JP2004288472A

JP2004288472A - Battery and battery pack

Info

Publication number: JP2004288472A
Application number: JP2003078963A
Authority: JP
Inventors: Ikuko Harada; 育幸原田; Kazuhiro Kitaoka; 和洋北岡; Katsuya Kono; 勝也河野; Takuya Tamagawa; 卓也玉川
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 2003-03-20
Filing date: 2003-03-20
Publication date: 2004-10-14

Abstract

PROBLEM TO BE SOLVED: To provide a battery with reduced electric resistance by thickening a sealing plate without damaging a conventional battery characteristics, reducing a total electric resistance as a battery pack by surely connecting plate tubs. SOLUTION: The battery airtightly fixes a sealing plate 4 made of metal plate by caulking an opening part of a metallic external case 3 in which an electrode group 5 and an electrolyte are filled. The sealing plate 4 is located at the part inner than a peripheral part 4A clamped by a caulking part 3a of the external case 3, and an outer surface protrusion part 10A protruding toward the surface side of the battery and a wall thickness part 10 thicker than the peripheral part 4A are arranged at a not clamped part 4B. The battery pack is formed by linearly jointing a plurality of batteries 1 through the plate tubs 2 interposed between batteries 1. The plate tub 2 jointed to the outer surface protrusion part 10A of the sealing plate 4 of the battery 1 at one side, and the external case 3 of the other battery 1 at the other side serially connects adjacent batteries 1. COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、外装缶の開口部をかしめて封口板を気密に固定してなる電池と、複数の二次電池を直線状に連結している組電池に関する。
【０００２】
【従来の技術】
二次電池の用途は、パーソナルコンピューター（ＰＣ）、携帯電話、電気自動車（ＥＶ）、ハイブリット車（ＨＥＶ）、電動自転車、電動工具など広範囲にわたる。特に電気自動車（ＥＶ）、ハイブリット車（ＨＥＶ）、電動自転車、電動工具などの大電流放電される高出力用途においては、より一層の特性向上のため、様々な開発が行われている。特に、構成部材の抵抗が大きいと、発熱による電力ロスを生じるため、抵抗を低減することが望まれる。
【０００３】
大電流放電に適した構造の組電池は、特許文献１の公報に示される。この組電池は、図１に示す断面構造で、複数の円筒型電池１を直線状に並べて直列に接続している。隣接する円筒型電池１は、封口板４と外装缶３に皿状の接続体である皿タブ２を溶接して、直列に接続している。この構造の組電池は、組電池を形成する円筒型電池自体の抵抗低減のみならず、電池−電池間の接続抵抗を低減させる必要がある。
【０００４】
【特許文献１】
特許第３３１２８５３号公報
【０００５】
【発明が解決しようとする課題】
以上の組電池は、皿タブ２で電池１と電池１を接続しているので、皿タブ２の電気抵抗を小さくして電池−電池間の電気抵抗を小さくできる。このことを実現するには、図２の断面図に示すように、封口板４を上方に突出するように折曲加工して実現できる。この構造の円筒型電池１を接続する皿タブ２は、かしめ部３ａの内側に突出させる突出量を小さくできる。このため、皿タブ２が浅くなって、皿タブ２における電流経路が短縮されて電気抵抗を小さくできる。しかしながら、この構造では、組電池としてトータルの電気抵抗を小さくできない。封口板４を上方に突出させることにより、電極５Ａを封口板４に電気接続する電極リード９が長くなり、この部分の電気抵抗が増加するからである。
【０００６】
封口板自体の電気抵抗は、図３に示すように封口板４を厚くして小さくできる。しかしながら、この封口板４は、周縁のかしめられる領域を含む全体で一様に厚くなっているので、円筒型電池１の電池内体積を減少させる。電池内体積の小さい円筒型電池は、異常時に電池の内圧が急激に上昇する欠点がある。電池内で発生するガスによる圧力上昇を吸収する体積が小さくなるからである。また、厚い封口板を使用して封口板の電気抵抗を小さくしても、皿タブを溶接する各電池間の距離が短縮されなければ、皿タブにおける電流経路を短縮することができず、皿タブの電気抵抗を減少することはできない。
【０００７】
皿タブは、厚い金属板で製作して電気抵抗を少なくできる。しかしながら、厚い皿タブは電池にしっかりと確実に接続するのが難しい。それは、厚い金属板の皿タブを溶接すると、無効電流が大きくなって確実に溶接するのが難しくなるからである。このため、皿タブの金属板は、厚さを３ｍｍ以下としているのが実状である。
【０００８】
本発明は、従来の電池及び組電池が有する以上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、従来の電池性能を損なうことなく、封口板を厚くして電気抵抗を小さくできる電池と、組電池としてトータルの電気抵抗を小さくできる組電池を提供することにある。
また、本発明の他の大切な目的は、皿タブを確実に接続して、電気抵抗を小さくできる電池及び組電池を提供することにある。
【０００９】
【課題を解決するための手段】
本発明の電池は、電極群５と電解質を充填している金属製の外装缶３の開口部をかしめて、金属板の封口板４を絶縁状態で気密に固定している。封口板４は、外装缶３のかしめ部３ａに挟まれた周縁部分４Ａより内側にあって、かしめ部３ａに挟まれない非挟着部分４Ｂに、電池１の表面側に突出する外面突出部１０Ａを設けて、かしめ部３ａに挟まれた周縁部分４Ａよりも厚くしてなる肉厚部１０を設けている。
【００１０】
本発明の請求項２の電池は、二次電池１の封口板４が、外装缶３のかしめ部３ａに挟まれた周縁部分４Ａより内側にあって、かしめ部３ａに挟まれない非挟着部分４Ｂに、電池１の表面側に突出する外面突出部１０Ａと内面側に突出する内面突出部１０Ｂとを設けて、かしめ部３ａに挟まれた周縁部分４Ａよりも厚くしてなる肉厚部１０を設けている。さらに、内面突出部１０Ｂには電極５Ａに接続している電極リード９を接続している。
【００１１】
本発明の請求項４の組電池は、二次電池１の間に皿タブ２を挟着して、皿タブ２を介して複数の二次電池１を直線状に連結している。二次電池１に挟着される皿タブ２は、一方の二次電池１の封口板４と、他方の二次電池１の外装缶３とに連結されて、隣接する二次電池１を直列接続して直線状に連結している。二次電池１は、電極群５と電解質を充填している金属製の外装缶３の開口部をかしめて、金属板の封口板４を絶縁状態で気密に固定している。封口板４は、外装缶３のかしめ部３ａに挟まれた周縁部分４Ａより内側にあって、かしめ部３ａに挟まれない非挟着部分４Ｂに、電池１の表面側に突出する外面突出部１０Ａを設けて、かしめ部３ａに挟まれた周縁部分４Ａよりも厚くしてなる肉厚部１０を設けている。封口板４の外面突出部１０Ａに、二次電池１を直列に接続する皿タブ２を連結している。
【００１２】
本発明の請求項５の組電池は、二次電池１の封口板４が、外装缶３のかしめ部３ａに挟まれた周縁部分４Ａより内側にあって、かしめ部３ａに挟まれない非挟着部分４Ｂに、電池１の表面側に突出する外面突出部１０Ａと内面側に突出する内面突出部１０Ｂとを設けて、かしめ部３ａに挟まれた周縁部分４Ａよりも厚くしてなる肉厚部１０を設けている。さらに、内面突出部１０Ｂには電極５Ａに接続している電極リード９を接続している。
【００１３】
封口板４の肉厚部１０の厚さは、皿タブ２よりも厚くすることができる。また、封口板４の肉厚部１０の厚さは、電極リード９よりも厚くすることができる。
【００１４】
【作用】
本発明の電池は、封口板４に肉厚部１０を設けている。封口板４は全体を厚くするのではなくて、周縁部分４Ａを薄くして、その内側部分に肉厚部１０を設けている。肉厚部１０は、外装缶３のかしめ部３ａに挟まれている周縁部分４Ａよりも内側にあって、かしめ部３ａに挟まれない非挟着部分４Ｂに設けている。封口板４は、非挟着部分４Ｂに外側に突出する外面突出部１０Ａを設け、あるいは外側に突出する外面突出部１０Ａと内側に突出する内面突出部１０Ｂの両方を設けて肉厚部１０としている。すなわち、本発明の電池は、かしめ部３ａにはさまれる周縁部分４Ａの厚みを、従来の電池の封口板４と同じ厚さとしながら、かしめ部３ａに挟まれていない非挟着部分４Ｂに肉厚部１０を設けている。この構造の電池は、肉厚部１０によって封口板４の厚みを増加できるので、封口板４の電気抵抗を小さくして、全体としての抵抗低減を実現できる。
【００１５】
さらに、この構造の電池を皿タブ２で連結する組電池は、電池特性を損なうことなく電気抵抗を低減できる。それは、封口板４の挟着部分４Ｂに肉厚部１０を設けて、肉厚部１０を外面突出部１０Ａとしているからである。この組電池は、皿タブ２で接続される一方の電池１の底部と、封口板上端との距離を短くして、電気抵抗を低減できる。この構造の組電池は、封口板４と、これに接続される電池底部の間の空間における、金属／空間の比率を高くして、電池間の電気抵抗を小さくできる。とくに、皿タブ２を確実に封口板４に溶接して接続するために、皿タブ２を封口板４よりも薄くする構造において、電気抵抗を小さくできる。皿タブ２に接続される封口板上端部と、外装缶底との距離を短くできるからである。
【００１６】
さらに、請求項２と５に記載しているように、封口板４に内面突出部１０Ｂを設けて肉厚部１０として、内面突出部１０Ｂに電極リード９を接続している構造は、電極リード９に封口板４の肉厚部１０よりも薄い金属板を使用しながら、電気抵抗を小さくできる特長がある。それは、内面突出部１０Ｂを電極に接近させて、正確には電極に接続している集電体８に封口板４の内面突出部１０Ｂを接近させて、間隔を短くできるからである。また、封口板４に内面突出部１０Ｂを設ける構造は、肉厚部１０をより厚くできるので、封口板４の電気抵抗をさらに小さくできる特長もある。
【００１７】
図２に示すように、全体の厚さが同じである封口板４を湾曲して、電池１の外部側に突出させる構造は、皿タブ２の電気抵抗は小さくできるが、封口板４の電気抵抗が増大されるため、全体としての抵抗低減を実現できない。また、図３に示すように、単に封口板全体を厚くする構造では、かしめ部においても厚くなってしまうので、その分、シーム位置が下がってしまう。このため、電極５Ａの全高を下げることが必要となって電極５Ａを小さくする必要がある。このことは、電池１の容量を低下させる等の電池特性低下をまねくことになる。また、封口板４を全体に厚くしても、封口板４の上面と、皿タブ２で接続される電池１の底部との距離は短くはならないので、皿タブ２で接続する部分の電気抵抗は低減されない。
【００１８】
これに対して本発明の電池及び組電池は、封口板４の全体を厚くするのではなく、部分的に厚くする。すなわち、外装缶３のかしめ部３ａで挟まれる部分に比較して、かしめ部３ａで挟まれない非挟着部分４Ｂに、外面突出部１０Ａや内面突出部１０Ｂを設けて肉厚部１０としている。この構造は、肉厚部１０によって封口板４の厚みを増加させることにより、封口板４の電気抵抗を小さくできる。さらに、組電池は、封口板４の外面突出部１０Ａに皿タブ２を接続して複数の電池を直線状に連結する。この構造は、皿タブ２を接続する封口板４の上面と、外装缶３の底面とを接近できるので皿タブ２の電気抵抗を小さくできる。したがって、本発明は、封口板４の電気抵抗を小さくすることと、皿タブ２の電気抵抗を小さくすることの相乗効果で組電池のトータルの電気抵抗を相当に小さくできる。このことは、１００個以上の二次電池を直列に接続してなる組電池、たとえば電気自動車やハイブリッドカーの電源に使用される組電池において特に大切である。たとえば２００個の二次電池を直列に接続している組電池が、１００Ａ以上の大電流で放電されと、発熱ロスが極めて大きくなるからである。
【００１９】
【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電池及び組電池を例示するものであって、本発明は電池及び組電池を以下のものに特定しない。
【００２０】
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」、「課題を解決するための手段の欄」、および「作用の欄」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。
【００２１】
図４と図５に示す組電池は、複数の二次電池１を直線状に連結している。二次電池１は、間に皿タブ２を挟着し、この皿タブ２を介して連結される。皿タブ２は、一方の二次電池１の封口板４と、他方の二次電池１の外装缶３とに連結されて、上下に隣接する二次電池１を直列接続して直線状に連結する。
【００２２】
皿タブ２は金属板で製作される。図の皿タブ２は、一方の二次電池１の外装缶３に連結される外装缶連結部２Ｂと、封口板４の外側面に接続される封口板連結部２Ａとからなる。外装缶連結部２Ｂと封口板連結部２Ａからなる皿タブ２は、１枚の金属板をプレス加工して製作される。外装缶連結部２Ｂは、外装缶３の底部を挿入できる筒状である。図の二次電池１は円筒型電池であるから、外装缶連結部２Ｂを円筒状としている。封口板連結部２Ａは、凸部電極１ａを貫通させる中心孔２ａを開口している。さらに、封口板連結部２Ａは、封口板４に連結する突出連結部２ｂを設けている。封口板連結部２Ａは、外装缶３のかしめ部３ａに接触しないように、突出連結部２ｂの外周に段差部２ｃを設けている。段差部２ｃの内側に設けられる突出連結部２ｂは、その外形をかしめ部３ａの内形よりも小さくして、封口板連結部２Ａとかしめ部３ａとが接触しないようにしている。皿タブ２は、外装缶連結部２Ｂと封口板連結部２Ａをスポット溶接して二次電池１に連結される。ただ、皿タブはレーザー溶接して二次電池１に連結することもできる。
【００２３】
二次電池１は、円筒型電池である。ただし、本発明の組電池は、二次電池を必ずしも円筒型電池には特定しない。二次電池は、外装缶をかしめて封口板を固定している全ての電池とすることができる。二次電池１は、ニッケル−水素電池である。ただ、本発明の組電池は、二次電池をニッケル−カドミウム電池、リチウムイオン電池等とする全ての種類の二次電池とすることもできる。
【００２４】
図の二次電池１は、電極群５と電解液を充填している金属製の外装缶３の開口部をかしめて、金属板の封口板４を絶縁状態で気密に固定している。外装缶３は、金属板をプレス加工して、底を閉塞している筒状にして製作される。円筒型電池は、金属板を円筒状に成形して外装缶３とする。角型電池は、金属板を角筒状に成形して外装缶とする。封口板４は、金属板をプレス加工し、あるいは鋳造して製作される。外装缶３と封口板４とは、絶縁状態でかしめられる。絶縁のために、外装缶３と封口板４との間に絶縁材６が挟着される。絶縁材６は、外装缶３と封口板４とを絶縁しながら隙間を気密に閉塞する。外装缶３は、かしめ部３ａで封口板４を挟んで固定するために、封口板４の下面に沿って凸条７を設けている。凸条７を設けた外装缶３に封口板４をセットし、開口部縁をかしめ加工して封口板４を固定する。その後、かしめ部３ａを上面からパンチによって加圧して、外装缶３の全体寸法を規定値とする。
【００２５】
図の二次電池１は、外装缶３の内部に入れている電極５Ａの上に集電体８を配設している。電極５Ａは、正負の極板を、間に挟着しているスペーサーで絶縁しながら積層している。電極５Ａの一方の極板は、電極５Ａの上に配置している集電体８に接続され、他方の電極は、外装缶３の底部に配置している集電体（図示せず）を介して外装缶３に接続される。電極５Ａの上に配置される集電体８は、電極リード９を介して封口板４に接続される。電極５Ａの下に配置される集電体は、外装缶３の内部で底部や側面にスポット溶接やレーザー溶接等の方法で外装缶３に接続され、あるいは外装缶３の内面に押圧して電気接続される。
【００２６】
組電池は、図６に示すように、複数の二次電池１を直線状に連結しながら直列に接続している。この構造の組電池は、図７に示すように、さらに複数組を直列に接続して、電気自動車やハイブリッドカー等を駆動する電源装置として使用される。ハイブリッドカーの電源装置に使用される電源装置は、１００個以上の二次電池１を直列に接続したものである。
【００２７】
図４と図５に示す組電池を構成する二次電池１は、封口板４全体を同じ厚さの金属板としない。封口板４は、外装缶３のかしめ部３ａに挟まれる周縁部分４Ａを薄く、皿タブ２の連結部を厚くしている。すなわち、封口板４は、外装缶３のかしめ部３ａに挟まれた周縁部分４Ａより内側にあって、かしめ部３ａに挟まれない非挟着部分４Ｂに、外面突出部１０Ａや内面突出部１０Ｂを設けて肉厚部１０としている。封口板４の肉厚部１０は、好ましくは、かしめ部３ａに挟着された周縁部分４Ａの厚さの１．５倍よりも大きくする。１．５倍よりも薄いと、皿タブ２の電気抵抗を充分に小さくできないからである。また、封口板４の肉厚部１０は、好ましくは、かしめ部３ａに挟着された周縁部分４Ａの厚さの５倍よりも薄くする。５倍よりも厚いと、外面突出部１０Ａが二次電池１のかしめ部３ａから突出し、あるいはかしめ部３ａに挟まれる周縁部分４Ａが薄くなるからである。
【００２８】
図４の二次電池１は、封口板４の非挟着部分４Ｂに外面突出部１０Ａを設けて、外面突出部１０Ａを設けている部分を肉厚部１０としている。外面突出部１０Ａには、二次電池１を直列に接続する皿タブ２を連結する。皿タブ２は、封口板連結部２Ａに設けている突出連結部２ｂを外面突出部１０Ａに連結する。図に示すように、肉厚部１０の外面突出部１０Ａを封口板４に設けて、ここに皿タブ２を溶接している組電池は、封口板４と接続電池底部の間の金属比率が高くなり、電池間の抵抗が低減される。とくに、従来の組電池では空気であった部分を金属とするので、電池性能を損なうことなく、組電池の電気抵抗を小さくできる。とくに、この構造は、皿タブ２を封口板４に確実に溶接しながら、組電池としてのトータルの電気抵抗を小さくできる。それは、皿タブ２を溶接する外面突出部１０Ａを肉厚部１０として厚くして、皿タブ２を外面突出部１０Ａの肉厚部１０よりも薄くできるからである。薄い皿タブ２は、スポット溶接するときの無効電流が小さくなって確実に封口板４に溶接される。薄い皿タブ２は、電気抵抗が大きくなるが、接近する外面突出部により電流の経路が短くなるので電気抵抗を小さくできる。
【００２９】
図５の二次電池１は、封口板４の非挟着部分４Ｂに、外側に突出する外面突出部１０Ａと内側に突出する内面突出部１０Ｂの両方を設けて、この部分を肉厚部１０としている。すなわち、この封口板４は、両面に突出させて肉厚部１０を設けている。電池の内側に突出する内面突出部１０Ｂは、電極リード９を介して電極５Ａに接続される。この構造は、電極リード９の電気抵抗を小さくして電池の内部抵抗を小さくできる。とくに、電極リード９を肉厚部１０よりも薄くして、確実に封口板４に溶接できる構造としながら、電極リード９を短くして電気抵抗を小さくできる。
【００３０】
図４に示すように、封口板４の肉厚部１０に、外面突出部のみ１０Ａを設けて内面突出部を設けないで肉厚部１０を設ける構造は、皿タブ２の電気抵抗を小さくして、組電池として組み立てられた状態での電気抵抗を小さくしながら、異常時に電池の内圧が急激に上昇するのを防止できる。電池の内容積を変更することなく、組電池の電気抵抗を小さくできるからである。
【００３１】
【実施例】
組電池は、以下の二次電池１を皿タブ２で直列に連結して製作される。以下の実施例は、二次電池１をニッケル−水素電池とする。ただし、二次電池は、ニッケル−水素電池以外の二次電池とすることもできるのは言うまでもない。
【００３２】
［実施例１］
図８の断面図に示すニッケル−水素電池は、外装缶３に電極群５を入れて電解液を充填している。外装缶３は、底の閉塞された円筒状に金属板をプレス成形したもので、開口部を封口板４で閉塞している。外装缶３は、開口部をかしめ加工して、開口部に絶縁状態で気密に封口板４を固定している。
【００３３】
電極群５は図９の斜視図に示すように、電極５Ａに集電体８を接続している。電極５Ａは、ニッケル正極板と、水素吸蔵合金負極板とをセパレータを介して積層している。ニッケル正極板は、パンチングメタルからなる極板芯体の表面にニッケル焼結多孔体を形成した後、化学含浸法により水酸化ニッケルを主体とする活物質をニッケル焼結多孔体内に充填して作製されている。一方、水素吸蔵合金負極板は、パンチングメタルからなる極板芯体の表面に、水素吸蔵合金からなるペースト状負極漬物質を充填し、含浸させた後、所定の厚みになるまで圧延して作製されている。
【００３４】
これらのニッケル正極板と水素吸蔵合金負極板との間にセパレータを介在させて渦巻状に巻回して渦巻状の電極５Ａを作製する。この電極５Ａの上端面には、ニッケル正極板の極板芯体であるパンチングメタルの残部が露出し、また、下端面には水素吸蔵合金負極板の極板芯体であるパンチングメタルの端部が露出している。電極５Ａの上端面に露出する正極芯体に、多数の開口を有する円板状の集電体８を溶接し、下端面に露出する負極芯体に、多数の開口を有する円板状の負極の集電体８を溶接して、渦巻状の電極群５Ａは作製される。
【００３５】
この渦巻状の電極群５に対して、筒状体の電極リード９を接続している。電極リード９である筒状体１１は、図９ないし図１２に示すように、円筒状のパイプ（例えば、ニッケル製で厚みが０．３ｍｍのもの）を用いて、その両端部を斜めに切り落として形成している。１１ａは、溶接を容易にするための突起である。そして、電極リード９は、筒状体１１の底面部１１Ａが正極集電体８の直径上に位置するように配置される。電極リード９である筒状体１１の底面部１１Ａは、正極の集電体８にスポット溶接（第１溶接）して接続される。さらに、封口板４の底面と、電極リード９である筒状体１１の上面部１１Ｂとが溶接（第２溶接）して接続される。
【００３６】
その後、外装缶３の開口部を封口板４で封口し、さらにパンチによって加圧して公称容量６．０Ａｈの円筒形ニッケルー水素蓄電池が作製される。パンチによる加圧力により、電極リード９の筒状体１１は、その断面形状が略楕円形状に押しつぶされる。
【００３７】
金属板である封口板４は、図１３に示すように肉厚部１０を設けている。この封口板４は、かしめ部３ａに挟まれない非挟着部分４Ｂに外面突出部１０Ａのみを設けて肉厚部１０としている。この封口板４は、かしめ部３ａに挟まれる周縁部分４Ａの厚さを１ｍｍ、外面突出部１０Ａを設けている肉厚部１０の厚さを１．５ｍｍとし、外面突出部１０Ａの突出高さを０．５ｍｍとしている。この封口板４は、凸部電極１ａを固定する電極嵌入部分４ａと、電極リード９の接続部分４ｂとを電池の内側に突出するようにプレス加工している。接続部分４ｂは、図１５に示す従来の封口板と同じように、電極嵌入部分４ａよりもわずかに下方に突出させている。この封口板４を使用して製作される二次電池１を実施例１の電池とする。
【００３８】
［実施例２］
この実施例の二次電池１は、図１４に示すように、金属板である封口板４の非挟着部分４Ｂに、外面突出部１０Ａと内面突出部１０Ｂを設けて肉厚部１０とする以外、実施例１と同様にして作成される。この封口板４は、開口部に挟まれる周縁部分４Ａの厚さを１ｍｍ、外面突出部１０Ａと内面突出部１０Ｂを設けている肉厚部１０の厚さを２ｍｍ、外面突出部１０Ａの突出高さを０．５ｍｍ、内面突出部１０Ｂの突出高さを０．５ｍｍとしている。この封口板４も、実施例１の封口板４と同じように、凸部電極１ａを固定する電極嵌入部分４ａと、電極リード９の接続部分４ｂとを電池の内側に突出するようにプレス加工している。この封口板も、図１５に示す従来の封口板と同じように、接続部分４ｂを電極嵌入部分４ａよりもわずかに下方に突出させている。この封口板４を使用して製作される二次電池を実施例２の電池とする。
【００３９】
［比較例］
比較例の二次電池１は、図１５に示すように、封口板４に肉厚部を設けることなく、封口板４全体の金属板の厚さを１ｍｍとしている。この封口板４も、実施例１の封口板４と同じように、凸部電極１ａを固定する電極嵌入部分４ａと、電極リード９の接続部分４ｂとを電池の内側に突出するようにプレス加工している。電極嵌入部分４ａと接続部分４ｂは、周縁部分４Ａと同じ厚さであって、周縁部分４Ａよりも厚くして内側に突出させる内面突出部ではない。この封口板４は、全体を同じ厚さとする金属板を使用して、実施例１と同じように、上下の両面を下方に突出するようにプレス加工している。この封口板４を使用して製作される二次電池を比較例の電池とする。
【００４０】
以上のようにして製作される実施例１、実施例２、比較例の電池の各部分の寸法であるＡ〜Ｄは、表１に示す値となる。各部の寸法を図８に示している。この図において、Ａ〜Ｄは以下の寸法である。各々の寸法の単位はｍｍである。
Ａ…外装缶最上端と封口板上面（外面突出部）との距離
Ｂ…封口板（肉厚部）の下面と集電体との距離
Ｃ…封口板（肉厚部）の厚さ
Ｄ…集電体と外装缶最上端との距離
【００４１】
【表１】

【００４２】
以上にように、実施例１、実施例２、比較例の電池は、集電体８と外装缶最上端との距離（Ｄ）を３．９ｍｍとして変更することなく、封口板上面の外面突出部１０Ａから電池肩部まで距離（Ａ）を、比較電池の１．２ｍｍから０．７ｍｍと短くできる。このことから、実施例１と２の電池は、電池一電池間の抵抗を削減することが可能となる。皿タブ２の封口板連結部２Ａに設けている突出連結部２ｂを低くできるからである。
【００４３】
また、実施例２の電池は、封口板４と集電体８との距離も、比較電池の１．７ｍｍから１．２ｍｍと接近できる。このことから、電極リード９を短くして、電池内部の抵抗を低減できる。
【００４４】
【発明の効果】
本発明の電池は、電池性能を損なうことなく封口板を厚くして電気抵抗を小さくできる特長がある。それは、本発明の電池が、封口板の周縁部分を厚くすることなく、かしめ部に挟まれていない非挟着部分に肉厚部を設けているからである。この構造の電池は、肉厚部によって封口板を厚くできるので、封口板の電気抵抗を小さくして、全体としての抵抗を小さくできる。さらに、肉厚部を設けて厚くしてなる封口板は、強度を強くできるので、内部圧力の変化や外部からの衝撃による変形を有効に防止できる特長もある。
【００４５】
さらに、本発明の組電池は、電池性能を損なうことなく、皿タブを確実に接続しながら、組電池としてトータルの電気抵抗を小さくできる特長がある。それは、本発明の組電池が、二次電池の封口板を、かしめ部に挟まれる周縁部分を薄くし、皿タブを連結する部分に外面突出部を設けて肉厚部を設けているからである。この構造の組電池は、二次電池を皿タブで直線状に連結する構造において、外装缶底面と封口板との間の金属／空間の比率を高くして、電池間の電気抵抗を小さくする。とくに、この構造は、皿タブを確実に溶接できる厚さとして確実に溶接できるようにしながら、電池間の電気抵抗を小さくできる特長もある。
【図面の簡単な説明】
【図１】従来の組電池の電池連結部を示す断面図
【図２】図１の組電池を改造した組電池の断面図
【図３】図１の組電池を改造した組電池の断面図
【図４】本発明の実施例１の組電池の電池連結部を示す断面図
【図５】本発明の実施例２の組電池の電池連結部を示す断面図
【図６】複数の電池を直線状に直列接続した状態を示す側面図
【図７】図６に示す組電池を複数組直列に接続した状態を示す概略平面図
【図８】本発明の実施例１の組電池に使用する電池の縦断面図
【図９】図８に示す電池に内蔵される電極群を示す斜視図
【図１０】図９に示す電極群を封口板に接続する電極リードの平面図
【図１１】図１０に示す電極リードの正面図
【図１２】図１０に示す電極リードの展開図
【図１３】本発明の実施例１の組電池に使用する電池の封口板を示す拡大断面図
【図１４】本発明の実施例２の組電池に使用する電池の封口板を示す拡大断面図
【図１５】従来の組電池であって比較例の組電池に使用する電池の封口板を示す拡大断面図
【符号の説明】
１…電池１ａ…凸部電極
２…皿タブ２Ａ…封口板連結部２Ｂ…外装缶連結部
２ａ…中心孔２ｂ…突出連結部
２ｃ…段差部
３…外装缶３ａ…かしめ部
４…封口板４Ａ…周縁部分４Ｂ…非挟着部分
４ａ…電極嵌入部分４ｂ…接続部分
５…電極群５Ａ…電極
６…絶縁材
７…凸条
８…集電体
９…電極リード
１０…肉厚部１０Ａ…外面突出部１０Ｂ…内面突出部
１１…筒状体１１Ａ…底面部１１Ｂ…上面部
１１ａ…突起[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a battery having a sealing plate hermetically fixed by caulking an opening of an outer can and an assembled battery in which a plurality of secondary batteries are linearly connected.
[0002]
[Prior art]
Rechargeable batteries are used in a wide range of applications such as personal computers (PCs), mobile phones, electric vehicles (EV), hybrid vehicles (HEV), electric bicycles, and electric tools. In particular, various developments have been made to further improve the characteristics of high-power applications in which a large current is discharged, such as electric vehicles (EV), hybrid vehicles (HEV), electric bicycles, and electric tools. In particular, when the resistance of the constituent members is large, power loss due to heat generation occurs, so it is desired to reduce the resistance.
[0003]
An assembled battery having a structure suitable for large-current discharge is disclosed in Japanese Patent Application Laid-Open No. H11-163,837. This assembled battery has a cross-sectional structure shown in FIG. 1 and has a plurality of cylindrical batteries 1 arranged in a straight line and connected in series. Adjacent cylindrical batteries 1 are connected in series by welding a dish tab 2 which is a dish-shaped connecting body to a sealing plate 4 and an outer can 3. In the assembled battery of this structure, it is necessary to reduce not only the resistance of the cylindrical battery itself forming the assembled battery but also the connection resistance between the batteries.
[0004]
[Patent Document 1]
Japanese Patent No. 3312853
[0005]
[Problems to be solved by the invention]
In the above assembled battery, since the batteries 1 are connected to each other by the plate tab 2, the electric resistance of the plate tab 2 can be reduced to reduce the electric resistance between the batteries. This can be realized by bending the sealing plate 4 so as to protrude upward as shown in the sectional view of FIG. The protruding amount of the dish tab 2 connecting the cylindrical battery 1 having this structure to the inside of the caulked portion 3a can be reduced. For this reason, the plate tab 2 becomes shallow, the current path in the plate tab 2 is shortened, and the electric resistance can be reduced. However, this structure cannot reduce the total electric resistance of the assembled battery. This is because, by projecting the sealing plate 4 upward, the electrode lead 9 for electrically connecting the electrode 5A to the sealing plate 4 becomes longer, and the electrical resistance of this portion increases.
[0006]
The electric resistance of the sealing plate itself can be reduced by making the sealing plate 4 thick as shown in FIG. However, since the sealing plate 4 is uniformly thick as a whole including the region where the peripheral edge is swaged, the internal volume of the cylindrical battery 1 is reduced. A cylindrical battery having a small internal battery volume has a drawback that the internal pressure of the battery rapidly increases when an abnormality occurs. This is because the volume for absorbing the pressure increase due to the gas generated in the battery becomes smaller. Further, even if the electric resistance of the sealing plate is reduced by using a thick sealing plate, the current path in the plate tab cannot be shortened unless the distance between the batteries to which the plate tab is welded is shortened. The electrical resistance of the tub cannot be reduced.
[0007]
The plate tab can be made of a thick metal plate to reduce the electric resistance. However, thick dish tabs are difficult to securely connect to the battery. This is because, when a thick metal plate dish tab is welded, the reactive current increases, and it becomes difficult to reliably weld. For this reason, the metal plate of the dish tab is actually 3 mm or less in thickness.
[0008]
The present invention has been developed to solve the above-mentioned drawbacks of conventional batteries and battery packs. An important object of the present invention is to provide a battery capable of reducing the electric resistance by increasing the thickness of the sealing plate without impairing the conventional battery performance, and an assembled battery capable of reducing the total electric resistance as an assembled battery.
Another important object of the present invention is to provide a battery and an assembled battery that can securely connect the plate tabs and reduce the electric resistance.
[0009]
[Means for Solving the Problems]
In the battery of the present invention, the opening of the metal outer can 3 filled with the electrode group 5 and the electrolyte is caulked to fix the metal plate sealing plate 4 in an insulated state in an airtight manner. The sealing plate 4 has an outer protruding portion that protrudes toward the front surface of the battery 1 at a non-clamped portion 4B that is inside the peripheral edge portion 4A sandwiched between the swaged portions 3a of the outer can 3 and that is not sandwiched between the swaged portions 3a. 10A is provided, and a thick portion 10 which is thicker than the peripheral portion 4A sandwiched between the caulked portions 3a is provided.
[0010]
In the battery according to claim 2 of the present invention, the sealing plate 4 of the secondary battery 1 is located inside the peripheral portion 4A of the outer can 3 between the swaged portions 3a, and is not sandwiched by the swaged portion 3a. A thick portion which is provided on the portion 4B with an outer protruding portion 10A protruding on the front surface side of the battery 1 and an inner protruding portion 10B protruding on the inner surface side so as to be thicker than the peripheral portion 4A interposed between the caulked portions 3a. 10 are provided. Further, an electrode lead 9 connected to the electrode 5A is connected to the inner projection 10B.
[0011]
In the battery pack according to the fourth aspect of the present invention, a plate tab 2 is sandwiched between the secondary batteries 1, and the plurality of secondary batteries 1 are connected linearly via the plate tab 2. The dish tab 2 sandwiched between the secondary batteries 1 is connected to the sealing plate 4 of one secondary battery 1 and the outer can 3 of the other secondary battery 1 to connect the adjacent secondary batteries 1 in series. Connected and connected linearly. In the secondary battery 1, the opening of the metal outer can 3 filled with the electrode group 5 and the electrolyte is caulked to fix the metal plate sealing plate 4 in an insulated state in an airtight manner. The sealing plate 4 has an outer protruding portion that protrudes toward the front surface of the battery 1 at a non-clamped portion 4B that is inside the peripheral edge portion 4A sandwiched between the swaged portions 3a of the outer can 3 and that is not sandwiched between the swaged portions 3a. 10A is provided, and a thick portion 10 which is thicker than the peripheral portion 4A sandwiched between the caulked portions 3a is provided. A plate tab 2 for connecting the secondary batteries 1 in series is connected to the outer projection 10A of the sealing plate 4.
[0012]
In the battery pack according to claim 5 of the present invention, the sealing plate 4 of the secondary battery 1 is located inside the peripheral edge portion 4A sandwiched by the swaged portion 3a of the outer can 3, and is not sandwiched by the swaged portion 3a. The attachment portion 4B is provided with an outer protrusion 10A protruding toward the front surface of the battery 1 and an inner protrusion 10B protruding toward the inner surface, so that the peripheral portion 4A sandwiched between the caulked portions 3a is thicker. The unit 10 is provided. Further, an electrode lead 9 connected to the electrode 5A is connected to the inner projection 10B.
[0013]
The thickness of the thick portion 10 of the sealing plate 4 can be greater than that of the dish tab 2. In addition, the thickness of the thick portion 10 of the sealing plate 4 can be larger than that of the electrode lead 9.
[0014]
[Action]
In the battery of the present invention, the sealing plate 4 is provided with the thick portion 10. The sealing plate 4 is not thickened as a whole, but has a thinner peripheral portion 4A, and a thick portion 10 is provided inside the sealing plate 4A. The thick portion 10 is provided on a non-clamped portion 4B which is located inside the peripheral portion 4A of the outer can 3 that is sandwiched between the swaged portions 3a and is not sandwiched by the swaged portion 3a. The sealing plate 4 is provided with an outer protruding portion 10A protruding outward on the non-clamping portion 4B, or is provided with both an outer protruding portion 10A protruding outward and an inner protruding portion 10B protruding inward to form the thick portion 10. I have. That is, in the battery of the present invention, while the thickness of the peripheral portion 4A sandwiched between the swaged portions 3a is the same as the thickness of the sealing plate 4 of the conventional battery, the non-clamped portion 4B not sandwiched between the swaged portions 3a has a thickness. A thick portion 10 is provided. In the battery having this structure, the thickness of the sealing plate 4 can be increased by the thick portion 10, so that the electrical resistance of the sealing plate 4 can be reduced, and the overall resistance can be reduced.
[0015]
Further, the assembled battery in which the batteries having this structure are connected by the plate tab 2 can reduce the electric resistance without impairing the battery characteristics. This is because the thick portion 10 is provided in the sandwiching portion 4B of the sealing plate 4, and the thick portion 10 is used as the outer surface protruding portion 10A. In this assembled battery, the electric resistance can be reduced by shortening the distance between the bottom of one of the batteries 1 connected by the plate tab 2 and the upper end of the sealing plate. In the battery pack having this structure, the metal / space ratio in the space between the sealing plate 4 and the bottom of the battery connected thereto can be increased to reduce the electric resistance between the batteries. In particular, in order to securely connect the dish tab 2 to the sealing plate 4 by welding, the electric resistance can be reduced in a structure in which the dish tab 2 is thinner than the sealing plate 4. This is because the distance between the upper end of the sealing plate connected to the dish tab 2 and the bottom of the outer can can be reduced.
[0016]
Further, as described in

claims

2 and 5, the structure in which the inner protruding portion 10B is provided on the sealing plate 4 to form the thick portion 10 and the electrode lead 9 is connected to the inner protruding

portion

10B, 9 has a feature that the electric resistance can be reduced while using a metal plate thinner than the thick portion 10 of the sealing plate 4. This is because the inner projection 10B can be made closer to the electrode, and more precisely, the inner projection 10B of the sealing plate 4 can be made closer to the current collector 8 connected to the electrode, thereby shortening the interval. Further, the structure in which the inner surface protruding portion 10B is provided on the sealing plate 4 has a feature that the electric resistance of the sealing plate 4 can be further reduced because the thick portion 10 can be made thicker.
[0017]
As shown in FIG. 2, the structure in which the sealing plate 4 having the same overall thickness is curved and protruded to the outside of the battery 1 can reduce the electric resistance of the plate tab 2, but the electric resistance of the sealing plate 4 can be reduced. Since the resistance is increased, a reduction in resistance as a whole cannot be realized. In addition, as shown in FIG. 3, in a structure in which the entire sealing plate is simply made thicker, the seam position is lowered correspondingly because the swaged portion also becomes thicker. For this reason, it is necessary to reduce the overall height of the electrode 5A, and it is necessary to reduce the size of the electrode 5A. This leads to a decrease in battery characteristics such as a decrease in the capacity of the battery 1. Even if the sealing plate 4 is made thicker, the distance between the upper surface of the sealing plate 4 and the bottom of the battery 1 connected by the plate tab 2 does not become short. Is not reduced.
[0018]
On the other hand, in the battery and the assembled battery of the present invention, the sealing plate 4 is partially thickened, not thickened. That is, as compared with a portion sandwiched by the caulked portion 3a of the outer can 3, a non-clamped portion 4B not sandwiched by the caulked portion 3a is provided with the outer surface protruding portion 10A and the inner surface protruding portion 10B to form the thick portion 10. . In this structure, the electric resistance of the sealing plate 4 can be reduced by increasing the thickness of the sealing plate 4 by the thick portion 10. Further, in the assembled battery, the plate tab 2 is connected to the outer surface protruding portion 10A of the sealing plate 4 to connect the plurality of batteries linearly. In this structure, the upper surface of the sealing plate 4 to which the dish tab 2 is connected and the bottom face of the outer can 3 can be approached, so that the electric resistance of the dish tab 2 can be reduced. Therefore, according to the present invention, the total electric resistance of the assembled battery can be considerably reduced by the synergistic effect of reducing the electric resistance of the sealing plate 4 and reducing the electric resistance of the plate tab 2. This is particularly important in an assembled battery in which 100 or more secondary batteries are connected in series, for example, an assembled battery used for a power supply of an electric vehicle or a hybrid car. This is because, for example, when a battery pack in which 200 secondary batteries are connected in series is discharged with a large current of 100 A or more, heat loss becomes extremely large.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the following examples illustrate batteries and assembled batteries for embodying the technical idea of the present invention, and the present invention does not specify batteries and assembled batteries as follows.
[0020]
Further, in this specification, in order to make it easy to understand the claims, the numbers corresponding to the members shown in the embodiments are referred to as "claims" and "means for solving the problem". , And the members shown in the “action column”. However, the members described in the claims are not limited to the members of the embodiments.
[0021]
In the battery pack shown in FIGS. 4 and 5, a plurality of secondary batteries 1 are linearly connected. The secondary battery 1 has a plate tab 2 interposed therebetween and is connected via the plate tab 2. The plate tab 2 is connected to the sealing plate 4 of one of the secondary batteries 1 and the outer can 3 of the other secondary battery 1, and connects the vertically adjacent secondary batteries 1 in series and linearly connects them. I do.
[0022]
The dish tab 2 is made of a metal plate. The dish tab 2 in the figure includes an outer can connecting portion 2B connected to the outer can 3 of one of the secondary batteries 1 and a sealing plate connecting portion 2A connected to the outer surface of the sealing plate 4. The dish tab 2 composed of the outer can connecting portion 2B and the sealing plate connecting portion 2A is manufactured by pressing a single metal plate. The outer can connecting portion 2B is a cylindrical shape into which the bottom of the outer can 3 can be inserted. Since the secondary battery 1 in the figure is a cylindrical battery, the outer can connecting portion 2B has a cylindrical shape. The sealing plate connecting portion 2A has a central hole 2a through which the convex electrode 1a passes. Further, the sealing plate connecting portion 2A is provided with a protruding connecting portion 2b connected to the sealing plate 4. The sealing plate connecting portion 2A is provided with a step 2c on the outer periphery of the projecting connecting portion 2b so as not to contact the caulking portion 3a of the outer can 3. The outer shape of the projecting connecting portion 2b provided inside the step portion 2c is smaller than the inner shape of the caulking portion 3a so that the sealing plate connecting portion 2A and the caulking portion 3a do not come into contact with each other. The dish tab 2 is connected to the secondary battery 1 by spot welding the outer can connecting portion 2B and the sealing plate connecting portion 2A. However, the plate tab can be connected to the secondary battery 1 by laser welding.
[0023]
The secondary battery 1 is a cylindrical battery. However, the assembled battery of the present invention does not necessarily specify a secondary battery as a cylindrical battery. The secondary battery can be any battery in which the sealing plate is fixed by caulking the outer can. The secondary battery 1 is a nickel-hydrogen battery. However, the assembled battery of the present invention can be any type of secondary battery such as a nickel-cadmium battery or a lithium ion battery as the secondary battery.
[0024]
In the secondary battery 1 shown in the figure, an opening of a metal outer can 3 filled with an electrode group 5 and an electrolytic solution is caulked to fix a metal plate sealing plate 4 in an insulated state in an airtight manner. The outer can 3 is manufactured by pressing a metal plate into a tubular shape having a closed bottom. In the cylindrical battery, a metal plate is formed into a cylindrical shape to form an outer can 3. In a prismatic battery, a metal plate is formed into a rectangular tube shape to form an outer can. The sealing plate 4 is manufactured by pressing or casting a metal plate. The outer can 3 and the sealing plate 4 are caulked in an insulated state. An insulating material 6 is sandwiched between the outer can 3 and the sealing plate 4 for insulation. The insulating material 6 hermetically closes the gap while insulating the outer can 3 from the sealing plate 4. The outer can 3 is provided with a ridge 7 along the lower surface of the sealing plate 4 in order to fix the sealing plate 4 with the caulking portion 3a therebetween. The sealing plate 4 is set on the outer can 3 provided with the ridges 7 and the opening edge is caulked to fix the sealing plate 4. Thereafter, the caulked portion 3a is pressed from above by a punch, and the overall dimensions of the outer can 3 are set to a specified value.
[0025]
In the illustrated secondary battery 1, a current collector 8 is disposed on an electrode 5 A placed inside an outer can 3. The electrode 5A is formed by laminating positive and negative electrode plates while insulating them with a spacer interposed therebetween. One electrode of the electrode 5A is connected to a current collector 8 disposed on the electrode 5A, and the other electrode is connected to a current collector (not shown) disposed on the bottom of the outer can 3. Is connected to the outer can 3 via the external can. The current collector 8 arranged on the electrode 5A is connected to the sealing plate 4 via the electrode lead 9. The current collector disposed under the electrode 5A is connected to the outer can 3 by a method such as spot welding or laser welding on the bottom and side surfaces inside the outer can 3, or is pressed against the inner surface of the outer can 3 to generate electricity. Connected.
[0026]
As shown in FIG. 6, the assembled battery connects a plurality of secondary batteries 1 in series while connecting them linearly. As shown in FIG. 7, the assembled battery having this structure is used as a power supply device for driving an electric vehicle, a hybrid car, or the like by further connecting a plurality of sets in series. The power supply device used in the power supply device of the hybrid car is one in which 100 or more secondary batteries 1 are connected in series.
[0027]
In the secondary battery 1 constituting the battery pack shown in FIGS. 4 and 5, the entire sealing plate 4 is not made of the same thickness of the metal plate. The sealing plate 4 has a thinner peripheral portion 4 A sandwiched between the caulked portions 3 a of the outer can 3, and a thicker connecting portion of the dish tab 2. That is, the sealing plate 4 is provided inside the outer peripheral portion 4A of the outer can 3 between the caulked portion 3a and the non-clamped portion 4B that is not sandwiched between the caulked portions 3a. Is provided as the thick portion 10. The thick portion 10 of the sealing plate 4 is preferably larger than 1.5 times the thickness of the peripheral portion 4A sandwiched between the caulking portions 3a. If the thickness is smaller than 1.5 times, the electric resistance of the dish tab 2 cannot be reduced sufficiently. Also, the thick portion 10 of the sealing plate 4 is preferably thinner than five times the thickness of the peripheral portion 4A sandwiched between the caulking portions 3a. If the thickness is more than five times, the outer surface protruding portion 10A protrudes from the caulked portion 3a of the secondary battery 1, or the peripheral portion 4A sandwiched between the caulked portions 3a becomes thinner.
[0028]
In the secondary battery 1 of FIG. 4, an outer surface protruding portion 10 A is provided on the non-clamping portion 4 B of the sealing plate 4, and a portion provided with the outer surface protruding portion 10 A is a thick portion 10. A plate tab 2 for connecting the secondary batteries 1 in series is connected to the outer protruding portion 10A. The dish tab 2 connects the protruding connecting portion 2b provided on the sealing plate connecting portion 2A to the outer protruding portion 10A. As shown in the drawing, the assembled battery in which the outer surface protruding portion 10A of the thick portion 10 is provided on the sealing plate 4 and the plate tab 2 is welded thereto has a metal ratio between the sealing plate 4 and the connection battery bottom portion. And the resistance between batteries is reduced. In particular, since the air portion in the conventional battery pack is made of metal, the electric resistance of the battery pack can be reduced without impairing the battery performance. In particular, this structure can reduce the total electric resistance of the assembled battery while reliably welding the dish tab 2 to the sealing plate 4. This is because the outer projection 10A to which the dish tab 2 is welded is made thicker as the thicker section 10, and the dish tab 2 can be made thinner than the thicker section 10 of the outer projection 10A. The thin plate tab 2 is reliably welded to the sealing plate 4 with a reduced reactive current during spot welding. The thin plate tab 2 has a large electric resistance, but the electric resistance can be reduced because the current path is shortened by the approaching outer projection.
[0029]
The secondary battery 1 of FIG. 5 is provided with both an outer protruding portion 10A protruding outward and an inner protruding portion 10B protruding inward on the non-clamped portion 4B of the sealing plate 4, and this portion is formed as a thick portion 10B. And That is, the sealing plate 4 is provided with the thick portion 10 protruding from both sides. An inner protrusion 10B protruding inside the battery is connected to the electrode 5A via the electrode lead 9. This structure can reduce the electric resistance of the electrode lead 9 and the internal resistance of the battery. In particular, the electrode lead 9 can be made thinner than the thick portion 10 so that the electrode lead 9 can be reliably welded to the sealing plate 4, and the electrical resistance can be reduced by shortening the electrode lead 9.
[0030]
As shown in FIG. 4, the structure in which the thick portion 10 of the sealing plate 4 is provided with only the outer protruding portion 10A and the thick portion 10 is provided without the inner protruding portion reduces the electric resistance of the dish tab 2. As a result, it is possible to prevent the internal pressure of the battery from rapidly increasing at the time of an abnormality while reducing the electric resistance in a state where the battery is assembled. This is because the electric resistance of the assembled battery can be reduced without changing the internal volume of the battery.
[0031]
【Example】
The assembled battery is manufactured by connecting the following secondary batteries 1 in series with a plate tab 2. In the following examples, the secondary battery 1 is a nickel-metal hydride battery. However, it goes without saying that the secondary battery can be a secondary battery other than a nickel-hydrogen battery.
[0032]
[Example 1]
In the nickel-hydrogen battery shown in the cross-sectional view of FIG. 8, the electrode group 5 is put in the outer can 3 and filled with the electrolytic solution. The outer can 3 is formed by press-forming a metal plate into a cylindrical shape with a closed bottom, and the opening is closed with a sealing plate 4. The outer can 3 has an opening portion caulked and the sealing plate 4 is fixed to the opening portion in an insulated state in an airtight manner.
[0033]
As shown in the perspective view of FIG. 9, the electrode group 5 has a current collector 8 connected to the electrode 5A. The electrode 5A has a nickel positive electrode plate and a hydrogen storage alloy negative electrode plate laminated via a separator. A nickel positive electrode plate is made by forming a nickel sintered porous body on the surface of an electrode core made of punched metal and then filling the nickel sintered porous body with an active material mainly composed of nickel hydroxide by a chemical impregnation method. Have been. On the other hand, the hydrogen-absorbing alloy negative electrode plate is prepared by filling the surface of an electrode plate core made of punching metal with a paste-like negative-electrode pickling material made of a hydrogen-absorbing alloy, impregnating the material, and rolling it to a predetermined thickness. Have been.
[0034]
A spiral electrode 5A is manufactured by spirally winding the nickel positive electrode plate and the hydrogen storage alloy negative electrode plate with a separator interposed therebetween. At the upper end surface of this electrode 5A, the rest of the punching metal, which is the electrode core of the nickel positive electrode plate, is exposed, and at the lower end surface, the end of the punching metal, which is the electrode core of the hydrogen storage alloy negative electrode plate. Is exposed. A disk-shaped current collector 8 having a large number of openings is welded to the positive electrode core exposed at the upper end surface of the electrode 5A, and a disk-shaped negative electrode having a large number of openings is welded to the negative electrode core exposed at the lower end surface. The current collector 8 is welded to form a spiral electrode group 5A.
[0035]
A cylindrical electrode lead 9 is connected to the spiral electrode group 5. As shown in FIGS. 9 to 12, the cylindrical body 11 serving as the electrode lead 9 is formed by using a cylindrical pipe (for example, made of nickel and having a thickness of 0.3 mm) and obliquely cutting off both ends thereof. It is formed. Reference numeral 11a is a projection for facilitating welding. The electrode lead 9 is arranged such that the bottom surface 11A of the tubular body 11 is located on the diameter of the positive electrode current collector 8. The bottom surface portion 11A of the tubular body 11, which is the electrode lead 9, is connected to the positive electrode current collector 8 by spot welding (first welding). Further, the bottom surface of the sealing plate 4 and the upper surface portion 11B of the tubular body 11, which is the electrode lead 9, are connected by welding (second welding).
[0036]
Thereafter, the opening of the outer can 3 is sealed with a sealing plate 4 and further pressurized by a punch to produce a cylindrical nickel-metal hydride storage battery having a nominal capacity of 6.0 Ah. The cylindrical body 11 of the electrode lead 9 is crushed into a substantially elliptical cross section by the pressing force of the punch.
[0037]
The sealing plate 4 made of a metal plate has a thick portion 10 as shown in FIG. The sealing plate 4 has a thick portion 10 by providing only the outer surface protruding portion 10A on a non-clamping portion 4B not caught by the caulking portion 3a. In this sealing plate 4, the thickness of the peripheral portion 4A sandwiched between the caulking portions 3a is 1 mm, the thickness of the thick portion 10 having the outer surface protruding portion 10A is 1.5 mm, and the protruding height of the outer surface protruding portion 10A. Is 0.5 mm. The sealing plate 4 is formed by pressing an electrode fitting portion 4a for fixing the projection electrode 1a and a connection portion 4b of the electrode lead 9 so as to protrude inside the battery. The connection portion 4b projects slightly below the electrode fitting portion 4a, similarly to the conventional sealing plate shown in FIG. The secondary battery 1 manufactured using the sealing plate 4 is referred to as a battery of the first embodiment.
[0038]
[Example 2]
As shown in FIG. 14, the secondary battery 1 of this embodiment is provided with an outer protruding portion 10A and an inner protruding portion 10B on a non-clamping portion 4B of a sealing plate 4 which is a metal plate to form a thick portion 10. Other than the above, it is created in the same manner as the first embodiment. The sealing plate 4 has a peripheral portion 4A sandwiched between the openings with a thickness of 1 mm, a thick portion 10 provided with the outer projecting portion 10A and the inner projecting portion 10B having a thickness of 2 mm, and a projecting height of the outer projecting portion 10A. The height is 0.5 mm, and the height of the protrusion of the inner surface protruding portion 10B is 0.5 mm. Similarly to the sealing plate 4 of the first embodiment, the sealing plate 4 is formed by pressing the electrode fitting portion 4a for fixing the convex electrode 1a and the connecting portion 4b of the electrode lead 9 so as to protrude inside the battery. are doing. In this sealing plate as well, the connecting portion 4b projects slightly below the electrode fitting portion 4a, as in the conventional sealing plate shown in FIG. A secondary battery manufactured using the sealing plate 4 is referred to as a battery of the second embodiment.
[0039]
[Comparative example]
In the secondary battery 1 of the comparative example, as shown in FIG. 15, the thickness of the metal plate of the entire sealing plate 4 is 1 mm without providing the sealing plate 4 with a thick portion. Similarly to the sealing plate 4 of the first embodiment, the sealing plate 4 is press-formed so that the electrode fitting portion 4a for fixing the convex electrode 1a and the connecting portion 4b of the electrode lead 9 project inside the battery. are doing. The electrode fitting portion 4a and the connection portion 4b have the same thickness as the peripheral portion 4A, but are not inner protrusions that are thicker than the peripheral portion 4A and protrude inward. This sealing plate 4 is formed by pressing a metal plate having the same thickness as a whole so as to project both upper and lower surfaces downward as in the first embodiment. A secondary battery manufactured using this sealing plate 4 is referred to as a battery of a comparative example.
[0040]
The values A to D of the respective parts of the batteries of Example 1, Example 2, and Comparative Example manufactured as described above have the values shown in Table 1. The dimensions of each part are shown in FIG. In this figure, A to D have the following dimensions. The unit of each dimension is mm.
A: Distance between the top end of the outer can and the top surface of the sealing plate (outer projection)
B: Distance between the lower surface of the sealing plate (thick portion) and the current collector
C: Thickness of sealing plate (thick part)
D: Distance between the current collector and the top end of the outer can
[0041]
[Table 1]

[0042]
As described above, in the batteries of Example 1, Example 2, and Comparative Example, the outer surface protruding from the upper surface of the sealing plate without changing the distance (D) between the current collector 8 and the uppermost end of the outer can without changing it to 3.9 mm. The distance (A) from the portion 10A to the battery shoulder can be reduced from 1.2 mm of the comparative battery to 0.7 mm. Thus, the batteries of Examples 1 and 2 can reduce the resistance between the batteries. This is because the protruding connecting portion 2b provided on the sealing plate connecting portion 2A of the dish tab 2 can be lowered.
[0043]
Further, in the battery of Example 2, the distance between the sealing plate 4 and the current collector 8 can be approached from 1.7 mm to 1.2 mm of the comparative battery. For this reason, the electrode lead 9 can be shortened, and the resistance inside the battery can be reduced.
[0044]
【The invention's effect】
The battery of the present invention has a feature that the electric resistance can be reduced by thickening the sealing plate without impairing the battery performance. This is because the battery of the present invention has a thick portion in a non-clamped portion that is not sandwiched between the swaged portions without increasing the peripheral portion of the sealing plate. In the battery having this structure, the sealing plate can be thickened by the thick portion, so that the electric resistance of the sealing plate can be reduced, and the overall resistance can be reduced. Further, since the sealing plate made thicker by providing a thicker portion can be strengthened, there is also a feature that deformation due to a change in internal pressure or an external impact can be effectively prevented.
[0045]
Further, the assembled battery of the present invention has a feature that the total electric resistance of the assembled battery can be reduced while securely connecting the plate tabs without impairing the battery performance. The reason is that the battery pack of the present invention has the sealing plate of the secondary battery thinned at the peripheral portion sandwiched between the caulked portions, and provided with a thickened portion by providing an outer projecting portion at a portion connecting the plate tabs. is there. The battery pack of this structure has a structure in which the secondary batteries are linearly connected by a plate tab, in which a metal / space ratio between the bottom surface of the outer can and the sealing plate is increased to reduce the electric resistance between the batteries. . In particular, this structure has a feature that the electric resistance between batteries can be reduced while ensuring that the plate tab can be reliably welded to a thickness that can be welded.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a battery connecting portion of a conventional battery pack.
FIG. 2 is a sectional view of an assembled battery obtained by modifying the assembled battery of FIG. 1;
FIG. 3 is a sectional view of a battery pack obtained by modifying the battery pack of FIG. 1;
FIG. 4 is a sectional view showing a battery connecting portion of the battery pack according to the first embodiment of the present invention.
FIG. 5 is a sectional view showing a battery connecting portion of the battery pack according to the second embodiment of the present invention.
FIG. 6 is a side view showing a state in which a plurality of batteries are linearly connected in series.
FIG. 7 is a schematic plan view showing a state in which a plurality of battery packs shown in FIG. 6 are connected in series.
FIG. 8 is a longitudinal sectional view of a battery used for the battery pack of Example 1 of the present invention.
9 is a perspective view showing an electrode group incorporated in the battery shown in FIG.
10 is a plan view of an electrode lead for connecting the electrode group shown in FIG. 9 to a sealing plate.
FIG. 11 is a front view of the electrode lead shown in FIG. 10;
FIG. 12 is a development view of the electrode lead shown in FIG. 10;
FIG. 13 is an enlarged sectional view showing a sealing plate of a battery used in the battery pack according to the first embodiment of the present invention.
FIG. 14 is an enlarged cross-sectional view showing a sealing plate of a battery used in the battery pack of Example 2 of the present invention.
FIG. 15 is an enlarged cross-sectional view showing a sealing plate of a battery that is a conventional assembled battery and that is used for an assembled battery of a comparative example.
[Explanation of symbols]
1: Battery 1a: Protruding electrode
2 ... Dish tab 2A ... Sealing plate connecting part 2B ... Outer can connecting part
2a: center hole 2b: projecting connecting portion
2c: Step
3: Exterior can 3a: Caulking section
4: sealing plate 4A: peripheral part 4B: non-clamping part
4a: electrode fitting portion 4b: connection portion
5 ... electrode group 5A ... electrode
6 ... Insulation material
7 ... ridge
8 ... current collector
9 ... Electrode lead
10: Thick portion 10A: Outer projection 10B: Inner projection
11: cylindrical body 11A: bottom part 11B: top part
11a ... projection

Claims

A battery comprising an electrode group (5) and an opening of a metal outer can (3) filled with an electrolyte, and a metal plate sealing plate (4) fixed in an airtight manner in an insulated state,
The sealing plate (4) is inside the peripheral portion (4A) sandwiched between the swaged portions (3a) of the outer can (3) and is located at the non-clamped portion (4B) not sandwiched between the swaged portions (3a). An outer projecting portion (10A) projecting toward the front surface of the battery, and a thicker portion (10) which is thicker than a peripheral portion (4A) sandwiched between the caulked portions (3a). Features battery.

The sealing plate (4) is inside the peripheral portion (4A) sandwiched between the swaged portions (3a) of the outer can (3), and is located at the non-clamped portion (4B) not sandwiched between the swaged portions (3a). An outer protrusion (10A) protruding toward the front surface of the battery (1) and an inner protrusion (10B) protruding toward the inner surface of the battery (1). 2. The device according to claim 1, further comprising a thickened portion (10) having a greater thickness, and further comprising an electrode lead (9) connected to the electrode (5A) connected to the inner surface protruding portion (10B). Battery.

The battery according to claim 2, wherein the thickness of the thick portion (10) of the sealing plate (4) is larger than that of the electrode lead (9).

A plate tab (2) is sandwiched between the secondary batteries (1), and the plurality of secondary batteries (1) are connected linearly via the plate tab (2). ) Is connected to the sealing plate (4) of one secondary battery (1) and the outer can (3) of the other secondary battery (1), and is adjacent to the plate. Secondary batteries (1) are connected in series and connected linearly,
In the secondary battery (1), the electrode group (5) and the opening of the metal outer can (3) filled with the electrolyte are caulked, and the metal plate sealing plate (4) is air-tightly fixed in an insulating state. And
The sealing plate (4) is inside the peripheral portion (4A) sandwiched between the swaged portions (3a) of the outer can (3) and is located at the non-clamped portion (4B) not sandwiched between the swaged portions (3a). An outer projection (10A) protruding from the surface of the battery (1) is provided, and a thicker portion (10) is provided which is thicker than a peripheral portion (4A) sandwiched between the caulked portions (3a). And an assembled battery in which a dish tab (2) is connected to the outer projection (10A).

The sealing plate (4) is inside the peripheral portion (4A) sandwiched between the swaged portions (3a) of the outer can (3), and is located at the non-clamped portion (4B) not sandwiched between the swaged portions (3a). An outer protrusion (10A) protruding toward the front surface of the battery (1) and an inner protrusion (10B) protruding toward the inner surface of the battery (1). The method according to claim 4, wherein the thickened portion (10) is provided, and the electrode lead (9) connected to the electrode (5A) is connected to the inner surface protruding portion (10B). Battery pack.

The assembled battery according to claim 4, wherein the thickness of the thick portion of the sealing plate is greater than the thickness of the flat plate tab.