JP2004111120A

JP2004111120A - Secondary battery

Info

Publication number: JP2004111120A
Application number: JP2002269492A
Authority: JP
Inventors: Koichi Sato; 佐藤　広一; Naoya Nakanishi; 中西　直哉; Atsuhiro Funabashi; 船橋　淳浩; Toshiyuki Noma; 能間　俊之
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 2002-09-17
Filing date: 2002-09-17
Publication date: 2004-04-08
Anticipated expiration: 2022-09-17
Also published as: JP4338372B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a secondary battery whose battery characteristics are not affected by a thermally sprayed metal when a current collecting plate 5 is joined to a wound electrode body 4 by metal spraying. <P>SOLUTION: In this secondary battery, end edges 48 of a core body making up an electrode project at an end part of the wound electrode body 4 and the current collecting plate 5 is joined to the end edges 48 of the core body. The collecting plate 5 has a plurality of protrusive parts 52 and cut-and-raised pieces 53 radially formed on a surface confronting the end edges 48. A slit is opened in a middle part of each protrusive part 52. With the circular arc-shaped protrusive parts 52 and the pieces 53 of the collecting plate 5 pressed against core body end parts 49 of the electrode body 4, metal spraying is performed to the slit, and the collecting plate 5 is joined and fixed to the electrode body 4. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、電池缶の内部に二次電池要素となる電極体が収容され、電池缶に設けた一対の電極端子部から電極体の発生電力を取り出すことが出来る二次電池に関するものである。
【０００２】
【従来の技術】
近年、携帯型電子機器の電源として、エネルギー密度の高いリチウムイオン二次電池が注目されている。又、電気自動車の電源として、大容量の円筒型二次電池が注目されている。
従来の円筒型リチウムイオン二次電池は、図８及び図９に示す様に、筒体（１１）の両端部に蓋体（１２）（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（４）を収容して構成されている。両蓋体（１２）（１２）には、正負一対の電極端子機構（９）（９）が取り付けられており、巻き取り電極体（４）の両極と両電極端子機構（９）（９）とが互いに接続されて、巻き取り電極体（４）が発生する電力を一対の電極端子機構（９）（９）から外部に取り出すことが可能となっている。又、各蓋体（１２）には圧力開閉式のガス排出弁（１３）が取り付けられている。
【０００３】
巻き取り電極体（４）は、図１０に示す様に、それぞれ帯状の正極（４１）と負極（４３）の間に帯状のセパレータ（４２）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。正極（４１）は、アルミニウム箔からなる帯状芯体（４５）の両面にリチウム複合酸化物からなる正極活物質（４４）を塗布して構成され、負極（４３）は、銅箔からなる帯状芯体（４７）の両面に炭素材料を含む負極活物質（４６）を塗布して構成されている。セパレータ（４２）には、非水電解液が含浸されている。
【０００４】
ここで、正極（４１）及び負極（４３）はそれぞれセパレータ（４２）上に幅方向へずらして重ね合わされ、渦巻き状に巻き取られている。これによって、巻き取り電極体（４）の巻き軸方向の両端部の内、一方の端部では、セパレータ（４２）の端縁よりも外方へ正極（４１）の芯体（４５）の端縁（４８）が突出すると共に、他方の端部では、セパレータ（４２）の端縁よりも外方へ負極（４３）の芯体（４７）の端縁（４８）が突出している。そして、巻き取り電極体（４）の両端部にはそれぞれ円板状の集電板（３２）が抵抗溶接され、該集電板（３２）がリード部材（３３）を介して図９に示す電極端子機構（９）の基端部に接続される。
【０００５】
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電極端子（９１）を具え、該電極端子（９１）の基端部には鍔部（９２）が形成されている。蓋体（１２）の貫通孔には絶縁パッキング（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。電極端子（９１）には、蓋体（１２）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。そして、第１ナット（９５）を締め付けて、電極端子（９１）の鍔部（９２）とワッシャ（９４）によって絶縁パッキング（９３）を挟圧することにより、シール性を高めている。
尚、前記リード部材（３３）の先端部は、電極端子（９１）の鍔部（９２）に、スポット溶接或いは超音波溶接によって固定されている。
【０００６】
しかしながら、図９に示す集電構造を有する非水電解液二次電池においては、巻き取り電極体（４）の正極（４１）及び負極（４３）を構成する芯体（４５）（４７）の端縁（４８）（４８）の面積が小さいため、芯体端縁と集電板（３２）の間の接触面積が小さく、これによって電池の内部抵抗が大きくなる問題があった。
そこで、生産性に優れた低抵抗な電池として、円板状の集電板に、複数の突起部を形成し、該集電板を芯体端縁に押さえ付けた状態で、前記突起部にレーザビームを照射することによって、集電板を極板群に溶接する構造が提案されている（特許文献１、特許文献２参照）。
【０００７】
ところで、巻き取り電極体に集電板を固定する方法として、集電板に貫通孔を開設して、該貫通孔に金属溶射を施すことによって、集電板を巻き取り電極体の端面に接合する方法が提案されている（特許文献３参照）。
【０００８】
【特許文献１】
特開２００１−２５６９５２号公報
【特許文献２】
特公平２−４１０２号公報
【特許文献３】
特開２０００−７７２６８号公報（
【００２３】、
【図３】）
【０００９】
【発明が解決しようとする課題】
しかしながら、特許文献３の如く、集電板に貫通孔を開設して、該貫通孔に金属溶射を施すことによって、集電板を巻き取り電極体に接合固定する方法においては、二次電池、特に非水系の二次電池の如く巻き取り電極体を構成する正極及び負極の芯体が薄く、然も、芯体間の隙間が大きい場合、金属溶射時に溶射金属が、芯体間を通過して活物質に至り、活物質に損傷を与えて電池特性を低下させる問題があった。
【００１０】
そこで本発明の目的は、電極体に集電板を接合固定する方法として金属溶射を用いた場合にも、溶射金属が電池特性に影響を及ぼすことのない二次電池を提供することである。
【００１１】
【課題を解決する為の手段】
本発明に係る二次電池においては、電池缶（１）の内部に、それぞれ帯状の正極（４１）と負極（４３）の間にセパレータ（４２）を介在させて積層した電極体（４）が収容され、正極（４１）及び負極（４３）はそれぞれ、帯状芯体の表面に活物質を塗布して構成され、巻き取り電極体（４）が発生する電力を一対の電極端子部から外部へ取り出すことが出来る。
電極体（４）の少なくとも何れか一方の端部には、正極（４１）或いは負極（４３）を構成する帯状芯体の端縁（４８）が突出し、該端縁（４８）を覆って集電板（５）が設置され、該集電板（５）には、芯体端縁（４８）に向かって突出する複数条の凸部（５２）が形成されると共に、各凸部（５２）の中央部には、集電板（５）を貫通する１或いは複数の孔が開設され、該集電板（５）が電極体（４）に押し付けられた状態で、各凸部（５２）の貫通孔に金属溶射が施されて、該集電板（５）が電極体（４）に接合され、該集電板（５）が一方の電極端子部と連結されている。
【００１２】
尚、前記集電板（５）の貫通孔としては、凸部（５２）の長手方向に沿って伸びるスリット（５７）が開設される。
又、集電板（５）の材質としては、Ｃｕ、Ａｌ、Ｎｉ、ＳＵＳ、Ｔｉ、或いはこれらの金属の合金が採用され、前記溶射金属としては、集電板（５）と同じ材質が採用される。
【００１３】
上記本発明の二次電池においては、電極体（４）を構成する複数枚の電極の芯体端部（４９）が間隔をおいて並んでいるが、組立工程にて集電板（５）を電極体（４）の芯体端縁（４８）に押し付けると、複数枚の芯体端部（４９）は、集電板（５）の凸部（５２）に押圧されて同一方向に折れ曲がり、互いに重なり合うことになる。この結果、少なくとも凸部（５２）の貫通孔が開口する領域では、芯体端部（４９）（４９）間の隙間が塞がれることになる。
従って、電極体（４）に集電板（５）を接合固定する工程で、凸部（５２）の貫通孔へ向けて吹き付けられた溶射金属は、芯体端部（４９）（４９）間の隙間への侵入が阻止され、電極活物質に達する虞はない。
【００１４】
具体的構成において、集電板（５）の凸部（５２）は断面円弧状を呈し、隣接する凸部（５２）（５２）の間には、電極体（４）に向かって突出する切り起し片（５３）が形成されている。
【００１５】
該具体的構成においては、電極体（４）の芯体端縁（４８）に集電板（５）を押し付けることによって、各円弧状凸部（５２）が芯体端部（４９）を押圧して、芯体端部（４９）との間に円筒面からなる接合面が形成される。この結果、金属溶射部にて、電極体（４）と集電板（５）が大きな面積で接触することとなり、低抵抗化が図られる。
又、各切り起し片（５３）が芯体端縁（４８）に深く食い込んで、集電板（５）と芯体端部（４９）の間に良好な接触状態が得られる。尚、集電板（５）には、切り起し片（５３）の形成に伴って貫通孔が形成されるので、該貫通孔によって、組立工程で電極体（４）に電解液を含浸させる際の電解液の通路が確保されることになる。
【００１６】
【発明の効果】
本発明に係る二次電池によれば、電極体に集電板を接合固定する際に溶射金属が電極活物質に達することがないので、金属溶射によって電池特性が影響を受ける虞はない。
【００１７】
【発明の実施の形態】
以下、本発明をリチウムイオン二次電池に実施した形態につき、図面に沿って具体的に説明する。
【００１８】
全体構成
本発明に係るリチウムイオン二次電池は、図８及び図１に示す如く、筒体（１１）の両端部に蓋体（１２）（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（４）を収容して構成されている。両蓋体（１２）（１２）には、正負一対の電極端子機構（９）（９）が取り付けられている。尚、電極端子機構（９）は、従来と同一の構成を具えている。又、各蓋体（１２）には圧力開閉式のガス排出弁（１３）が取り付けられている。
【００１９】
巻き取り電極体（４）の両端部にはそれぞれ集電板（５）が設置され、芯体端縁（４８）に金属溶射によって接合固定されている。該集電板（５）の端部に突設されたリード部（５５）の先端は、電極端子機構（９）を構成する電極端子（９１）の鍔部（９２）に、スポット溶接、超音波溶接或いはレーザ溶接によって接合されている。
【００２０】
巻き取り電極体（４）
巻き取り電極体（４）は、図２に示す様に、それぞれ帯状の正極（４１）と負極（４３）の間に帯状のセパレータ（４２）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。正極（４１）は、アルミニウム箔からなる帯状芯体（４５）の両面にリチウム複合酸化物からなる正極活物質（４４）を塗布して構成され、負極（４３）は、銅箔からなる帯状芯体（４７）の両面に炭素材料を含む負極活物質（４６）を塗布して構成されている。セパレータ（４２）には、非水電解液が含浸されている。
【００２１】
正極（４１）には、正極活物質（４４）の塗布されている塗工部と、正極活物質の塗布されていない非塗工部とが形成されている。又、負極（４３）にも、負極活物質（４６）の塗布されている塗工部と、負極活物質の塗布されていない非塗工部とが形成されている。
正極（４１）及び負極（４３）は、それぞれセパレータ（４２）上に幅方向へずらして重ね合わせ、正極（４１）及び負極（４３）の前記非塗工部をセパレータ（４２）の両端縁からそれぞれ外側へ突出させる。そして、これらを渦巻き状に巻き取ることによって巻き取り電極体（４）が構成される。該巻き取り電極体（４）においては、巻き軸方向の両端部の内、一方の端部では、正極（４１）の非塗工部の芯体端縁（４８）が、セパレータ（４２）の一方の端縁よりも外方へ突出し、他方の端部では、負極（４３）の非塗工部の芯体端縁（４８）が、セパレータ（４２）の他方の端縁よりも外方へ突出している。
【００２２】
集電構造
集電板（５）は、図２〜図４に示す如く円板状本体（５１）を具え、該円板状本体（５１）には、中央孔（５４）が開設されている。円板状本体（５１）には、中央孔（５４）を中心として放射状に伸びる複数条（実施例では４条）の円弧状凸部（５２）が一体成型され、巻き取り電極体（４）側に突出している。該円弧状凸部（５２）は、円板状本体（５１）の半径線に直交する断面形状が半円の円弧状を呈している。
集電板（５）の各円弧状凸部（５２）の中央部には、円弧状凸部（５２）の長手方向に伸びるスリット（５７）が開設されている。該スリット（５７）は、後述の組立工程にて溶射金属を吹き付けるための貫通孔となる。
【００２３】
又、円板状本体（５１）には、隣接する円弧状凸部（５２）（５２）の間にそれぞれ、複数条（実施例では２条）の切り起し片（５３）が形成され、巻き取り電極体（４）側に突出している。該切り起し片（５３）の切り起こしに伴って形成された貫通孔は、後述の組立工程にて巻き取り電極体（４）に電解液を含浸させる際の電解液の通路となる。
更に、円板状本体（５１）の端部には、短冊状のリード部（５５）が一体に形成されている。
【００２４】
組立工程
先ず、図１に示す電池缶（１）、電極端子機構（９）、図２に示す巻き取り電極体（４）、及び図３に示す集電板（５）をそれぞれ作製する。
その後、図５及び図７（ａ）に示す如く、巻き取り電極体（４）の各端部に形成されている芯体端縁（４８）に集電板（５）を押し付ける。これによって、巻き取り電極体（４）の芯体端部（４９）は集電板（５）の円弧状凸部（５２）に押圧されて、図６の如く一方向に折れ曲がり、隣接する芯体端部（４９）どうしが互いに重なり合うことになる。この結果、集電板（５）のスリット（５７）が開口する領域では、芯体端部（４９）（４９）間の隙間が塞がれることになる。又、円弧状凸部（５２）と芯体端部（４９）の間には、円筒面からなる接合面が形成される。
又、集電板（５）の切り起し片（５３）は、巻き取り電極体（４）の芯体端縁（４８）に深く食い込み、芯体端縁（４８）と圧着することになる。
【００２５】
この状態で、図７（ａ）中に矢印で示す様に、集電板（５）の円弧状凸部（５２）のスリット（５７）に、集電板（５）と同じ材質の金属微粒子を溶融状態で吹き付け、金属溶射を施す。この際、集電板（５）のスリット（５７）が開口する領域では、図６の如く芯体端部（４９）どうしが重なり合って芯体端部（４９）（４９）間の隙間が塞がれているので、溶射金属が芯体端部（４９）（４９）間の隙間へ侵入し、電極活物質に至る虞はない。
この結果、図７（ｂ）の如く集電板（５）のスリット（５７）には溶射金属（６）が充填され、該溶射金属（６）によって巻き取り電極体（４）と集電板（５）とが互いに接合固定され、集電板（５）の円弧状凸部（５２）と巻き取り電極体（４）の芯体端部（４９）との間に大きな接触面積が維持されると共に、切り起し片（５３）と芯体端縁（４８）の間の圧着状態が維持される。
【００２６】
【実施例】
図２に示す如く、アルミニウム製の芯体（４５）にコバルト酸リチウムからなる正極活物質（４４）を塗布してなる正極（４１）と、銅製の芯体（４７）に黒鉛からなる負極活物質（４６）を塗布してなる負極（４３）と、イオン透過性のポリプロピレン製微多孔膜からなるセパレータ（４２）とを重ね合わせ、これらを渦巻き状に巻き取って、巻き取り電極体（４）を作製した。尚、正極（４１）及び負極（４３）の幅方向の端部には、一定幅の非塗工部が設けられている。
【００２７】
又、半径２０ｍｍ、厚さ０．５ｍｍの円板状本体（５１）に複数条の円弧状凸部（５２）が放射状に形成されると共に、各円弧状凸部（５２）にはスリット（５７）が開設され、更に複数条の切り起し片（５３）が放射状に形成されたアルミニウム製の集電板（５）を作製し、該集電板（５）を巻き取り電極体（４）の正極側の芯体端縁（４８）に被せて、上部から治具により押さえ付けた。
【００２８】
この状態で集電板（５）の円弧状凸部（５２）のスリット（５７）に対し、アルミニウムを用いた金属溶射を施して、集電板（５）を巻き取り電極体（４）に溶接した。その後、アルミニウム製リード片の基端部を集電板（５）の表面に、先端部をアルミニウム製電極端子の裏面にレーザ溶接し、正極側の集電構造を構成した。
又、集電板の材質並びに溶射金属が銅であること以外は正極側の集電構造と同様にして、負極側の集電構造を構成した。
【００２９】
その後、筒体（１１）の内部に巻き取り電極体（４）を収容し、筒体（１１）の両開口部にそれぞれ、電極端子機構（９）が組み付けられた蓋体（１２）を溶接固定し、電池缶（１）のガス排出弁（１３）のねじ孔から有機電解液を注入した後、電池缶（１）にガス排出弁（１３）をねじ込んで、本発明の二次電池を組み立てた。
【００３０】
上記本発明のリチウムイオン二次電池においては、巻き取り電極体（４）に集電板（５）を接合固定する際に溶射金属が電極活物質に達することがないので、金属溶射によって電池特性が影響を受ける虞はない。
又、集電板（５）は、各円弧状凸部（５２）と巻き取り電極体（４）の芯体端部（４９）との接合部にて大きな接触面積で、金属溶射により巻き取り電極体（４）に接合されると共に、該溶射接合部以外の領域では、各切り起し片（５３）が芯体端縁（４８）に食い込んで、良好な接触状態が得られるため、集電板（５）と巻き取り電極体（４）の間の接触抵抗が小さくなる。然も、集電板（５）に形成された複数条の切り起し片（５３）によって、芯体端縁（４８）の全域から集電が行なわれるので、高い集電性能が得られる。
【図面の簡単な説明】
【図１】本発明に係る円筒型リチウムイオン二次電池の一部破断正面図である。
【図２】巻き取り電極体及び集電板の分解斜視図である。
【図３】集電板の平面図である。
【図４】図３のＡ−Ａ線に沿う拡大断面とＢ−Ｂ線に沿う拡大断面を示す図である。
【図５】巻き取り電極体に集電板の円弧状凸部を押し付ける工程を示す斜視図である。
【図６】巻き取り電極体の芯体端部に集電板の円弧状凸部が押し付けられた状態を示す図である。
【図７】巻き取り電極体に集電板を溶射接合する工程を示す断面図である。
【図８】円筒型リチウムイオン二次電池の外観を示す斜視図である。
【図９】従来のリチウムイオン二次電池の一部破断正面図である。
【図１０】従来のリチウムイオン二次電池に用いられている集電板と巻き取り電極体の分解斜視図である。
【符号の説明】
（１）　電池缶
（１１）　筒体
（１２）　蓋体
（４）　巻き取り電極体
（４１）　正極
（４３）　負極
（４８）　芯体端縁
（４９）　芯体端部
（５）　集電板
（５１）　円板状本体
（５２）　円弧状凸部
（５３）　切り起し片
（５７）　スリット
（６）　溶射金属[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a secondary battery in which an electrode body serving as a secondary battery element is accommodated in a battery can and power generated by the electrode body can be taken out from a pair of electrode terminals provided in the battery can.
[0002]
[Prior art]
2. Description of the Related Art In recent years, lithium-ion secondary batteries with high energy density have attracted attention as power supplies for portable electronic devices. In addition, large-capacity cylindrical secondary batteries have attracted attention as power sources for electric vehicles.
As shown in FIGS. 8 and 9, a conventional cylindrical lithium ion secondary battery has a cylindrical battery can (see FIG. 8) in which lids (12) and (12) are fixed to both ends of a cylindrical body (11) by welding. The winding electrode body (4) is accommodated in the inside of 1). A pair of positive and negative electrode terminal mechanisms (9) and (9) are attached to the both lids (12) and (12), respectively, and both poles of the winding electrode body (4) and both electrode terminal mechanisms (9) and (9). Are connected to each other, so that the electric power generated by the winding electrode body (4) can be taken out from the pair of electrode terminal mechanisms (9) and (9). A pressure opening / closing gas discharge valve (13) is attached to each lid (12).
[0003]
As shown in FIG. 10, the winding electrode body (4) has a strip-shaped separator (42) interposed between a strip-shaped positive electrode (41) and a strip-shaped negative electrode (43) and spirally winds them. It is configured. The positive electrode (41) is formed by applying a positive electrode active material (44) made of a lithium composite oxide to both surfaces of a band-shaped core (45) made of aluminum foil, and the negative electrode (43) is made of a band-shaped core made of copper foil. A negative electrode active material (46) containing a carbon material is applied to both surfaces of the body (47). The separator (42) is impregnated with a non-aqueous electrolyte.
[0004]
Here, the positive electrode (41) and the negative electrode (43) are superposed on the separator (42) while being shifted in the width direction, and are wound in a spiral shape. As a result, at one end of the two ends of the winding electrode body (4) in the winding axis direction, the end of the core body (45) of the positive electrode (41) is located outward of the edge of the separator (42). At the other end, the edge (48) of the core (47) of the negative electrode (43) protrudes outward from the edge of the separator (42). Then, disk-shaped current collectors (32) are resistance-welded to both ends of the wound electrode body (4), respectively, and the current collectors (32) are shown in FIG. 9 via lead members (33). It is connected to the base end of the electrode terminal mechanism (9).
[0005]
The electrode terminal mechanism (9) includes an electrode terminal (91) attached through the lid (12) of the battery can (1), and a flange (92) is provided at a base end of the electrode terminal (91). ) Is formed. An insulating packing (93) is attached to the through-hole of the lid (12), so that electrical insulation and sealing between the lid (12) and the fastening member (91) are maintained. A washer (94) is fitted to the electrode terminal (91) from the outside of the lid (12), and a first nut (95) and a second nut (96) are screwed into the electrode terminal (91). Then, the first nut (95) is tightened, and the insulating packing (93) is sandwiched between the flange (92) of the electrode terminal (91) and the washer (94) to enhance the sealing performance.
The tip of the lead member (33) is fixed to the flange (92) of the electrode terminal (91) by spot welding or ultrasonic welding.
[0006]
However, in the nonaqueous electrolyte secondary battery having the current collecting structure shown in FIG. 9, the cores (45) and (47) constituting the positive electrode (41) and the negative electrode (43) of the wound electrode body (4) are not included. Since the area of the edges (48) and (48) is small, the contact area between the core body edge and the current collector plate (32) is small, which causes a problem that the internal resistance of the battery increases.
Therefore, as a low-resistance battery with excellent productivity, a plurality of protrusions are formed on a disk-shaped current collector, and the current collector is pressed against the core edge, and There has been proposed a structure in which a current collector is welded to an electrode group by irradiating a laser beam (see Patent Documents 1 and 2).
[0007]
By the way, as a method of fixing the current collecting plate to the winding electrode body, a through hole is formed in the current collecting plate, and the through hole is subjected to metal spraying so that the current collecting plate is joined to the end surface of the winding electrode body. (See Patent Document 3).
[0008]
[Patent Document 1]
JP 2001-256952 A [Patent Document 2]
Japanese Patent Publication No. 2-4102 [Patent Document 3]
JP-A-2000-77268 (
[0023]
FIG. 3)
[0009]
[Problems to be solved by the invention]
However, as disclosed in Patent Document 3, in a method in which a through-hole is formed in a current collector plate and metal spraying is performed on the through-hole, the current collector plate is wound and fixed to an electrode body. In particular, when the cores of the positive electrode and the negative electrode constituting the wound electrode body are thin, as in a non-aqueous secondary battery, and when the gap between the cores is large, the metal sprayed during metal spraying passes between the cores. As a result, there is a problem that the active material is damaged, and the active material is damaged to deteriorate the battery characteristics.
[0010]
Therefore, an object of the present invention is to provide a secondary battery in which the sprayed metal does not affect battery characteristics even when metal spraying is used as a method for bonding and fixing a current collector plate to an electrode body.
[0011]
[Means for solving the problem]
In the secondary battery according to the present invention, an electrode body (4) laminated with a separator (42) between a strip-shaped positive electrode (41) and a negative electrode (43) is provided inside a battery can (1). Each of the positive electrode (41) and the negative electrode (43) is formed by applying an active material to the surface of a band-shaped core, and the electric power generated by the wound electrode body (4) is supplied from a pair of electrode terminals to the outside. You can take it out.
At least one of the ends of the electrode body (4) protrudes an edge (48) of a band-shaped core constituting the positive electrode (41) or the negative electrode (43), and gathers over the edge (48). An electric plate (5) is installed, and a plurality of convex portions (52) projecting toward the core body edge (48) are formed on the current collector plate (5). One or a plurality of holes penetrating the current collector plate (5) are formed in the center of (), and each of the projections (52) is pressed with the current collector plate (5) pressed against the electrode body (4). ) Is subjected to metal spraying, the current collector plate (5) is joined to the electrode body (4), and the current collector plate (5) is connected to one electrode terminal.
[0012]
In addition, a slit (57) extending along the longitudinal direction of the projection (52) is formed as a through hole of the current collector (5).
In addition, as a material of the current collector plate (5), Cu, Al, Ni, SUS, Ti, or an alloy of these metals is used, and as the sprayed metal, the same material as the current collector plate (5) is used. Is done.
[0013]
In the above secondary battery of the present invention, the ends (49) of the cores of the plurality of electrodes constituting the electrode body (4) are arranged at intervals, but the current collector plate (5) is assembled in the assembling process. Is pressed against the core edge (48) of the electrode body (4), the plurality of core ends (49) are pressed by the convex portions (52) of the current collector plate (5) and bent in the same direction. Will overlap each other. As a result, at least in the region where the through hole of the projection (52) is open, the gap between the core body end portions (49) (49) is closed.
Therefore, in the step of joining and fixing the current collector plate (5) to the electrode body (4), the sprayed metal sprayed toward the through holes of the projections (52) is applied between the core body end portions (49) and (49). Is prevented from entering the gap, and there is no possibility of reaching the electrode active material.
[0014]
In a specific configuration, the convex portion (52) of the current collector plate (5) has an arc-shaped cross section, and a cutout protruding toward the electrode body (4) is provided between the adjacent convex portions (52) and (52). Raised pieces (53) are formed.
[0015]
In this specific configuration, each arc-shaped projection (52) presses the core end (49) by pressing the current collector plate (5) against the core end (48) of the electrode body (4). Thus, a joint surface formed of a cylindrical surface is formed between the core body end portion (49). As a result, the electrode body (4) and the current collector (5) come into contact with each other in a large area in the metal sprayed portion, and the resistance is reduced.
Further, the cut-and-raised pieces (53) penetrate deeply into the core body edge (48), and a good contact state is obtained between the current collector plate (5) and the core body edge (49). Since a through hole is formed in the current collector plate (5) along with the formation of the cut-and-raised piece (53), the electrode body (4) is impregnated with the electrolytic solution in the assembling process by the through hole. In this case, a passage for the electrolytic solution is secured.
[0016]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the secondary battery which concerns on this invention, since a spray metal does not reach an electrode active material at the time of joining and fixing a current collector plate to an electrode body, there is no possibility that battery characteristics may be affected by metal spray.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a lithium ion secondary battery will be specifically described with reference to the drawings.
[0018]
Overall configuration As shown in FIGS. 8 and 1, the lithium ion secondary battery according to the present invention has a cylindrical body formed by welding and fixing lids (12) and (12) to both ends of a cylindrical body (11). A wound electrode body (4) is housed inside a battery can (1) in the shape of a circle. A pair of positive and negative electrode terminal mechanisms (9) (9) are attached to both lids (12) (12). The electrode terminal mechanism (9) has the same configuration as the conventional one. A pressure opening / closing gas discharge valve (13) is attached to each lid (12).
[0019]
Current collecting plates (5) are provided at both ends of the wound electrode body (4), respectively, and are fixed to the core edge (48) by metal spraying. The tip of the lead portion (55) projecting from the end of the current collector plate (5) is spot-welded to the flange (92) of the electrode terminal (91) constituting the electrode terminal mechanism (9). They are joined by sonic welding or laser welding.
[0020]
Winding electrode body ( 4 )
As shown in FIG. 2, the winding electrode body (4) has a strip-shaped separator (42) interposed between a strip-shaped positive electrode (41) and a strip-shaped negative electrode (43) and spirally winds these. It is configured. The positive electrode (41) is formed by applying a positive electrode active material (44) made of a lithium composite oxide to both surfaces of a band-shaped core (45) made of aluminum foil, and the negative electrode (43) is made of a band-shaped core made of copper foil. A negative electrode active material (46) containing a carbon material is applied to both surfaces of the body (47). The separator (42) is impregnated with a non-aqueous electrolyte.
[0021]
The positive electrode (41) has a coated portion on which the positive electrode active material (44) is applied and a non-coated portion on which the positive electrode active material is not applied. The negative electrode (43) also has a coated portion on which the negative electrode active material (46) is applied and a non-coated portion on which the negative electrode active material is not applied.
The positive electrode (41) and the negative electrode (43) are superimposed on the separator (42) so as to be shifted in the width direction, and the uncoated portions of the positive electrode (41) and the negative electrode (43) are separated from both end edges of the separator (42). Each project outward. Then, these are spirally wound to form a wound electrode body (4). In the winding electrode body (4), at one end of both ends in the winding axis direction, the core edge (48) of the uncoated portion of the positive electrode (41) is connected to the separator (42). At the other end, the core edge (48) of the non-coated portion of the negative electrode (43) extends outward from the other edge of the separator (42). It is protruding.
[0022]
Current collecting structure The current collecting plate (5) includes a disc-shaped main body (51) as shown in FIGS. 2 to 4, and the disc-shaped main body (51) has a central hole (54). Has been established. The disk-shaped main body (51) is integrally formed with a plurality of (four in this embodiment) arc-shaped convex portions (52) extending radially around the central hole (54), and the winding electrode body (4). Protruding to the side. The arc-shaped convex portion (52) has a semicircular arc shape in cross section orthogonal to the radius line of the disk-shaped main body (51).
A slit (57) extending in the longitudinal direction of the arc-shaped projection (52) is provided at the center of each arc-shaped projection (52) of the current collector (5). The slits (57) serve as through holes for spraying spray metal in an assembling process described later.
[0023]
Also, a plurality of (two in this embodiment) cut-and-raised pieces (53) are formed on the disc-shaped main body (51) between the adjacent arc-shaped convex parts (52) and (52), respectively. It protrudes toward the winding electrode body (4). The through-hole formed along with the cut-and-raised piece (53) serves as a passage for the electrolyte when the wound electrode body (4) is impregnated with the electrolyte in an assembling process described later.
Further, a strip-shaped lead portion (55) is integrally formed at an end of the disc-shaped main body (51).
[0024]
Assembly process First, the battery can (1) shown in FIG. 1, the electrode terminal mechanism (9), the wound electrode body (4) shown in FIG. 2, and the current collector plate (5) shown in FIG. Make it.
Then, as shown in FIG. 5 and FIG. 7A, the current collector plate (5) is pressed against the core edge (48) formed at each end of the wound electrode body (4). As a result, the end portion (49) of the core of the winding electrode body (4) is pressed by the arc-shaped projection (52) of the current collector plate (5), and is bent in one direction as shown in FIG. The body ends (49) will overlap each other. As a result, in the region where the slit (57) of the current collector (5) is open, the gap between the core body end portions (49) (49) is closed. In addition, a joint surface formed of a cylindrical surface is formed between the arc-shaped convex portion (52) and the end portion (49) of the core body.
The cut-and-raised pieces (53) of the current collector plate (5) bite into the core edge (48) of the winding electrode body (4) and are pressed against the core edge (48). .
[0025]
In this state, as shown by an arrow in FIG. 7A, metal fine particles of the same material as the current collector plate (5) are provided in the slits (57) of the arc-shaped convex portion (52) of the current collector plate (5). Is sprayed in a molten state, and metal spraying is performed. At this time, in the region where the slit (57) of the current collector plate (5) is open, the ends of the cores (49) overlap as shown in FIG. Because of the peeling, there is no possibility that the sprayed metal will enter the gap between the core end portions (49) and (49) and reach the electrode active material.
As a result, the spray metal (6) is filled in the slit (57) of the current collector plate (5) as shown in FIG. 7B, and the wound electrode body (4) and the current collector plate are filled by the spray metal (6). (5) are joined and fixed to each other, and a large contact area is maintained between the arc-shaped convex portion (52) of the current collector plate (5) and the core end portion (49) of the winding electrode body (4). At the same time, the pressed state between the cut and raised piece (53) and the core body edge (48) is maintained.
[0026]
【Example】
As shown in FIG. 2, a positive electrode (41) obtained by coating a positive electrode active material (44) made of lithium cobalt oxide on an aluminum core (45) and a negative electrode active material made of graphite on a copper core (47). The negative electrode (43) coated with the substance (46) and the separator (42) made of an ion-permeable polypropylene microporous film are overlapped and spirally wound to form a wound electrode body (4). ) Was prepared. In addition, the non-coating part of a fixed width | variety is provided in the edge part of the width direction of the positive electrode (41) and the negative electrode (43).
[0027]
A plurality of arc-shaped protrusions (52) are radially formed on a disk-shaped main body (51) having a radius of 20 mm and a thickness of 0.5 mm, and a slit (57) is formed in each arc-shaped protrusion (52). ) Is opened, and a plurality of cut-and-raised pieces (53) are formed radially to form an aluminum current collector plate (5), and the current collector plate (5) is wound up to form an electrode body (4). And was pressed down from above with a jig.
[0028]
In this state, metal slits using aluminum are applied to the slits (57) of the arc-shaped projections (52) of the current collector plate (5), and the current collector plate (5) is wound on the electrode body (4). Welded. Thereafter, the base end portion of the aluminum lead piece was laser-welded to the surface of the current collector plate (5), and the tip end portion was laser-welded to the back surface of the aluminum electrode terminal, thereby forming a current collecting structure on the positive electrode side.
Further, a current collecting structure on the negative electrode side was configured in the same manner as the current collecting structure on the positive electrode side except that the material of the current collecting plate and the sprayed metal were copper.
[0029]
Thereafter, the take-up electrode body (4) is housed inside the cylinder body (11), and the lid body (12) to which the electrode terminal mechanism (9) is assembled is welded to each opening of the cylinder body (11). After fixing and injecting the organic electrolyte through the screw hole of the gas discharge valve (13) of the battery can (1), the gas discharge valve (13) is screwed into the battery can (1) to mount the secondary battery of the present invention. Assembled.
[0030]
In the above-mentioned lithium ion secondary battery of the present invention, when the current collector plate (5) is joined and fixed to the wound electrode body (4), the sprayed metal does not reach the electrode active material. Is not affected.
The current collector plate (5) is wound by metal spraying with a large contact area at the junction between each arc-shaped projection (52) and the end (49) of the core of the winding electrode body (4). In addition to being joined to the electrode body (4), the cut and raised pieces (53) bite into the core body edge (48) in a region other than the thermal-sprayed joint, and a good contact state is obtained. The contact resistance between the electric plate (5) and the winding electrode body (4) is reduced. Naturally, a plurality of cut-and-raised pieces (53) formed on the current collector plate (5) allow current to be collected from the entire edge of the core body (48), so that high current collecting performance can be obtained.
[Brief description of the drawings]
FIG. 1 is a partially cutaway front view of a cylindrical lithium ion secondary battery according to the present invention.
FIG. 2 is an exploded perspective view of a winding electrode body and a current collector.
FIG. 3 is a plan view of a current collecting plate.
FIG. 4 is an enlarged sectional view taken along line AA of FIG. 3 and an enlarged sectional view taken along line BB of FIG. 3;
FIG. 5 is a perspective view showing a step of pressing an arc-shaped convex portion of a current collector plate against a wound electrode body.
FIG. 6 is a view showing a state where an arc-shaped convex portion of a current collector is pressed against a core end portion of a wound electrode body.
FIG. 7 is a cross-sectional view showing a step of spray-bonding a current collector to a wound electrode body.
FIG. 8 is a perspective view showing an appearance of a cylindrical lithium ion secondary battery.
FIG. 9 is a partially cutaway front view of a conventional lithium ion secondary battery.
FIG. 10 is an exploded perspective view of a current collecting plate and a wound electrode body used in a conventional lithium ion secondary battery.
[Explanation of symbols]
(1) Battery can (11) Cylindrical body (12) Lid (4) Winding electrode body (41) Positive electrode (43) Negative electrode (48) Core body edge (49) Core body edge (5) Current collector plate (51) Disc-shaped main body (52) Arc-shaped convex part (53) Cut-and-raised piece (57) Slit (6) Sprayed metal

Claims

An electrode body (4) laminated with a separator (42) interposed between a strip-shaped positive electrode (41) and a negative electrode (43) is accommodated inside the battery can (1), and the positive electrode (41) and the negative electrode ( Reference numeral 43) designates an electrode in a secondary battery in which an active material is applied to the surface of a strip-shaped core, and the electric power generated by the wound electrode body (4) can be taken out from a pair of electrode terminals. At least one end of the body (4) protrudes an edge (48) of a strip-shaped core constituting the positive electrode (41) or the negative electrode (43), and covers the edge (48) to collect current. A plate (5) is installed, and a plurality of protrusions (52) projecting toward the core body edge (48) are formed on the current collector plate (5), and each protrusion (52) is formed. One or a plurality of holes penetrating the current collector (5) are formed in the center of the In a state of being pressed against the body (4), metal spraying is applied to the through holes of each projection (52), and the current collector (5) is joined to the electrode body (4), and the current collector ( 5) is connected to one of the electrode terminals.

2. The secondary according to claim 1, wherein a slit (57) extending along the longitudinal direction of the projection (52) is formed as the through hole in each projection (52) of the current collector plate (5). battery.

The convex portion (52) of the current collector plate (5) has an arc-shaped cross section, and between the adjacent convex portions (52) (52), a cut-out piece (53) protruding toward the electrode body (4). The secondary battery according to claim 1, wherein the secondary battery is formed.

The secondary battery according to any one of claims 1 to 3, wherein the same material as that of the current collector plate (5) is employed as a material of the sprayed metal.