JP3831595B2

JP3831595B2 - Cylindrical secondary battery

Info

Publication number: JP3831595B2
Application number: JP2000292306A
Authority: JP
Inventors: 昇中野; 広一佐藤; 俊之能間; 育郎米津
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 2000-09-26
Filing date: 2000-09-26
Publication date: 2006-10-11
Anticipated expiration: 2020-09-26
Also published as: JP2002100342A

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巻き取り電極体が収容され、電池缶に設けた一対の電極端子部から巻き取り電極体の発生電力を取り出すことが出来る円筒型二次電池に関し、特に、巻き取り電極体を電極端子部に連結するためにタブを使用しない所謂タブレスタイプの円筒型二次電池に関するものである。
【０００２】
【従来の技術】
近年、携帯型電子機器、電気自動車等の電源として、エネルギー密度の高いリチウムイオン二次電池が注目されている。例えば電気自動車に用いられる比較的大きな容量の円筒型リチウムイオン二次電池は、図４及び図５に示す様に、筒体(11)の両端部に蓋体(12)(12)を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６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５に示す電極端子機構(９)の基端部に接続される。
尚、正極側の集電板(32)はアルミニウム製、負極側の集電板(32)はニッケル製である。
【０００５】
電極端子機構(９)は、図５の如く、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】
又、電池の出力特性向上のために、図７に示す如く、正極(81)においては、活物質(84)が塗布された塗工部から上方へ突出する非塗工部の幅を長手方向に変化させると共に、負極(82)においては、活物質(85)が塗布された塗工部から下方に突出する非塗工部の幅を長手方向に変化させて、これらの正極(81)と負極(82)の間にセパレータ(83)を挟んで渦巻き状に巻き取り、これによって図８に示す如く円錐状の突出部(86)を具えた巻き取り電極体(８)を作製して、該巻き取り電極体(８)を電池缶(１)内に収容し、各電極の突出部(86)を集電リード(80)を介して電極端子(90)に連結した円筒型二次電池が提案されている(特開平11-329398号)。
【０００７】
【発明が解決しようとする課題】
しかしながら、図５に示すタブレスタイプの円筒型二次電池においては、巻き取り電極体(４)の端部に渦巻き状に突出する電極端縁(48)と集電板(32)との間の接触面積が小さいために、接触抵抗が大きく、充分に高い出力特性が得られない問題があった。
又、巻き取り電極体(４)の最外周に位置する電極端縁に集電板(32)の最外周部をレーザ溶接する際、レーザ光が集電板(32)から漏れ出て、電極やセパレータを直接に照射する虞があり、これによって電極やセパレータが損傷する問題があった。
【０００８】
一方、図８に示す円筒型二次電池によれば、出力特性はある程度改善されるものの、図７の如く、正極(81)及び負極(82)の端縁を斜めに切断する工程が必要となるため、製造工程が複雑となるばかりでなく、図８の如く両電極を巻き取ることによって巻き取り電極体(８)の突出部(86)を精度の高い円錐面に仕上げることは困難であり、この結果、歩留まりの低下や電池性能のバラツキが生じる問題があった。
【０００９】
そこで本発明の目的は、タブレスタイプの円筒型二次電池において、巻き取り電極体の端面に集電板を溶接する際、電極やセパレータが損傷する虞がなく、製造工程が簡易であり、然も、優れた出力特性を発揮する円筒型二次電池を提供することである。
【００１０】
【課題を解決する為の手段】
本発明に係る円筒型二次電池は、円筒状の電池缶(１)の内部に、それぞれ帯状の正極(41)と負極(43)の間に非水電解液を含むセパレータ(42)を介在させてこれらを渦巻き状に巻き取った巻き取り電極体(４)が収納され、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。
正極(41)及び負極(43)の両電極はそれぞれ、帯状の芯体と、該芯体の表面に塗布された活物質とから構成され、各電極には、活物質の塗布された塗工部が芯体の長手方向に形成されると共に、活物質の塗布されていない非塗工部が芯体端縁に沿って形成されている。
そして、巻き取り電極体(４)の巻き軸方向の少なくとも一方の端部に突出する前記非塗工部からなる円筒状突出部(40)には、金属製の集電板(５)が被せられる。該集電板(５)は、円筒状突出部(40)の端面に接触する天板部(51)と、円筒状突出部(40)の外周面に略全周に亘って密着可能な円筒状のスカート部(52)とを具え、該集電板 ( ５ ) の天板部 (51) 及びスカート部 (52) はそれぞれ、巻き取り電極体 ( ４ ) の円筒状突出部の端面及び外周面にレーザ溶接され、該集電板(５)がリード部材(53)を介して一方の電極端子部に連結されている。
【００１１】
上記本発明の円筒型二次電池においては、巻き取り電極体(４)の円筒状突出部(40)の端面と集電板(５)の天板部(51)の内面とが互いに接触すると共に、円筒状突出部の外周面と集電板(５)のスカート部(52)の内周面とが互いに密着し、天板部 (51) 及びスカート部 (52) はそれぞれ、巻き取り電極体 ( ４ ) の円筒状突出部 (40) の端面及び外周面にレーザ溶接されているので、巻き取り電極体(４)の各電極と集電板(５)との間の接触抵抗は低く、これによって電池の内部抵抗が低減されて、高い出力特性が得られる。
又、上記本発明の円筒型二次電池においては、巻き取り電極体(４)の円筒状突出部(40)に集電板(５)を被せてレーザ溶接する工程にて、巻き取り電極体(４)の最外周に位置する電極端縁に集電板(５)の天板部(51)の最外周部をレーザ溶接する際、巻き取り電極体(４)の円筒状突出部(40)の外周面は集電板(５)のスカート部(52)によって覆われているため、電極やセパレータが直接にレーザ光を受けることはなく、これによって電極やセパレータの損傷が防止される。
更に、巻き取り電極体(４)を構成する正極(41)及び負極(43)はそれぞれ、一定の幅を有する帯状に形成すればよいので、製造工程は簡易であり、両電極を巻き取ることによって、巻き取り電極体(４)の円筒状突出部(40)は精度の良い円筒面に仕上げることが出来る。従って、歩留まりの低下や電池性能のバラツキが生じることはない。
【００１３】
【発明の効果】
本発明に係る円筒型二次電池によれば、巻き取り電極体の端面に集電板を溶接する際、電極やセパレータが損傷する虞がなく、製造工程は簡易である。然も、電池の内部抵抗の低減によって、優れた出力特性が得られる。
【００１４】
【発明の実施の形態】
以下、本発明を円筒型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。
本発明に係る円筒型リチウムイオン二次電池は、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。
【００１５】
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、巻き取り電極体(４)の円筒状突出部(40)にレーザ溶接されている。該集電板(５)の上面には、リード部材(53)の基端部がスポット溶接され、その先端部は、電極端子機構(９)を構成する電極端子(91)の鍔部(92)の裏面にスポット溶接されている。
【００１６】
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。
【００１７】
正極(41)には、正極活物質(44)の塗布されている塗工部Ａが形成されると共に、正極活物質の塗布されていない非塗工部Ｂが芯体端縁(48)に沿って形成されている。又、負極(43)には、負極活物質(46)の塗布されている塗工部Ａが形成されると共に、負極活物質の塗布されていない非塗工部Ｂが芯体端縁(48)に沿って形成されている。
【００１８】
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て、正極側の円筒状突出部(40)を形成している。又、巻き取り電極体(４)の他方の端部では、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、負極側の円筒状突出部(40)を形成している。
【００１９】
集電板(５)は、図１及び図２に示す如く、円板状の天板部(51)と円筒状のスカート部(52)とから構成されており、天板部(51)の内面が円筒状突出部(40)の端面に密着してレーザ溶接されると共に、スカート部(52)の内周面が円筒状突出部(40)の外周面に密着してレーザ溶接されている。
集電板(５)の天板部(51)の表面はリード部材(53)を介して電極端子機構(９)の鍔部(92)に連結されている。
【００２０】
上記本発明の円筒型リチウムイオン二次電池の製造工程においては、先ず、図２に示す如く、セパレータ(42)、負極(43)、セパレータ(42)及び正極(41)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)を作製する。
又、アルミニウムを材料として正極側の集電板(５)を作製すると共に、ニッケルを材料として負極側の集電板(５)を作製する。
次に、巻き取り電極体(４)の両円筒状突出部(40)(40)にそれぞれ集電板(５)をレーザ溶接する。ここで、レーザ溶接は、巻き取り電極体(４)の円筒状突出部(40)に集電板(５)を被せた状態で、集電板(５)の天板部(51)の表面に対しては放射状の軌跡でレーザ光を照射し、集電板(５)のスカート部(52)の外周面に対しては該外周面を一周する軌跡でレーザ光を照射する。
又、各集電板(５)の表面には、リード部材(53)の基端部をスポット溶接する。
【００２１】
その後、電池缶(１)を構成する筒体(11)の内部に巻き取り電極体(４)を収容し、各集電板(５)から伸びるリード部材(53)の先端部を締結部材(91)の鍔部(92)の裏面にスポット溶接する。そして、各蓋体(12)に電極端子機構(９)を組み付け、第１ナット(95)を締め込んで、絶縁パッキング(93)に充分な液密性を与える。
続いて、筒体(11)の各開口部に蓋体(12)をレーザ溶接し、電池缶(１)の内部に電解液を注入した後、図１に示す如く各蓋体(12)にガス排出弁(13)をねじ込んで固定する。これによって、本発明の円筒型リチウムイオン二次電池が完成する。
【００２２】
尚、集電板(５)は、図３に示す如く円板状の天板部(51)に、複数の円弧片(54)を突設してスカート部(52)を形成したものであってもよい。
【００２３】
【実施例】
正極の作製
正極活物質としての平均粒径５μｍを有するリチウム複合酸化物(ＬｉＣｏＯ_２)の粉末と導電剤としての人造黒鉛とを重量比９:１で混合して、正極合剤を得た。次に、結着剤であるポリフッ化ビニリデンをＮ−メチル−２−ピロリドン(ＮＭＰ)に溶解させて、ＮＭＰ溶液を調製した。そして、正極合剤とポリフッ化ビニリデンの重量比が９５:５となる様に正極合剤とＮＭＰ溶液を混合して、スラリーを調製し、その後、このスラリーを正極芯体となる厚さ２０μｍのアルミニウム箔の両面にドクターブレード法により塗布し、１５０℃で２時間の真空乾燥を施して、図２に示す正極(41)を作製した。
【００２４】
負極の作製
炭素塊(ｄ００２＝３.３５６Å；Ｌｃ＞１０００)に空気流を噴射して粉砕し、炭素粉末を作製した。また、結着剤であるポリフッ化ビニリデンをＮＭＰに溶解させてＮＭＰ溶液を調製し、炭素粉末とポリフッ化ビニリデンの重量比が８５:１５となる様に混練してスラリーを調製した。このスラリーを負極芯体となる厚さ２０μｍの銅箔の両面にドクターブレード法により塗布し、１５０℃で２時間の真空乾燥を施して、図２に示す負極(43)を作製した。
【００２５】
電解液の調製
エチレンカーボネートとジエチルカーボネートを体積比１:１で混合した溶媒に、ＬｉＰＦ６を１ｍｏｌ／Ｌの割合で溶解させて、電解液を調製した。
【００２６】
本発明電池の組立
直径１０ｍｍの巻芯に、セパレータとなるイオン透過性のポリプロピレン製微多孔膜を数回巻いた後、セパレータが正極と負極との間に介在する様に、セパレータ、正極、セパレータ及び負極の４枚を重ね合わせて、これらを渦巻き状に多数回巻き、最後に巻芯を抜き取って、図２に示す巻き取り電極体(４)を作製した。
そして、この巻き取り電極体(４)を用いて本発明の円筒型リチウムイオン二次電池を組み立てた。該電池の外径は５７ｍｍ、長さは２２０ｍｍである。
【００２７】
但し、巻き取り電極体(４)の各円筒状突出部(40)に被せるべき集電板として、図３に示す如くスカート部(52)が２つの円弧片(54)(54)に分かれた集電板(５)と、図２に示す如くスカート部(52)が円筒状を呈する集電板(５)の２種類を作製し、図３の集電板(５)を用いた電池を参照例電池とし、図２に示す集電板(５)を用いた電池を本発明電池とした。参照例電池においては、集電板(５)のスカート部(52)が円筒状突出部(40)の外周面の全面積の３０％を覆い、本発明電池においては、集電板(５)のスカート部(52)が円筒状突出部(40)の外周面の全面積の９０％を覆っている。
【００２８】
比較例電池の組立
巻き取り電極体(４)の端部に図６に示す円板状の集電板(32)を接合したこと以外は上記本発明電池と同様にして、比較例電池を組み立てた。
【００２９】
電池の評価
本発明電池及び参照例電池と比較例電池を対象として、それぞれの出力特性(放電深度５０％、１５秒間放電時の出力密度)を調べた。
その結果を表１に示す。
【００３０】
【表１】

【００３１】
表１から明らかな様に、本発明電池及び参照例電池の何れも、比較例電池に比べて高い出力密度が得られている。これは、本発明電池及び参照例電池では、集電板(５)がスカート部(52)を有しているために、集電板(５)の集電性能が向上し、電池の内部抵抗が低減したためであると考えられる。
又、本発明電池と参照例電池の比較において、集電板(５)のスカート部(52)と円筒状突出部(40)との接触面積が大きい方が、出力密度が大きくなっていることからも、集電板(５)のスカート部(52)が集電性能の向上に寄与していることが明らかである。
【００３２】
上述の如く、本発明の円筒型リチウムイオン二次電池によれば、巻き取り電極体(４)の各電極と集電板(５)との間の接触抵抗が低くなって、優れた出力特性が得られる。
又、本発明の円筒型二次電池の製造工程においては、巻き取り電極体(４)の円筒状突出部(40)に電板(５)を被せてレーザ溶接する工程にて、巻き取り電極体(４)の円筒状突出部(40)の略全体が集電板(５)によって覆われているため、電極やセパレータがレーザ光を直接に受ける虞はなく、これによって、電極やセパレータの損傷が防止される。
更に、巻き取り電極体(４)を構成する正極(41)及び負極(43)はそれぞれ、一定の幅を有する帯状に形成すればよいので、製造工程は簡易であり、両電極を巻き取ることによって、巻き取り電極体(４)の円筒状突出部(40)は精度の良い円筒面に仕上げることが出来る。従って、歩留まりの低下や電池性能のバラツキが生じることはない。
【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】該電池に装備されている巻き取り電極体及び集電板の分解斜視図である。
【図３】集電板の他の構成例を表わす斜視図である。
【図４】円筒型リチウムイオン二次電池の外観を表わす斜視図である。
【図５】従来の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６】該電池に装備されている巻き取り電極体及び集電板の分解斜視図である。
【図７】従来の他の二次電池を構成する正極、セパレータ及び負極の展開図である。
【図８】該二次電池の要部を表わす一部破断正面図である。
【符号の説明】
(１) 電池缶
(11) 筒体
(12) 蓋体
(４) 巻き取り電極体
(40) 円筒状突出部
(41) 正極
(42) セパレータ
(43) 負極
(44) 正極活物質
(45) 芯体
(46) 負極活物質
(47) 芯体
(５) 集電板
(51) 天板部
(52) スカート部
(９) 電極端子機構[0001]
BACKGROUND OF THE INVENTION
The present invention provides a cylindrical secondary battery in which a wound electrode body serving as a secondary battery element is accommodated in a battery can and the generated power of the wound electrode body can be taken out from a pair of electrode terminal portions provided in the battery can. More particularly, the present invention relates to a so-called tabless type cylindrical secondary battery that does not use a tab to connect a winding electrode body to an electrode terminal portion.
[0002]
[Prior art]
In recent years, lithium ion secondary batteries with high energy density have attracted attention as power sources for portable electronic devices and electric vehicles. For example, in a relatively large capacity cylindrical lithium ion secondary battery used in an electric vehicle, as shown in FIGS. 4 and 5, lids (12) and (12) are fixed to both ends of the cylinder (11). The cylindrical battery can (1) is configured to accommodate the winding electrode body (4). A pair of positive and negative electrode terminal mechanisms (9), (9) is attached to both the lids (12), (12), and both poles of the winding electrode body (4) and both electrode terminal mechanisms (9), (9) Are connected to each other, and the electric power generated by the winding electrode body (4) can be taken out from the pair of electrode terminal mechanisms (9) and (9). Each lid (12) is provided with a pressure open / close gas discharge valve (13).
[0003]
As shown in FIG. 6, the take-up electrode body (4) is formed by interposing a strip-shaped separator (42) between a strip-shaped positive electrode (41) and a negative electrode (43), and winding them in a spiral shape. It is configured. The positive electrode (41) is configured by applying a positive electrode active material (44) made of a lithium composite oxide on both surfaces of a band-shaped core (45) made of an aluminum foil, and the negative electrode (43) is made of a band-shaped core made of a copper foil. The 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 superimposed on the separator (42) while being shifted in the width direction, and wound in a spiral shape. As a result, the end of the core body (45) of the positive electrode (41) is more outward than the edge of the separator (42) at one end of both ends in the winding axis direction of the winding electrode body (4). The edge (48) protrudes, and at the other end, the end edge (48) of the core (47) of the negative electrode (43) protrudes outward from the end edge of the separator (42).
Then, a disk-shaped current collector plate (32) is resistance-welded to both ends of the winding electrode body (4), and the current collector plate (32) is shown in FIG. 5 via a lead member (33). Connected to the base end of the electrode terminal mechanism (9).
The positive current collector (32) is made of aluminum, and the negative current collector (32) is made of nickel.
[0005]
As shown in FIG. 5, the electrode terminal mechanism (9) includes an electrode terminal (91) attached through the lid (12) of the battery can (1), and is provided at the base end of the electrode terminal (91). Has a flange (92). An insulating packing (93) is attached to the through hole of the lid (12), and electrical insulation and sealing between the lid (12) and the fastening member (91) are maintained. A washer (94) is fitted to the electrode terminal (91) from the outside of the lid (12), and a first nut (95) and a second nut (96) are screwed together. The first nut (95) is tightened, and the insulating packing (93) is clamped by the flange (92) and the washer (94) of the electrode terminal (91), thereby improving 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]
Further, in order to improve the output characteristics of the battery, as shown in FIG. 7, in the positive electrode (81), the width of the non-coated portion protruding upward from the coated portion coated with the active material (84) is set in the longitudinal direction. In the negative electrode (82), the width of the non-coated part protruding downward from the coated part coated with the active material (85) is changed in the longitudinal direction, and the positive electrode (81) and A separator (83) is sandwiched between the negative electrode (82) and wound up in a spiral shape, thereby producing a wound electrode body (8) having a conical protrusion (86) as shown in FIG. A cylindrical secondary battery in which the wound electrode body (8) is accommodated in a battery can (1), and a protruding portion (86) of each electrode is connected to an electrode terminal (90) through a current collecting lead (80). Has been proposed (Japanese Patent Laid-Open No. 11-329398).
[0007]
[Problems to be solved by the invention]
However, in the tabless type cylindrical secondary battery shown in FIG. 5, the spirally protruding electrode edge (48) between the electrode edge (48) and the current collector plate (32) is formed at the end of the winding electrode body (4). Since the contact area is small, there is a problem that contact resistance is large and sufficiently high output characteristics cannot be obtained.
Further, when the outermost periphery of the current collector plate (32) is laser welded to the electrode edge located on the outermost periphery of the winding electrode body (4), the laser light leaks from the current collector plate (32), and the electrode Further, there is a risk that the separator and the separator may be directly irradiated, which causes a problem that the electrode and the separator are damaged.
[0008]
On the other hand, according to the cylindrical secondary battery shown in FIG. 8, although the output characteristics are improved to some extent, a step of obliquely cutting the edges of the positive electrode (81) and the negative electrode (82) is required as shown in FIG. Therefore, not only the manufacturing process becomes complicated, but it is difficult to finish the protruding portion (86) of the winding electrode body (8) into a highly accurate conical surface by winding both electrodes as shown in FIG. As a result, there is a problem in that yield decreases and battery performance varies.
[0009]
Therefore, the object of the present invention is a tabless type cylindrical secondary battery, and when the current collector plate is welded to the end face of the take-up electrode body, there is no possibility of damaging the electrode and separator, and the manufacturing process is simple. However, it is to provide a cylindrical secondary battery that exhibits excellent output characteristics.
[0010]
[Means for solving the problems]
In the cylindrical secondary battery according to the present invention, a separator (42) containing a non-aqueous electrolyte is interposed between a strip-shaped positive electrode (41) and a negative electrode (43) in a cylindrical battery can (1). Thus, the take-up electrode body (4) wound up in a spiral shape is stored, and the electric power generated by the take-up electrode body (4) can be taken out from the pair of electrode terminal portions.
Both electrodes of the positive electrode (41) and the negative electrode (43) are each composed of a strip-shaped core body and an active material applied to the surface of the core body, and each electrode is coated with an active material applied The part is formed in the longitudinal direction of the core body, and the non-coated part where the active material is not applied is formed along the edge of the core body.
A cylindrical current collector plate (5) is covered with a cylindrical protrusion (40) made of the non-coated portion protruding at least one end in the winding axis direction of the winding electrode body (4). It is done. The current collector plate (5) includes a top plate portion (51) that contacts the end surface of the cylindrical protrusion (40) and a cylinder that can be in close contact with the outer peripheral surface of the cylindrical protrusion (40) over substantially the entire circumference. Jo skirt portion (52) comprises, top plate (51) and the end face and the outer circumference of the cylindrical projection of the skirt (52), respectively, the wound electrode body (4) of the current collector plates (5) The current collector plate (5) is connected to one electrode terminal portion via a lead member (53).
[0011]
In the cylindrical secondary battery of the present invention, the end surface of the cylindrical protrusion (40) of the winding electrode body (4) and the inner surface of the top plate portion (51) of the current collector plate (5) are in contact with each other. In addition, the outer peripheral surface of the cylindrical protrusion and the inner peripheral surface of the skirt portion (52) of the current collector plate (5) are in close contact with each other, and the top plate portion (51) and the skirt portion (52) are respectively wound-up electrodes. because it is laser welded to the end surface and the outer peripheral surface of the cylindrical projection of the body (4) (40), each electrode and the current collector plate of the take-up electrode unit (4) (5) contact resistance was low between the This reduces the internal resistance of the battery and provides high output characteristics.
In the above-described cylindrical secondary battery of the present invention, the winding electrode body is subjected to laser welding by covering the cylindrical protrusion (40) of the winding electrode body (4) with the current collector plate (5). When laser welding the outermost peripheral part of the top plate part (51) of the current collector plate (5) to the electrode edge located on the outermost peripheral part of (4), the cylindrical protruding part (40 ) Is covered with the skirt portion (52) of the current collector plate (5), so that the electrodes and the separator are not directly subjected to laser light, thereby preventing the electrodes and the separator from being damaged.
Furthermore, since the positive electrode (41) and the negative electrode (43) constituting the winding electrode body (4) may be formed in a strip shape having a certain width, the manufacturing process is simple and both electrodes are wound. Thus, the cylindrical protrusion (40) of the winding electrode body (4) can be finished into a highly accurate cylindrical surface. Therefore, there is no decrease in yield or variation in battery performance.
[0013]
【The invention's effect】
According to the cylindrical secondary battery according to the present invention, when the current collector plate is welded to the end face of the winding electrode body, there is no possibility that the electrode and the separator are damaged, and the manufacturing process is simple. However, excellent output characteristics can be obtained by reducing the internal resistance of the battery.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention applied to a cylindrical lithium ion secondary battery will be described in detail with reference to the drawings.
As shown in FIG. 1, a cylindrical lithium ion secondary battery according to the present invention has a cylindrical battery can (1) formed by welding and fixing lids (12) and (12) to both ends of a cylinder (11). The take-up electrode body (4) is accommodated in the interior. A pair of positive and negative electrode terminal mechanisms (9) and (9) are attached to the lids (12) and (12). The electrode terminal mechanism (9) has the same configuration as the conventional one. Each lid (12) is provided with a pressure open / close gas discharge valve (13).
[0015]
Current collector plates (5) are respectively installed at both ends of the winding electrode body (4), and are laser-welded to the cylindrical protrusion (40) of the winding electrode body (4). The base end portion of the lead member (53) is spot-welded to the upper surface of the current collector plate (5), and the distal end portion is a flange portion (92) of the electrode terminal (91) constituting the electrode terminal mechanism (9). ) Spot welded to the back.
[0016]
As shown in FIG. 2, the take-up electrode body (4) is formed by interposing a strip-shaped separator (42) between the strip-shaped positive electrode (41) and the negative electrode (43), and winding them in a spiral shape. It is configured. The positive electrode (41) is configured by applying a positive electrode active material (44) made of a lithium composite oxide on both surfaces of a band-shaped core (45) made of an aluminum foil, and the negative electrode (43) is made of a band-shaped core made of a copper foil. The 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.
[0017]
On the positive electrode (41), a coated part A to which the positive electrode active material (44) is applied is formed, and an uncoated part B to which the positive electrode active material is not applied is formed on the core body edge (48). Are formed along. The negative electrode (43) is provided with a coated part A to which the negative electrode active material (46) is applied, and an uncoated part B to which the negative electrode active material is not applied has a core edge (48). ).
[0018]
The positive electrode (41) and the negative electrode (43) are respectively superimposed on the separator (42) while being 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 protrudes outward. And a winding electrode body (4) is comprised by winding up these in the shape of a spiral. In the wound electrode body (4), the core body edge (48) of the non-coated portion of the positive electrode (41) is at one end of the both ends in the winding axis direction of the separator (42). A cylindrical protrusion (40) on the positive electrode side is formed protruding outward from one end edge. Further, at the other end of the winding electrode body (4), the core body edge (48) of the non-coated part of the negative electrode (43) protrudes outward from the other edge of the separator (42). Thus, the negative cylindrical protrusion (40) is formed.
[0019]
As shown in FIGS. 1 and 2, the current collector plate (5) is composed of a disk-shaped top plate portion (51) and a cylindrical skirt portion (52). The inner surface is in close contact with the end surface of the cylindrical protrusion (40) and laser welded, and the inner peripheral surface of the skirt portion (52) is in close contact with the outer peripheral surface of the cylindrical protrusion (40) and laser welded. .
The surface of the top plate portion (51) of the current collector plate (5) is connected to the flange portion (92) of the electrode terminal mechanism (9) via the lead member (53).
[0020]
In the manufacturing process of the cylindrical lithium ion secondary battery of the present invention, first, as shown in FIG. 2, the separator (42), the negative electrode (43), the separator (42) and the positive electrode (41) are overlapped, A wound electrode body (4) is produced by winding in a spiral.
In addition, the current collector plate (5) on the positive electrode side is manufactured using aluminum as a material, and the current collector plate (5) on the negative electrode side is manufactured using nickel as a material.
Next, the current collector plate (5) is laser welded to both cylindrical protrusions (40) and (40) of the winding electrode body (4). Here, in the laser welding, the surface of the top plate portion (51) of the current collector plate (5) is covered with the current collector plate (5) covered with the cylindrical protrusion (40) of the winding electrode body (4). Is irradiated with a laser beam along a radial locus, and the outer peripheral surface of the skirt portion (52) of the current collector plate (5) is irradiated with a laser beam along a locus that goes around the outer peripheral surface.
Further, the base end portion of the lead member (53) is spot-welded to the surface of each current collecting plate (5).
[0021]
Thereafter, the take-up electrode body (4) is accommodated in the cylindrical body (11) constituting the battery can (1), and the leading end portion of the lead member (53) extending from each current collector plate (5) is connected to the fastening member ( Spot-welded to the back of the flange (92) of 91). Then, the electrode terminal mechanism (9) is assembled to each lid (12), and the first nut (95) is tightened to give the insulating packing (93) sufficient liquid tightness.
Subsequently, the lid (12) is laser welded to each opening of the cylinder (11), and an electrolyte is injected into the battery can (1). Then, as shown in FIG. Screw in and fix the gas discharge valve (13). Thereby, the cylindrical lithium ion secondary battery of the present invention is completed.
[0022]
The current collector plate (5) is formed by projecting a plurality of arc pieces (54) on a disc-shaped top plate portion (51) as shown in FIG. 3 to form a skirt portion (52). May be.
[0023]
【Example】
Production of positive electrode A mixture of lithium composite oxide (LiCoO ₂ ) having an average particle diameter of 5 µm as a positive electrode active material and artificial graphite as a conductive agent was mixed at a weight ratio of 9: 1 to obtain a positive electrode mixture. Got. Next, polyvinylidene fluoride as a binder was dissolved in N-methyl-2-pyrrolidone (NMP) to prepare an NMP solution. Then, the positive electrode mixture and the NMP solution were mixed so that the weight ratio of the positive electrode mixture and polyvinylidene fluoride was 95: 5 to prepare a slurry, and then the slurry had a thickness of 20 μm serving as the positive electrode core. It applied to both surfaces of aluminum foil with the doctor blade method, and vacuum-dried at 150 degreeC for 2 hours, and produced the positive electrode (41) shown in FIG.
[0024]
Production of negative electrode A carbon powder (d002 = 3.356Å; Lc> 1000) was jetted and pulverized to produce a carbon powder. Further, polyvinylidene fluoride as a binder was dissolved in NMP to prepare an NMP solution, and a slurry was prepared by kneading so that the weight ratio of carbon powder to polyvinylidene fluoride was 85:15. This slurry was applied to both surfaces of a 20 μm-thick copper foil serving as a negative electrode core by a doctor blade method, followed by vacuum drying at 150 ° C. for 2 hours to produce a negative electrode (43) shown in FIG.
[0025]
Preparation of electrolyte solution LiPF6 was dissolved at a ratio of 1 mol / L in a solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1 to prepare an electrolyte solution.
[0026]
Assembling the battery of the present invention After winding an ion-permeable polypropylene microporous membrane serving as a separator several times around a core having a diameter of 10 mm, the separator is interposed between the positive electrode and the negative electrode. Then, four sheets of the positive electrode, the separator, and the negative electrode were superposed, and these were wound in a spiral shape, and finally the core was removed to produce a wound electrode body (4) shown in FIG.
And the cylindrical lithium ion secondary battery of this invention was assembled using this winding electrode body (4). The battery has an outer diameter of 57 mm and a length of 220 mm.
[0027]
However, as shown in FIG. 3, the skirt portion (52) is divided into two circular arc pieces (54) and (54) as a current collecting plate to be placed on each cylindrical protrusion (40) of the winding electrode body (4). Two types of current collector plate (5) and current collector plate (5) having a cylindrical skirt portion (52) as shown in FIG. 2 were prepared, and a battery using the current collector plate (5) of FIG. a reference example batteries, was present battery the battery using the current collector plate shown in FIG. 2 (5). In the reference battery, the skirt portion (52) of the current collector plate (5) covers 30% of the entire area of the outer peripheral surface of the cylindrical protrusion (40). In the battery of the present invention , the current collector plate (5) The skirt portion (52) covers 90% of the total area of the outer peripheral surface of the cylindrical protrusion (40).
[0028]
Assembling of comparative battery Comparative example battery was compared in the same manner as the battery of the present invention except that the disc-shaped current collector plate (32) shown in Fig. 6 was joined to the end of the winding electrode body (4). Example A battery was assembled.
[0029]
Battery evaluation
The output characteristics (discharge depth 50%, output density at the time of discharge for 15 seconds) were examined for the present invention battery, the reference example battery, and the comparative example battery.
The results are shown in Table 1.
[0030]
[Table 1]

[0031]
As is clear from Table 1, both the battery of the present invention and the reference example battery have a higher output density than the comparative example battery. This is because the current collecting plate (5) has the skirt portion (52) in the battery of the present invention and the reference example battery , so that the current collecting performance of the current collecting plate (5) is improved and the internal resistance of the battery is increased. This is considered to be because of the reduction.
Further, in the comparison between the battery of the present invention and the reference battery , the output density is larger when the contact area between the skirt (52) of the current collector plate (5) and the cylindrical protrusion (40) is larger. From this, it is clear that the skirt portion (52) of the current collecting plate (5) contributes to the improvement of the current collecting performance.
[0032]
As described above, according to the cylindrical lithium ion secondary battery of the present invention, the contact resistance between each electrode of the winding electrode body (4) and the current collector plate (5) is lowered, and excellent output characteristics are obtained. Is obtained.
Further, in the manufacturing process of the cylindrical secondary battery of the present invention, the winding electrode is formed in the process of laser welding by covering the cylindrical protrusion (40) of the winding electrode body (4) with the electric plate (5). Since the substantially whole cylindrical protrusion (40) of the body (4) is covered with the current collector plate (5), there is no possibility that the electrode or the separator receives the laser beam directly. Damage is prevented.
Furthermore, since the positive electrode (41) and the negative electrode (43) constituting the winding electrode body (4) may be formed in a strip shape having a certain width, the manufacturing process is simple and both electrodes are wound. Thus, the cylindrical protrusion (40) of the winding electrode body (4) can be finished into a highly accurate cylindrical surface. Therefore, there is no decrease in yield or variation in battery performance.
[Brief description of the drawings]
FIG. 1 is a partially broken 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 plate provided in the battery.
FIG. 3 is a perspective view illustrating another configuration example of the current collector plate.
FIG. 4 is a perspective view illustrating an appearance of a cylindrical lithium ion secondary battery.
FIG. 5 is a partially cutaway front view of a conventional cylindrical lithium ion secondary battery.
FIG. 6 is an exploded perspective view of a winding electrode body and a current collector plate equipped in the battery.
FIG. 7 is a development view of a positive electrode, a separator, and a negative electrode constituting another conventional secondary battery.
FIG. 8 is a partially broken front view showing a main part of the secondary battery.
[Explanation of symbols]
(1) Battery can
(11) Tube
(12) Lid
(4) Winding electrode body
(40) Cylindrical protrusion
(41) Positive electrode
(42) Separator
(43) Negative electrode
(44) Cathode active material
(45) Core
(46) Negative electrode active material
(47) Core
(5) Current collector
(51) Top plate
(52) Skirt
(9) Electrode terminal mechanism

Claims

Inside a cylindrical battery can (1), a separator (42) containing a non-aqueous electrolyte is interposed between a strip-like positive electrode (41) and a negative electrode (43), respectively, and these are wound in a spiral shape. In the cylindrical secondary battery in which the take-up electrode body (4) is housed and the electric power generated by the take-up electrode body (4) can be taken out from the pair of electrode terminal portions,
Both electrodes of the positive electrode (41) and the negative electrode (43) are each composed of a strip-shaped core body and an active material applied to the surface of the core body, and each electrode is coated with an active material applied A portion is formed in the longitudinal direction of the core body, and an uncoated portion to which no active material is applied is formed along the edge of the core body, and at least one of the winding electrode bodies (4) in the winding axis direction. The cylindrical protrusion (40) made of the non-coating portion protruding at the end is covered with a metal current collector plate (5), and the current collector plate (5) is formed of a cylindrical protrusion (40). ) And a cylindrical skirt portion (52) that can be in close contact with the outer peripheral surface of the cylindrical protrusion (40) over the entire circumference , the current collector plate (5) top plate (51) and the skirt (52), respectively, are laser welded to the end surface and the outer peripheral surface of the cylindrical projection of the wound electrode body (4) (40), the current collector plates (5 ) Is connected to one electrode end via the lead member (53). Cylindrical secondary battery, characterized by being connected to the part.

Each of the cylindrical protrusions (40) protruding at both ends in the winding axis direction of the winding electrode body (4) is covered with a metal current collector plate (5), and the positive current collector plate (5) together with formed of the same material as the core of the positive electrode, the negative electrode side of the current collector plate (5) is formed of the same material as the core body of the negative electrode, both current collector plates (5) (5) of the pair The cylindrical secondary battery according to claim 1, wherein the cylindrical secondary battery is connected to an electrode terminal portion.