred.
The results are shown in Table 2.
[0049]
[Table 2]

[0050]
As shown in Table 2, in the case of a comparative example, except for Comparative Example 1, Comparative Examples 2 to 4 are inferior in load resistance. In the case of Example and Comparative Example 1, since the unit cell's own weight is smaller than that of Comparative Example 2 to Comparative Example 4, and the length of the unit cell is small and the interval between the connection parts is small, it is added to the connection part. It is considered that load resistance is high because the addition (force) is reduced. Thus, in order to increase the load resistance of the battery module, it is preferable that the ratio (A / B) between the shoulder height and the diameter of the unit cell is 1.5 or less. In the case of Example and Comparative Example 1, the deflection when mounted horizontally is small and the reliability with respect to vibration and acceleration is high. However, although Comparative Example 1 is excellent in load resistance, as shown in the results of Table 1, the output is small and the output density is low. Further, as shown in Table 1, since excellent output characteristics exceeding 800 W / Kg can be obtained in Examples 1 to 4, the A / B of the unit cell constituting the battery module according to the present invention is 1 It can be seen that it is preferably 0.1 to 1.5, more preferably 1.2 to 1.5.
[0051]
Although omitted in the table, the weight of the battery module of Comparative Example 4 composed of six conventional single-sized single cells is 1100 g, whereas the weight of the battery module of Example 2 is 800 g. The weight of Example 2 is reduced by about 27% compared to Example 4, and the volume of the battery module of Comparative Example 4 is 287 ml, whereas the volume of the battery module of Example 2 is 242 ml. Was 16% smaller. Further, in W / l, the battery module of Comparative Example 4 was 270 W / l, whereas Example 2 was significantly improved to 460 W / l. Thus, the battery module according to the present invention exhibits a remarkable effect in reducing the weight and volume of the battery by improving the output characteristics (W / kg, W / l) of the single battery.
[0052]
Although details are omitted in this specification, the cylindrical nickel-metal hydride storage battery according to the present invention and the battery module and the assembled battery formed by applying the same are charged when charged at a higher rate than conventional batteries. It turned out that it was excellent also in performance.
【The invention's effect】
[0053]
Main departure Clearly According to this, a cylindrical nickel-metal hydride storage battery (single potential) having a high output density can be obtained. In addition, by applying the unit cell, it is possible to reduce the size and weight of the battery module that requires high output and the assembled battery including the battery module.
[0054]
Main departure Clearly According to this, a battery module in which a plurality of cylindrical nickel-metal hydride storage batteries are connected in a straight line, which is strong against an external force such as vibration or bending, can be obtained.
[Brief description of the drawings]
FIG. 1 is a perspective view of a group of electrode plates according to the present invention.
FIG. 2 is a cross-sectional view schematically showing the internal structure of a nickel metal hydride storage battery according to the present invention.
FIG. 3 is a plan view showing the shape of a positive electrode plate of a nickel metal hydride storage battery according to the present invention.
FIG. 4 is a perspective view schematically showing the external appearance of a battery module according to the present invention.
FIG. 5 is a diagram schematically showing a configuration of a battery module according to the present invention.
FIG. 6 is a front view showing an appearance of a cylindrical nickel-metal hydride storage battery according to the present invention.
FIG. 7 is a graph showing the relationship between the output density of a cylindrical nickel-metal hydride storage battery and D / C.
FIG. 8 is a graph showing the relationship between the power density of a cylindrical nickel-metal hydride storage battery and the battery capacity.
FIG. 9 is a graph showing the relationship between the energy density of a cylindrical nickel-metal hydride storage battery and D / C.
[Explanation of symbols]
1 Cylindrical nickel metal hydride storage battery
10 Winding plate group
11 Positive electrode plate
12 Negative electrode plate
13 Separator
14 Exposed part of positive electrode substrate
15 Negative substrate exposed part
30 Battery module
31 Connection ring
32 Insulation ring

Claims

It has a rectangular positive electrode plate and a negative electrode plate carrying an active material on a metallic substrate, with the positive electrode substrate end exposed on one long side of the positive electrode plate, and the negative electrode substrate end on one long side of the negative electrode plate A winding type in which a separator is disposed between the positive electrode plate and the negative electrode plate, and the laminate is wound with the positive electrode substrate end protruding on one long side and the negative electrode substrate end protruding on the other long side. In a cylindrical alkaline storage battery in which a positive electrode current collector terminal is joined to an end surface of the positive electrode substrate end portion of the electrode plate group and a negative electrode current collector terminal is joined to an end surface of the negative electrode substrate end portion, the length (D) of the long side of the positive electrode plate And the ratio (D / C) of the length (C) of the short side is 16 to 24 , the length of the short side of the positive electrode plate is 30 mm to 45 mm, and the capacity is 4 to 7 Ah. Cylindrical nickel-metal hydride storage battery.

2. The cylindrical nickel-metal hydride storage battery according to claim 1, wherein the ratio (A / B) of the shoulder height (A) to the diameter (B) of the cylindrical nickel-metal hydride storage battery is 1.1 to 1.5 .

An assembled battery comprising a battery module including a plurality of the cylindrical nickel-metal hydride storage batteries according to claim 1 .