JP3749127B2

JP3749127B2 - Sealed battery and method of manufacturing sealed battery

Info

Publication number: JP3749127B2
Application number: JP2001006706A
Authority: JP
Inventors: 和照森; 尚垣内
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 2001-01-15
Filing date: 2001-01-15
Publication date: 2006-02-22
Anticipated expiration: 2021-01-15
Also published as: JP2002216709A

Description

【０００１】
【発明の属する技術分野】
【０００２】
本発明は、外装缶に電極体を入れて開口部を閉塞した後、縮径工程で外装缶を細く加工する密閉形電池とその製造方法に関する。
【従来の技術】
密閉形電池は、底を塞いでいる筒状の金属筒製の外装缶に、電極体と電解液を入れた後、閉塞工程で外装缶の開口部に封口体を固定して、外装缶を気密に閉塞して製造される。閉塞工程においては、封口体と外装缶との間にガスケットを入れ、外装缶をカシメ加工して封口体を固定している。この構造の密閉形電池は、図１に示す工程で以下のようにして製造される。
【０００３】
(1) 電極挿入工程において、底を閉塞している金属筒である外装缶２に、正極板１Ａと負極板１Ｂをセパレータ１Ｃを介して積層して捲回している電極体１を挿入する。電極体１を入れた後、電極体１の上面に絶縁セパレータ８を入れる。絶縁セパレータ８は、外装缶２の周壁６が電極体１に接触して内部ショートするのを防止するために電極体１の外周部の上面に配設される。
(2) 外装缶２を外周面から溝入れ加工して周壁６を設ける。周壁６は、電極体１と封口体３との境界に設けられて、封口体３が外装缶２に押し込まれるのを阻止するストッパの役目をする。
(3) 外装缶２に電解液を注入して電極体１に浸透させる。
(4) 電極体１に接続しているリード７を、スポット溶接して封口体３に接続する。
(5) 閉塞工程において、封口体３を外装缶２の開口部にセットした後、外装缶２の開口縁を内側にＬ字状に折曲し、Ｌ字折曲部９と周壁６とで封口体３を挟着して固定する。この状態で封口体３は、ガスケット４を介して挟着される。ガスケット４は、封口体３を気密に固定すると共に、封口体３と外装缶２を絶縁する。したがって、ガスケット４にはゴム状弾性体である絶縁材が使用される。
(6) 矢印で示すように、Ｌ字折曲部９を上からプレスして、Ｌ字折曲部９と周壁６とでガスケット４を確実に挟着して気密な状態とする。この工程で、周壁６も押し潰されて、電極体１の上面に接触する。ただ、周壁６と電極体１との間に絶縁セパレータ８を配設しているので、電極体１が外装缶２の周壁６に接触してショートすることはない。
(7) 最後に、縮径工程において外装缶を外周から押圧して細く絞り加工して、所定の寸法の外形とする。
【０００４】
【発明が解決しようとする課題】
以上の工程で製造される密閉形電池は、耐衝撃性を向上させるのが難しい欠点がある。それは、金属筒製の外装缶に電極体を挿入して製作されるので、電極体の外径を外装缶の内径よりも多少は小さくする必要があるからである。電極体が外装缶の内径より太いと、電極体をスムーズに外装缶に入れることができない。電極体と外装缶の隙間を少なくするために、最後の縮径工程で外装缶を細くしているが、この加工をした後も、必ずしも好ましい耐衝撃性とするのは極めて難しい。
【０００５】
このような弊害を解消するために、外装缶をシーム加工している密閉形電池が開発されている。この電池は、図２と図３に示すように、外装缶２を外側から内側に突出するようにシーム加工して、外装缶２の一部を電極体１に押し付ける構造としている。この密閉形電池は、外装缶２で電極体１を押圧できるので、耐衝撃性を向上できる。ただ、この構造は、シーム加工した部分で外装缶２が薄くなり、この部分の強度が低下する欠点がある。密閉形電池は、外装缶２をできるかぎり薄くすることが要求される。内部に入れる電極体１をできるかぎり太くして、充電容量を大きくするためである。このため、外装缶２の強度を低下させないために、厚い金属筒を使用することはできない。さらに、図２と図３に示す密閉形電池は、外装缶２をシーム加工するので特別な工程を必要とするために、製造工程が多くなって製造コストも高くなる欠点もある。
【０００６】
本発明は、この欠点を解決することを目的に開発されたものである。本発明の重要な目的は、極めて簡単な構造で外装缶に入れている電極体をしっかりと保持して耐衝撃性を向上できる密閉形電池とその製造方法を提供することにある。
【０００７】
【課題を解決するための手段】
本発明の密閉形電池は、正極板と負極板との間にセパレータを配設している電極体１と、この電極体１を収容している外装缶２と、この外装缶２の開口部をカシメ加工して閉塞している封口体３とを備える。外装缶２は、電極体１との対向位置を厚くして外装缶２の内面に突出する押圧部５を有し、この押圧部５が電極体１の外周面を押圧している。
【０００８】
外装缶２は、缶底から開口部の方向に向かって次第に厚くして押圧部５とすることができる。外装缶２は、電極体１の上部において、開口部の方向に向かって次第に厚くして押圧部５を設けることができる。外装缶２は電極体１の上部で厚くして押圧部５としている。
【０００９】
さらに密閉形電池は、封口体３と電極体１との間で外装缶２を内側に突出させて周壁６を設けて、周壁６と電極体１との間に絶縁セパレータを配置することなく、周壁６で電極体１のずれを阻止することができる。
【００１０】
本発明の密閉形電池の製造方法は、正極板と負極板との間にセパレータを配設している電極体１を外装缶２に入れる電極挿入工程と、電極体１を入れている外装缶２の開口部を封口体３で閉塞する閉塞工程と、開口部を閉塞している外装缶２を細くする縮径工程とからなる。電極体１を入れる外装缶２には、挿入される電極体１との対向位置を外側に突出させて厚くしている底の閉塞された金属筒を使用している。電極挿入工程でこの金属筒に電極体１を入れて、閉塞工程で開口部を閉塞した後、縮径工程で外装缶２の外形を細くして、外側に突出させて厚くしている部分を電極体１との対向位置で内側に突出させて開口部の内面に電極体１の外周面を押圧する押圧部５を設けている。
【００１１】
電極挿入工程で電極体１を入れる外装缶２には、缶底から開口部の方向に向かって次第に厚くして外形を大きくしている金属筒を使用することができる。さらに、外装缶２には、挿入される電極体１の上部に対向する部分において、開口部の方向に向かって次第に厚くしている金属筒を使用することもできる。また、挿入される電極体１の上部に位置する部分を厚くしている金属筒を使用する。
【００１２】
さらに、密閉形電池の製造方法は、閉塞工程において、外装缶２の開口部をカシメ加工して封口体３を固定する。
【００１３】
【発明の実施の形態】
以下、本発明の実施例を図面に基づいて説明する。ただし、以下に示す実施例は、本発明の技術思想を具体化するための密閉形電池とその製造方法を例示するものであって、本発明は密閉形電池と製造方法を以下のものに特定しない。
【００１４】
さらに、この明細書は、特許請求の範囲を理解しやすいように、実施例に示される部材に対応する番号を、「特許請求の範囲の欄」、および「課題を解決するための手段の欄」に示される部材に付記している。ただ、特許請求の範囲に示される部材を、実施例の部材に特定するものでは決してない。
【００１５】
図４に示す密閉形電池は、電極体１と、この電極体１を収容している外装缶２と、外装缶２の開口部をガスケット４を介して気密に閉塞している封口体３とを備える。この図の密閉形電池は、ニッケル−水素電池、ニッケル−カドミウム電池、リチウムイオン二次電池等の二次電池である。
【００１６】
電極体１は、正極板と負極板をセパレータを介して積層している。電池がニッケル−水素電池の場合、負極板には、芯体に水素吸蔵合金を主体とした活物質を塗布した極板を使用し、正極板には、ニッケルの芯体に、スラリー状の水酸化ニッケルを主体とした活物質を含浸して圧延した極板を使用する。正極板と負極板を、ポリプロピレン製不織布からなるセパレータを介して積層して捲回して電極体とする。電解液には、水酸化カリウム系電解液を使用する。
【００１７】
電池がニッケル−カドミウム電池の場合、負極板には、極板芯体に酸化カドミウムを主成分としているペースト活物質を充填した帯状の非焼結式負極板を使用し、正極板には、ニッケルの芯体に、スラリー状の水酸化ニッケルを主体とした活物質を含浸して圧延した極板を使用する。ただ、極板は、焼結式の製法で製造することもできる。この極板は、有機増粘剤を含有するスラリを塗着した有孔薄鋼板を還元雰囲気中において焼結したニッケル多孔質焼結基板に、化学含浸あるいは電解含浸によって、カドミウムを充填して負極板とし、あるいは、ニッケルを充填して正極板とする。正極板と負極板を、ポリプロピレン製不織布からなるセパレータを介して積層して捲回して電極体とする。電解液には、水酸化カリウムを主成分とする電解液を使用する。
【００１８】
電池がリチウムイオン二次電池の場合、正極板には、リチウム含有複合酸化物である正極活物質、たとえば、ＬｉＣｏＯ_２を主成分とする正極スラリーを芯体に塗布して圧延した極板を使用し、負極板には、リチウムイオンを吸蔵・放出する炭素質材料である負極活物質、たとえば、天然黒鉛粉末を主成分とする負極スラリーを芯体に塗布して圧延した極板を使用する。正極板と負極板を、ポリエチレン製の微多孔膜であるセパレータを介して積層して捲回して電極体とする。電解液には、非水の非プロトン有機溶媒に、電解質としてリチウム塩を溶解したものを使用する。
【００１９】
円筒型電池の電極体１は、セパレータを介して互いに積層された正極板と負極板を捲回したものである。渦巻状の電極体１は、円筒状の外装缶２に挿入される。渦巻状の電極体は、両側からプレスして楕円形に変形させて、楕円形または角形の外装缶に挿入することもできる。さらに、角筒状の外装缶に挿入される電極体は、板状に裁断された複数枚の正極板と負極板を、セパレータを介して極性の異なる極板を交互に積層して製作することもできる。
【００２０】
外装缶２は、金属板を、底を閉塞している筒状に加工して製作される。外装缶２は、鉄の表面をニッケル等でメッキしたもの、アルミニウムやアルミニウム合金、あるいは複数の金属を積層したクラッド材等が使用される。底を閉塞している外装缶２は、金属板をプレス加工して製作される。
【００２１】
密閉形電池は、外装缶２の電極体１との対向位置を厚くして、外装缶２の内面に突出する押圧部５を設けている。押圧部５は、電極体１の外周面を押圧して、電極体１が外装缶２の内部で振動しないように、また、外装缶２から抜けないように保持する。図４の密閉形電池は、外装缶２を缶底から開口部の方向に向かって次第に厚くして、缶底から開口部に向かって次第に高く突出する押圧部５を設けている。
【００２２】
この密閉形電池は、電極体１を入れる前工程では、内面に突出する押圧部５を設けない。内面に突出する押圧部５は、電極体１を入れた後の工程で設けられる。電極体１を外装缶２にスムーズに入れるためである。外装缶２となる底を閉塞している金属筒は、電極体１を入れるときは、図５と図６に示すように、開口部の内形を缶底から開口部まで同じ大きさにする。ただ、図示しないが、外装缶となる金属筒は、電極体を入れるときに、缶底よりも開口部を大きくして電極体をよりスムーズに入れられる形状とすることもできる。さらに図示しないが、外装缶となる金属筒は、電極体を入れることができる程度に、缶底よりも開口部がわずかに小さくすることもできる。
【００２３】
外装缶２となる金属筒は、電極体１を入れる前工程においては、挿入される電極体１との対向位置を外側に突出させて厚くしている。図５の密閉形電池は、缶底から開口部の方向に向かって次第に厚くして外形を大きくしている金属筒を外装缶２としている。この金属筒を使用して製作される外装缶２は、図４に示すように、電極体１を入れて外形を細く絞る縮径工程の後において、缶底から電極体１の上端に向かって次第に内形が小さくなる。いいかえると、缶底から電極体１の上端に向かって次第に高く突出する押圧部５でもって、電極体１をしっかりと振動しないように、また外装缶２から抜けないように保持できる。この押圧部５は、外装缶２の内形を缶底に向かって内形が大きくなるテーパー状にして、電極体１をしっかりと保持する。
【００２４】
外装缶２となる金属筒は、図７に示すように、挿入される電極体の上部に対向する部分においてのみ、開口部の方向に向かって次第に厚くすることもできる。この金属筒を使用して製作される密閉形電池は、縮径工程の後、電極体の上部に位置して押圧部が設けられる。この押圧部は、電極体の上部を、上方に向かって次第に細くなるテーパー面で押圧して、電極体をしっかりと振動しないように、また抜けないように保持する。図５と図７の外装缶２は、上方に向かって次第に内形が細くなる押圧部で電極体の外周を押圧するので、電極体をしっかりと理想的な状態で保持できる。
【００２５】
さらに、外装缶２となる金属筒は、図８に示すように、挿入される電極体の上部に位置する部分を厚くすることもできる。この金属筒を使用して製作される密閉形電池は、縮径工程の後、電極体の上部に位置して押圧部が設けられる。この押圧部は、電極体の上部を局部的に押圧して、電極体をしっかりと振動しないように、また抜けないように保持する。
【００２６】
封口体３は、金属板をプレス加工して製作される。封口体３の外形は、外装缶２の内形よりも多少小さく、ガスケット４を介して外装缶２に固定される形状としている。封口体３は安全弁（図示せず）を内蔵している。安全弁は、外装缶２の内圧が設定圧よりも高くなると開弁して、外装缶２の内圧が異常に高くなって外装缶２が破壊されるのを防止する。封口体３は、２枚の金属板の間にゴム状弾性体を入れて安全弁とすることができる。ただ、安全弁は、図示しないが、封口体を構成する２枚の金属板の間に、ゴム板と板材とスプリングとを配設して、ゴム板をスプリングで弾性的に弁口に押圧する構造とすることもできる。
【００２７】
外装缶２は、封口体３と電極体１との間に位置して、外装缶２を内面に突出させている周壁６を設けている。周壁６を有する電池は、電極体１の上面と周壁６との間に、絶縁セパレータを配設することができる。ただ、本発明の密閉形電池は、外装缶２の内面に突出して設けている押圧部５で電極体１をしっかりと保持できるので、絶縁セパレータを省略することもできる。絶縁セパレータのない密閉形電池は、押圧部５と周壁６で電極体１が上方にずれるのを阻止する。
【００２８】
周壁６は、電極体１を入れた外装缶２を外側から線状に押す溝入れ加工でもって、外装缶２の外側に連続して溝ができるように折曲加工して設けられる。周壁６は、封口体３と電極体１との間にあって、封口体３の下面に沿って設けられる。この位置に設けられる周壁６は、封口体３が外装缶２に押し込まれるのを防止して、封口体３を定位置に配置する。周壁６は、外装缶２に電極体１を入れるときに邪魔にならないように、電極体１を外装缶２に入れた後、絶縁セパレータを入れている密閉形電池は、外装缶に電極体を入れて、電極体の上に絶縁セパレータを入れた後に設けられる。
【００２９】
絶縁セパレータを電極体と周壁との間に設ける密閉形電池は、絶縁セパレータに、プラスチック等の絶縁材を成形して製作したものを使用する。絶縁セパレータは、電極体の上面やリードが周壁に接触して内部ショートするのを防止するために、電極体と周壁の間に配設される。
【００３０】
電極体１は、一方の電極板、たとえば負極板を外装缶２に接続して、他方の電極板である正極板をリード７を介して封口体３に接続している。外装缶２は、−側となるので、電極体１の＋側である正極板と、＋側を封口体３に接続するリード７から絶縁する必要がある。外装缶２は、周壁６が内側に突出しているので、電極体１がずれると、＋側のリード７や正極板に接触してショートしやすくなる。本発明の密閉形電池は、押圧部５で電極体１をしっかりとずれないように保持するので、＋側のリード７や正極板が周壁６に接触してショートするのを有効に防止できる。電極体１と周壁６との間に絶縁セパレータを配設すると、さらに完全にこの部分のショートを阻止できる。
【００３１】
絶縁セパレータは、電極体の上面を外装缶から絶縁するものであるから、外形を、たとえば外装缶の内形に沿う形状として、中央を開口しているリング状、いいかえると、電極体の外周部を覆うリング状に成形される。ただ、絶縁セパレータを大きくして電極体の周囲をより確実に絶縁することもできるのはいうまでもない。
【００３２】
【実施例】
［実施例１］
図４の電池は、以下の工程で製造される。
(1) この密閉形電池は、図５に示すように、缶底から開口部に向かって次第に厚くしている金属筒を外装缶２として使用する。この金属筒は、内形を缶底から開口部まで同じとし、外形を缶底から開口部に向かって大きくしている。金属筒は、鉄の表面をニッケル等でメッキした金属板をプレス加工して製作する。この金属筒は、缶底から開口部まで全ての部分の内径を２１．８ｍｍと同じ内径とし、缶底の外径を２２．５ｍｍ、開口部の外径を２２．８ｍｍとする。この金属筒に電極体１を入れる。
(2) 電極体１を入れた外装缶２を、外周面から溝入れ加工して周壁６を設ける。周壁６は、電極体１と封口体３との境界に設けられて、封口体３が外装缶２に押し込まれるのを阻止するストッパの役目をする。
(3) 外装缶２に電解液を注入して電極体１に浸透させる。
(4) 電極体１に接続しているリード７を、スポット溶接して封口体３に接続する。
(5) 封口体３を外装缶２の開口部にセットした後、図６に示すように、カシメ加工して、封口体３を外装缶２に気密に固定する。
(6) 図４に示すように、外装缶２の外形が多少小さくなるように外装缶２を縮径工程で絞り加工する。絞り加工は、円筒状である外装缶２の缶底の内径が２１．３ｍｍ、電極体の上面における内径が２１．０ｍｍ、外径が２２．０ｍｍとなるようにする。縮径工程における絞り加工は、外装缶２の外径が、０．２〜０．８ｍｍ細くなるようにすることもできる。絞り加工で外装缶２が細くなると、外装缶２の厚い部分は、内面に押し出されて押圧部５となる。この押圧部５は、電極体１の外周面を押圧して、電極体１を外装缶２の内部にしっかりと保持する。
【００３３】
［比較例１］
外装缶となる金属筒の内径を２１．８ｍｍ、外径を２２．５ｍｍとし、内径と外径を缶底から開口部まで同じとし、さらに、縮径工程で絞り加工した後の内径を２１．３ｍｍ、外径を２２．０ｍｍとする以外、実施例１と同様にして密閉形電池を製作する。ただし、この密閉形電池は、電極体と周壁との間に絶縁セパレータを入れる。
【００３４】
［比較例２］
電極体と周壁との間に絶縁セパレータを入れない以外は、比較例１と同様にして密閉形電池を製作する。
【００３５】
実施例１と比較例１、２の密閉形電池は、振動試験後の内部ショート率と、封口体の引き抜き強度が以下の表１のようになる。
【００３６】
【表１】

【００３７】
この試験において、振動試験は、以下の条件で密閉形電池をサイン波で上下縦方向に振動させる。この振動試験の後、内部ショートする電池の個数から内部ショートする確率を計算する。内部ショート率は、内部ショートする電池の個数／全体の電池の個数に１００を掛けて計算する。
振動数は、１０Ｈｚから５００Ｈｚまで上昇させた後、さらに１０Ｈｚまで下げるのを１サイクルとして、これを５サイクル繰り返す。振動数は１オクターブ／分の率で変化させる。すなわち、１分毎に２倍の率で上昇し、その後１分毎に１／２の率で低下させる。振幅は０．３５ｍｍとする。
【００３８】
封口体の引き抜き強度は、固定している外装缶から封口体を引き抜きするときの引張力で、比較例１と２の電池の引き抜き力を１００％とする。
【００３９】
この表から明かなように、本発明の実施例の密閉形電池は、絶縁セパレータを使用することなく、振動試験後の内部ショートを皆無として、耐衝撃性を著しく向上できる。さらに、封口体の引き抜き強度も著しく強くできる特長がある。
【００４０】
【発明の効果】
本発明の密閉形電池とその製造方法は、極めて簡単な構造で外装缶に入れている電極体をしっかりと保持して耐衝撃性を向上できる特長がある。それは、本発明の密閉形電池とその製造方法が、電極体を収容している外装缶の電極体との対向位置を厚くして外装缶の内面に突出する押圧部を設けて、この押圧部で電極体の外周面を押圧しているからである。このように、外装缶の電極体との対向する部分を厚くして、外装缶の内面に突出する押圧部を設ける構造は、この押圧部で電極体の外周面を押圧して、外装缶に入れている電極体をしっかりと保持できるので、極めて簡単な構造として耐衝撃性を向上できる。
【００４１】
さらに、本発明の密閉形電池の製造方法は、電極挿入工程で電極体を入れる外装缶に、挿入される電極体との対向位置を外側に突出させて厚くしている底の閉塞された金属筒を使用している。すなわち、電極体を入れる金属筒は、電極挿入工程では、内側に突出する押圧部を設けていないので、電極体をスムーズに外装缶に入れることができる。さらに、電極体を挿入した外装缶は、閉塞工程で開口部を閉塞した後、縮径工程で外装缶の外形を細くして、外側に突出させて厚くしている部分を内側に突出させて押圧部を設けるので、極めて簡単に、しかも少ない製造工程で能率よく、耐衝撃性に優れた密閉形電池を低コストに製造できる。
【図面の簡単な説明】
【図１】従来の密閉形電池の製造工程を示す断面図
【図２】従来の他の構造の密閉形電池の一部断面正面図
【図３】従来の他の構造の密閉形電池の一部断面正面図
【図４】本発明の実施例の密閉形電池の断面図
【図５】図４に示す密閉形電池に使用する外装缶となる金属筒の断面図
【図６】図４に示す密閉形電池の縮径工程の状態を示す断面図
【図７】外装缶となる金属筒の他の一例を示す断面図
【図８】外装缶となる金属筒の他の一例を示す断面図
【符号の説明】
１…電極体１Ａ…正極板１Ｂ…負極板
１Ｃ…セパレータ
２…外装缶
３…封口体
４…ガスケット
５…押圧部
６…周壁
７…リード
８…絶縁セパレータ
９…Ｌ字折曲部[0001]
BACKGROUND OF THE INVENTION
[0002]
The present invention relates to a sealed battery and a method for manufacturing the same, in which an electrode body is put in an outer can and the opening is closed, and then the outer can is processed into a thin diameter in a diameter reducing step.
[Prior art]
A sealed battery is made by placing an electrode body and electrolyte in a cylindrical metal tube outer can that closes the bottom, and then fixing the sealing body to the opening of the outer can in the closing process. Manufactured in an airtight manner. In the closing process, a gasket is inserted between the sealing body and the outer can, and the outer can is crimped to fix the sealing body. The sealed battery of this structure is manufactured as follows in the process shown in FIG.
[0003]
(1) In the electrode insertion step, the electrode body 1 in which the positive electrode plate 1A and the negative electrode plate 1B are stacked and wound via the separator 1C is inserted into the outer can 2 which is a metal cylinder whose bottom is closed. After putting the electrode body 1, the insulating separator 8 is put on the upper surface of the electrode body 1. The insulating separator 8 is disposed on the upper surface of the outer peripheral portion of the electrode body 1 in order to prevent the peripheral wall 6 of the outer can 2 from contacting the electrode body 1 and causing an internal short circuit.
(2) Groove the outer can 2 from the outer peripheral surface to provide the peripheral wall 6. The peripheral wall 6 is provided at the boundary between the electrode body 1 and the sealing body 3 and serves as a stopper that prevents the sealing body 3 from being pushed into the outer can 2.
(3) An electrolyte is injected into the outer can 2 and penetrates into the electrode body 1.
(4) The lead 7 connected to the electrode body 1 is spot welded and connected to the sealing body 3.
(5) In the closing process, after the sealing body 3 is set in the opening of the outer can 2, the opening edge of the outer can 2 is bent in an L shape inside, and the L-shaped bent portion 9 and the peripheral wall 6 The sealing body 3 is clamped and fixed. In this state, the sealing body 3 is clamped via the gasket 4. The gasket 4 hermetically fixes the sealing body 3 and insulates the sealing body 3 from the outer can 2. Therefore, an insulating material that is a rubber-like elastic body is used for the gasket 4.
(6) As indicated by the arrow, the L-shaped bent portion 9 is pressed from above, and the gasket 4 is securely clamped between the L-shaped bent portion 9 and the peripheral wall 6 to be in an airtight state. In this step, the peripheral wall 6 is also crushed and comes into contact with the upper surface of the electrode body 1. However, since the insulating separator 8 is disposed between the peripheral wall 6 and the electrode body 1, the electrode body 1 does not contact the peripheral wall 6 of the outer can 2 and short-circuit.
(7) Finally, in the diameter reduction process, the outer can is pressed from the outer periphery and drawn into a thin shape to obtain an outer shape with a predetermined dimension.
[0004]
[Problems to be solved by the invention]
The sealed battery manufactured by the above process has a drawback that it is difficult to improve the impact resistance. This is because the outer diameter of the electrode body needs to be made slightly smaller than the inner diameter of the outer can because it is manufactured by inserting the electrode body into the outer can made of a metal tube. If the electrode body is thicker than the inner diameter of the outer can, the electrode body cannot be smoothly put into the outer can. In order to reduce the gap between the electrode body and the outer can, the outer can is thinned in the final diameter reduction step, but it is extremely difficult to obtain a preferable impact resistance even after this processing.
[0005]
In order to eliminate such harmful effects, a sealed battery in which an outer can is seamed has been developed. As shown in FIGS. 2 and 3, this battery has a structure in which the outer can 2 is seamed so as to protrude from the outside to the inside, and a part of the outer can 2 is pressed against the electrode body 1. Since this sealed battery can press the electrode body 1 with the outer can 2, the impact resistance can be improved. However, this structure has a drawback in that the outer can 2 becomes thin at the seam-processed portion, and the strength of this portion is reduced. The sealed battery is required to make the outer can 2 as thin as possible. This is to increase the charging capacity by making the electrode body 1 placed inside as thick as possible. For this reason, in order not to reduce the strength of the outer can 2, a thick metal tube cannot be used. Further, the sealed battery shown in FIGS. 2 and 3 has a drawback that the manufacturing process is increased and the manufacturing cost is increased because a special process is required because the outer can 2 is seamed.
[0006]
The present invention has been developed for the purpose of solving this drawback. An important object of the present invention is to provide a sealed battery capable of improving impact resistance by firmly holding an electrode body placed in an outer can with a very simple structure, and a method for manufacturing the same.
[0007]
[Means for Solving the Problems]
The sealed battery of the present invention includes an electrode body 1 in which a separator is disposed between a positive electrode plate and a negative electrode plate, an outer can 2 containing the electrode body 1, and an opening of the outer can 2 And a sealing body 3 closed by caulking . The outer can 2 has a pressing portion 5 that is thickened at a position facing the electrode body 1 and protrudes to the inner surface of the outer can 2, and the pressing portion 5 presses the outer peripheral surface of the electrode body 1.
[0008]
The outer can 2 can be formed into a pressing portion 5 by gradually increasing the thickness from the bottom of the can toward the opening. The outer can 2 can be gradually thickened in the direction of the opening in the upper part of the electrode body 1 to provide the pressing part 5 . The outer can 2 is thickened at the upper part of the electrode body 1 to form a pressing portion 5 .
[0009]
Further, the sealed battery is provided with a peripheral wall 6 by projecting the outer can 2 between the sealing body 3 and the electrode body 1 without disposing an insulating separator between the peripheral wall 6 and the electrode body 1. The peripheral wall 6 can prevent the electrode body 1 from shifting.
[0010]
The method for manufacturing a sealed battery according to the present invention includes an electrode insertion step in which an electrode body 1 in which a separator is disposed between a positive electrode plate and a negative electrode plate is placed in an outer can 2, and an outer can in which the electrode body 1 is placed. 2 includes a closing step for closing the opening portion 2 with the sealing body 3 and a diameter reducing step for narrowing the outer can 2 closing the opening portion. For the outer can 2 into which the electrode body 1 is placed, a closed metal cylinder whose bottom is thickened by projecting the position facing the inserted electrode body 1 to the outside is used. After putting the electrode body 1 in this metal cylinder in the electrode insertion process and closing the opening in the closing process, the outer diameter of the outer can 2 is narrowed in the diameter reducing process, and the portion that is made to protrude outward is thickened. A pressing portion 5 that protrudes inward at a position facing the electrode body 1 and presses the outer peripheral surface of the electrode body 1 is provided on the inner surface of the opening.
[0011]
For the outer can 2 in which the electrode body 1 is inserted in the electrode insertion step, a metal cylinder that is gradually thickened from the can bottom toward the opening to increase the outer shape can be used. Furthermore, the outer can 2 may be a metal cylinder that is gradually thickened in the direction of the opening at a portion facing the upper portion of the electrode body 1 to be inserted . Moreover, the metal cylinder which thickens the part located in the upper part of the electrode body 1 inserted is used.
[0012]
Furthermore, the manufacturing method of a sealed battery fixes the sealing body 3 by crimping the opening part of the armored can 2 in a closure process .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. However, the examples shown below illustrate the sealed battery and the manufacturing method for embodying the technical idea of the present invention, and the present invention specifies the sealed battery and the manufacturing method as follows. do not do.
[0014]
Further, in this specification, in order to facilitate understanding of the scope of claims, the numbers corresponding to the members shown in the examples are referred to as “the scope of claims” and “the means for solving the problems”. It is added to the member shown by. However, the members shown in the claims are not limited to the members in the embodiments.
[0015]
The sealed battery shown in FIG. 4 includes an electrode body 1, an outer can 2 that accommodates the electrode body 1, and a sealing body 3 that hermetically closes an opening of the outer can 2 via a gasket 4. Is provided. The sealed battery in this figure is a secondary battery such as a nickel-hydrogen battery, a nickel-cadmium battery, or a lithium ion secondary battery.
[0016]
In the electrode body 1, a positive electrode plate and a negative electrode plate are laminated via a separator. When the battery is a nickel-hydrogen battery, the negative electrode plate is an electrode plate coated with an active material mainly composed of a hydrogen storage alloy, and the positive electrode plate is a nickel core with slurry water. An electrode plate rolled with an active material mainly composed of nickel oxide is used. A positive electrode plate and a negative electrode plate are laminated via a separator made of polypropylene nonwoven fabric and wound to obtain an electrode body. A potassium hydroxide electrolyte is used as the electrolyte.
[0017]
When the battery is a nickel-cadmium battery, a strip-shaped non-sintered negative electrode plate in which a paste active material mainly composed of cadmium oxide is filled in the electrode plate core is used for the negative electrode plate, and nickel is used for the positive electrode plate. An electrode plate rolled by impregnating an active material mainly composed of slurry-like nickel hydroxide is used. However, the electrode plate can also be manufactured by a sintered manufacturing method. This electrode plate is made by filling cadmium into a nickel porous sintered substrate obtained by sintering a perforated thin steel plate coated with a slurry containing an organic thickener in a reducing atmosphere by chemical or electrolytic impregnation. A plate or a positive electrode plate filled with nickel. A positive electrode plate and a negative electrode plate are laminated via a separator made of polypropylene nonwoven fabric and wound to obtain an electrode body. An electrolytic solution containing potassium hydroxide as a main component is used as the electrolytic solution.
[0018]
When the battery is a lithium ion secondary battery, the positive electrode plate is a positive electrode active material that is a lithium-containing composite oxide, for example, an electrode plate that is rolled by applying a positive electrode slurry mainly composed of LiCoO ₂ to the core. For the negative electrode plate, a negative electrode active material that is a carbonaceous material that occludes / releases lithium ions, for example, an electrode plate that is rolled by applying a negative electrode slurry mainly composed of natural graphite powder to the core is used. The positive electrode plate and the negative electrode plate are laminated through a separator that is a microporous film made of polyethylene and wound to obtain an electrode body. As the electrolytic solution, a non-aqueous aprotic organic solvent in which a lithium salt is dissolved as an electrolyte is used.
[0019]
An electrode body 1 of a cylindrical battery is obtained by winding a positive electrode plate and a negative electrode plate that are laminated with a separator interposed therebetween. The spiral electrode body 1 is inserted into a cylindrical outer can 2. The spiral electrode body can be pressed from both sides to be deformed into an elliptical shape and inserted into an elliptical or rectangular outer can. Furthermore, the electrode body to be inserted into the rectangular tube-shaped outer can is manufactured by laminating a plurality of positive plates and negative plates that are cut into a plate shape, and alternately laminating electrode plates having different polarities via separators. You can also.
[0020]
The outer can 2 is manufactured by processing a metal plate into a cylindrical shape with a closed bottom. As the outer can 2, an iron surface plated with nickel or the like, aluminum, an aluminum alloy, a clad material in which a plurality of metals are laminated, or the like is used. The outer can 2 whose bottom is closed is manufactured by pressing a metal plate.
[0021]
The sealed battery is provided with a pressing portion 5 that protrudes on the inner surface of the outer can 2 by thickening the facing position of the outer can 2 with the electrode body 1. The pressing part 5 presses the outer peripheral surface of the electrode body 1 to hold the electrode body 1 so as not to vibrate inside the outer can 2 and so as not to come out of the outer can 2. The sealed battery of FIG. 4 is provided with a pressing portion 5 that gradually increases the thickness of the outer can 2 from the bottom of the can toward the opening, and gradually protrudes from the bottom of the can toward the opening.
[0022]
This sealed battery does not have the pressing portion 5 that protrudes to the inner surface in the previous step of inserting the electrode body 1. The pressing part 5 protruding to the inner surface is provided in a process after the electrode body 1 is put. This is because the electrode body 1 can be smoothly put into the outer can 2. As shown in FIGS. 5 and 6, the metal cylinder closing the bottom that becomes the outer can 2 has the same size from the bottom to the opening as shown in FIGS. . However, although not shown in the drawings, the metal cylinder that becomes the outer can can be shaped so that the electrode body can be inserted more smoothly by making the opening larger than the bottom of the can when the electrode body is inserted. Further, although not shown, the opening of the metal cylinder serving as the outer can can be made slightly smaller than the bottom of the can so that the electrode body can be inserted.
[0023]
In the previous step of putting the electrode body 1, the metal cylinder that becomes the outer can 2 is thickened by projecting the position facing the electrode body 1 to be inserted outward. In the sealed battery of FIG. 5, the outer can 2 is a metal cylinder that is gradually thickened from the bottom of the can toward the opening to increase the outer shape. As shown in FIG. 4, the outer can 2 manufactured using this metal tube is placed from the bottom of the can toward the upper end of the electrode body 1 after the diameter reduction process of putting the electrode body 1 and narrowing the outer shape. The inner shape gradually becomes smaller. In other words, it is possible to hold the electrode body 1 so that it does not vibrate firmly and does not come out of the outer can 2 with the pressing portion 5 that gradually protrudes higher from the bottom of the can toward the upper end of the electrode body 1. The pressing portion 5 holds the electrode body 1 firmly by making the inner shape of the outer can 2 into a taper shape with the inner shape increasing toward the bottom of the can.
[0024]
As shown in FIG. 7, the metal cylinder that becomes the outer can 2 can be gradually thickened in the direction of the opening only in the portion facing the upper portion of the electrode body to be inserted. The sealed battery manufactured using this metal cylinder is provided with a pressing portion at the upper part of the electrode body after the diameter reduction process. The pressing portion presses the upper portion of the electrode body with a tapered surface that gradually becomes thinner upward, and holds the electrode body so that it does not vibrate firmly and does not come off. The outer can 2 of FIGS. 5 and 7 presses the outer periphery of the electrode body with a pressing portion whose inner shape gradually becomes thinner upward, so that the electrode body can be firmly held in an ideal state.
[0025]
Furthermore, the metal cylinder used as the armored can 2 can also thicken the part located in the upper part of the electrode body inserted, as shown in FIG. The sealed battery manufactured using this metal cylinder is provided with a pressing portion at the upper part of the electrode body after the diameter reduction process. The pressing portion locally presses the upper part of the electrode body, and holds the electrode body so as not to vibrate firmly and from coming off.
[0026]
The sealing body 3 is manufactured by pressing a metal plate. The outer shape of the sealing body 3 is slightly smaller than the inner shape of the outer can 2 and is shaped to be fixed to the outer can 2 via the gasket 4. The sealing body 3 incorporates a safety valve (not shown). The safety valve opens when the internal pressure of the outer can 2 becomes higher than the set pressure, and prevents the outer can 2 from being destroyed due to an abnormally high internal pressure of the outer can 2. The sealing body 3 can be a safety valve by putting a rubber-like elastic body between two metal plates. However, although not shown, the safety valve has a structure in which a rubber plate, a plate material, and a spring are disposed between two metal plates constituting the sealing body, and the rubber plate is elastically pressed against the valve port by the spring. You can also.
[0027]
The outer can 2 is located between the sealing body 3 and the electrode body 1 and has a peripheral wall 6 that projects the outer can 2 to the inner surface. In the battery having the peripheral wall 6, an insulating separator can be disposed between the upper surface of the electrode body 1 and the peripheral wall 6. However, since the sealed battery of the present invention can firmly hold the electrode body 1 with the pressing portion 5 provided protruding from the inner surface of the outer can 2, the insulating separator can be omitted. The sealed battery without an insulating separator prevents the electrode body 1 from being displaced upward by the pressing portion 5 and the peripheral wall 6.
[0028]
The peripheral wall 6 is provided by grooving so that a groove is continuously formed on the outside of the outer can 2 by grooving that pushes the outer can 2 containing the electrode body 1 linearly from the outside. The peripheral wall 6 is provided between the sealing body 3 and the electrode body 1 and is provided along the lower surface of the sealing body 3. The peripheral wall 6 provided at this position prevents the sealing body 3 from being pushed into the outer can 2 and places the sealing body 3 in a fixed position. In order to prevent the peripheral wall 6 from interfering with the electrode body 1 when the electrode body 1 is put into the outer can 2, the sealed battery in which the insulating separator is put after the electrode body 1 is put into the outer can 2 has the electrode body attached to the outer can. It is provided after putting an insulating separator on the electrode body.
[0029]
A sealed battery in which an insulating separator is provided between an electrode body and a peripheral wall uses an insulating separator formed by molding an insulating material such as plastic. The insulating separator is disposed between the electrode body and the peripheral wall in order to prevent the upper surface and leads of the electrode body from contacting the peripheral wall and causing an internal short circuit.
[0030]
In the electrode body 1, one electrode plate, for example, a negative electrode plate is connected to the outer can 2, and the positive electrode plate which is the other electrode plate is connected to the sealing body 3 via a lead 7. Since the outer can 2 is on the − side, it is necessary to insulate from the positive electrode plate that is the + side of the electrode body 1 and the lead 7 that connects the + side to the sealing body 3. Since the outer wall 2 protrudes inward from the outer can 2, if the electrode body 1 is displaced, the outer can 2 is easily short-circuited by contacting the lead 7 on the + side or the positive electrode plate. In the sealed battery of the present invention, the electrode body 1 is held firmly by the pressing portion 5 so that it is possible to effectively prevent the positive lead 7 and the positive electrode plate from contacting the peripheral wall 6 and short-circuiting. If an insulating separator is disposed between the electrode body 1 and the peripheral wall 6, it is possible to completely prevent this portion from being short-circuited.
[0031]
Since the insulating separator insulates the upper surface of the electrode body from the outer can, the outer shape is, for example, a shape that follows the inner shape of the outer can, and in other words, a ring shape that opens at the center, in other words, the outer periphery of the electrode body It is molded into a ring shape that covers. However, it goes without saying that the periphery of the electrode body can be more reliably insulated by increasing the insulating separator.
[0032]
【Example】
[Example 1]
The battery of FIG. 4 is manufactured by the following steps.
(1) In this sealed battery, as shown in FIG. 5, a metal tube that gradually increases in thickness from the bottom of the can toward the opening is used as the outer can 2. In this metal cylinder, the inner shape is the same from the bottom to the opening, and the outer shape is increased from the bottom to the opening. The metal cylinder is manufactured by pressing a metal plate having an iron surface plated with nickel or the like. In this metal cylinder, the inner diameter of all the parts from the can bottom to the opening is the same as 21.8 mm, the outer diameter of the can bottom is 22.5 mm, and the outer diameter of the opening is 22.8 mm. The electrode body 1 is put in this metal cylinder.
(2) The outer can 2 containing the electrode body 1 is grooved from the outer peripheral surface to provide the peripheral wall 6. The peripheral wall 6 is provided at the boundary between the electrode body 1 and the sealing body 3 and serves as a stopper that prevents the sealing body 3 from being pushed into the outer can 2.
(3) An electrolyte is injected into the outer can 2 and penetrates into the electrode body 1.
(4) The lead 7 connected to the electrode body 1 is spot welded and connected to the sealing body 3.
(5) After the sealing body 3 is set in the opening of the outer can 2, the sealing body 3 is airtightly fixed to the outer can 2 by caulking as shown in FIG. 6.
(6) As shown in FIG. 4, the outer can 2 is drawn in a diameter reducing step so that the outer shape of the outer can 2 becomes somewhat small. In the drawing process, the inner diameter of the cylindrical outer can 2 is 21.3 mm, the inner diameter of the upper surface of the electrode body is 21.0 mm, and the outer diameter is 22.0 mm. The drawing process in the diameter reducing step can be such that the outer diameter of the outer can 2 becomes thinner by 0.2 to 0.8 mm. When the outer can 2 is thinned by drawing, the thick portion of the outer can 2 is pushed out to the inner surface and becomes the pressing portion 5. The pressing portion 5 presses the outer peripheral surface of the electrode body 1 to hold the electrode body 1 firmly inside the outer can 2.
[0033]
[Comparative Example 1]
The inner diameter of the metal cylinder used as the outer can is 21.8 mm, the outer diameter is 22.5 mm, the inner diameter and the outer diameter are the same from the bottom of the can to the opening, and the inner diameter after drawing in the diameter reduction process is 21. A sealed battery is manufactured in the same manner as in Example 1 except that the outer diameter is 3 mm and 22.0 mm. However, in this sealed battery, an insulating separator is inserted between the electrode body and the peripheral wall.
[0034]
[Comparative Example 2]
A sealed battery is manufactured in the same manner as in Comparative Example 1 except that an insulating separator is not inserted between the electrode body and the peripheral wall.
[0035]
The sealed batteries of Example 1 and Comparative Examples 1 and 2 have the internal short-circuit rate after the vibration test and the pull-out strength of the sealing body as shown in Table 1 below.
[0036]
[Table 1]

[0037]
In this test, in the vibration test, the sealed battery is vibrated vertically and vertically with a sine wave under the following conditions. After this vibration test, the probability of internal short-circuiting is calculated from the number of internal short-circuited batteries. The internal short-circuit rate is calculated by multiplying the number of internal short-circuited batteries / the total number of batteries by 100.
The frequency is raised from 10 Hz to 500 Hz and then lowered to 10 Hz as one cycle, and this is repeated 5 cycles. The frequency is changed at a rate of 1 octave / minute. That is, it increases at a rate of twice every minute and then decreases at a rate of ½ every minute. The amplitude is 0.35 mm.
[0038]
The pulling strength of the sealing body is a tensile force when the sealing body is pulled out from the fixed outer can, and the pulling force of the batteries of Comparative Examples 1 and 2 is set to 100%.
[0039]
As is clear from this table, the sealed batteries of the examples of the present invention can significantly improve the impact resistance without using an insulating separator and without any internal short circuit after the vibration test. Furthermore, there is a feature that the pull-out strength of the sealing body can be remarkably increased.
[0040]
【The invention's effect】
The sealed battery and the manufacturing method thereof according to the present invention has an advantage that the impact resistance can be improved by firmly holding the electrode body in the outer can with an extremely simple structure. That is, the sealed battery of the present invention and the manufacturing method thereof are provided with a pressing portion that protrudes on the inner surface of the outer can by thickening the position facing the electrode body of the outer can containing the electrode body. This is because the outer peripheral surface of the electrode body is pressed. In this way, the structure in which the portion facing the electrode body of the outer can is thickened and the pressing portion protruding on the inner surface of the outer can is provided, the outer peripheral surface of the electrode body is pressed by this pressing portion, Since the inserted electrode body can be firmly held, the impact resistance can be improved with an extremely simple structure.
[0041]
Furthermore, the method for manufacturing a sealed battery according to the present invention includes a metal with a closed bottom that is thickened by projecting the position facing the inserted electrode body to the outside of the outer can into which the electrode body is inserted in the electrode insertion step. A cylinder is used. That is, the metal cylinder into which the electrode body is placed does not have a pressing portion protruding inward in the electrode insertion step, and therefore the electrode body can be smoothly put into the outer can. Furthermore, after closing the opening in the closing process, the outer can in which the electrode body is inserted narrows the outer shape of the outer can in the diameter reducing process, and protrudes the thickened part to the outside to the inside. Since the pressing portion is provided, a sealed battery excellent in impact resistance can be manufactured at a low cost with a very simple and efficient manufacturing process with few manufacturing steps.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a manufacturing process of a conventional sealed battery. FIG. 2 is a partially sectional front view of a sealed battery having another conventional structure. FIG. FIG. 4 is a sectional view of a sealed battery according to an embodiment of the present invention. FIG. 5 is a sectional view of a metal cylinder used as an outer can used in the sealed battery shown in FIG. FIG. 7 is a cross-sectional view showing another example of a metal cylinder serving as an outer can. FIG. 8 is a cross-sectional view showing another example of a metal cylinder serving as an outer can. [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electrode body 1A ... Positive electrode plate 1B ... Negative electrode plate
DESCRIPTION OF SYMBOLS 1C ... Separator 2 ... Exterior can 3 ... Sealing body 4 ... Gasket 5 ... Pressing part 6 ... Peripheral wall 7 ... Lead 8 ... Insulating separator 9 ... L-shaped bending part

Claims

An electrode body (1) in which a separator is disposed between the positive electrode plate and the negative electrode plate, an outer can (2) containing the electrode body (1), and an opening of the outer can (2) And a sealing body (3) that is closed by crimping ,
The outer can (2) has a pressing portion (5) which is thickened at a position facing the electrode body (1) and protrudes to the inner surface of the outer can (2), and this pressing portion (5) is the electrode body (1 while pressing the outer peripheral surface of), sealed battery, characterized by that the pressing portion by thickening the outer can (2) at the top of the electrode body (1) and (5).

The sealed battery according to claim 1, wherein the outer can (2) is gradually thickened from the bottom of the can toward the opening to form the pressing portion (5).

The sealed battery according to claim 1, wherein the outer can (2) is gradually thickened toward the opening in the upper part of the electrode body (1) to provide a pressing part (5).

The outer can (2) is protruded inward between the sealing body (3) and the electrode body (1) to provide a peripheral wall, and an insulating separator is not disposed between the peripheral wall and the electrode body (1). The sealed battery according to claim 1, wherein displacement of the electrode body is prevented by the peripheral wall.

An electrode insertion step of inserting the electrode body (1) having a separator between the positive electrode plate and the negative electrode plate into the outer can (2), and an opening of the outer can (2) containing the electrode body (1) A method for producing a sealed battery comprising: a closing step for closing a part with a sealing body (3); and a diameter reducing step for narrowing an outer can (2) closing an opening,
The outer can (2) into which the electrode body (1) is inserted in the electrode insertion process uses a metal tube with a closed bottom that protrudes outward from the inserted electrode body (1) and thickens. Then, after putting the electrode body (1) in this metal cylinder and closing the opening in the closing process, the outer diameter of the outer can (2) is made thin in the diameter reducing process, and the part is made to protrude outward and thickened At the position facing the electrode body (1) and providing a pressing portion (5) for pressing the outer peripheral surface of the electrode body (1) on the inner surface of the opening , and in the electrode insertion step, the electrode body (1) Use a metal cylinder that thickens the part located at the top of the electrode body (1) to be inserted into the outer can (2)
Furthermore, in the closing step, the sealed battery (3) is manufactured by crimping the opening of the outer can (2 ) to fix the sealing body (3) .

The outer can put the electrode body in the electrode inserting step (1) (2), as described in claim 5 using a metal tube that increase the external shape and gradually thicker toward the can bottom in the direction of the opening A manufacturing method of a sealed battery.

In the outer can (2) into which the electrode body (1) is inserted in the electrode insertion step, a metal cylinder that is gradually thickened in the direction of the opening is used in the portion facing the upper part of the electrode body (1) to be inserted. A method for producing a sealed battery according to claim 5 .