JP3588265B2

JP3588265B2 - Cylindrical secondary battery

Info

Publication number: JP3588265B2
Application number: JP04371199A
Authority: JP
Inventors: 広一佐藤; 直哉中西; 俊之能間; 育郎米津
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 1999-02-22
Filing date: 1999-02-22
Publication date: 2004-11-10
Anticipated expiration: 2019-02-22
Also published as: JP2000243373A

Description

【０００１】
【発明の属する技術分野】
本発明は、筒状の電池缶の内部に巻き取り電極体が収容されて、電池缶に取り付けられた電極端子機構から巻き取り電極体の発生電力を取り出すことが可能な筒型二次電池に関するものである。
【０００２】
【従来の技術】
近年、携帯型電子機器、電気自動車等の電源として、エネルギー密度が高く、然もカドミウムや鉛の如き有害物質を含まないリチウム二次電池が注目されている。
例えば電気自動車に用いられる比較的大きな容量の円筒型リチウム二次電池は、図３に示す様に、筒体（１１）の開口部に蓋体（１２）を溶接固定してなる円筒状の電池缶（１）の内部に、巻き取り電極体（２）を収容して構成されている。蓋体（１２）には、電極端子機構（９）が取り付けられており、巻き取り電極体（２）と電極端子機構（９）とが複数本の集電タブ（３）により互いに接続されて、巻き取り電極体（２）が発生する電力を電極端子機構（９）から外部に取り出すことが可能となっている。又、蓋体（１２）にはバネ復帰式の安全弁（１３）が取り付けられている。
尚、筒体（１１）の他方の開口部に固定された蓋体（図示省略）にも同じ構成の電極端子機構が取り付けられて、両電極端子機構が正負一対を為している。
【０００３】
巻き取り電極体（２）は、リチウム複合酸化物を含む正極（２１）と炭素材料を含む負極（２３）の間に、非水電解液が含浸されたセパレータ（２２）を介在させて、これらを渦巻き状に巻回して構成されている。巻き取り電極体（２）の正極（２１）及び負極（２３）からは夫々複数本の集電タブ（３）が引き出され、極性が同じ複数本の集電タブ（３）の先端部（３１）が１つの電極端子機構（９）に接続されている。
尚、図３は、一部の集電タブの先端部が電極端子機構（９）に接続されている状態を示し、他の集電タブについては、電極端子機構（９）との接続部を図示省略している。
【０００４】
電極端子機構（９）は、電池缶（１）の蓋体（１２）を貫通して取り付けられたネジ部材（９１）を具え、該ネジ部材（９１）の基端部にはフランジ部（９２）が形成されている。蓋体（１２）の貫通孔には、例えばポリプロピレン製の絶縁パッキン（９３）が装着され、蓋体（１２）と締結部材（９１）の間の電気的絶縁性とシール性が保たれている。ネジ部材（９１）には、筒体（１１）の外側からワッシャ（９４）が嵌められると共に、第１ナット（９５）及び第２ナット（９６）が螺合している。第１ナット（９５）を締め付けて、ネジ部材（９１）のフランジ部（９２）とワッシャ（９４）によって絶縁パッキン（９３）を挟圧することにより、シール性を高めている。
前記複数本の集電タブ（３）の先端部（３１）は、ネジ部材（９１）のフランジ部（９２）の裏面に、スポット溶接或いは超音波溶接によって連結されている（特開平９−２９８０５５号参照）。
【０００５】
尚、複数本の集電タブ（３）の先端部を電極端子機構に連結する方法としては、電極端子機構のフランジ部に対向させて円板状の挟圧部材を設け、該フランジ部と挟圧部材の間に、集電タブ（３）の先端部を挟持する方法がある。
【０００６】
【発明が解決しようとする課題】
しかしながら、図３に示す従来の円筒型二次電池においては、電池の高出力化を図るために集電タブ（３）を厚く形成した場合、複数本の集電タブ（３）をネジ部材（９１）のフランジ部（９２）に溶接するときに、熱が周囲に逃げて、溶接部の温度が十分に上がらないので、溶接が困難である問題があった。又、スポット溶接や超音波溶接では、集電タブ（３）とフランジ部（９２）との間に十分な接触面積を得ることが出来ず、この結果、接触抵抗が大きくなって、ジュール熱による損失が発生する問題があった。
【０００７】
一方、集電タブ（３）の先端部をフランジ部と挟圧部材の間に挟持する方法では、ネジ部材（９１）を締め付けて集電タブ（３）の先端部を挟圧するときに、挟圧部材の伴回りを阻止することが必要であるが、複数本の集電タブ（３）が挟圧部材の周囲を包囲しているため、集電タブ（３）が邪魔になって、挟圧部材に回り止めを施す作業が困難である問題があった。
【０００８】
本発明の目的は、集電タブと電極端子機構との間に十分な接触面積を得ることが出来、然も、電極端子機構の組立が容易となる筒型二次電池を提供することである。
【０００９】
【課題を解決する為の手段】
本発明に係る筒型二次電池は、筒体（１１）の開口部に蓋体（１２）を固定してなる電池缶（１）の内部に、巻き取り電極体（２）が収容され、蓋体（１２）には、蓋体（１２）に対して電気的絶縁と気密性を保って電極端子機構（４）が取り付けられ、巻き取り電極体（２）と電極端子機構（４）とが、複数本の集電タブ（３）により互いに接続されている。
電極端子機構（４）は、
蓋体（１２）に開設された中央孔（１８）を貫通して配置され、蓋体（１２）の外側へ突出するねじ軸部（５３）と、蓋体（１２）の内側に位置するフランジ部（５１）とを具えた端子部材（５）と、
蓋体（１２）から突出する端子部材（５）のねじ軸部（５３）に螺合するナット（８）と、
端子部材（５）のフランジ部（５１）に係合して固定され、該フランジ部（５１）と対向する平板部（６３）を具えて、該平板部（６３）には中央孔（６１）が開設されているキャップ部材（６）
とを具え、巻き取り電極体（２）から引き出された複数本の集電タブ（３）の先端部は、キャップ部材（６）の中央孔（６１）から平板部（６３）の内面へ伸びて、該内面と端子部材（５）のフランジ部（５１）の間に挟持されている。
【００１０】
尚、キャップ部材（６）は、アルミニウム、ニッケル、銅、若しくはこれらの中から選ばれた複数の金属の合金から形成することが出来る。
【００１１】
上記本発明の筒型二次電池においては、端子部材（５）のねじ軸部（５３）に対してナット（８）を締め付けることによって、電極端子機構（４）が蓋体（１２）に固定される。又、端子部材（５）のフランジ部（５１）に対し、キャップ部材（６）を固定する際、フランジ部（５１）とキャップ部材（６）の平板部（６３）の間に、集電タブ（３）の先端部を挟み込んで挟圧することによって、集電タブ（３）が電極端子機構（４）に連結される。
ここで、各集電タブ（３）の先端部は、端子部材（５）のフランジ部（５１）とキャップ部材（６）の平板部（６３）の間に十分な接触面積で挟持されるので、接触抵抗は小さくなる。又、複数本の集電タブ（３）はそれぞれ、キャップ部材（６）の平板部（６３）の中央孔（６１）から平板部（６３）の内面（フランジ部（５１）との対向面）へ伸びているので、キャップ部材（６）の周囲が複数本の集電タブ（３）によって包囲されることはなく、キャップ部材（６）の外周面は露出する。従って、端子部材（５）のフランジ部（５１）をキャップ部材（６）に固定する作業において、キャップ部材（６）を周囲から挟持することが可能となり、作業が容易となる。
【００１２】
具体的には、キャップ部材（６）は、平板部（６３）の外周部に端子部材（５）側へ突出する筒部（６４）を具え、該筒部（６４）に対して端子部材（５）のフランジ部（５１）がねじ込まれて固定されている。
該具体的構成によれば、キャップ部材（６）の筒部（６４）に対して端子部材（５）のフランジ部（５１）をねじ込む際、ねじ込みトルクを調整することによって、集電タブ（３）の先端部を確実に挟持することが出来る。
【００１３】
又、具体的構成において、複数本の集電タブ（３）の先端部は、キャップ部材（６）の平板部（６３）の内面に、抵抗溶接若しくは超音波溶接によって仮り止めされる。
これによって、キャップ部材（６）に端子部材（５）のフランジ部（５１）を固定する作業が容易となる。
【００１４】
更に具体的には、キャップ部材（６）の平板部（６３）の中央孔（６１）の開口面積は、平板部（６３）の外周縁で包囲された面積の８０％以下である。
該具体的構成によれば、集電タブ（３）の先端部が十分な接触面積でキャップ部材（６）の平板部（６３）と端子部材（５）のフランジ部（５１）の間に挟持されて、接触抵抗が小さくなり、この結果、高い出力特性が得られる。
【００１５】
【発明の効果】
本発明に係る筒型二次電池によれば、集電タブと電極端子機構との間に十分な接触面積を得ることが出来るので、電池の内部抵抗が低減して、特に大電流を流したときの出力特性を改善することが出来る。然も、キャップ部材に端子部材のフランジ部を固定する作業においては、集電タブに邪魔されることなく、キャップ部材を周囲から挟持することが出来るので、電極端子機構の組立が容易となる。
【００１６】
【発明の実施の形態】
以下、本発明を円筒型二次電池に実施した例につき、図面に沿って具体的に説明する。
本発明に係る円筒型二次電池は、図１に示す如く、筒体（１１）の両開口部にそれぞれ蓋体（１２）を溶接固定してなる円筒状のアルミニウム製電池缶（１）の内部に、巻き取り電極体（２）を収容して構成されている。
尚、電池缶（１）の外径は６５ｍｍ、長さは３００ｍｍであって、蓋体（１２）の厚さは３ｍｍに形成されている。又、電池容量は、７０Ａｈ（０．１２５Ｃ充電）である。
【００１７】
巻き取り電極体（２）は、正極集電体となるアルミニウム箔の表面にリチウム複合酸化物を含む正極層を形成してなる正極と、負極集電体となる銅箔の表面に炭素粉末を含む負極層を形成してなる負極との間に、非水電解液が含浸されたセパレータを介在させて、これらを渦巻き状に巻回したものであって、正極からは１４本のアルミニウム製の集電タブが引き出されている。又、負極からは１４本の銅製の集電タブが引き出されている。尚、正極側の集電タブは厚さ１００μｍに、負極側の集電タブは厚さ８０μｍに形成されている。
各蓋体（１２）には、電極端子機構（４）が取り付けられており、巻き取り電極体（２）と各電極端子機構（４）とがそれぞれ、前記１４本の集電タブ（３）により互いに接続されて、巻き取り電極体（２）が発生する電力を一対の電極端子機構（４）（４）から外部に取り出すことが可能となっている。
【００１８】
又、蓋体（１２）には、図２に示す如く、電極端子機構（４）が貫通すべき断面円形の中央孔（１８）が開設され、中央孔（１８）の両側には、組立時に電解液注入のために用いるねじ孔（１７）と、リング部材（１４ａ）及び弁膜（１４ｂ）からなる圧力開放型の安全弁（１４）を取り付けるための圧力逃し孔（１５）が開設されている。尚、電解液の注入後、ねじ孔（１７）にはねじ栓（１６）がねじ込まれる。又、安全弁（１４）は、蓋体（１２）の圧力逃し孔（１５）の開口縁にて溶接固定される。
【００１９】
正極側の電極端子機構（４）は、蓋体（１２）を貫通して取り付けられるアルミニウム製の端子部材（５）を具えている。端子部材（５）は、蓋体（１２）に開設された中央孔（１８）を貫通する円柱部（５２）と、円柱部（５２）に上向きに突設されたねじ軸部（５３）と、円柱部（５２）の下端部に形成されたフランジ部（５１）とから構成され、フランジ部（５１）の上面には、フッ素樹脂製のＯリング（７２）が嵌まるリング溝（５４）が凹設されている。又、フランジ部（５１）の外周面には、外ねじ（５５）が形成されている。
【００２０】
端子部材（５）のフランジ部（５１）には、アルミニウム製のキャップ部材（６）が螺合している。キャップ部材（６）は、中央孔（６１）が開設された平板部（６３）の外周部に筒部（６４）を上向きに突設したもので、筒部（６４）の内周面に、前記端子部材（５）の外ねじ（５５）が螺合する内ねじ（６２）が形成されている。
尚、キャップ部材（６）の中央孔（６１）の内径Ａは２０ｍｍ、筒部（６４）の外径Ｂは４０ｍｍである。
【００２１】
又、電極端子機構（４）は、蓋体（１２）と端子部材（５）のフランジ部（５１）との間に介在する第１パッキン部材（７）を具えている。第１パッキン部材（７）は、ポリプロピレン、ポリエチレン、テフロン、若しくはフッ素樹脂を用いて一体成型され、蓋体（１２）と端子部材（５）のフランジ部（５１）によって挟圧される円板部（７４）と、該円板部（７４）の上面に上向きに突設された円筒部（７５）とから構成され、中央孔（７７）を有している。第１パッキン部材（７）の円筒部（７５）は、蓋体（１２）の中央孔（１８）を貫通して、筒体（１１）の上面から僅かに突出する。
【００２２】
更に、第１パッキン部材（７）の蓋体（１２）との対向面には、フッ素樹脂製のＯリング（７３）が嵌まるリング溝（７６）が凹設されている。
尚、第１パッキン部材（７）の端子部材（５）との対向面や、蓋体（１２）の内面にも、それぞれ前記Ｏリング（７２）（７３）が嵌まるリング溝（図示省略）が凹設されている。
【００２３】
蓋体（１２）の上面に突出した第１パッキン部材（７）の円筒部（７５）には、テフロン製のリング状第２パッキン部材（７１）が係合する。
更に、蓋体（１２）の中央孔（１８）から突出する端子部材（５）のねじ軸部（５３）には、アルミニウム製のワッシャ（８１）が嵌められ、更にその上部に、アルミニウム製のナット（８）が螺合され、締め付けられる。
負極側の電極端子機構（４）も、端子部材（５）及びキャップ部材（６）をニッケル製とする以外は同様の構成を有している。
【００２４】
上記円筒型リチウム二次電池の組立工程においては、電池缶（１）を構成すべき蓋体（１２）に電極端子機構（４）を取り付ける一方、筒体（１１）の内部に巻き取り電極体（２）を装入した状態で、巻き取り電極体（２）から伸びる複数本の集電タブ（３）の先端部をキャップ部材（６）の中央孔（６１）から平板部（６３）の内面（端子部材（５）との対向面）へ導いて、該先端部を平板部（６３）の内面に３点でスポット溶接して仮止めする。
次に、キャップ部材（６）に対して、端子部材（５）のフランジ部（５１）をねじ込み、集電タブ（３）の先端部を、端子部材（５）のフランジ部（５１）とキャップ部材（６）の平板部（６３）の間に挟持する。尚、ねじ込みは、５０Ｋｇｆ・ｃｍのトルクで行なうことが出来る。
その後、蓋体（１２）を筒体（１１）の開口部に被せて、両者を互いに溶接固定する。そして、蓋体（１２）のねじ孔（１７）から電池缶（１）内に電解液を注入した後、ねじ孔（１７）にねじ栓（１６）をねじ込み、更にナット（８）を増し締めして、組立を完了する。
これによって、図１に示す円筒型二次電池が完成する。
【００２５】
上記円筒型二次電池においては、第１パッキン部材（７）によって、電池缶（１）の蓋体（１２）と端子部材（５）との間の電気的絶縁性が保たれると共に、第２パッキン部材（７１）によって、蓋体（１２）とワッシャ（８１）の間の電気的絶縁性が保たれる。又、Ｏリング（７２）（７３）によって、電池缶（１）の蓋体（１２）と端子部材（５）の間の気密性が保たれる。
【００２６】
上記円筒型二次電池においては、各集電タブ（３）の先端部が、端子部材（５）のフランジ部（５１）とキャップ部材（６）の平板部（６３）の間に十分な接触面積で挟持されるので、接触抵抗は小さくなる。この結果、従来よりも大きな電池出力が得られる。
又、複数本の集電タブ（３）はそれぞれ、キャップ部材（６）の平板部（６３）の中央孔（６１）から平板部（６３）の内面（フランジ部（５１）との対向面）へ伸びているので、キャップ部材（６）の周囲が複数本の集電タブ（３）によって包囲されることはなく、キャップ部材（６）の外周面は露出する。従って、端子部材（５）をキャップ部材（６）にねじ込む作業において、キャップ部材（６）を周囲から挟持することが可能となり、電極端子機構（４）の取り付け作業が容易となる。
【００２７】
上記本発明の円筒型二次電池の性能を従来の円筒型二次電池と比較するべく、本発明電池Ａを作製すると共に、図３に示す従来例電池Ｂを作製した。該従来例電池の電池缶の外径は６５ｍｍ、長さは３００ｍｍである。
従来例電池の巻き取り電極体（２）は本発明電池Ａと同一構成であって、巻き取り電極体から引き出された１４本の厚さ５０μｍのアルミニウム製集電タブ（３）をアルミニウム製のフランジ部（９２）の裏面に５点でスポット溶接した。又、巻き取り電極体から引き出された１４本の厚さ４０μｍの銅製集電タブ（３）をニッケル製のフランジ部（９２）の裏面に５点でスポット溶接した。
【００２８】
そして、本発明電池Ａと従来例電池Ｂについて、下記に示す条件で充放電サイクルを１０回繰り返した。
充放電サイクル条件
充電：（充電レート）０．１２５Ｃ（終止電圧）４．１Ｖ
放電：（放電レート）０．５Ｃ（終止電圧）２．７Ｖ
定格容量：７０Ａｈ
【００２９】
その後、本発明電池Ａと従来例電池Ｂについて、０．１２５Ｃで４．１Ｖまで充電を行なった後、０．５Ｃで放電深度５０％まで放電を行ない、続いて、以下の条件で出力特性試験を行なった。尚、出力値は３Ｃのときの値を用いた。
出力特性試験条件
放電レート：０．５Ｃ、１Ｃ、２Ｃ、３Ｃ
放電時間：１０秒
【００３０】
出力特性試験の結果を表１に示す。
【００３１】
【表１】

【００３２】
表１から明らかな様に、本発明電池Ａは従来例電池Ｂに比べて高い出力特性値を示している。これは、本発明電池の集電タブと端子部材との間の接触抵抗が従来例電池よりも小さくなったためであると考えられる。
【００３３】
次に、上記本発明電池に装備した巻き取り電極体と同一の巻き取り電極体を用いて、キャップ部材（６）の中央孔（６１）の大きさが異なる５種類の本発明電池を作製した。即ち、キャップ部材（６）の平板部（６３）の外周縁で包囲された円形の面積に対する中央孔（６１）の開口面積の比（開口面積比）を、６％、２５％、６０％、８０％、９０％に変化させた。
これらの電池に対し、上記と同じ条件で出力特性試験を行なった。その結果を表２に示す。
【００３４】
【表２】

【００３５】
表２から明らかな様に、開口面積比が８０％を越えると、出力が大きく低下している。これは、キャップ部材（６）の中央孔（６１）の開口が大きいために、集電タブの先端部とキャップ部材の間に十分な接触面積を確保することが出来ず、電池の内部抵抗が大きくなったためであると考えられる。
従って、電池の内部抵抗を低減させて高い出力特性を得るためには、開口面積比を８０％以下に抑えることが好ましい。
【００３６】
尚、本発明の各部構成は上記実施の形態に限らず、特許請求の範囲に記載の技術的範囲内で種々の変形が可能である。例えば、キャップ部材（６）の筒部（６４）の外周面は円筒面に限らず、多角筒面に形成することも可能であり、これによってキャップ部材（６）の回り止めが更に容易となる。
又、集電タブ（３）の先端部をキャップ部材（６）の平板部（６３）に溶接等によって仮止めする構成は、必ずしも必要ではない。更に、キャップ部材（６）をフランジ部（５１）に固定する構造は、ネジ止め固定に限らず、溶接固定等、種々の固定構造を採用することが可能である。
【図面の簡単な説明】
【図１】本発明に係る円筒型二次電池の要部を示す断面図である。
【図２】該円筒型二次電池に装備される電極端子機構の分解斜視図である。
【図３】従来の円筒型二次電池の要部を示す断面図である。
【符号の説明】
（１）電池缶
（１１）筒体
（１２）蓋体
（２）巻き取り電極体
（３）集電タブ
（４）電極端子機構
（５）端子部材
（５１）フランジ部
（５２）円柱部
（５３）ねじ軸部
（５５）外ねじ
（６）キャップ部材
（６１）中央孔
（６２）内ねじ
（６３）平板部
（６４）筒部
（７）第１パッキン部材
（７１）第２パッキン部材
（８１）ワッシャ
（８）ナット[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a cylindrical secondary battery in which a wound electrode body is housed inside a cylindrical battery can, and power generated by the wound electrode body can be taken out from an electrode terminal mechanism attached to the battery can. Things.
[0002]
[Prior art]
In recent years, lithium secondary batteries that have a high energy density and do not contain harmful substances such as cadmium and lead have attracted attention as power sources for portable electronic devices and electric vehicles.
For example, as shown in FIG. 3, a cylindrical lithium secondary battery having a relatively large capacity used in an electric vehicle is a cylindrical battery having a lid (12) welded and fixed to an opening of a cylinder (11). The winding electrode body (2) is accommodated in the can (1). An electrode terminal mechanism (9) is attached to the lid (12), and the winding electrode body (2) and the electrode terminal mechanism (9) are connected to each other by a plurality of current collecting tabs (3). The power generated by the winding electrode body (2) can be taken out from the electrode terminal mechanism (9). The lid (12) is provided with a spring-return type safety valve (13).
An electrode terminal mechanism of the same configuration is also attached to a lid (not shown) fixed to the other opening of the cylindrical body (11), and the two electrode terminal mechanisms form a pair of positive and negative electrodes.
[0003]
The wound electrode body (2) has a separator (22) impregnated with a non-aqueous electrolyte interposed between a positive electrode (21) containing a lithium composite oxide and a negative electrode (23) containing a carbon material. Is spirally wound. A plurality of current collecting tabs (3) are respectively drawn from the positive electrode (21) and the negative electrode (23) of the winding electrode body (2), and the leading end portions (31) of the plurality of current collecting tabs (3) having the same polarity. ) Are connected to one electrode terminal mechanism (9).
FIG. 3 shows a state in which the tip of a part of the current collecting tab is connected to the electrode terminal mechanism (9), and the other current collecting tab is connected to the electrode terminal mechanism (9). Illustration is omitted.
[0004]
The electrode terminal mechanism (9) includes a screw member (91) attached through the lid (12) of the battery can (1), and a flange portion (92) is provided at a base end of the screw member (91). ) Is formed. An insulating packing (93) made of, for example, polypropylene is mounted in the through-hole of the lid (12), and electrical insulation and sealing between the lid (12) and the fastening member (91) are maintained. . A washer (94) is fitted into the screw member (91) from the outside of the cylinder (11), and a first nut (95) and a second nut (96) are screwed together. By tightening the first nut (95) and pressing the insulating packing (93) between the flange portion (92) of the screw member (91) and the washer (94), the sealing performance is improved.
The tip portions (31) of the plurality of current collecting tabs (3) are connected to the back surface of the flange portion (92) of the screw member (91) by spot welding or ultrasonic welding (Japanese Patent Laid-Open No. 9-298055). No.).
[0005]
In addition, as a method of connecting the tip portions of the plurality of current collecting tabs (3) to the electrode terminal mechanism, a disk-shaped pressure member is provided so as to face the flange portion of the electrode terminal mechanism, and the flange portion is sandwiched. There is a method of sandwiching the tip of the current collecting tab (3) between the pressure members.
[0006]
[Problems to be solved by the invention]
However, in the conventional cylindrical secondary battery shown in FIG. 3, when the current collecting tab (3) is formed thick in order to increase the output of the battery, a plurality of current collecting tabs (3) are screwed with a screw member ( When welding to the flange portion (92) of (91), heat escapes to the surroundings, and the temperature of the welded portion does not rise sufficiently, so that there is a problem that welding is difficult. Further, in the spot welding or the ultrasonic welding, a sufficient contact area between the current collecting tab (3) and the flange portion (92) cannot be obtained, and as a result, the contact resistance increases and the Joule heat is generated. There was a problem that loss occurred.
[0007]
On the other hand, in the method in which the distal end of the current collecting tab (3) is clamped between the flange portion and the clamping member, when the screw member (91) is tightened to clamp the distal end of the current collecting tab (3), Although it is necessary to prevent the entrainment of the pressure member, since the plurality of current collection tabs (3) surround the periphery of the pressure member, the current collection tab (3) hinders the pinch. There has been a problem that it is difficult to perform the work of stopping the rotation of the pressure member.
[0008]
An object of the present invention is to provide a cylindrical secondary battery that can obtain a sufficient contact area between the current collecting tab and the electrode terminal mechanism, and can easily assemble the electrode terminal mechanism. .
[0009]
[Means for solving the problem]
In the cylindrical secondary battery according to the present invention, a wound electrode body (2) is accommodated in a battery can (1) in which a lid (12) is fixed to an opening of a cylindrical body (11), An electrode terminal mechanism (4) is attached to the lid (12) while maintaining electrical insulation and airtightness with respect to the lid (12), and the winding electrode body (2) and the electrode terminal mechanism (4) are attached. Are connected to each other by a plurality of current collecting tabs (3).
The electrode terminal mechanism (4)
A screw shaft portion (53) disposed through a central hole (18) formed in the lid (12) and protruding outside the lid (12); and a flange located inside the lid (12). A terminal member (5) comprising a portion (51);
A nut (8) screwed into the screw shaft (53) of the terminal member (5) projecting from the lid (12);
A flat plate portion (63) is engaged with and fixed to the flange portion (51) of the terminal member (5) and faces the flange portion (51). The flat plate portion (63) has a central hole (61). Member (6) where is established
The tip portions of the plurality of current collecting tabs (3) drawn out from the winding electrode body (2) extend from the central hole (61) of the cap member (6) to the inner surface of the flat plate portion (63). Thus, it is sandwiched between the inner surface and the flange portion (51) of the terminal member (5).
[0010]
The cap member (6) can be formed of aluminum, nickel, copper, or an alloy of a plurality of metals selected from these.
[0011]
In the cylindrical secondary battery of the present invention, the electrode terminal mechanism (4) is fixed to the lid (12) by tightening the nut (8) with respect to the screw shaft portion (53) of the terminal member (5). Is done. When the cap member (6) is fixed to the flange portion (51) of the terminal member (5), a current collecting tab is provided between the flange portion (51) and the flat plate portion (63) of the cap member (6). The current collecting tab (3) is connected to the electrode terminal mechanism (4) by sandwiching and pressing the tip of (3).
Here, the leading end of each current collecting tab (3) is sandwiched between the flange (51) of the terminal member (5) and the flat plate (63) of the cap member (6) with a sufficient contact area. , The contact resistance decreases. Further, each of the plurality of current collecting tabs (3) extends from the center hole (61) of the flat plate portion (63) of the cap member (6) to the inner surface of the flat plate portion (63) (the surface facing the flange portion (51)). Therefore, the periphery of the cap member (6) is not surrounded by the plurality of current collecting tabs (3), and the outer peripheral surface of the cap member (6) is exposed. Therefore, in the operation of fixing the flange portion (51) of the terminal member (5) to the cap member (6), the cap member (6) can be sandwiched from the periphery, and the operation becomes easy.
[0012]
Specifically, the cap member (6) includes a cylindrical portion (64) projecting toward the terminal member (5) on the outer peripheral portion of the flat plate portion (63), and the terminal member ( The flange part (51) of 5) is screwed and fixed.
According to the specific configuration, when the flange portion (51) of the terminal member (5) is screwed into the cylindrical portion (64) of the cap member (6), the screwing torque is adjusted to thereby adjust the current collecting tab (3). ) Can be securely clamped.
[0013]
In a specific configuration, the distal ends of the plurality of current collecting tabs (3) are temporarily fixed to the inner surface of the flat plate portion (63) of the cap member (6) by resistance welding or ultrasonic welding.
This facilitates the work of fixing the flange portion (51) of the terminal member (5) to the cap member (6).
[0014]
More specifically, the opening area of the central hole (61) of the flat plate portion (63) of the cap member (6) is 80% or less of the area surrounded by the outer peripheral edge of the flat plate portion (63).
According to this specific configuration, the tip of the current collecting tab (3) is sandwiched between the flat plate (63) of the cap member (6) and the flange (51) of the terminal member (5) with a sufficient contact area. As a result, the contact resistance is reduced, and as a result, high output characteristics are obtained.
[0015]
【The invention's effect】
According to the cylindrical secondary battery according to the present invention, since a sufficient contact area can be obtained between the current collecting tab and the electrode terminal mechanism, the internal resistance of the battery is reduced, and particularly a large current flows. The output characteristics at the time can be improved. Of course, in the operation of fixing the flange portion of the terminal member to the cap member, the cap member can be sandwiched from the surroundings without being disturbed by the current collecting tab, so that the electrode terminal mechanism can be easily assembled.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, examples in which the present invention is applied to a cylindrical secondary battery will be specifically described with reference to the drawings.
As shown in FIG. 1, a cylindrical secondary battery according to the present invention has a cylindrical aluminum battery can (1) formed by welding and fixing lids (12) to both openings of a cylindrical body (11). The winding electrode body (2) is housed inside.
The outer diameter of the battery can (1) is 65 mm, the length is 300 mm, and the thickness of the lid (12) is 3 mm. The battery capacity is 70 Ah (0.125 C charge).
[0017]
The wound electrode body (2) includes a positive electrode obtained by forming a positive electrode layer containing a lithium composite oxide on the surface of an aluminum foil serving as a positive electrode current collector, and carbon powder on a surface of a copper foil serving as a negative electrode current collector. A separator impregnated with a non-aqueous electrolyte is interposed between the negative electrode formed with the negative electrode layer including the negative electrode layer, and these are spirally wound. The current collection tab has been pulled out. In addition, 14 copper current collection tabs are drawn out from the negative electrode. The current collecting tab on the positive electrode side is formed with a thickness of 100 μm, and the current collecting tab on the negative electrode side is formed with a thickness of 80 μm.
An electrode terminal mechanism (4) is attached to each lid (12), and the wound electrode body (2) and each electrode terminal mechanism (4) are each provided with the fourteen current collecting tabs (3). And the power generated by the winding electrode body (2) can be taken out from the pair of electrode terminal mechanisms (4) and (4).
[0018]
As shown in FIG. 2, the lid (12) is provided with a central hole (18) having a circular cross section through which the electrode terminal mechanism (4) is to penetrate. A screw hole (17) used for injecting the electrolyte and a pressure relief hole (15) for mounting a pressure relief type safety valve (14) composed of a ring member (14a) and a valve membrane (14b) are provided. After the injection of the electrolyte, a screw plug (16) is screwed into the screw hole (17). The safety valve (14) is fixed by welding at the opening edge of the pressure relief hole (15) of the lid (12).
[0019]
The electrode terminal mechanism (4) on the positive electrode side includes an aluminum terminal member (5) that is attached through the lid (12). The terminal member (5) includes a cylindrical portion (52) penetrating a central hole (18) formed in the lid (12), and a screw shaft portion (53) projecting upward from the cylindrical portion (52). A ring groove (54) in which an O-ring (72) made of a fluororesin is fitted on the upper surface of the flange portion (51). Is recessed. An outer screw (55) is formed on the outer peripheral surface of the flange portion (51).
[0020]
An aluminum cap member (6) is screwed into the flange portion (51) of the terminal member (5). The cap member (6) has a cylindrical portion (64) projecting upward from an outer peripheral portion of a flat plate portion (63) in which a central hole (61) is opened, and is provided on an inner peripheral surface of the cylindrical portion (64). An internal screw (62) into which the external screw (55) of the terminal member (5) is screwed is formed.
The inner diameter A of the central hole (61) of the cap member (6) is 20 mm, and the outer diameter B of the cylindrical portion (64) is 40 mm.
[0021]
The electrode terminal mechanism (4) includes a first packing member (7) interposed between the lid (12) and the flange portion (51) of the terminal member (5). The first packing member (7) is integrally molded using polypropylene, polyethylene, Teflon, or a fluororesin, and is a disc portion pressed between the lid (12) and the flange portion (51) of the terminal member (5). (74) and a cylindrical portion (75) projecting upward from the upper surface of the disk portion (74), and has a central hole (77). The cylindrical portion (75) of the first packing member (7) penetrates through the central hole (18) of the lid (12) and slightly projects from the upper surface of the cylindrical body (11).
[0022]
Further, a ring groove (76) in which an O-ring (73) made of a fluororesin is fitted is formed in a surface of the first packing member (7) facing the lid (12).
A ring groove (not shown) in which the O-rings (72) and (73) fit respectively on the surface of the first packing member (7) facing the terminal member (5) and on the inner surface of the lid (12). Is recessed.
[0023]
A ring-shaped second packing member (71) made of Teflon is engaged with the cylindrical portion (75) of the first packing member (7) protruding from the upper surface of the lid (12).
Further, an aluminum washer (81) is fitted into the screw shaft portion (53) of the terminal member (5) projecting from the central hole (18) of the lid body (12), and further, an aluminum made washer is further provided thereon. The nut (8) is screwed and tightened.
The electrode terminal mechanism (4) on the negative electrode side has the same configuration except that the terminal member (5) and the cap member (6) are made of nickel.
[0024]
In the process of assembling the cylindrical lithium secondary battery, the electrode terminal mechanism (4) is attached to the lid (12) that constitutes the battery can (1), and the electrode body is wound inside the cylindrical body (11). With (2) inserted, the tips of a plurality of current collecting tabs (3) extending from the winding electrode body (2) are inserted through the central hole (61) of the cap member (6) into the flat portion (63). It is guided to the inner surface (the surface facing the terminal member (5)), and the front end portion is temporarily welded to the inner surface of the flat plate portion (63) by spot welding at three points.
Next, the flange (51) of the terminal member (5) is screwed into the cap member (6), and the tip of the current collecting tab (3) is connected to the flange (51) of the terminal member (5). It is sandwiched between the flat portions (63) of the member (6). The screwing can be performed with a torque of 50 kgf · cm.
Thereafter, the lid (12) is placed over the opening of the cylindrical body (11), and the two are welded and fixed to each other. Then, after injecting the electrolytic solution into the battery can (1) from the screw hole (17) of the lid (12), the screw plug (16) is screwed into the screw hole (17), and the nut (8) is further tightened. To complete the assembly.
Thus, the cylindrical secondary battery shown in FIG. 1 is completed.
[0025]
In the cylindrical secondary battery, the first packing member (7) maintains electrical insulation between the cover (12) of the battery can (1) and the terminal member (5), The two packing members (71) maintain electrical insulation between the lid (12) and the washer (81). The O-rings (72) and (73) maintain the airtightness between the lid (12) of the battery can (1) and the terminal member (5).
[0026]
In the cylindrical secondary battery, the tip of each current collecting tab (3) has sufficient contact between the flange (51) of the terminal member (5) and the flat plate (63) of the cap member (6). Since it is sandwiched by the area, the contact resistance is reduced. As a result, a larger battery output than before can be obtained.
Further, each of the plurality of current collecting tabs (3) extends from the center hole (61) of the flat plate portion (63) of the cap member (6) to the inner surface of the flat plate portion (63) (the surface facing the flange portion (51)). Therefore, the periphery of the cap member (6) is not surrounded by the plurality of current collecting tabs (3), and the outer peripheral surface of the cap member (6) is exposed. Therefore, in the operation of screwing the terminal member (5) into the cap member (6), the cap member (6) can be sandwiched from the periphery, and the work of mounting the electrode terminal mechanism (4) becomes easy.
[0027]
In order to compare the performance of the cylindrical secondary battery of the present invention with that of a conventional cylindrical secondary battery, a battery A of the present invention was prepared and a conventional battery B shown in FIG. 3 was prepared. The outer diameter of the battery can of the conventional battery is 65 mm and the length is 300 mm.
The winding electrode body (2) of the conventional battery has the same configuration as the battery A of the present invention, and fourteen 50 μm-thick aluminum current collection tabs (3) drawn out from the winding electrode body are made of aluminum. Spot welding was performed at five points on the back surface of the flange portion (92). Fourteen 40 μm thick copper current collecting tabs (3) drawn out from the wound electrode body were spot-welded at five points to the back surface of the nickel flange portion (92).
[0028]
The battery A of the present invention and the battery B of the conventional example were subjected to 10 charge / discharge cycles under the following conditions.
Charge / discharge cycle conditions Charge: (charge rate) 0.125C (final voltage) 4.1V
Discharge: (discharge rate) 0.5C (final voltage) 2.7V
Rated capacity: 70Ah
[0029]
Thereafter, the battery A of the present invention and the battery B of the conventional example were charged to 4.1 V at 0.125 C, and then discharged to a depth of discharge of 50% at 0.5 C. Then, an output characteristic test was performed under the following conditions. Was performed. In addition, the value at the time of 3C was used for the output value.
Output characteristics test conditions Discharge rate: 0.5C, 1C, 2C, 3C
Discharge time: 10 seconds
Table 1 shows the results of the output characteristic test.
[0031]
[Table 1]

[0032]
As is clear from Table 1, the battery A of the present invention has a higher output characteristic value than the battery B of the related art. This is probably because the contact resistance between the current collecting tab and the terminal member of the battery of the present invention was smaller than that of the conventional battery.
[0033]
Next, five kinds of batteries of the present invention having different sizes of the central hole (61) of the cap member (6) were produced using the same wound electrode body as that provided in the battery of the present invention. . That is, the ratio (opening area ratio) of the opening area of the central hole (61) to the circular area surrounded by the outer peripheral edge of the flat plate portion (63) of the cap member (6) is 6%, 25%, 60%, It was changed to 80% and 90%.
An output characteristic test was performed on these batteries under the same conditions as described above. Table 2 shows the results.
[0034]
[Table 2]

[0035]
As is clear from Table 2, when the opening area ratio exceeds 80%, the output is greatly reduced. This is because the opening of the central hole (61) of the cap member (6) is large, so that a sufficient contact area cannot be secured between the tip of the current collecting tab and the cap member, and the internal resistance of the battery is reduced. It is thought that it was because it became big.
Therefore, in order to reduce the internal resistance of the battery and obtain high output characteristics, it is preferable to suppress the opening area ratio to 80% or less.
[0036]
The configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims. For example, the outer peripheral surface of the cylindrical portion (64) of the cap member (6) is not limited to a cylindrical surface, but may be formed into a polygonal cylindrical surface, thereby further facilitating the rotation of the cap member (6). .
Further, a configuration in which the tip of the current collecting tab (3) is temporarily fixed to the flat plate portion (63) of the cap member (6) by welding or the like is not always necessary. Further, the structure for fixing the cap member (6) to the flange portion (51) is not limited to screw fixing, and various fixing structures such as welding fixing can be adopted.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a main part of a cylindrical secondary battery according to the present invention.
FIG. 2 is an exploded perspective view of an electrode terminal mechanism provided in the cylindrical secondary battery.
FIG. 3 is a sectional view showing a main part of a conventional cylindrical secondary battery.
[Explanation of symbols]
(1) Battery can (11) Cylindrical body (12) Lid (2) Winding electrode body (3) Current collecting tab (4) Electrode terminal mechanism (5) Terminal member (51) Flange part (52) Column part ( 53) Screw shaft part (55) Outer screw (6) Cap member (61) Center hole (62) Inner screw (63) Flat plate part (64) Tube part (7) First packing member (71) Second packing member ( 81) Washer (8) Nut

Claims

A wound electrode body (2) is accommodated in a battery can (1) in which a lid (12) is fixed to an opening of a cylindrical body (11), and a lid (12) is placed in the lid (12). The electrode terminal mechanism (4) is mounted on the electrode terminal mechanism (4) while maintaining electrical insulation and airtightness with respect to the element (12). In the cylindrical secondary battery which is connected to each other and can take out the electric power generated by the winding electrode body (2) to the outside from the electrode terminal mechanism (4), the electrode terminal mechanism (4)
A screw shaft portion (53) disposed through a central hole (18) formed in the lid (12) and protruding outside the lid (12); and a flange located inside the lid (12). A terminal member (5) comprising a portion (51);
The nut (8) screwed into the screw shaft (53) of the terminal member (5) projecting from the lid (12) and the flange (51) of the terminal member (5) are engaged and fixed. A cap member (6) having a flat plate portion (63) opposed to the flange portion (51), and having a central hole (61) in the flat plate portion (63).
The end portions of the plurality of current collection tabs (3) drawn out from the winding electrode body (2) extend from the central hole (61) of the cap member (6) to the inner surface of the flat plate portion (63). A cylindrical secondary battery which is sandwiched between the inner surface and a flange portion (51) of the terminal member (5).

The cap member (6) includes a cylindrical portion (64) protruding toward the terminal member (5) on an outer peripheral portion of the flat plate portion (63), and a flange portion of the terminal member (5) is provided with respect to the cylindrical portion (64). The cylindrical secondary battery according to claim 1, wherein (51) is screwed and fixed.

The tip of each of the plurality of current collecting tabs (3) is temporarily fixed to the inner surface of the flat plate portion (63) of the cap member (6) by resistance welding or ultrasonic welding. Cylindrical secondary battery.

The cylindrical secondary battery according to any one of claims 1 to 3, wherein the cap member (6) is formed of aluminum, nickel, copper, or an alloy of a plurality of metals selected from these.

The opening area of the central hole (61) of the flat plate portion (63) of the cap member (6) is 80% or less of the area surrounded by the outer peripheral edge of the flat plate portion (63). A cylindrical secondary battery according to any one of the above.