JP2004055511A

JP2004055511A - Battery

Info

Publication number: JP2004055511A
Application number: JP2002374599A
Authority: JP
Inventors: Yasuhiro Yamauchi; 山内　康弘; Hironori Katayama; 片山　裕規
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 2002-05-31
Filing date: 2002-12-25
Publication date: 2004-02-19
Anticipated expiration: 2022-12-25
Also published as: JP4822647B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery in which an electrode and a current collector can be easily welded, and which has a current collecting structure having uniform current distribution and capable of reducing current collecting resistance, and has superior high-rate discharge performance. <P>SOLUTION: The battery is provided with a group of electrodes wherein a positive electrode 11 coated on a positive electrode core 11a with a positive electrode mix, and a negative electrode coated on a negative electrode core with a negative electrode mix, are laminated opposing each other through a separator 15. An uncoated part being not coated on the end of the positive electrode core 11a with the active material is formed, the current collector 12 being welded to the uncoated part. The current collector 12 has a connecting portion 12a-3 squeezed into the uncoated part of the core 11a of the electrode group, and a projected part 12a-3a projecting toward the bottom face of a main body 12a-1 of the current collector 12 from the bottom face of a recess 12a-3b of the connecting portion 12a-3. The uncoated part of the core 11a entering the projected part 12a-3a is welded to the projected part 12a-3a. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は正極芯体に正極合剤が塗布された正極と、負極芯体に負極合剤が塗布された負極がセパレータを介して相対向するように積層あるいは巻回された電極群を備え、正極芯体あるいは負極芯体の少なくとも一方の端部は正極合剤あるいは負極合剤が未塗布の未塗布部が形成されていて、該未塗布部に正極集電体あるいは負極集電体が溶接された集電構造を有する電池に関する。
【０００２】
【従来の技術】
一般に、リチウムイオン電池などの非水電解質二次電池、あるいはニッケル−水素化物蓄電池、ニッケル−カドミウム蓄電池などのアルカリ蓄電池は、正極および負極の間にセパレータを介在させ、これらを渦巻状に巻回した後、正極あるいは負極の端部に集電体を接続して電極体を形成する。ついで、この電極体を金属製電池ケースに収納して集電体から延伸するリード部を封口体に溶接した後、封口体を電池ケースの開口部に絶縁ガスケットを介在させて装着して密閉することにより製造するようになされている。
【０００３】
このような非水電解質二次電池やアルカリ蓄電池が電動工具や電気自動車などの用途に使用される場合、高率での放電性能が要求されるため、内部抵抗の低減や電流分布の均一化を図る必要性が生じた。そこで、正極あるいは負極の少なくとも一方の電極の活物質が塗布されていない未塗布部側の芯体の端縁を他方の電極より突出させて、セパレータを介して積層あるいは巻回して電極群を形成した後、未塗布部側の芯体の端縁に集電体を溶接して集電を行う方法が提案されるようになった。
【０００４】
この場合、未塗布部側の芯体の端縁と集電体が溶接不良を生じないように、特許文献１（特開平１０−２６１４４１号公報）においては、集電体にスリットを形成し、このスリットに未塗布部側の芯体の端縁を差し込み、この部分にレーザを照射して未塗布部側の芯体の端縁と集電体とを溶接する方法が提案されている。これにより、信頼性良く未塗布部側の芯体の端縁と集電体とが溶接できるようになって、電池の内部抵抗が低減し、かつ抵抗のばらつきが少ない電池が得られるというものである。
【特許文献１】
特開平１０−２６１４４１号公報
【０００５】
【発明が解決しようとする課題】
ここで、金属板にレーザを照射する場合、例えば、図１３（ａ）に示すように、平板の金属板ＭにレーザＬを照射すると、レーザＬの照射により溶融した金属が保持される部分がないため、図１３（ｂ）に示すように、溶融した金属Ｍｍは飛散して金属板Ｍに穴あきＨが生じるようになる。このため、上述した特開平１０−２６１４４１号公報に記載の方法により集電体にレーザを照射すると、レーザが集電体を透過したり、あるいは透過しない場合でも溶融した金属は表面張力で保持されることなく飛散することとなる。このため、溶接不良が発生して、場合によっては飛散した金属により内部短絡も発生するという問題も生じた。
【０００６】
一方、図１４（ａ）に示すように、金属板２０に凸部２１を形成し、この凸部２１の稜線に沿ってレーザＬを照射すると、レーザＬの照射により溶融した凸部２１の稜線近傍の金属２１ａは表面張力により凸部２１の稜線付近に保持されるため、図１４（ｂ）に示すように、凸部２１の頂点に穴あきが生じることはない。そこで、図１５（ａ）に示すような凸部２１を備えた金属板を集電体２０とし、この集電体２０の凸部２１内に電極１１の芯体露出部（活物質の未塗布部）１１ａの端縁を収束して差し込み、凸部２１の稜線に沿ってレーザＬを照射して溶接することを試みた。
【０００７】
この場合、集電体２０の平板部に位置する電極１１の芯体露出部１１ａの端縁は、集電体２０の押圧力により押し潰されるために、集電体２０の凸部２１内に収束して差し込まれた芯体露出部１１ａの端縁は、凸部２１内の先端部までは充分に差し込まれないこととなる。すると、凸部２１の稜線に沿ってレーザＬを照射すると、溶融した金属が芯体露出部１１ａの端縁から電極の中心部に向けて吸い込まれるので、図１５（ｂ）に示すように、集電体２０の凸部２１の稜線付近に穴あき２２が生じるとともに、溶融して飛散した金属２１ｂが電極間に落下して内部短絡が生じる原因ともなることが分かった。
【０００８】
そこで、本発明は上記問題点を解消するためになされたものであって、電極と集電体が容易に溶接でき、かつ電流分布が均一で集電抵抗を低減できる集電構造にして高率放電特性に優れた電池を提供できるようにすることを目的とする。
【０００９】
【課題を解決するための手段】
上記目的を達成するため、本発明の電池は、正極芯体に正極合剤が塗布された正極と、負極芯体に負極合剤が塗布された負極がセパレータを介して相対向するように積層あるいは巻回された電極群を備え、正極芯体あるいは負極芯体の少なくとも一方の端部は正極合剤あるいは負極合剤が未塗布の未塗布部が形成されていて、該芯体の未塗布部に正極集電体あるいは負極集電体が溶接されている。そして、正極集電体あるいは負極集電体の少なくとも一方は電極群の芯体の未塗布部内に嵌入する凹部からなる接続部を備えるとともに、この接続部に凹部の底面から正極集電体あるいは負極集電体の底面に向けて突出する凸部を備え、この凸部内に収束された芯体の未塗布部の一部と該凸部の一部が溶接された集電構造を有している。
【００１０】
このように、少なくとも一方の集電体に凹部からなる接続部を備え、この接続部の凹部の底面から集電体の底面に向けて突出する凸部を備えていると、集電体の接続部を芯体の未塗布部に嵌入させたときに、接続部の凸部内に芯体の未塗布部が適度に収束して進入するこことなる。これにより、芯体の未塗布部が過度に押し潰されることなく、凸部内に収束された芯体の未塗布部の一部と該凸部の一部を溶接することが可能となる。この場合、芯体の未塗布部が収束して進入した凸部の稜線に沿ってレーザなどのエネルギービームを照射することにより、集電体の溶融した金属が飛散することなく溶接できるようになる。これにより、正、負極間での短絡が防止できて内部抵抗が低減し、かつ電流分布が均一な集電構造が得られるようになる。この結果、高率放電特性に優れた電池を提供できるようになる。
【００１１】
そして、正極と負極がセパレータを介して渦巻状に巻回された渦巻状電極群を電極群として用いる場合には、正極集電体あるいは負極集電体に備えられた接続部の底面から突出する凸部の稜線が渦巻状電極群の略巻回軌跡に沿うように連続してあるいは不連続に配設されていると、芯体の未塗布部と接続部の凸部との溶接が強固になるので望ましい。この場合、正極集電体あるいは負極集電体に備えられた接続部の凹部および凸部はこれらの集電体の半径方向に連続してあるいは不連続に配設されていると、さらに好ましい。
【００１２】
【発明の実施の形態】
以下に、本発明を非水電解質二次電池に適用した場合の一実施の形態について、図１〜図１２に基づいて以下に説明するが、本発明はこの実施の形態に何ら限定されるものでなく、本発明の目的を変更しない範囲で適宜変更して実施することが可能である。なお、図１は本発明の一実施の形態の非水電解質二次電池を模式的に示す電極群を除く部分の断面を示す一部未破断の断面図である。また、図２は図１の非水電解質二次電池に用いられる正極と負極をセパレータを介して重ね合わせた状態を模式的に示す正面図である。図３は図２の積層状態のものを渦巻状に巻回して形成した電極群を示す斜視図である。図４は実施例の集電体を示す図であり、図４（ａ）は斜視図を示し、図４（ｂ）は図４（ａ）のＡ−Ａ断面を示す図である。また、図５〜図７は本発明にかかる他の実施例の集電体を表わす図である。
【００１３】
図８は比較例（従来例）の集電体を示す図であり、図８（ａ）は斜視図を示し、図８（ｂ）は図８（ａ）のＢ−Ｂ断面を示す図である。また、図９は図３の電極群に図４の集電体を取り付けて形成した電極体を示す斜視図である。また、図１０は図９の電極体の要部を示す断面図であり、図１０（ａ）は図３の電極群の上部に図４の集電体を配置した状態を示す断面図であり、図１０（ｂ）は集電体にレーザを照射して電極群の一方の電極と集電体を溶接した状態を示す断面図である。図１１は図３の電極群の上部および下部にそれぞれの集電体を溶接して形成した電極体を示す斜視図であり、図１２は図１１の電極体を外装缶内に収容する状態を示す斜視図である。
【００１４】
１．非水電解質二次電池
図１に示す本実施の形態の非水電解質二次電池１０は、図２に示すように、リチウム含有遷移金属複合酸化物を正極活物質として含有する正極１１と、天然黒鉛を負極活物質として含有する負極１３と、これらを隔離するセパレータ１５とを備えている。そして、セパレータ１５を間にして正極１１と負極１３を積層し、これを渦巻状に巻回した渦巻状電極群１０ａ’（図３参照）を金属製外装缶１６内に収容して備えている。この外装缶１６の開口部には正極端子１７ａと正極カバー１７ｂからなる封口蓋１７が配設されていて、ガスケット１８を介して外装缶１６の開口部が気密に封止されている。
【００１５】
この場合、後述するように渦巻状電極群１０ａ’の正極１１の上部には正極集電体１２ａ（１２ｂ，１２ｃ，１２ｄ）が接続されていて、この正極集電体１２ａ（１２ｂ，１２ｃ，１２ｄ）より延出する正極集電タブ１２ａ−２（１２ｂ−２，１２ｃ−２，１２ｄ−２）が封口蓋１７の正極カバー１７ｂに溶接されている。そして、正極集電体１２ａ（１２ｂ，１２ｃ，１２ｄ）の上部には絶縁板１９が配置されている。
【００１６】
また、後述するように渦巻状電極群１０ａ’の負極１３の下部には負極集電体１４ａ（１４ｂ，１４ｃ，１４ｄ）が接続されていて、この負極集電体１４ａ（１４ｂ，１４ｃ，１４ｄ）より延出する負極集電タブ１４ａ−２（１４ｂ−２，１４ｃ−２，１４ｄ−２）が外装缶１６の内底部に溶接されている。そして、封口蓋１７の正極端子１７ａと正極カバー１７ｂの間には図示しない圧力弁が配設されていて、電池内の圧力が上昇した際に、圧力弁が作動して電池内が所定の圧力以上にならないようになされている。
【００１７】
ここで、正極集電体１２ａは、図４（ａ）に示すように、略円板状の本体部１２ａ−１と、この本体部１２ａ−１より延出する略長方形状の集電タブ部１２ａ−２を備えている。本体部１２ａ−１は直線形状の接続部１２ａ−３を備えており、図４（ｂ）に示すように、この接続部１２ａ−３には、凹部１２ａ−３ｂの底面から本体部１２ａ−１の底面に向けて突出する凸部１２ａ−３ａが形成されている。同様に、負極集電体１４ａは、図４（ａ）に示すように、略円板状の本体部１４ａ−１と、この本体部１４ａ−１より延出する略長方形状の集電タブ部１４ａ−２を備えている。本体部１４ａ−１は直線形状の接続部１４ａ−３を備えており、図４（ｂ）に示すように、この接続部１４ａ−３には、凹部１４ａ−３ｂの底面から本体部１４ａ−１の底面に向けて突出する凸部１４ａ−３ａが形成されている。
【００１８】
また、正極集電体１２ｂは、図５（ａ）に示すように、略円板状の本体部１２ｂ−１と、この本体部１２ｂ−１より延出する略長方形状の集電タブ部１２ｂ−２を備えている。本体部１２ｂ−１は円弧状の接続部１２ｂ−３を備えており、図５（ｂ）に示すように、この接続部１２ｂ−３には、凹部１２ｂ−３ｂの底面から本体部１２ｂ−１の底面に向けて突出する凸部１２ｂ−３ａが形成されている。同様に、負極集電体１４ｂは、図５（ａ）に示すように、略円板状の本体部１４ｂ−１と、この本体部１４ｂ−１より延出する略長方形状の集電タブ部１４ｂ−２を備えている。本体部１４ｂ−１は円弧状の接続部１４ｂ−３を備えており、図４（ｂ）に示すように、この接続部１４ｂ−３には、凹部１４ｂ−３ｂの底面から本体部１４ｂ−１の底面に向けて突出する凸部１４ｂ−３ａが形成されている。
【００１９】
また、正極集電体１２ｃは、図６（ａ）に示すように、略円板状の本体部１２ｃ−１と、この本体部１２ｃ−１より延出する略長方形状の集電タブ部１２ｃ−２を備えている。本体部１２ｃ−１は円弧状の接続部１２ｃ−３を備えており、図６（ｂ）に示すように、この接続部１２ｃ−３には、凹部１２ｃ−３ｂの底面から本体部１２ｃ−１の底面に向けて突出する凸部１２ｃ−３ａが形成されている。同様に、負極集電体１４ｃは、図６（ａ）に示すように、略円板状の本体部１４ｃ−１と、この本体部１４ｃ−１より延出する略長方形状の集電タブ部１４ｃ−２を備えている。本体部１４ｃ−１は円弧状の接続部１４ｃ−３を備えており、図６（ｂ）に示すように、この接続部１４ｃ−３には、凹部１４ｃ−３ｂの底面から本体部１４ｃ−１の底面に向けて突出する凸部１４ｃ−３ａが形成されている。
【００２０】
また、正極集電体１２ｄは、図７（ａ）に示すように、略円板状の本体部１２ｄ−１と、この本体部１２ｄ−１より延出する略長方形状の集電タブ部１２ｄ−２を備えている。本体部１２ｄ−１は円弧状の接続部１２ｄ−３を備えており、図７（ｂ）に示すように、この接続部１２ｄ−３には、凹部１２ｄ−３ｂの底面から本体部１２ｄ−１の底面に向けて突出する凸部１２ｄ−３ａが形成されている。同様に、負極集電体１４ｄは、図７（ａ）に示すように、略円板状の本体部１４ｄ−１と、この本体部１４ｄ−１より延出する略長方形状の集電タブ部１４ｄ−２を備えている。本体部１４ｄ−１は円弧状の接続部１４ｄ−３を備えており、図７（ｂ）に示すように、この接続部１４ｄ−３には、凹部１４ｄ−３ｂの底面から本体部１４ｄ−１の底面に向けて突出する凸部１４ｄ−３ａが形成されている。
【００２１】
そして、正極集電体１２ａと渦巻状電極群１０ａ’の正極１１との接続（この場合、負極集電体１４ａと渦巻状電極群１０ａ’の負極１３との接続も同様であるので、その説明は省略する）は以下のようにしてなされている。即ち、図１０に示すように、凸部１２ａ−３ａ内に正極１１の上部に延出する芯体露出部（活物質の未塗布部）１１ａの一部が進入し、凸部１２ａ−３ａの稜線に沿って照射されたレーザ光により、凸部１２ａ−３ａの一部が溶融して該凸部１２ａ−３ａ内に進入した芯体露出部１１ａに溶着している。なお、他の正極集電体１２ｂ，１２ｃ，１２ｄを用いる場合も、正極集電体１２ａを用いた場合と同様である。
【００２２】
この場合、正極１１はアルミニウム箔（厚み：１５μｍ）からなる正極芯体１１ａの上端から４．０ｍｍ幅の部分を除く両面に正極活物質が塗布されて形成されている。また、正極集電体１２ａは厚みが０．３ｍｍのアルミニウム板をプレス加工により成形して形成されている。そして、正極芯体１１ａの４．０ｍｍ幅の未塗布部の一部が正極集電体１２ａの凸部１２ａ−３ａ内に進入して、溶着されている。なお、他の正極集電体１２ｂ，１２ｃ，１２ｄを用いる場合も、正極集電体１２ａを用いた場合とほぼ同様である。
【００２３】
また、負極１３は銅箔（厚み：１０μｍ）からなる負極芯体１３ａの下端から３．０ｍｍ幅の部分を除く両面に負極活物質が塗布されて形成されている。また、負極集電体１４ａは、厚みが０．３ｍｍのニッケル板あるいは銅板の表面にニッケルメッキを施したものをプレス加工により成形して形成されている。そして、負極芯体１３ａの３．０ｍｍ幅の未塗布部の一部が負極集電体１４ａの凸部１４ａ−３ａ内に進入して、溶着されている。なお、他の負極集電体１４ｂ，１４ｃ，１４ｄを用いる場合も、負極集電体１４ａを用いた場合とほぼ同様である。
【００２４】
２．非水電解質二次電池の作製工程
ついで、上述のように構成される非水電解質二次電池の作製工程について、正極の作製工程、負極の作製工程、集電体の作製工程、電池の組立工程の順で、以下に具体的に説明する。
【００２５】
（１）正極の作製
まず、正極合剤として、コバルト酸リチウム（ＬｉＣｏＯ_２）８５質量部と、導電剤としての黒鉛粉末５質量部とカーボンブラック５質量部とを充分に混合した。この後、Ｎ−メチル−２−ピロリドン（ＮＭＰ）に溶かした結着剤としてのフッ化ビニリデン系重合体を固形分として５質量部となるように混合して、正極合剤スラリーを作製した。ついで、得られた正極合剤スラリーを厚みが１５μｍの正極芯体（アルミニウム箔）１１ａの両面にドクターブレード法により塗布して、正極芯体１１ａの両面に正極合剤層１１ｂを形成した。
【００２６】
ついで、正極合剤層１１ｂを乾燥させた後、所定の厚み（例えば、厚みが１２０μｍ）になるまでローラプレス機により圧延した。この後、所定の寸法（例えば、幅が３２．５ｍｍで、長さが１１５５ｍｍ）になるように切断して正極１１を作製した。この場合、正極芯体１１ａの上端から４．０ｍｍまでは、正極芯体１１ａの両面に正極合剤層１１ｂが存在せずに、正極芯体１１ａの露出部分（未塗布部分）となるように正極合剤スラリーを塗布するようにしている。
【００２７】
（２）負極の作製
一方、天然黒鉛（Ｌｃ値が１５０Å以上で、ｄ値が３．３８Å以下のもの）粉末９５質量部に、Ｎ−メチル−２−ピロリドン（ＮＭＰ）に溶かした結着剤としてのフッ化ビニリデン系重合体を固形分として５質量部となるように混合して、負極合剤スラリーを調製した。この後、得られた負極合剤スラリーを厚みが１０μｍの負極芯体（銅箔）１３ａの両面にドクターブレード法により塗布して、負極芯体１３ａの両面に負極合剤層１３ｂを形成した。
【００２８】
ついで、負極合剤層１３ｂを乾燥させた後、所定の厚み（例えば、厚みが９５μｍ）になるまでローラプレス機により圧延した。この後、所定の寸法（例えば、幅が３３．５ｍｍで、長さが１２２０ｍｍ）になるように切断して負極１３を作製した。この場合、負極芯体１３ａの下端から３．０ｍｍまでは、負極芯体１３ａの両面に負極合剤層１３ｂが存在せずに、負極芯体１３ａの露出部分（未塗布部分）となるように負極合剤スラリーを塗布するようにしている。
【００２９】
ついで、上述のようにして作製した正極１１と負極１３とを用い、これらの正極１１と負極１３が厚みが２５〜３０μｍのポリエチレン製のセパレータ１５を介して相対向するように配置した。この場合、図２に示すように、正極１１の正極芯体１１ａの露出部（活物質未塗布部）が上方に突出するとともに、負極１３の負極芯体１３ａの露出部（活物質未塗布部）が下方に突出するように配置した。この後、これらの積層状態で渦巻状に巻回して、図３に示すような渦巻状電極群１０ａ’とした。
【００３０】
（３）集電体の作製
ａ．実施例１
まず、所定の厚み（例えば、０．３０ｍｍ）のアルミニウム板を用意し、このアルミニウム板をプレス成形により、図４（ａ），（ｂ）に示すように、略円板状の本体部１２ａ−１と、この本体部１２ａ−１より延出する略長方形状の集電タブ部１２ａ−２とを備えるように正極集電体１２ａを成形した。なお、本体部１２ａ−１の４箇所（上述した渦巻状電極群１０ａ’の渦巻の軌跡に沿う４箇所）に直線形状の接続部１２ａ−３を形成するとともに、この接続部１２ａ−３に凹部１２ａ−３ｂの底面から本体部１２ａ−１の底面に向けて突出する凸部１２ａ−３ａを形成するようにした。この場合、凸部１２ａ−３ａの頂部（稜線部）は本体部１２ａ−１の底面と略同一平面になるように形成している。これを実施例１の正極集電体１２ａとした。なお、本体部１２ａ−１の中心部には注液用の開口部１２ａ−４を形成している。この場合、本体部１２ａ−１の厚みｔ１と、凹部１２ａ−３ｂの厚みｔ２と、凸部１２ａ−３ａの厚みｔ３とが等しく（ｔ１＝ｔ２＝ｔ３＝０．３０ｍｍ）なるように形成されている。
【００３１】
同様に、所定の厚み（例えば、０．３０ｍｍ）のニッケル板あるいは銅板の表面にニッケルメッキを施したものを用意し、このニッケル板をプレス成形により、図４（ａ），（ｂ）に示すように、略円板状の本体部１４ａ−１と、この本体部１４ａ−１より延出する略長方形状の集電タブ部１４ａ−２とを備えるように負極集電体１４ａを成形した。この場合も、本体部１４ａ−１の厚みｔ１と、凹部１４ａ−３ｂの厚みｔ２と、凸部１４ａ−３ａの厚みｔ３とが等しく（ｔ１＝ｔ２＝ｔ３＝０．３０ｍｍ）なるように形成されている。
【００３２】
ｂ．実施例２
同様に、所定の厚み（例えば、０．４０ｍｍ）のアルミニウム板を用意し、このアルミニウム板をプレス成形により、図５（ａ），（ｂ）に示すように、略円板状の本体部１２ｂ−１と、この本体部１２ｂ−１より延出する略長方形状の集電タブ部１２ｂ−２とを備えるように正極集電体１２ｂを成形した。なお、本体部１２ｂ−１の４箇所（上述した渦巻状電極群１０ａ’の渦巻の軌跡に沿う４箇所）に渦巻の軌跡に沿う円弧状の接続部１２ｂ−３を形成するとともに、この接続部１２ｂ−３に凹部１２ｂ−３ｂの底面から本体部１２ｂ−１の底面に向けて突出する凸部１２ｂ−３ａを形成するようにした。この場合、凸部１２ｂ−３ａの頂部（稜線部）は本体部１２ｂ−１の底面から若干突出するように形成している。これを実施例２の正極集電体１２ｂとした。なお、本体部１２ｂ−１の中心部には注液用の開口部１２ｂ−４を形成している。この場合、本体部１２ｂ−１の厚みｔ１は０．４０ｍｍ（ｔ１＝０．４０ｍｍ）で、凹部１２ｂ−３ｂの厚みｔ２は０．２１ｍｍ（ｔ２＝０．２１ｍｍ）で、凸部１２ｂ−３ａの厚みｔ３は０．３３ｍｍ（ｔ３＝０．３３ｍｍ：ｔ３＞ｔ２）になるように形成されている。
【００３３】
同様に、所定の厚み（例えば、０．４０ｍｍ）のニッケル板あるいは銅板の表面にニッケルメッキを施したものを用意し、このニッケル板をプレス成形により、図５（ａ），（ｂ）に示すように、略円板状の本体部１４ｂ−１と、この本体部１４ｂ−１より延出する略長方形状の集電タブ部１４ｂ−２とを備えるように負極集電体１４ｂを成形した。この場合も、本体部１４ｂ−１の厚みｔ１は０．４０ｍｍ（ｔ１＝０．４０ｍｍ）で、凹部１４ｂ−３ｂの厚みｔ２は０．２１ｍｍ（ｔ２＝０．２１ｍｍ）で、凸部１４ｂ−３ａの厚みｔ３は０．３３ｍｍ（ｔ３＝０．３３ｍｍ：ｔ３＞ｔ２）になるように形成されている。
【００３４】
ｃ．実施例３
同様に、所定の厚み（例えば、０．３０ｍｍ）のアルミニウム板を用意し、このアルミニウム板をプレス成形により、図６（ａ），（ｂ）に示すように、略円板状の本体部１２ｃ−１と、この本体部１２ｃ−１より延出する略長方形状の集電タブ部１２ｃ−２とを備えるように正極集電体１２ｃを成形した。なお、本体部１２ｃ−１の４箇所（上述した渦巻状電極群１０ａ’の渦巻の軌跡に沿う４箇所）に渦巻の軌跡に沿う円弧状の接続部１２ｃ−３を形成するとともに、この接続部１２ｃ−３に凹部１２ｃ−３ｂの底面から本体部１２ｃ−１の底面に向けて突出する凸部１２ｃ−３ａを形成するようにした。この場合、凸部１２ｃ−３ａの頂部（稜線部）は本体部１２ｃ−１の底面から若干突出するように形成している。これを実施例３の正極集電体１２ｃとした。なお、本体部１２ｃ−１の中心部には注液用の開口部１２ｃ−４を形成している。この場合、本体部１２ｃ−１の厚みｔ１は０．３０ｍｍ（ｔ１＝０．３０ｍｍ）で、凹部１２ｃ−３ｂの厚みｔ２は０．２１ｍｍ（ｔ２＝０．２１ｍｍ）で、凸部１２ｂ−３ａの厚みｔ３は０．３３ｍｍ（ｔ３＝０．３３ｍｍ：ｔ３＞ｔ２，ｔ１）になるように形成されている。
【００３５】
同様に、所定の厚み（例えば、０．３０ｍｍ）のニッケル板あるいは銅板の表面にニッケルメッキを施したものを用意し、このニッケル板をプレス成形により、図６（ａ），（ｂ）に示すように、略円板状の本体部１４ｃ−１と、この本体部１４ｃ−１より延出する略長方形状の集電タブ部１４ｃ−２とを備えるように負極集電体１４ｃを成形した。この場合も、本体部１４ｃ−１の厚みｔ１は０．３０ｍｍ（ｔ１＝０．３０ｍｍ）で、凹部１４ｃ−３ｂの厚みｔ２は０．２１ｍｍ（ｔ２＝０．２１ｍｍ）で、凸部１４ｃ−３ａの厚みｔ３は０．３３ｍｍ（ｔ３＝０．３３ｍｍ：ｔ３＞ｔ２，ｔ１）になるように形成されている。
【００３６】
ｄ．実施例４
同様に、所定の厚み（例えば、０．３０ｍｍ）のアルミニウム板を用意し、このアルミニウム板をプレス成形により、図７（ａ），（ｂ）に示すように、略円板状の本体部１２ｄ−１と、この本体部１２ｄ−１より延出する略長方形状の集電タブ部１２ｄ−２とを備えるように正極集電体１２ｄを成形した。なお、本体部１２ｄ−１の４箇所（上述した渦巻状電極群１０ａ’の渦巻の軌跡に沿う４箇所）に渦巻の軌跡に沿う円弧状の接続部１２ｄ−３を形成するとともに、この接続部１２ｄ−３に凹部１２ｄ−３ｂの底面から本体部１２ｄ−１の底面に向けて突出する凸部１２ｄ−３ａを形成するようにした。この場合、凸部１２ｄ−３ａの頂部（稜線部）は本体部１２ｄ−１の底面と略同一平面になるように形成している。これを実施例４の正極集電体１２ｄとした。なお、本体部１２ｄ−１の中心部には注液用の開口部１２ｄ−４を形成している。この場合、本体部１２ｄ−１の厚みｔ１と、凹部１２ｄ−３ｂの厚みｔ２と、凸部１２ｄ−３ａの厚みｔ３とが等しく（ｔ１＝ｔ２＝ｔ３＝０．３０ｍｍ）なるように形成されている。
【００３７】
同様に、所定の厚み（例えば、０．３０ｍｍ）のニッケル板あるいは銅板の表面にニッケルメッキを施したものを用意し、このニッケル板をプレス成形により、図７（ａ），（ｂ）に示すように、略円板状の本体部１４ｄ−１と、この本体部１４ｄ−１より延出する略長方形状の集電タブ部１４ｄ−２とを備えるように負極集電体１４ｄを成形した。この場合も、本体部１４ｄ−１の厚みｔ１と、凹部１４ｄ−３ｂの厚みｔ２と、凸部１４ｄ−３ａの厚みｔ３とが等しく（ｔ１＝ｔ２＝ｔ３＝０．３０ｍｍ）なるように形成されている。
【００３８】
ｅ．比較例（従来例）
一方、所定の厚み（例えば、０．３０ｍｍ）のアルミニウム板を用意し、このアルミニウム板をプレス成形により、図８に示すように、略円板状の本体部２０ａと、この本体部２０ａより延出する略長方形状の集電タブ部２０ｂとを備え、かつ本体部２０ａの４箇所（上述した渦巻状電極群１０ａ’の渦巻の軌跡に沿う４箇所）に凸部２１を備えるとともに、この凸部２１の底部が本体部２０ａと略同一平面になるように正極集電体２０を成形した。これを比較例の正極集電体とした。なお、本体部２０ａの中心部には注液用の開口部２０ｄを形成している。
【００３９】
同様に、所定の厚み（例えば、０．３０ｍｍ）のニッケル板あるいは銅板の表面にニッケルメッキを施したものを用意し、このニッケル板をプレス成形により、図８に示すように、略円板状の本体部２２ａと、この本体部２２ａより延出する略長方形状の集電タブ部２２ｂとを備え、かつ本体部２２ａの４箇所（上述した渦巻状電極群１０ａ’の渦巻の軌跡に沿う４箇所）に凸部２３を備えるとともに、この凸部２３の底部が本体部２０ａと略同一平面になるように負極集電体２２を成形した。これを比較例の負極集電体とした。なお、本体部２２ａの中心部には注液用の開口部２２ｄを形成している。
【００４０】
（４）電池の組み立て工程
ついで、上述のようにして作製した正極集電体１２ａ〜１２ｄおよび２０を用い、これを上述のように作製した渦巻状電極群１０ａ’の上面に図９（なお、図９においては正極集電体１２ａを配置した場合のみ示しているが、正極集電体１２ｂ，１２ｃ，１２ｄ，２０においても同様である）に示すようにそれぞれ配置した。
このとき、正極集電体１２ａ（１２ｂ，１２ｃ，１２ｄ）においては、図１０（ａ）に示すように、凸部１２ａ−３ａ（１２ｂ−３ａ，１２ｃ−３ａ，１２ｄ−３ａ）内に正極１１の上部に延出する芯体露出部（活物質の未塗布部）１１ａの一部が進入するようになるとともに、本体部１２ａ−１（１２ｂ−１，１２ｃ−１，１２ｄ−１）の底面に芯体露出部１１ａが接触するようになる。
一方、正極集電体２０においては、図１５（ａ）に示すように、集電体２０の平板部に位置する電極１１の芯体露出部１１ａの端縁は、集電体２０の押圧力により押し潰されるために、集電体２０の凸部２１内に差し込まれた芯体露出部１１ａの端縁は凸部２１内の先端部までは充分に差し込まれないこととなる。
【００４１】
この後、正極集電体１２ａ（１２ｂ，１２ｃ，１２ｄ）においては、凸部１２ａ−３ａ（１２ｂ−３ａ，１２ｃ−３ａ，１２ｄ−３ａ）の稜線に沿ってレーザを照射して凸部１２ａ−３ａ（１２ｂ−３ａ，１２ｃ−３ａ，１２ｄ−３ａ）の一部を溶融させた。これにより、図１０（ｂ）に示すように、凸部１２ａ−３ａ（１２ｂ−３ａ，１２ｃ−３ａ，１２ｄ−３ａ）内に進入した芯体露出部１１ａと凸部１２ａ−３ａ（１２ｂ−３ａ，１２ｃ−３ａ，１２ｄ−３ａ）の一部とを溶着させた。また、正極集電体２０においては、凸部２１の頂点にレーザを照射して凸部２１の一部を溶融させて、凸部２１内に進入した芯体露出部１１ａと凸部２１の一部とを溶着させた。
【００４２】
同様に、上述のようにして作製した負極集電体１４ａ〜１４ｄおよび２２を用い、これを渦巻状電極群１０ａ’の下面にそれぞれ配置した。この後、正極集電体１２ａ（あるいは正極集電体１２ｂ，１２ｃ，１２ｄ，２０）と同様に、レーザを照射して、渦巻状電極群１０ａ’の下面にそれぞれ負極集電体１４ａ（１４ｂ，１４ｃ，１４ｄ）および２２を溶接した。
これにより、図１１に示すように、渦巻状電極群１０ａ’の上下面に、それぞれ正極集電体１２ａ（１２ｂ，１２ｃ，１２ｄ）と負極集電体１４ａ（１４ｂ，１４ｃ，１４ｄ）が溶接された渦巻状電極体１０ａを作製した。なお、図１１には、渦巻状電極群１０ａ’の上下面にそれぞれ正極集電体２０と負極集電体２２を溶接した渦巻状電極体を示していないが、この渦巻状電極体は渦巻状電極体１０ａとほぼ同様（以下においても、同様である）である。
【００４３】
ついで、図１に示すように、渦巻状電極体１０ａの正極集電体１２ａ（１２ｂ，１２ｃ，１２ｄ）の上部に絶縁板１９を配置するとともに、渦巻状電極体１０ａの外周部にポリプロピレン（ＰＰ）製の絶縁テープを巻き付けて、渦巻状電極体１０ａを固定した。ついで、正極集電体１２ａ（１２ｂ，１２ｃ，１２ｄ）（２０）の集電タブ部１２ａ−２（１２ｂ−２，１２ｃ−２，１２ｄ−２）（２０ｂ）を所定形状に折り曲げるとともに、負極集電体１４ａ（１４ｂ，１４ｃ，１４ｄ）（２２）の集電タブ部１４ａ−２（１４ｂ−２，１４ｃ−２，１４ｄ−２）（２２ｂ）も所定形状に折り曲げた。この後、図１２に示すように、円筒状の金属製（鉄にニッケルメッキを施したもの）外装缶１６を用意し、この外装缶１６内に上述のようにして作製した渦巻状電極体１０ａをそれぞれ挿入した。
【００４４】
ついで、正極集電体１２ａ（１２ｂ，１２ｃ，１２ｄ）（２０）の注液用の開口部１２ａ−４（１２ｂ−４，１２ｃ−４，１２ｄ−４）（２０ｄ）より溶接電極を挿入して、負極集電体１４ａ（１４ｂ，１４ｃ，１４ｄ）（２２）の集電タブ部１４ａ−２（１４ｂ−２，１４ｃ−２，１４ｄ−２）（２２ｂ）と外装缶１６の内底部とを抵抗溶接した。この後、外装缶１６の上部外周部の所定位置に溝入れ加工を施して、外装缶１６の上部外周部に凹部１６ａを形成した後、この凹部１６ａ上に絶縁ガスケット１８を装着した。ついで、正極端子１７ａと正極カバー１７ｂからなる封口蓋１７を用意した後、正極集電体１２ａ（１２ｂ，１２ｃ，１２ｄ）（２０）より延出する集電タブ部１２ａ−２（１２ｂ−２，１２ｃ−２，１２ｄ−２）（２０ｂ）の先端部を正極カバー１７ｂ底面に超音波溶接した。
【００４５】
この後、８０〜１１０℃に加熱された真空雰囲気中に配置して乾燥処理を行った後、外装缶１６の内部に非水電解液を注液し、封口蓋１７を絶縁ガスケット１８に装着して、外装缶１６の開口部をカシメて密封した。これにより、実施例１の非水電解質二次電池Ａと、実施例２の非水電解質二次電池Ｂと、実施例３の非水電解質二次電池Ｃと、実施例４の非水電解質二次電池Ｄと、比較例の非水電解質二次電池Ｘをそれぞれ作製した。なお、正極集電体１２ａおよび負極集電体１４ａを用いたものを非水電解質二次電池Ａとし、正極集電体１２ｂおよび負極集電体１４ｂを用いたものを非水電解質二次電池Ｂとし、正極集電体１２ｃおよび負極集電体１４ｃを用いたものを非水電解質二次電池Ｃとし、正極集電体１２ｄおよび負極集電体１４ｄを用いたものを非水電解質二次電池Ｄとし、正極集電体２０および負極集電体２２を用いたものを非水電解質二次電池Ｘとした。
【００４６】
ここで、電解液としては、エチレンカーボネート（ＥＣ）とジエチルカーボネート（ＤＥＣ）との等体積混合溶媒に、ＬｉＰＦ_６を１モル／リットル溶解した非水電解液を注入した。なお、溶媒に溶解される溶質としては、ＬｉＰＦ_６以外に、ＬｉＢＦ_４、ＬｉＣＦ_３ＳＯ_３、ＬｉＡｓＦ_６、ＬｉＮ（ＣＦ_３ＳＯ_２）_２、ＬｉＣ（ＣＦ_３ＳＯ_２）_３、ＬｉＣＦ_３（ＣＦ_２）_３ＳＯ_３等を用いてもよい。さらに、ポリマー電解質、ポリマーに非水電解液を含浸させたようなゲル状電解質、固体電解質なども使用できる。
【００４７】
また、混合溶媒としては、上述したエチレンカーボネート（ＥＣ）にジエチルカーボネート（ＤＥＣ）を混合したもの以外に、水素イオンを供給する能力のない非プロトン性溶媒を使用し、例えば、プロピレンカーボネート（ＰＣ）、ビニレンカーボネート（ＶＣ）、ブチレンカーボネート（ＢＣ）、γ−ブチロラクトン（ＧＢＬ）等の有機溶媒や、これらとジメチルカーボネート（ＤＭＣ）、メチルエチルカーボネート（ＥＭＣ）、１，２−ジエトキシエタン（ＤＥＥ）、１，２−ジメトキシ工タン（ＤＭＥ）、エトキシメトキシエタン（ＥＭＥ）などの低沸点溶媒との混合溶媒を用いてもよい。
【００４８】
３．試験
（１）溶接不良
上述のようにして非水電解質二次電池Ａ，Ｂ，Ｃ，Ｄ，Ｘをそれぞれ１００個ずつ作製する過程において、まず、渦巻状電極群１０ａ’の上下面に、それぞれ正極集電体１２ａ（１２ｂ，１２ｃ，１２ｄ）（２０）と負極集電体１４ａ（１４ｂ，１４ｃ，１４ｄ）（２２）を溶接して渦巻状電極体１０ａを作製する際に、正極集電体１２ａ（１２ｂ，１２ｃ，１２ｄ）（２０）あるいは負極集電体１４ａ（１４ｂ，１４ｃ，１４ｄ）（２２）に穴空きが生じたか否かを目視により観測して、いずれかの集電体に穴空きが生じた個数を求めた。
すると、非水電解質二次電池Ａ，Ｂ，Ｃ，Ｄにおいては、穴空きが生じた個数は０個であったのに対して、非水電解質二次電池Ｘにおいては、穴空きが生じた個数は２７個であった。そして、穴空きが生じた２７個（２７％）の非水電解質二次電池Ｘにおいては、穴空きが生じた位置に対応するセパレータが溶融して、正極１１と負極１３が短絡した状態であることが分かった。
【００４９】
（２）短絡不良
ついで、各集電体１２ａ（１２ｂ，１２ｃ，１２ｄ）（２０）および１４ａ（１４ｂ，１４ｃ，１４ｄ）（２２）の溶接時に穴空きが生じなかった各１００個の渦巻状電極体１０ａを用い、これの正、負極間にそれぞれ３００Ｖの交流電圧を印加して、１０ｍＡ以上の電流が流れた場合には短絡不良と判定する短絡試験を行って、短絡不良の個数を求めた。すると、非水電解質二次電池Ａにおいては、短絡不良が生じた個数は３個であった。そして、短絡不良が生じた３個の電池Ａにおいては、全てが活物質粉末や異物に起因する短絡で、集電体１２ａ（１４ａ）の溶接とは関係のない部分の短絡であることが分かった。また、非水電解質二次電池Ｂ，Ｃにおいては、短絡不良が生じた個数は０個であり、非水電解質二次電池Ｄにおいては、短絡不良が生じた個数は２個であった。この場合も、全てが活物質粉末や異物に起因する短絡で、集電体１２ｄ（１４ｄ）の溶接とは関係のない部分の短絡であることが分かった。
【００５０】
これに対して、非水電解質二次電池Ｘにおいては、短絡不良が生じた個数は１１個であった。そして、短絡不良が生じた１１個の内、５個は集電体の溶融時の流れ込みに起因して生じたセパレータ溶融による正、負極間の短絡であることが分かった。また、３個は、芯体１１ａ（１３ａ）の未塗布部が過度に押し潰されたことにより生じた芯体１１ａ（１３ａ）のエッジによるセパレータ貫通に起因する正、負極間の短絡であることが分かった。更に、３個は、活物質粉末や異物に起因する短絡であることが分かった。
【００５１】
（３）電圧不良
ついで、上述のようにして作製した非水電解質二次電池Ａ，Ｂ，Ｃ，Ｄ，Ｘにおいて、上述の溶接不良および短絡不良が生じなかった各１００個の電池Ａ，Ｂ，Ｃ，Ｄ，Ｘを用い、これらの各電池Ａ，Ｂ，Ｃ，Ｄ，Ｘの定格容量の３０％を充電した後、室温で６日間放置した。ここで、６日間の放置により、０．１Ｖ以上の電圧降下が生じた電池を電圧不良と判定する放置試験を行って、電圧不良の個数を求めた。すると、非水電解質二次電池Ａ，Ｂ，Ｃ，Ｄにおいては、電圧不良が生じた個数は０個であった。
【００５２】
これに対して、非水電解質二次電池Ｘにおいては、電圧不良が生じた個数は３個であった。そして、電圧不良が生じた全ての電池Ｘにおいては、芯体１１ａ（１３ａ）の未塗布部が過度に押し潰されたことにより生じた芯体１１ａ（１３ａ）のエッジによるセパレータ貫通に起因する正、負極間の短絡であることが分かった。そして、上述の各試験結果をまとめて表にすると、下記の表１に示すような結果となった。
【００５３】
（４）注液不良
ついで、上述のようにして作製した非水電解質二次電池Ａ，Ｂ，Ｃ，Ｄ，Ｘにおいて、上述の溶接不良、短絡不良および電圧不良が生じなかった各１００個の電池Ａ，Ｂ，Ｃ，Ｄ，Ｘを用い、これらの各電池Ａ，Ｂ，Ｃ，Ｄ，Ｘに電解液を注液した際に、３００秒以内に電解液の注液が完了しなかったものを注液不良と判定する注液試験を行った。この結果、下記の表１に示すような結果が得られた。
【００５４】
【表１】

【００５５】
上記表１の結果から明らかなように、比較例の電池Ｘは溶接不良、短絡不良、電圧不良、注液不良の発生が大きいのに対して、実施例の各電池Ａ，Ｂ，Ｃ，Ｄはこれらの不良の発生が少ないことが分かる。これは、実施例の電池Ａ，Ｂ，Ｃ，Ｄにおいては、各正極集電体１２ａ（１２ｂ，１２ｃ，１２ｄ）の本体部１２ａ−１（１２ｂ−１，１２ｃ−１，１２ｄ−１）に接続部１２ａ−３（１２ｂ−３，１２ｃ−３，１２ｄ−３）が形成されているとともに、この接続部１２ａ−３（１２ｂ−３，１２ｃ−３，１２ｄ−３）に凹部１２ａ−３ｂ（１２ｂ−３ｂ，１２ｃ−３ｂ，１２ｄ−３ｂ）の底面から本体部１２ａ−１（１２ｂ−１，１２ｃ−１，１２ｄ−１）の底面に向けて突出する凸部１２ａ−３ａ（１２ｂ−３ａ，１２ｃ−３ａ，１２ｄ−３ａ）が形成されている。そして、芯体露出部１１ａを凸部１２ａ−３ａ（１２ｂ−３ａ，１２ｃ−３ａ，１２ｄ−３ａ）内に進入させた後、凸部１２ａ−３ａ（１２ｂ−３ａ，１２ｃ−３ａ，１２ｄ−３ａ）の稜線に沿ってレーザを照射して、凸部１２ａ−３ａ（１２ｂ−３ａ，１２ｃ−３ａ，１２ｄ−３ａ）の一部を溶融させている。
【００５６】
また、負極集電体１４ａ（１４ｂ，１４ｃ，１４ｄ）の本体部１４ａ−１（１４ｂ−１，１４ｃ−１，１４ｄ−１）接続部１４ａ−３（１４ｂ−３，１４ｃ−３，１４ｄ−３）が形成されているとともに、この接続部１４ａ−３（１４ｂ−３，１４ｃ−３，１４ｄ−３）に凹部１４ａ−３ｂ（１４ｂ−３ｂ，１４ｃ−３ｂ，１４ｄ−３ｂ）の底面から本体部１４ａ−１（１４ｂ−１，１４ｃ−１，１４ｄ−１）の底面に向けて突出する凸部１４ａ−３ａ（１４ｂ−３ａ，１４ｃ−３ａ，１４ｄ−３ａ）が形成されている。そして、芯体露出部１３ａを凸部１４ａ−３ａ（１４ｂ−３ａ，１４ｃ−３ａ，１４ｄ−３ａ）内に進入させた後、凸部１４ａ−３ａ（１４ｂ−３ａ，１４ｃ−３ａ，１４ｄ−３ａ）の稜線に沿ってレーザを照射して、凸部１４ａ−３ａ（１４ｂ−３ａ，１４ｃ−３ａ，１４ｄ−３ａ）の一部を溶融させている。
【００５７】
このため、比較例の電池Ｘのように、集電体２０（２２）の溶融金属の飛散によるセパレータ１５の溶融や、集電体２０（２２）の圧接時の芯体１１ａ（１３ａ）の未塗布部が過度に押し潰されたことにより生じた芯体１１ａ（１３ａ）のエッジによるセパレータ貫通に起因する正、負極間の短絡が生じなかったためと考えられる。
【００５８】
また、電池Ｂ，Ｃ，Ｄは電池Ａに比較して、溶接不良、短絡不良、電圧不良、注液不良の発生が少ないことが分かる。これは、電池Ｂ，Ｃ，Ｄにおいては、接続部１４ｂ−３（１４ｃ−３，１４ｄ−３）は直線形状ではなく、渦巻の軌跡に沿う円弧状に形成されているため、芯体露出部１１ａ（１３ａ）が凸部１２ｂ−３ａ（１２ｃ−３ａ，１２ｄ−３ａ）（１４ｂ−３ａ（１４ｃ−３ａ，１４ｄ−３ａ））内に進入するのが容易になる。これにより、溶接不良、短絡不良、電圧不良、注液不良の発生が減少したと考えられる。さらに、電池Ｂ，Ｃにおいては、凸部１２ｂ−３ａ，１２ｃ−３ａの厚みが凹部１２ｂ−３ｂ，１２ｃ−３ｂの厚みよりも肉厚に形成されている。このため、電池Ｄのように、凸部１２ｄ−３ａの厚みと凹部１２ｄ−３ｂの厚みが等しい場合に比べて溶接強度が向上して、溶接不良が生じないこととなる。
【００５９】
なお、上述した実施の形態においては、正極集電体および負極集電体に形成した凹部と凸部からなる接続部を、これらの集電体の本体部の渦巻状電極群の略巻回軌跡に沿う４箇所に不連続に形成する例について説明したが、接続部の配設箇所についてはこれに限らず、渦巻状電極群の略巻回軌跡に沿う適宜の数カ所に形成するようにしても良いし、あるいは略巻回軌跡に沿うように連続して形成するようにしてもよい。
【００６０】
また、上述した実施の形態においては、正極集電体および負極集電体に形成した凹部と凸部からなる接続部を集電体の半径方向の４箇所に不連続に配設する例について説明したが、これらの接続部を集電体の半径方向に連続して配設するようにしてもよく、その配設方向も集電体の半径方向の数カ所にしてもよい。また、上述した実施の形態においては、レーザを照射して各集電体と各電極を溶接する例について説明したが、レーザに代えて電子ビーム、イオンビームなどの他のエネルギービームを用いるようにしてもよい。
【００６１】
また、上述した実施の形態においては、本発明を非水電解質二次電池に適用する例について説明したが、本発明は非水電解質二次電池に限らず、ニッケル−水素化物蓄電池、ニッケル−カドミウム蓄電池などのアルカリ蓄電池、あるいは他の種類の電池に適用できることは明らかである。この場合、電極芯体として金属箔を用いた電極を使用した電池に適用すると特に効果的である。
【図面の簡単な説明】
【図１】本発明の一実施の形態の非水電解質二次電池を模式的に示す電極群を除く部分の断面を示す一部破断の断面図である。
【図２】図１の非水電解質二次電池に用いられる正極と負極をセパレータを介して重ね合わせた状態を示す正面図である。
【図３】図２の積層状態のものを渦巻状に巻回して形成した電極群を示す斜視図である。
【図４】実施例１の集電体を示す図であり、図４（ａ）は斜視図を示し、図４（ｂ）は図４（ａ）のＡ−Ａ断面を示す図である。
【図５】実施例２の集電体を示す図であり、図５（ａ）は斜視図を示し、図５（ｂ）は図５（ａ）のＢ−Ｂ断面を示す図である。
【図６】実施例３の集電体を示す図であり、図６（ａ）は斜視図を示し、図６（ｂ）は図６（ａ）のＣ−Ｃ断面を示す図である。
【図７】実施例４の集電体を示す図であり、図７（ａ）は斜視図を示し、図７（ｂ）は図７（ａ）のＤ−Ｄ断面を示す図である。
【図８】比較例（従来例）の集電体を示す図であり、図８（ａ）は斜視図を示し、図８（ｂ）は図８（ａ）のＥ−Ｅ断面を示す図である。
【図９】図３の電極群に図４の集電体を取り付けて形成した電極体を示す斜視図である。
【図１０】図９の電極体の要部を示す断面図であり、図１０（ａ）は図３の電極群の上部に図４の集電体を配置した状態を示す断面図であり、図１０（ｂ）は集電体にレーザを照射して電極群の一方の電極と集電体を溶接した状態を示す断面図である。
【図１１】図３の電極群の上部および下部にそれぞれの集電体を溶接して形成した電極体を示す斜視図である。
【図１２】図１１の電極体を外装缶内に収容する状態を示す斜視図である。
【図１３】平板の金属板にレーザを照射して金属を溶融させる例を模式的に示す図であり、図１３（ａ）はレーザを照射する状態を模式的に示す断面図であり、図１３（ｂ）はレーザ照射後の状態を模式的に示す断面図である。
【図１４】凸部を形成した金属板の凸部にレーザを照射して金属を溶融させる例を模式的に示す図であり、図１４（ａ）はレーザを照射する状態を模式的に示す断面図であり、図１４（ｂ）はレーザ照射後の状態を模式的に示す断面図である。
【図１５】凸部を形成した金属板の凸部内に差し込まれた電極の芯体と凸部とをレーザにより溶融接合する例を模式的に示す図であり、図１５（ａ）はレーザを照射する状態を模式的に示す断面図であり、図１５（ｂ）はレーザ照射後の状態を模式的に示す断面図である。
【符号の説明】
１０…非水電解質二次電池、１０ａ…渦巻状電極体、１０ａ’…渦巻状電極群、１１…正極、１１ａ…正極芯体、１１ｂ…正極合剤層、１２ａ，１２ｂ，１２ｃ，１２ｄ…正極集電体、１２ａ−１，１２ｂ−１，１２ｃ−１，１２ｄ−１…本体部、１２ａ−２，１２ｂ−２，１２ｃ−２，１２ｄ−２…正極集電タブ、１２ａ−３，１２ｂ−３，１２ｃ−３，１２ｄ−３…接続部、１２ａ−３ａ，１２ｂ−３ａ，１２ｃ−３ａ，１２ｄ−３ａ…凸部、１２ａ−３ｂ，１２ｂ−３ｂ，１２ｃ−３ｂ，１２ｄ−３ｂ…凹部、１２ａ−４，１２ｂ−４，１２ｃ−４，１２ｄ−４…開口部、１３…負極、１３ａ…負極芯体、１３ｂ…負極合剤層、１４ａ，１４ｂ，１４ｃ，１４ｄ…負極集電体、１４ａ−１，１４ｂ−１，１４ｃ−１，１４ｄ−１…本体部、１４ａ−２，１４ｂ−２，１４ｃ−２，１４ｄ−２…負極集電タブ、１４ａ−３，１４ｂ−３，１４ｃ−３，１４ｄ−３…接続部、１４ａ−３ａ，１４ｂ−３ａ，１４ｃ−３ａ，１４ｄ−３ａ…凸部、１４ａ−３ｂ，１４ｂ−３ｂ，１４ｃ−３ｂ，１４ｄ−３ｂ…凹部、１４ａ−４，１４ｂ−４，１４ｃ−４，１４ｄ−４…注液用の開口部、１５…セパレータ、１６…金属製外装缶、１６ａ…凹部、１７…封口蓋、１７ａ…正極端子、１７ｂ…正極カバー、１８…絶縁ガスケット、１９…絶縁板[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention includes a positive electrode in which a positive electrode mixture is applied to a positive electrode core, and an electrode group in which a negative electrode in which a negative electrode mixture is applied to a negative electrode core is laminated or wound so as to face each other via a separator, At least one end of the positive electrode core or the negative electrode core has an uncoated portion where the positive electrode mixture or the negative electrode mixture is not applied, and the positive electrode current collector or the negative electrode current collector is welded to the uncoated portion. The present invention relates to a battery having an improved current collecting structure.
[0002]
[Prior art]
Generally, non-aqueous electrolyte secondary batteries such as lithium ion batteries, or alkaline storage batteries such as nickel-hydride storage batteries and nickel-cadmium storage batteries have a separator interposed between a positive electrode and a negative electrode, and these are spirally wound. Thereafter, a current collector is connected to an end of the positive electrode or the negative electrode to form an electrode body. Then, the electrode body is housed in a metal battery case, and a lead extending from the current collector is welded to a sealing body, and the sealing body is attached to the opening of the battery case with an insulating gasket interposed therebetween, and sealed. It is made to manufacture by doing.
[0003]
When such non-aqueous electrolyte secondary batteries or alkaline storage batteries are used in applications such as power tools and electric vehicles, high-rate discharge performance is required, so reducing the internal resistance and making the current distribution uniform are required. There is a need to plan. Therefore, an electrode group is formed by protruding the edge of the core on the side of the uncoated portion where the active material of at least one of the positive electrode and the negative electrode is not coated from the other electrode, and laminating or winding through a separator. After that, there has been proposed a method of collecting a current by welding a current collector to an edge of a core body on an uncoated portion side.
[0004]
In this case, a slit is formed in the current collector in Patent Literature 1 (Japanese Patent Application Laid-Open No. 10-261441) so as to prevent welding failure between the edge of the core on the uncoated portion side and the current collector. A method has been proposed in which the edge of the core on the uncoated portion side is inserted into the slit, and a laser beam is applied to this portion to weld the edge of the core on the uncoated portion and the current collector. As a result, the edge of the core body on the uncoated portion side and the current collector can be reliably welded, and the internal resistance of the battery is reduced, and a battery with less variation in resistance is obtained. is there.
[Patent Document 1]
JP-A-10-261441
[0005]
[Problems to be solved by the invention]
Here, when the metal plate is irradiated with the laser, for example, as shown in FIG. 13A, when the flat metal plate M is irradiated with the laser L, the portion where the metal melted by the laser L is held is held. Therefore, as shown in FIG. 13 (b), the molten metal Mm scatters and a hole H is formed in the metal plate M. Therefore, when the current collector is irradiated with a laser by the method described in JP-A-10-261441, the molten metal is held at the surface tension even when the laser passes through the current collector or does not pass through the current collector. Will be scattered. For this reason, there has been a problem that poor welding occurs and, in some cases, an internal short circuit also occurs due to the scattered metal.
[0006]
On the other hand, as shown in FIG. 14A, when a convex portion 21 is formed on the metal plate 20 and the laser L is irradiated along the ridge line of the convex portion 21, the ridge line of the convex portion 21 melted by the irradiation of the laser L Since the nearby metal 21a is held near the ridge line of the convex portion 21 by the surface tension, as shown in FIG. 14B, no hole is formed at the vertex of the convex portion 21. Therefore, a metal plate having a convex portion 21 as shown in FIG. 15A is used as the current collector 20, and the core exposed portion of the electrode 11 (the active material is not coated) is provided in the convex portion 21 of the current collector 20. The edge of the portion 11a was converged and inserted, and an attempt was made to irradiate and weld the laser L along the ridge line of the convex portion 21.
[0007]
In this case, since the edge of the core exposed portion 11 a of the electrode 11 located on the flat plate portion of the current collector 20 is crushed by the pressing force of the current collector 20, The edge of the core exposed portion 11a that has been converged and inserted is not sufficiently inserted up to the tip portion within the convex portion 21. Then, when the laser L is irradiated along the ridge line of the convex portion 21, the molten metal is sucked from the edge of the core exposed portion 11a toward the center of the electrode, and as shown in FIG. It was found that a hole 22 was formed near the ridgeline of the convex portion 21 of the current collector 20, and that the metal 21b melted and scattered fell between the electrodes to cause an internal short circuit.
[0008]
Therefore, the present invention has been made to solve the above-mentioned problem, and has a high current collection structure capable of easily welding an electrode and a current collector, having a uniform current distribution and reducing a current collection resistance. An object is to provide a battery having excellent discharge characteristics.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the battery of the present invention has a structure in which a positive electrode in which a positive electrode mixture is applied to a positive electrode core and a negative electrode in which a negative electrode mixture is applied to a negative electrode core face each other via a separator. Alternatively, a wound electrode group is provided, and at least one end of the positive electrode core or the negative electrode core has an uncoated portion where the positive electrode mixture or the negative electrode mixture is not applied, and the uncoated portion of the core is not applied. A positive electrode current collector or a negative electrode current collector is welded to the portion. At least one of the positive electrode current collector and the negative electrode current collector includes a connection portion formed of a concave portion that fits into an uncoated portion of the core of the electrode group. The current collector has a projection protruding toward the bottom surface, and has a current collecting structure in which a part of the uncoated portion of the core converged in the projection and a part of the projection are welded. .
[0010]
As described above, when at least one of the current collectors includes the connection portion including the concave portion, and includes the convex portion protruding from the bottom surface of the concave portion of the connection portion toward the bottom surface of the current collector, the connection of the current collector When the portion is fitted into the uncoated portion of the core, the uncoated portion of the core is appropriately converged and enters the projection of the connection portion. Accordingly, it is possible to weld a part of the uncoated part of the core body converged in the convex part and a part of the convex part without excessively crushing the uncoated part of the core body. In this case, by irradiating an energy beam such as a laser along the ridge line of the convex portion where the uncoated portion of the core body has converged and entered, welding can be performed without scattering of the molten metal of the current collector. . As a result, a short circuit between the positive and negative electrodes can be prevented, the internal resistance can be reduced, and a current collecting structure with a uniform current distribution can be obtained. As a result, a battery excellent in high-rate discharge characteristics can be provided.
[0011]
When a spiral electrode group in which a positive electrode and a negative electrode are spirally wound via a separator is used as an electrode group, the positive electrode and the negative electrode protrude from the bottom surface of a connection portion provided on the positive electrode current collector or the negative electrode current collector. If the ridge lines of the convex portions are arranged continuously or discontinuously along the spiral winding trajectory of the spiral electrode group, the welding between the uncoated portion of the core and the convex portion of the connection portion will be strong. Is desirable. In this case, it is more preferable that the concave portion and the convex portion of the connection portion provided on the positive electrode current collector or the negative electrode current collector are continuously or discontinuously arranged in the radial direction of the current collector.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a non-aqueous electrolyte secondary battery will be described below with reference to FIGS. 1 to 12, but the present invention is not limited to this embodiment. Instead, the present invention can be implemented with appropriate changes without departing from the scope of the present invention. FIG. 1 is a partially unbroken cross-sectional view showing a cross section of a portion excluding an electrode group schematically showing a nonaqueous electrolyte secondary battery according to an embodiment of the present invention. FIG. 2 is a front view schematically showing a state in which a positive electrode and a negative electrode used in the non-aqueous electrolyte secondary battery of FIG. 1 are overlapped with a separator interposed therebetween. FIG. 3 is a perspective view showing an electrode group formed by spirally winding the stacked structure of FIG. 4A and 4B are diagrams showing the current collector of the example, FIG. 4A is a perspective view, and FIG. 4B is a diagram showing a cross section taken along line AA of FIG. 4A. FIGS. 5 to 7 show current collectors according to other embodiments of the present invention.
[0013]
FIG. 8 is a diagram showing a current collector of a comparative example (conventional example), FIG. 8 (a) is a perspective view, and FIG. 8 (b) is a diagram showing a BB cross section of FIG. 8 (a). is there. FIG. 9 is a perspective view showing an electrode body formed by attaching the current collector of FIG. 4 to the electrode group of FIG. 10 is a cross-sectional view showing a main part of the electrode body of FIG. 9, and FIG. 10 (a) is a cross-sectional view showing a state where the current collector of FIG. 4 is arranged above the electrode group of FIG. FIG. 10B is a cross-sectional view showing a state where the current collector is irradiated with a laser to weld one of the electrodes of the electrode group to the current collector. FIG. 11 is a perspective view showing an electrode body formed by welding current collectors to upper and lower portions of the electrode group of FIG. 3, and FIG. 12 shows a state in which the electrode body of FIG. 11 is housed in an outer can. FIG.
[0014]
1. Non-aqueous electrolyte secondary battery
As shown in FIG. 2, the nonaqueous electrolyte secondary battery 10 of the present embodiment shown in FIG. 1 has a positive electrode 11 containing a lithium-containing transition metal composite oxide as a positive electrode active material, and natural graphite as a negative electrode active material. A negative electrode 13 to be contained and a separator 15 for isolating them are provided. Then, the positive electrode 11 and the negative electrode 13 are stacked with the separator 15 interposed therebetween, and a spirally wound electrode group 10a '(see FIG. 3) obtained by spirally winding the stacked positive and negative electrodes 13 is accommodated in a metal outer can 16 and provided. . A sealing lid 17 composed of a positive electrode terminal 17a and a positive electrode cover 17b is provided in the opening of the outer can 16, and the opening of the outer can 16 is hermetically sealed via a gasket 18.
[0015]
In this case, as described later, a positive electrode current collector 12a (12b, 12c, 12d) is connected to the upper part of the positive electrode 11 of the spiral electrode group 10a ', and the positive electrode current collector 12a (12b, 12c, 12d). The positive electrode current collecting tabs 12a-2 (12b-2, 12c-2, 12d-2) extending from) are welded to the positive electrode cover 17b of the sealing lid 17. Then, an insulating plate 19 is arranged above the positive electrode current collector 12a (12b, 12c, 12d).
[0016]
As described later, a negative electrode current collector 14a (14b, 14c, 14d) is connected to a lower portion of the negative electrode 13 of the spiral electrode group 10a ', and the negative electrode current collector 14a (14b, 14c, 14d) is provided. Further extending negative electrode current collecting tabs 14a-2 (14b-2, 14c-2, 14d-2) are welded to the inner bottom of the outer can 16. A pressure valve (not shown) is provided between the positive electrode terminal 17a of the sealing lid 17 and the positive electrode cover 17b. When the pressure in the battery rises, the pressure valve operates and the inside of the battery has a predetermined pressure. It is done so as not to be over.
[0017]
Here, as shown in FIG. 4A, the positive electrode current collector 12a includes a substantially disk-shaped main body 12a-1 and a substantially rectangular current collector tab extending from the main body 12a-1. 12a-2. The main body portion 12a-1 includes a linear connection portion 12a-3. As shown in FIG. 4B, the connection portion 12a-3 is provided on the main body portion 12a-1 from the bottom surface of the concave portion 12a-3b. The projections 12a-3a protruding toward the bottom surface are formed. Similarly, as shown in FIG. 4A, the negative electrode current collector 14a includes a substantially disk-shaped main body 14a-1 and a substantially rectangular current collector tab extending from the main body 14a-1. 14a-2. The main body portion 14a-1 includes a linear connection portion 14a-3. As shown in FIG. 4B, the connection portion 14a-3 is provided on the main body portion 14a-1 from the bottom surface of the concave portion 14a-3b. The projections 14a-3a protruding toward the bottom surface of are formed.
[0018]
As shown in FIG. 5A, the positive electrode current collector 12b includes a substantially disk-shaped main body 12b-1 and a substantially rectangular current collector tab 12b extending from the main body 12b-1. -2. The main body 12b-1 includes an arc-shaped connecting portion 12b-3. As shown in FIG. 5B, the connecting portion 12b-3 is provided on the main body 12b-1 from the bottom surface of the concave portion 12b-3b. The projections 12b-3a protruding toward the bottom surface are formed. Similarly, as shown in FIG. 5A, the negative electrode current collector 14b includes a substantially disk-shaped main body 14b-1 and a substantially rectangular current collector tab extending from the main body 14b-1. 14b-2. The main body portion 14b-1 includes an arc-shaped connecting portion 14b-3. As shown in FIG. 4B, the connecting portion 14b-3 is provided on the main body portion 14b-1 from the bottom surface of the concave portion 14b-3b. The projections 14b-3a projecting toward the bottom surface of are formed.
[0019]
As shown in FIG. 6A, the positive electrode current collector 12c includes a substantially disk-shaped main body 12c-1 and a substantially rectangular current collector tab 12c extending from the main body 12c-1. -2. The main body portion 12c-1 includes an arc-shaped connecting portion 12c-3. As shown in FIG. 6B, the connecting portion 12c-3 is provided on the main body portion 12c-1 from the bottom surface of the concave portion 12c-3b. The convex portion 12c-3a protruding toward the bottom surface of is formed. Similarly, as shown in FIG. 6A, the negative electrode current collector 14c has a substantially disk-shaped main body 14c-1 and a substantially rectangular current collector tab extending from the main body 14c-1. 14c-2. The main body portion 14c-1 includes an arc-shaped connecting portion 14c-3. As shown in FIG. 6B, the connecting portion 14c-3 is provided on the main body portion 14c-1 from the bottom surface of the concave portion 14c-3b. The convex part 14c-3a which protrudes toward the bottom surface of is formed.
[0020]
As shown in FIG. 7A, the positive electrode current collector 12d includes a substantially disk-shaped main body 12d-1 and a substantially rectangular current collector tab 12d extending from the main body 12d-1. -2. The main body 12d-1 includes an arc-shaped connecting portion 12d-3. As shown in FIG. 7B, the connecting portion 12d-3 is provided with a main body 12d-1 from the bottom surface of the concave portion 12d-3b. The convex portion 12d-3a protruding toward the bottom surface of is formed. Similarly, as shown in FIG. 7A, the negative electrode current collector 14d includes a substantially disk-shaped main body portion 14d-1 and a substantially rectangular current collection tab portion extending from the main body portion 14d-1. 14d-2. The main body portion 14d-1 includes an arc-shaped connecting portion 14d-3. As shown in FIG. 7B, the connecting portion 14d-3 is provided on the main body portion 14d-1 from the bottom surface of the concave portion 14d-3b. A convex portion 14d-3a protruding toward the bottom surface of is formed.
[0021]
Then, the connection between the positive electrode current collector 12a and the positive electrode 11 of the spiral electrode group 10a '(in this case, the connection between the negative electrode current collector 14a and the negative electrode 13 of the spiral electrode group 10a' is also the same. Is omitted) in the following manner. That is, as shown in FIG. 10, a part of the core exposed portion (uncoated portion of the active material) 11 a extending above the positive electrode 11 enters the convex portion 12 a-3 a and enters the convex portion 12 a-3 a. A part of the convex portion 12a-3a is melted by the laser beam irradiated along the ridge line and is welded to the core exposed portion 11a that has entered the convex portion 12a-3a. The case where the other positive electrode

current collectors

12b, 12c and 12d are used is the same as the case where the positive electrode current collector 12a is used.
[0022]
In this case, the positive electrode 11 is formed by applying a positive electrode active material to both surfaces of the positive electrode core 11a made of aluminum foil (thickness: 15 μm) except for a portion having a width of 4.0 mm from the upper end. The positive electrode current collector 12a is formed by pressing a 0.3 mm thick aluminum plate by pressing. Then, a part of the uncoated portion having a width of 4.0 mm of the positive electrode core 11a enters the projections 12a-3a of the positive electrode current collector 12a and is welded. The case where the other positive electrode

current collectors

12b, 12c and 12d are used is almost the same as the case where the positive electrode current collector 12a is used.
[0023]
The negative electrode 13 is formed by applying a negative electrode active material to both surfaces of a negative electrode core 13 a made of copper foil (thickness: 10 μm) except for a portion having a width of 3.0 mm from the lower end. The negative electrode current collector 14a is formed by pressing a nickel plate or a copper plate having a thickness of 0.3 mm on the surface of which is plated with nickel. Then, a part of the uncoated portion having a width of 3.0 mm of the negative electrode core 13a enters the projections 14a-3a of the negative electrode current collector 14a and is welded. The case where the other negative electrode

current collectors

14b, 14c and 14d are used is almost the same as the case where the negative electrode current collector 14a is used.
[0024]
2. Manufacturing process of non-aqueous electrolyte secondary battery
Next, regarding the manufacturing process of the non-aqueous electrolyte secondary battery configured as described above, the following specifically describes the manufacturing process of the positive electrode, the manufacturing process of the negative electrode, the manufacturing process of the current collector, and the assembly process of the battery. explain.
[0025]
(1) Preparation of positive electrode
First, as a positive electrode mixture, lithium cobalt oxide (LiCoO ₂ ) 85 parts by mass, 5 parts by mass of graphite powder as a conductive agent, and 5 parts by mass of carbon black were sufficiently mixed. Thereafter, a vinylidene fluoride polymer as a binder dissolved in N-methyl-2-pyrrolidone (NMP) was mixed so as to have a solid content of 5 parts by mass to prepare a positive electrode mixture slurry. Next, the obtained positive electrode mixture slurry was applied to both surfaces of a positive electrode core (aluminum foil) 11a having a thickness of 15 μm by a doctor blade method to form a positive electrode mixture layer 11b on both surfaces of the positive electrode core 11a.
[0026]
Next, after drying the positive electrode mixture layer 11b, the positive electrode mixture layer 11b was rolled by a roller press until a predetermined thickness (for example, a thickness of 120 μm) was obtained. Thereafter, the positive electrode 11 was manufactured by being cut into a predetermined size (for example, a width of 32.5 mm and a length of 1155 mm). In this case, up to 4.0 mm from the upper end of the positive electrode core 11a, the positive electrode mixture layer 11b does not exist on both surfaces of the positive electrode core 11a, and the exposed portion (uncoated portion) of the positive electrode core 11a is formed. The positive electrode mixture slurry is applied.
[0027]
(2) Preparation of negative electrode
On the other hand, vinylidene fluoride as a binder dissolved in N-methyl-2-pyrrolidone (NMP) was added to 95 parts by mass of natural graphite (having an Lc value of 150 ° or more and a d value of 3.38 ° or less) powder. The polymer was mixed so as to be 5 parts by mass as a solid content to prepare a negative electrode mixture slurry. Thereafter, the obtained negative electrode mixture slurry was applied to both surfaces of a 10 μm-thick negative electrode core (copper foil) 13a by a doctor blade method to form a negative electrode mixture layer 13b on both surfaces of the negative electrode core 13a.
[0028]
Next, after drying the negative electrode mixture layer 13b, the negative electrode mixture layer 13b was rolled by a roller press until a predetermined thickness (for example, the thickness was 95 μm) was obtained. After that, the negative electrode 13 was manufactured by cutting to a predetermined size (for example, a width of 33.5 mm and a length of 1220 mm). In this case, the negative electrode mixture layer 13b does not exist on both surfaces of the negative electrode core 13a from the lower end of the negative electrode core 13a to 3.0 mm, so that the negative electrode core 13a is exposed (uncoated portion). The negative electrode mixture slurry is applied.
[0029]
Next, the positive electrode 11 and the negative electrode 13 manufactured as described above were used, and the positive electrode 11 and the negative electrode 13 were arranged so as to face each other via a polyethylene separator 15 having a thickness of 25 to 30 μm. In this case, as shown in FIG. 2, the exposed portion of the positive electrode core 11a of the positive electrode 11 (the portion not coated with the active material) protrudes upward, and the exposed portion of the negative electrode core 13a of the negative electrode 13 (the portion not coated with the active material). ) Project downward. Thereafter, these layers are spirally wound in a laminated state to form a spiral electrode group 10a 'as shown in FIG.
[0030]
(3) Production of current collector
a. Example 1
First, an aluminum plate having a predetermined thickness (for example, 0.30 mm) is prepared, and this aluminum plate is subjected to press molding to form a substantially disk-shaped main body portion 12a- as shown in FIGS. 1, and a positive electrode current collector 12a was formed to include a substantially rectangular current collection tab portion 12a-2 extending from the main body portion 12a-1. In addition, a linear connection portion 12a-3 is formed at four locations (four locations along the spiral trajectory of the spiral electrode group 10a 'described above) of the main body portion 12a-1, and a concave portion is formed in the connection portion 12a-3. Protrusions 12a-3a projecting from the bottom surface of 12a-3b toward the bottom surface of main body 12a-1 are formed. In this case, the tops (ridges) of the protrusions 12a-3a are formed so as to be substantially flush with the bottom surface of the main body 12a-1. This was used as the positive electrode current collector 12a of Example 1. An opening 12a-4 for liquid injection is formed at the center of the main body 12a-1. In this case, the thickness t1 of the main body portion 12a-1, the thickness t2 of the concave portions 12a-3b, and the thickness t3 of the convex portions 12a-3a are formed to be equal (t1 = t2 = t3 = 0.30 mm). I have.
[0031]
Similarly, a nickel plate or a copper plate having a predetermined thickness (for example, 0.30 mm) having a surface plated with nickel is prepared, and this nickel plate is subjected to press molding to be shown in FIGS. 4 (a) and 4 (b). Thus, the negative electrode current collector 14a was formed so as to include the substantially disk-shaped main body 14a-1 and the substantially rectangular current collection tab 14a-2 extending from the main body 14a-1. Also in this case, the thickness t1 of the main body portion 14a-1, the thickness t2 of the concave portions 14a-3b, and the thickness t3 of the convex portions 14a-3a are equal (t1 = t2 = t3 = 0.30 mm). ing.
[0032]
b. Example 2
Similarly, an aluminum plate having a predetermined thickness (for example, 0.40 mm) is prepared, and this aluminum plate is press-formed to form a substantially disk-shaped main body 12b as shown in FIGS. 5 (a) and 5 (b). -1, and a positive electrode current collector 12b was formed so as to include a substantially rectangular current collection tab portion 12b-2 extending from the main body portion 12b-1. In addition, arc-shaped connecting portions 12b-3 along the spiral locus are formed at four locations (four locations along the spiral locus of the spiral electrode group 10a 'described above) of the main body portion 12b-1, and the connecting portions are formed. A protrusion 12b-3a projecting from the bottom surface of the concave portion 12b-3b toward the bottom surface of the main body portion 12b-1 is formed on the 12b-3. In this case, the tops (ridges) of the protrusions 12b-3a are formed so as to slightly protrude from the bottom surface of the main body 12b-1. This was used as the positive electrode current collector 12b of Example 2. An opening 12b-4 for liquid injection is formed in the center of the main body 12b-1. In this case, the thickness t1 of the main body portion 12b-1 is 0.40 mm (t1 = 0.40 mm), the thickness t2 of the concave portion 12b-3b is 0.21 mm (t2 = 0.21 mm), and the thickness t1 of the convex portion 12b-3a. The thickness t3 is formed to be 0.33 mm (t3 = 0.33 mm: t3> t2).
[0033]
Similarly, a nickel plate or a copper plate having a predetermined thickness (for example, 0.40 mm) having a surface plated with nickel is prepared, and this nickel plate is press-formed and shown in FIGS. 5 (a) and 5 (b). As described above, the negative electrode current collector 14b was formed so as to include the substantially disk-shaped main body portion 14b-1 and the substantially rectangular current collecting tab portion 14b-2 extending from the main body portion 14b-1. Also in this case, the thickness t1 of the main body portion 14b-1 is 0.40 mm (t1 = 0.40 mm), the thickness t2 of the concave portion 14b-3b is 0.21 mm (t2 = 0.21 mm), and the convex portion 14b-3a is formed. Is formed to have a thickness t3 of 0.33 mm (t3 = 0.33 mm: t3> t2).
[0034]
c. Example 3
Similarly, an aluminum plate having a predetermined thickness (for example, 0.30 mm) is prepared, and this aluminum plate is press-formed to form a substantially disk-shaped main body 12c as shown in FIGS. 6 (a) and 6 (b). -1 and a current collector tab 12c-2 having a substantially rectangular shape extending from the main body 12c-1 to form a positive electrode current collector 12c. In addition, arc-shaped connecting portions 12c-3 along the spiral locus are formed at four locations of the main body 12c-1 (four locations along the spiral locus of the spiral electrode group 10a 'described above), and the connecting portions are formed. A convex portion 12c-3a projecting from the bottom surface of the concave portion 12c-3b toward the bottom surface of the main body portion 12c-1 is formed on 12c-3. In this case, the tops (ridges) of the protrusions 12c-3a are formed so as to slightly protrude from the bottom surface of the main body 12c-1. This was used as a positive electrode current collector 12c of Example 3. An opening 12c-4 for liquid injection is formed in the center of the main body 12c-1. In this case, the thickness t1 of the main body 12c-1 is 0.30 mm (t1 = 0.30 mm), the thickness t2 of the concave portion 12c-3b is 0.21 mm (t2 = 0.21 mm), and the thickness t1 of the convex portion 12b-3a. The thickness t3 is formed to be 0.33 mm (t3 = 0.33 mm: t3> t2, t1).
[0035]
Similarly, a nickel plate or a copper plate having a predetermined thickness (for example, 0.30 mm) having a surface plated with nickel is prepared, and this nickel plate is subjected to press molding, as shown in FIGS. 6 (a) and 6 (b). As described above, the negative electrode current collector 14c was formed so as to include the substantially disk-shaped main body portion 14c-1 and the substantially rectangular current collecting tab portion 14c-2 extending from the main body portion 14c-1. Also in this case, the thickness t1 of the main body portion 14c-1 is 0.30 mm (t1 = 0.30 mm), the thickness t2 of the concave portion 14c-3b is 0.21 mm (t2 = 0.21 mm), and the convex portion 14c-3a. Is formed so as to have a thickness t3 of 0.33 mm (t3 = 0.33 mm: t3> t2, t1).
[0036]
d. Example 4
Similarly, an aluminum plate having a predetermined thickness (for example, 0.30 mm) is prepared, and this aluminum plate is press-formed to form a substantially disk-shaped main body 12d as shown in FIGS. 7 (a) and 7 (b). -1, and a positive electrode current collector 12d was formed so as to include a substantially rectangular current collection tab portion 12d-2 extending from the main body portion 12d-1. In addition, the arc-shaped connecting portion 12d-3 along the spiral locus is formed at four locations (four locations along the spiral locus of the spiral electrode group 10a 'described above) of the main body portion 12d-1, and this connecting portion is formed. A protrusion 12d-3a is formed on 12d-3 to protrude from the bottom of the recess 12d-3b toward the bottom of the main body 12d-1. In this case, the tops (ridges) of the protrusions 12d-3a are formed so as to be substantially flush with the bottom surface of the main body 12d-1. This was used as a positive electrode current collector 12d of Example 4. An opening 12d-4 for liquid injection is formed at the center of the main body 12d-1. In this case, the thickness t1 of the main body 12d-1, the thickness t2 of the concave portion 12d-3b, and the thickness t3 of the convex portion 12d-3a are equal (t1 = t2 = t3 = 0.30 mm). I have.
[0037]
Similarly, a nickel plate or a copper plate having a predetermined thickness (for example, 0.30 mm) having a surface plated with nickel is prepared, and this nickel plate is press-formed and shown in FIGS. 7A and 7B. As described above, the negative electrode current collector 14d was formed so as to include the substantially disk-shaped main body portion 14d-1 and the substantially rectangular current collecting tab portion 14d-2 extending from the main body portion 14d-1. Also in this case, the thickness t1 of the main body portion 14d-1, the thickness t2 of the concave portion 14d-3b, and the thickness t3 of the convex portion 14d-3a are equal (t1 = t2 = t3 = 0.30 mm). ing.
[0038]
e. Comparative example (conventional example)
On the other hand, an aluminum plate having a predetermined thickness (for example, 0.30 mm) is prepared, and this aluminum plate is formed by press molding as shown in FIG. And a projecting portion 21 at four locations of the main body 20a (four locations along the spiral trajectory of the spiral electrode group 10a '). The positive electrode current collector 20 was formed such that the bottom of the portion 21 was substantially flush with the main body portion 20a. This was used as a positive electrode current collector of a comparative example. An opening 20d for liquid injection is formed in the center of the main body 20a.
[0039]
Similarly, a nickel plate or a copper plate having a predetermined thickness (for example, 0.30 mm) having a surface plated with nickel is prepared, and the nickel plate is formed into a substantially disk-like shape by press molding as shown in FIG. And a substantially rectangular current collecting tab portion 22b extending from the main body portion 22a, and at four positions of the main body portion 22a (four points along the spiral trajectory of the spiral electrode group 10a 'described above). ), And the negative electrode current collector 22 was formed such that the bottom of the projection 23 was substantially flush with the main body 20a. This was used as a negative electrode current collector of a comparative example. An opening 22d for liquid injection is formed at the center of the main body 22a.
[0040]
(4) Battery assembly process
Next, the positive electrode current collectors 12a to 12d and 20 produced as described above were used, and these were placed on the upper surface of the spiral electrode group 10a 'produced as described above with reference to FIG. Although only the case where the body 12a is arranged is shown, the same applies to the positive electrode

current collectors

12b, 12c, 12d and 20).
At this time, in the positive electrode current collector 12a (12b, 12c, 12d), as shown in FIG. 10A, the positive electrode 11 is provided in the protrusion 12a-3a (12b-3a, 12c-3a, 12d-3a). A portion of the core exposed portion (uncoated portion of the active material) 11a extending to the upper portion of the body enters, and the bottom surface of the main body portion 12a-1 (12b-1, 12c-1, 12d-1). The core exposed portion 11a comes into contact with the contact.
On the other hand, in the positive electrode current collector 20, as shown in FIG. 15A, the edge of the core exposed portion 11 a of the electrode 11 located on the flat plate portion of the current collector 20 is pressed by the pressing force of the current collector 20. As a result, the edge of the core exposed portion 11a inserted into the convex portion 21 of the current collector 20 is not sufficiently inserted to the tip portion within the convex portion 21.
[0041]
Thereafter, in the positive electrode current collector 12a (12b, 12c, 12d), laser is irradiated along the ridge line of the projection 12a-3a (12b-3a, 12c-3a, 12d-3a) to project the projection 12a-. A part of 3a (12b-3a, 12c-3a, 12d-3a) was melted. Thus, as shown in FIG. 10B, the core exposed portion 11a and the convex portions 12a-3a (12b-3a) that have entered the convex portions 12a-3a (12b-3a, 12c-3a, 12d-3a). , 12c-3a, and 12d-3a). Further, in the positive electrode current collector 20, a laser is applied to the apex of the convex portion 21 to melt a part of the convex portion 21, and the core exposed portion 11 a that has entered the convex portion 21 and one of the convex portions 21. Parts were welded.
[0042]
Similarly, the negative electrode current collectors 14a to 14d and 22 produced as described above were used, and were disposed on the lower surface of the spiral electrode group 10a '. Thereafter, similarly to the positive electrode current collector 12a (or the positive electrode

current collectors

12b, 12c, 12d, and 20), laser irradiation is performed, and the negative electrode current collectors 14a (14b, 14b, 14c, 14d) and 22 were welded.
Thereby, as shown in FIG. 11, the positive electrode current collectors 12a (12b, 12c, 12d) and the negative electrode current collectors 14a (14b, 14c, 14d) are welded to the upper and lower surfaces of the spiral electrode group 10a ', respectively. A spiral electrode body 10a was manufactured. FIG. 11 does not show a spiral electrode body in which the positive electrode current collector 20 and the negative electrode current collector 22 are welded to the upper and lower surfaces of the spiral electrode group 10a ', respectively. It is almost the same as the electrode body 10a (the same applies to the following).
[0043]
Next, as shown in FIG. 1, an insulating plate 19 is disposed on the positive electrode current collector 12a (12b, 12c, 12d) of the spiral electrode body 10a, and polypropylene (PP) is formed on the outer periphery of the spiral electrode body 10a. ) Was wound to fix the spiral electrode body 10a. Next, the current collecting tab portions 12a-2 (12b-2, 12c-2, 12d-2) (20b) of the positive electrode current collectors 12a (12b, 12c, 12d) (20) are bent into a predetermined shape, and The current collecting tab portions 14a-2 (14b-2, 14c-2, 14d-2) (22b) of the electric bodies 14a (14b, 14c, 14d) (22) were also bent into a predetermined shape. Thereafter, as shown in FIG. 12, a cylindrical metal (nickel-plated iron) outer can 16 is prepared, and the spirally wound electrode body 10a manufactured as described above is provided in the outer can 16. Was inserted.
[0044]
Next, a welding electrode is inserted from the opening 12a-4 (12b-4, 12c-4, 12d-4) (20d) for pouring the positive electrode current collector 12a (12b, 12c, 12d) (20). The current collecting tabs 14a-2 (14b-2, 14c-2, 14d-2) (22b) of the negative electrode current collectors 14a (14b, 14c, 14d) (22) and the inner bottom of the outer can 16 are connected by resistance. Welded. Thereafter, a groove was formed at a predetermined position in the upper outer peripheral portion of the outer can 16 to form a concave portion 16a in the upper outer peripheral portion of the outer can 16, and an insulating gasket 18 was mounted on the concave portion 16a. Next, after preparing a sealing lid 17 comprising a positive electrode terminal 17a and a positive electrode cover 17b, a current collecting tab portion 12a-2 (12b-2, 12b-2, 12b-2) extending from the positive electrode current collector 12a (12b, 12c, 12d) (20). 12c-2, 12d-2) (20b) was ultrasonically welded to the bottom surface of the positive electrode cover 17b.
[0045]
After that, after being placed in a vacuum atmosphere heated to 80 to 110 ° C. to perform a drying process, a non-aqueous electrolyte is poured into the outer can 16, and the sealing lid 17 is attached to the insulating gasket 18. Then, the opening of the outer can 16 was caulked and sealed. Thus, the non-aqueous electrolyte secondary battery A of Example 1, the non-aqueous electrolyte secondary battery B of Example 2, the non-aqueous electrolyte secondary battery C of Example 3, and the non-aqueous electrolyte secondary battery of Example 4 A secondary battery D and a non-aqueous electrolyte secondary battery X of a comparative example were produced. A battery using the positive electrode current collector 12a and the negative electrode current collector 14a is referred to as a non-aqueous electrolyte secondary battery A, and a battery using the positive electrode current collector 12b and the negative electrode current collector 14b is referred to as a non-aqueous electrolyte secondary battery B. A battery using the positive electrode current collector 12c and the negative electrode current collector 14c is referred to as a nonaqueous electrolyte secondary battery C, and a battery using the positive electrode current collector 12d and the negative electrode current collector 14d is referred to as a nonaqueous electrolyte secondary battery D. The non-aqueous electrolyte secondary battery X was obtained using the positive electrode current collector 20 and the negative electrode current collector 22.
[0046]
Here, as the electrolytic solution, LiPF was used in an equal volume mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC). ₆ Was dissolved and dissolved in a non-aqueous electrolyte. The solute dissolved in the solvent is LiPF ₆ Besides, LiBF ₄ , LiCF ₃ SO ₃ , LiAsF ₆ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiCF ₃ (CF ₂ ) ₃ SO ₃ Etc. may be used. Further, a polymer electrolyte, a gel electrolyte obtained by impregnating a polymer with a non-aqueous electrolyte, a solid electrolyte, and the like can also be used.
[0047]
As the mixed solvent, an aprotic solvent having no ability to supply hydrogen ions other than the above-mentioned mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) is used. For example, propylene carbonate (PC) , Vinylene carbonate (VC), butylene carbonate (BC), and organic solvents such as .gamma.-butyrolactone (GBL), and dimethyl carbonate (DMC), methyl ethyl carbonate (EMC), and 1,2-diethoxyethane (DEE). , 1,2-dimethoxyethane (DME), ethoxymethoxyethane (EME) and other low-boiling solvents.
[0048]
3. test
(1) Poor welding
In the process of manufacturing 100 non-aqueous electrolyte secondary batteries A, B, C, D, and X as described above, first, the positive electrode current collectors 12a ( 12b, 12c, 12d) (20) and the negative electrode current collectors 14a (14b, 14c, 14d), (22) when the spiral electrode body 10a is manufactured by welding, the positive electrode current collectors 12a (12b, 12c, 12d) (20) or the negative electrode current collectors 14a (14b, 14c, 14d) (22) are visually observed to determine whether or not holes have been formed. I asked.
Then, in the non-aqueous electrolyte secondary batteries A, B, C, and D, the number of holes formed was 0, whereas in the non-aqueous electrolyte secondary battery X, holes were formed. The number was 27. Then, in the 27 (27%) non-aqueous electrolyte secondary batteries X with holes, the separator corresponding to the position where the holes were formed melted, and the positive electrode 11 and the negative electrode 13 were short-circuited. I found out.
[0049]
(2) Short circuit failure
Next, 100 spiral electrode bodies 10a, each of which has no hole when welding the current collectors 12a (12b, 12c, 12d) (20) and 14a (14b, 14c, 14d) (22), are used. An AC voltage of 300 V was applied between the positive electrode and the negative electrode, and when a current of 10 mA or more flowed, a short-circuit test for determining a short-circuit was performed, and the number of short-circuits was determined. Then, in the non-aqueous electrolyte secondary battery A, the number of short-circuit failures was three. Then, in the three batteries A in which the short-circuit failure occurred, it was found that all of the short-circuits were caused by the active material powder or foreign matter, and were short-circuits not related to the welding of the current collector 12a (14a). Was. In the non-aqueous electrolyte secondary batteries B and C, the number of short-circuit failures was zero, and in the non-aqueous electrolyte secondary battery D, the number of short-circuit failures was two. In this case as well, it was found that all of the short-circuits were caused by the active material powder or foreign matter, and were short-circuited in a portion unrelated to the welding of the current collector 12d (14d).
[0050]
On the other hand, in the nonaqueous electrolyte secondary battery X, the number of short-circuit failures was eleven. It was found that out of the eleven short-circuit failures, five were short-circuits between the positive and negative electrodes due to the melting of the separator caused by the flow of the current collector during melting. The three are short-circuits between the positive electrode and the negative electrode caused by the penetration of the separator due to the edge of the core 11a (13a) caused by excessively crushing the uncoated portion of the core 11a (13a). I understood. Further, it was found that three were short-circuits caused by the active material powder and foreign matter.
[0051]
(3) Voltage failure
Next, in the non-aqueous electrolyte secondary batteries A, B, C, D, and X manufactured as described above, 100 batteries A, B, C, D, and 100 each in which the above-described welding failure and short-circuit failure did not occur. Using X, 30% of the rated capacity of each of these batteries A, B, C, D, and X was charged, and then left at room temperature for 6 days. Here, a battery test in which a voltage drop of 0.1 V or more occurred after being left for 6 days was determined as a voltage defect, and the number of voltage defects was determined. Then, in the non-aqueous electrolyte secondary batteries A, B, C, and D, the number of voltage failures was zero.
[0052]
On the other hand, in the non-aqueous electrolyte secondary battery X, the number of voltage failures was three. In all of the batteries X in which the voltage failure has occurred, the non-coated portion of the core 11a (13a) is excessively crushed, and the positive electrode caused by the penetration of the separator by the edge of the core 11a (13a). It was found that this was a short circuit between the negative electrodes. When the above test results were put together in a table, the results were as shown in Table 1 below.
[0053]
(4) Poor injection
Next, in the non-aqueous electrolyte secondary batteries A, B, C, D, and X produced as described above, 100 batteries A, B, and C each of which did not have the above-described welding failure, short-circuit failure, and voltage failure. , D, and X, when the electrolyte was injected into each of the batteries A, B, C, D, and X, and the injection of the electrolyte was not completed within 300 seconds. A judging test was performed. As a result, the results shown in Table 1 below were obtained.
[0054]
[Table 1]

[0055]
As is clear from the results in Table 1, the battery X of the comparative example has large occurrences of welding failure, short-circuit failure, voltage failure, and liquid injection failure, whereas the batteries A, B, C, and D of the example are large. Indicates that the occurrence of these defects is small. This is because, in the batteries A, B, C, and D of the embodiment, the main body 12a-1 (12b-1, 12c-1, 12d-1) of each positive electrode current collector 12a (12b, 12c, 12d). The connection parts 12a-3 (12b-3, 12c-3, 12d-3) are formed, and the connection parts 12a-3 (12b-3, 12c-3, 12d-3) have recesses 12a-3b ( Convex parts 12a-3a (12b-3a, 12b-3a, 12b-3a, 12b-3a, 12d-3b) protruding from the bottom surface of the main body 12a-1 (12b-1, 12c-1, 12d-1) from the bottom surface of the main body 12a-1 (12b-1, 12c-1, 12d-1). 12c-3a, 12d-3a) are formed. Then, after the core body exposed portion 11a enters the convex portions 12a-3a (12b-3a, 12c-3a, 12d-3a), the convex portions 12a-3a (12b-3a, 12c-3a, 12d-3a). ) Is irradiated along the ridge line to melt a part of the projections 12a-3a (12b-3a, 12c-3a, 12d-3a).
[0056]
Further, the main body 14a-1 (14b-1, 14c-1, 14d-1) connecting portion 14a-3 (14b-3, 14c-3, 14d-3) of the negative electrode current collector 14a (14b, 14c, 14d). ) Is formed, and the connecting portion 14a-3 (14b-3, 14c-3, 14d-3) is formed from the bottom of the concave portion 14a-3b (14b-3b, 14c-3b, 14d-3b) to the main body portion. Protrusions 14a-3a (14b-3a, 14c-3a, 14d-3a) projecting toward the bottom surface of 14a-1 (14b-1, 14c-1, 14d-1) are formed. Then, after the core body exposing portion 13a enters the projections 14a-3a (14b-3a, 14c-3a, 14d-3a), the projections 14a-3a (14b-3a, 14c-3a, 14d-3a). ) Is irradiated along the ridge line to melt a part of the projections 14a-3a (14b-3a, 14c-3a, 14d-3a).
[0057]
For this reason, like the battery X of the comparative example, the melting of the separator 15 due to the scattering of the molten metal of the current collector 20 (22) and the unloading of the core 11a (13a) when the current collector 20 (22) is pressed. It is considered that a short circuit between the positive electrode and the negative electrode did not occur due to the penetration of the separator by the edge of the core body 11a (13a) caused by excessively crushing the application portion.
[0058]
In addition, it can be seen that batteries B, C, and D have fewer occurrences of poor welding, short-circuit, voltage, and liquid injection than battery A. This is because, in the batteries B, C, and D, the connecting portions 14b-3 (14c-3, 14d-3) are not formed in a straight line but in an arc shape following the trajectory of the spiral. 11a (13a) can easily enter the protrusions 12b-3a (12c-3a, 12d-3a) (14b-3a (14c-3a, 14d-3a)). As a result, it is considered that the occurrence of welding failure, short-circuit failure, voltage failure, and injection failure was reduced. Further, in the batteries B and C, the thickness of the convex portions 12b-3a and 12c-3a is formed to be thicker than the thickness of the concave portions 12b-3b and 12c-3b. For this reason, compared with the case where the thickness of the convex part 12d-3a and the thickness of the concave part 12d-3b are equal to each other as in the battery D, the welding strength is improved and welding failure does not occur.
[0059]
Note that, in the above-described embodiment, the connection portion formed of the concave portion and the convex portion formed on the positive electrode current collector and the negative electrode current collector is substantially connected to the spiral path of the spiral electrode group of the main body of the current collector. The example in which the connection portions are discontinuously formed at four locations along the line has been described. However, the location of the connection portions is not limited to this, and the connection portions may be formed at appropriate several locations along a substantially spiral locus of the spiral electrode group. Alternatively, it may be formed continuously along the winding locus.
[0060]
Further, in the above-described embodiment, an example will be described in which connection portions formed on the positive electrode current collector and the negative electrode current collector and formed of concave portions and convex portions are discontinuously arranged at four radial positions of the current collector. However, these connecting portions may be continuously arranged in the radial direction of the current collector, and the disposing direction may be several places in the radial direction of the current collector. Further, in the above-described embodiment, an example in which each current collector and each electrode are welded by irradiating a laser has been described, but another energy beam such as an electron beam or an ion beam may be used instead of the laser. You may.
[0061]
Also, in the above-described embodiment, an example in which the present invention is applied to a non-aqueous electrolyte secondary battery has been described. However, the present invention is not limited to a non-aqueous electrolyte secondary battery, and a nickel-hydride storage battery, a nickel-cadmium Obviously, it can be applied to alkaline storage batteries such as storage batteries or other types of batteries. In this case, it is particularly effective when applied to a battery using an electrode using a metal foil as an electrode core.
[Brief description of the drawings]
FIG. 1 is a partially broken cross-sectional view showing a cross section of a portion excluding an electrode group schematically showing a nonaqueous electrolyte secondary battery according to an embodiment of the present invention.
FIG. 2 is a front view showing a state where a positive electrode and a negative electrode used in the non-aqueous electrolyte secondary battery of FIG. 1 are overlapped with a separator interposed therebetween.
FIG. 3 is a perspective view showing an electrode group formed by spirally winding the stacked structure of FIG. 2;
4A and 4B are diagrams showing a current collector of Example 1, FIG. 4A is a perspective view, and FIG. 4B is a diagram showing a cross section taken along line AA of FIG. 4A.
5A and 5B are views showing a current collector of Example 2, FIG. 5A is a perspective view, and FIG. 5B is a view showing a cross section taken along line BB of FIG. 5A.
6A and 6B are diagrams showing a current collector of Example 3, FIG. 6A is a perspective view, and FIG. 6B is a diagram showing a cross section taken along line CC of FIG. 6A.
7A and 7B are diagrams showing a current collector of Example 4, FIG. 7A is a perspective view, and FIG. 7B is a diagram showing a cross section taken along line DD of FIG. 7A.
8A and 8B are views showing a current collector of a comparative example (conventional example), FIG. 8A is a perspective view, and FIG. 8B is a view showing a cross section taken along line EE of FIG. 8A. It is.
9 is a perspective view showing an electrode body formed by attaching the current collector of FIG. 4 to the electrode group of FIG. 3;
10 is a cross-sectional view showing a main part of the electrode body of FIG. 9; FIG. 10A is a cross-sectional view showing a state where the current collector of FIG. 4 is arranged above the electrode group of FIG. 3; FIG. 10B is a cross-sectional view illustrating a state where the current collector is irradiated with a laser to weld one of the electrodes of the electrode group and the current collector.
11 is a perspective view showing an electrode body formed by welding current collectors to upper and lower portions of the electrode group of FIG. 3;
FIG. 12 is a perspective view showing a state in which the electrode body of FIG. 11 is housed in an outer can.
FIG. 13 is a diagram schematically showing an example of irradiating a flat metal plate with a laser to melt the metal, and FIG. 13A is a cross-sectional view schematically showing a state of irradiating the laser; FIG. 13B is a cross-sectional view schematically showing a state after laser irradiation.
FIG. 14 is a view schematically showing an example in which a metal is melted by irradiating a convex part of a metal plate having a convex part with a laser, and FIG. 14 (a) schematically shows a state in which a laser is irradiated; FIG. 14B is a cross-sectional view schematically showing a state after laser irradiation.
FIG. 15 is a diagram schematically showing an example in which a core of an electrode inserted into a convex portion of a metal plate having a convex portion and a convex portion are fusion-bonded with a laser, and FIG. FIG. 15B is a cross-sectional view schematically illustrating a state of irradiation, and FIG. 15B is a cross-sectional view schematically illustrating a state after laser irradiation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Non-aqueous electrolyte secondary battery, 10a ... spiral electrode body, 10a '... spiral electrode group, 11 ... positive electrode, 11a ... positive electrode core body, 11b ... positive electrode mixture layer, 12a, 12b, 12c, 12d ... positive electrode Current collectors, 12a-1, 12b-1, 12c-1, 12d-1: Main body, 12a-2, 12b-2, 12c-2, 12d-2: Positive current collector tabs, 12a-3, 12b- 3, 12c-3, 12d-3 ... connecting portion, 12a-3a, 12b-3a, 12c-3a, 12d-3a ... convex portion, 12a-3b, 12b-3b, 12c-3b, 12d-3b ... concave portion, 12a-4, 12b-4, 12c-4, 12d-4: opening, 13: negative electrode, 13a: negative electrode core, 13b: negative electrode mixture layer, 14a, 14b, 14c, 14d: negative electrode current collector, 14a -1, 14b-1, 14c-1, 14d-1 ... body ., 14a-2, 14b-2, 14c-2, 14d-2... Negative electrode current collecting tabs, 14a-3, 14b-3, 14c-3, 14d-3... Connections, 14a-3a, 14b-3a, 14c -3a, 14d-3a: convex portion, 14a-3b, 14b-3b, 14c-3b, 14d-3b: concave portion, 14a-4, 14b-4, 14c-4, 14d-4: opening portion for liquid injection , 15 ... separator, 16 ... metal outer can, 16a ... recess, 17 ... sealing lid, 17a ... positive terminal, 17b ... positive cover, 18 ... insulating gasket, 19 ... insulating plate

Claims

A positive electrode in which a positive electrode mixture is applied to a positive electrode core, and an electrode group in which a negative electrode in which a negative electrode mixture is applied to a negative electrode core are laminated or wound so as to face each other with a separator interposed therebetween. At least one end of the body or the negative electrode core has an uncoated portion where the positive electrode mixture or the negative electrode mixture is not applied, and the positive electrode current collector or the negative electrode current collector is formed on the uncoated portion of the core. Is a battery having a welded current collecting structure,
At least one of the positive electrode current collector or the negative electrode current collector includes a connection portion that fits into an uncoated portion of the core of the electrode group,
The connection portion includes a convex portion projecting from the bottom surface of the concave portion toward the bottom surface of the positive electrode current collector or the negative electrode current collector,
A battery wherein a part of the uncoated portion of the core converged in the projection and a part of the projection are welded.

2. The battery according to claim 1, wherein the projection and the uncoated portion are welded by an energy beam applied to the projection. 3.

The electrode group is a spiral electrode group in which a positive electrode and a negative electrode are spirally wound via a separator,
The connection portion provided on the positive electrode current collector or the negative electrode current collector is continuously or discontinuously arranged along a substantially winding locus of the spiral electrode group. The battery according to claim 1 or 2.

The said connection part provided in the said positive electrode current collector or the negative electrode current collector is formed in the shape of an arc so that it may follow the substantially spiral locus | trajectory of the said spiral electrode group. battery.

The battery according to any one of claims 1 to 4, wherein the thickness of the protrusion is greater than the thickness of the recess.

The said connection part provided in the said positive electrode current collector or the negative electrode current collector is arrange | positioned continuously in the radial direction of the said current collector, or discontinuous, The said collector is characterized by the above-mentioned. The battery according to any one of the above.

The battery according to any one of claims 2 to 6, wherein the energy beam is a laser beam.