JP4373049B2

JP4373049B2 - Storage battery

Info

Publication number: JP4373049B2
Application number: JP2002103155A
Authority: JP
Inventors: 不二夫平野; 正春宮久
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2002-04-05
Filing date: 2002-04-05
Publication date: 2009-11-25
Anticipated expiration: 2022-04-05
Also published as: JP2003297335A

Description

【０００１】
【発明の属する技術分野】
本発明は、一方極の端子を兼ねる電池ケース内に電極体が収容され、その電極体の正，負極板の何れかの端部に接続された集電体を他方の極の端子を兼ねる封口体に接続された構成を有する蓄電池に関するものである。
【０００２】
【従来の技術】
一般に、ニッケル−水素蓄電池やニッケル−カドミウム蓄電池などのアルカリ蓄電池は、正極板および負極板をこれらの間にセパレータを介在させて渦巻状に巻回してなる電極群の正極板および／または負極板の端部に集電体を接続して電極体を形成し、この電極体を電池ケース内に収納して、集電体から導出されたリード部の先端部を封口体に溶接により接続したのち、封口体を電池ケースの開口部に絶縁ガスケットを介在させて装着し、電池ケースの開口周縁部を内方にかしめ加工することによって電池ケースを密閉した構成になっている。このようなアルカリ蓄電池が電動工具や電気自動車などの高率で充放電を行う用途に使用される場合には、電池構成のなかでも特に集電体と封口体とを相互に接続するためのリード部での電気抵抗が電池特性に大きな影響を与える。すなわち、リード部での電気抵抗が大きい場合には、大電流で放電を行うと、リード部での電気抵抗に起因する大きな電圧降下が生じて、電池電圧が低下するという問題が生じる。
【０００３】
そこで、従来では、集電部品を複数枚にしてリード部を構成したり、集電部品の厚みを大きくすることにより、リード部での電気抵抗の低減を図ることが提案されている（特許第２７６２５９９号公報参照）。ところが、リード部を構成する集電部品を複数枚にした場合には、部品点数が多くなってコスト高となるだけでなく、リード部に柔軟性がなくなることから、リード部と封口体との溶接が困難となり、且つ封口体を電池ケースの開口部に挿入する際にリード部を折り曲げることが困難となり、生産性が劣るという問題が生じる。また、リード部を構成する集電部品の厚みを大きくすると、抵抗溶接するときの溶接電流に無効な電流が多くなって、封口体の溶接性が悪くなるとともに、封口体を電池ケースの開口部に挿入する際にリード部を折り曲げることが困難となり、生産性が劣るという問題が生じる。
【０００４】
一方、封口体にリード部を溶接する場合には、まず、集電体から垂直に立ち上がったリード部に封口体を接触させて、そのリード部の側面に溶接電極を押し当てながら封口体にリード部を抵抗溶接している。一般的に、厚みが大きいリード部を用いた方が、その比抵抗が小さくなって電池内部抵抗が低減する。ところが、リード部を封口体に溶接したのちに封口体を電池ケースの開口部に装着する際にはリード部を屈曲させる必要があり、この封口体を電池ケース内に好適に挿入するためには、長くて薄いリード部を用いる必要がある。ところが、リード部の抵抗はその長さに比例して断面積に反比例するため、上述の長くて薄いリード部は、その比抵抗が大きいため、このようなリード部を用いた蓄電池は電池内部抵抗の大きなものになってしまう。
【０００５】
そこで、従来では、電極体から封口体までの集電経路を短縮して電池内部抵抗を低減させる接続方法が提案されている（特開平１０−２６１３９７号公報参照）。このものは、電極体を電池ケース内に収納した後に、その電極体の集電体に溶接されたリード部に封口体下面を接触させた状態で電池ケースの開口部をかしめ加工により密閉し、そののち、電池ケースと封口体との間に電流を長すことにより、リード部と封口体との接触部分を溶接するようにしている。これにより、リード部は折り曲げる必要がないことから、短いリード部であっても、封口体を電池ケースの開口部に容易に装着することが可能となり、集電距離を短縮して電池内部抵抗を低減することができる。
【０００６】
しかし、上述のような集電体と封口体との溶接方法では、電池ケース内に収容される電極体の高さに製造ばらつきがあった場合に、封口体にリード部を確実に接触させることができない事態が生じ、安定して溶接品質の溶接を行えない課題がある。また、封口体にリード部を接触させるだけでは、溶接後の溶接点の溶接強度や溶接品質が劣り、製品歩留りが悪くなることがある。
【０００７】
上述のような問題を解消できるものとして、特開平１３−１４３６８４号公報および特開平１３−１５５７１０号公報にそれぞれ開示された蓄電池が知られている。前者の蓄電池は、図８に示すように、渦巻状に巻回した電極群５２の上下端に正極集電体５３および負極集電体５４をそれぞれ溶接して電極体５１が構成され、この電極体５１を電池ケース（図示せず）内に収納したのちに、正極集電体５３上に、筒状体５７ａと一対の羽部５７ｂとを一体に有するリード部５７を載置した状態で、一対の羽部５７ｂを正極集電体５３に溶接し、続いて、封口体（図示せず）の底面を筒状体５７ａの周側面に接触させて、封口体と電池ケースに一対の溶接電極を接触させて封口体と筒状体５７ａとの接触部分を溶接することにより、正極集電体５３と封口体とを筒状のリード部５７を介して接続した構成になっている。
【０００８】
一方、後者の蓄電池は、図９（ａ），（ｂ）の平面図および側面図に示すように、渦巻状に巻回した電極群５２の上下端に正極集電体５３および負極集電体（図示せず）をそれぞれ溶接して電極体５１が構成され、この電極体５１を電池ケース（図示せず）内に収納したのちに、正極集電体５３と封口体（図示せず）とが、長さ方向の中央部が凹んだ鼓状筒体５９からなるリード部５８により相互に接続された構成になっている。リード部５８は、鼓状筒体５９の上下端部に幅広部６０ａ，６１ａと幅狭部６０ｂ，６１ｂとが交互に形成された鍔部６０，６１を備えており、幅広部６０ａと幅狭部６１ｂは空間を隔てて互いに重なりあい、幅狭部６０ｂと幅広部６１ａは空間を隔てて互いに重なりあうように配設されている。
【０００９】
前者の蓄電池では、リード部５７が中空部を有する筒状体５７ａからなるので、電池として機能したときの電流が筒状体５７ａの周側壁に沿って２経路に分かれて流れるため、一般的な１枚の短冊状のリード板を用いた場合に比較してリード部５７での電圧降下を半分に低減させることが可能であるから、リード部５７の筒状体５７ａの厚みを大きくする必要がない利点がある。一方、後者の蓄電池では、リード部５８の断面積（筒体の円周の長さ×筒体の基材の厚み）が大きくなるとともに、リード部５８の長さも短くできるので、リード部５８での電気抵抗が低減する利点がある。
【００１０】
【発明が解決しようとする課題】
しかしながら、上述の何れの蓄電池においても、リード部５７，５８が筒状であって、この筒状のリード部５７，５８を横置き配置または縦置き配置で正極集電体５３と封口体との間に介在させているため、このリード部５７，５８と封口体および集電体５３とが何れも線接触となり、例えば抵抗溶接を行うに際して均一に抵抗発熱させることが困難となるだけでなく、リード部５７，５８と封口体とを十分に加圧接触させることが困難であるから、溶融した金属が飛散する現象である、所謂「溶接ちり」が発生して、これが電池を短絡させる原因となるおそれがある。また、集電体５３を電極群５２に抵抗溶接するに際して、電極群５２を通じて溶接電流を流す場合には電極群５２の製造ばらつきに起因して溶接電流が不安定となり易い。そのため、上記構成の蓄電池では、特にリード部５７と封口体とを常に安定した溶接品質を維持しながら溶接するのが困難である。さらに、正極集電体５３とリード部５７，５８との溶接時には、電極群５２が熱的ダメージを受けるおそれがある。
【００１１】
そこで、本発明は、上記従来の課題に鑑みてなされたもので、リード部材を集電体および封口体に対し常に安定した溶接品質を確保しながら溶接することができるとともに、電池内部抵抗を低減できる構成を備えた蓄電池を提供することを目的とするものである。
【００１２】
【課題を解決するための手段】
上記目的を達成するために、本発明に係る蓄電池は、一方極を兼ねる有底筒状の電池ケースと、正極板と負極板とがこれらの間にセパレータを介在して積層された電極群の少なくとも一方の端部に集電体が接続されて、前記電池ケース内に収容された電極体と、前記電池ケースの開口部を絶縁ガスケットを介在して密閉する他方極を兼ねる封口体と、前記集電体と前記封口体とをこれらの間に介在されて相互に接続するリード部材とを備えてなり、前記リード部材が、前記封口体に溶接により接続される平板部と、この平板部の対向両側から同一方向に延び、中間部に内方への屈曲部を有するく字状の断面形状となった一対の側面部と、この両側面部の先端部からそれぞれ内方に突出されて前記集電体に溶接により接続された複数の接続突片とを一体に備えて、略矩形状の断面形状を有している蓄電池であって、前記リード部材は、一対の側面部の先端部から内側の直交方向にそれぞれ屈曲形成された一対の支持突片と、この各支持突片の両端部分と接続突片との間に設けられて前記接続突片を前記支持突片に対し内方側に凹んだ配置で突設させる段差部とを有し、前記集電体は、中央部に設けられた注液孔と、この注液孔の対向両側から前記リード部材側に前記段差部の高さと同一高さに膨れ出るよう屈曲形成された一対の膨出受部とを有し、前記一対の膨出受部の各々の両側に２つずつの前記接続突片が嵌合状態に重ね合わされて相互に溶接されていることを特徴としている。
【００１３】
この蓄電池では、リード部の複数の接続突片と集電体とが面接触で溶接され、且つ封口体とリード部の平板部とが面接触で溶接され、しかも、リード部材と封口体との溶接時には、封口体に加えられる押圧力により、リード部材の側面部の屈曲部が僅かに屈曲する状態に弾性変形するので、この側面部の弾性変形による復元力によってリード部材の平板部が封口体に押し付けられて面接触で確実に密接されるから、その溶接部には常に安定した溶接品質を確保することができる。また、電池として機能したときの通電電流が、集電体から封口体に向けてリード部材の両側面部に沿った２経路に分かれて流れるから、電流の通電経路が短くなってリード部材での電圧降下が小さくなり、電池内部抵抗が著しく低減されて、高率放電性能に優れたものとなる。しかも、この蓄電池は、リード部材を厚みの小さな基材で形成できるから、電池ケースの開口周縁部のかしめ加工を容易に行うことができ、製造が容易となる。また、この蓄電池は、振動や衝撃が加わったときに、これらによる外部圧力を、リード部材の弾性を有する側面部の僅かな弾性変形によって吸収することができ、耐振性に優れて信頼性が向上する。
【００１４】
【００１５】
また上記構成によれば、集電体を電極群に例えば抵抗溶接した際に集電体に変形が生じた場合であっても、膨出受部は、屈曲形成されて変形の生じ難い状態に設けられているから、元の形状を確実に保持し続ける。一方、各接続突片は、支持突片から段差部を介し突設されて、変形可能な弾力性を有しているから、リード部材が集電体に押し付けられたときに、各接続突片は自体の僅かな変形を伴いながら膨出受部に確実に密接される。このように、４つの接続突片は２つの膨出受部に対し面接触で確実に密接するので、リード部材と集電体との溶接部には良好で安定した溶接品質を常に確保することができる。
【００１６】
上記発明において、封口体は、電池ケースの開口部を封口する蓋板と、この蓋板の中央部に固着されて他方極の外部端子となるキャップと、前記蓋板とキャップとで囲まれた内部空間に収容された弁体とを有し、前記蓋板とリード部材とが、前記キャップの溶接用切欠きを通じてレーザ溶接または電子ビーム溶接によって相互に接続固着されている構成とすることが好ましい。この構成によれば、封口体の蓋板とリード部材とをレーザ溶接または電子ビーム溶接によって相互に接続固着するので、抵抗溶接のような「溶接ちり」が発生するおそれがない。
【００１７】
上記発明において、リード部材は、電池ケースの開口周縁部の内方へのかしめ加工時に電池ケースの内方側へ押し込められる封口体から加圧力を受けて一対の側面部の屈曲部が屈曲する状態に弾性変形されている構成とすることができる。この構成によれば、リード部材の弾性変形による復元力により、リード部材と集電体および封口体との接続状態を、外部圧力を受けた場合にも安定に保持し続けることができる。
【００１８】
【００１９】
【００２０】
【００２１】
【００２２】
【発明の実施の形態】
以下、本発明の好ましい実施の形態について、図面を参照しながら製造工程順に説明する。図１は本発明の一実施の形態に係る蓄電池における電極体１とリード部材２を示す分解斜視図、図２（ａ），（ｂ）はそれぞれ同蓄電池における電極体１を電池ケース３内に収納して固定した状態を示す平面図および縦断面図である。電極体１は、図２（ｂ）に示すように、正極板４と負極板７とをこれらの間にセパレータ８を介在させて渦巻状に巻回してなる電極群９の上下端面に正極集電体１０および負極集電体１１をそれぞれ溶接により取り付けて構成されている。正極集電体１０および負極集電体１１は、電極群９の上端面および下端面にそれぞれ露出された正，負極板４，７の正，負極芯体に溶接されている。リード部材２は、電極体１と後述の封口体との間に介在されて、これらを溶接によって相互に接続するためのものである。このリード部材２の詳細については後述する。
【００２３】
正極集電体１０は、図１に示すように、電極群９の端面形状に対応した円板状の本体平板部１２の中央部に矩形状の注液孔１３が穿設され、その注液孔１３の近傍箇所から外周縁に達する長方形状の６つの切欠き部１４が互いに等間隔で放射状の配置で形成されている。各切欠き部１４の相対向する縁部には、一方向（図の下方向）に折り曲げられることにより、リブ状突起片１７がそれぞれ形成されている。
【００２４】
前記正極集電体１０を電極群９に溶接するに際しては、正極集電体１０を、これのリブ状突起片１７を電極群９に対向させて電極群９の端面上に載置し、一対の溶接電極を本体平板部１２における切欠き部１４を挟んだ両側箇所に当てがって通電することにより行われる。この溶接時、リブ状突起片１７より外側の本体平板部１２に流れる溶接電流は少なく、溶接電流の多くはリブ状突起片１７に集中するので、リブ状突起片１７と正極板４の上端部に露出された正極芯体とが交又する各点でリブ状突起片１７が正極芯体に食い込んだ状態で溶融して、この部分は強く溶着される。これにより、蓄電池としたときには、内部抵抗が低くなって大電流を取り出すことが可能となり、放電容量も高くなる効果が得られる。
【００２５】
また、前記正極集電体１０は、矩形状の注液孔１３の相対向する２辺に、長方形状に上方へ膨れ出た一対の膨出受部１８が屈曲形成されている。この一対の膨出受部１８には、図１に矢印で示すように、リード部材２の４つの接続突片２８が重ね合わせた状態で溶接されるようになっているが、このリード部材２の正極集電体１０への溶接は、電極体１を電池ケース３内に収納して固定した状態としたのちに行われる。
【００２６】
すなわち、上述した渦巻状電極群９の両端面に正，負極集電体１０，１１が溶接して構成された電極体１は、正極を兼ねる有底円筒状の金属製の電池ケース３内に収納され、そののち、一方の溶接電極を、正極集電体１０の注液孔１３から電極群９の中央部の空間部に通して負極集電体１１に押し当て、他方の溶接電極を電池ケース３の外面に押し当てて通電することにより、負極集電体１１が電池ケース３の底面にスポット溶接される。続いて、図２（ｂ）に示すように、絶縁リング１９が電池ケース３の内周面に嵌め入れられて正極集電体１０上に載置される。この状態で、電池ケース３には、その外周面に溝入れ加工が施されて、絶縁リング１９の上方近傍箇所に環状溝２０が形成される。これにより、電極体１は、環状溝２０の形成により電池ケース３の内方に膨出形成された環状支持部２１により、絶縁リング１９を介して電池ケース３内に固定される。
【００２７】
ここで、上記リード部材２について説明する。このリード部材２は、図１に示すように、後述の封口体に接続するための平板部２２と、この平板部２２の対向両辺からそれぞれ同一の直交方向に屈曲形成された一対の側面部２３と、この両側面部２３からそれぞれ内側の直交方向に向けて屈曲形成された一対の支持突片２４と、この両支持突片２４の各々の両端部分からそれぞれ段差部２７を介して前記支持突片２４に対し内方に凹んだ配置で一体に突設された計４つの接続突片２８とを有して、断面形状が略長方形に形成されている。前記段差部２７は、前記正極集電体１０の膨出受部１８と同一高さｈに設定されている。また、両側面部２３は、中央部に屈曲部２３ａが設けられて、内方へくびれた断面く字形状に形成されて、上下方向に変形可能な弾性を有している。両側に２つずつ配設された接続突片２８は、各々の先端部がそれぞれ間隙を存して相対向している。平板部２２の中央部にはガス抜き孔２９が穿設されている。
【００２８】
図２に示すように電極体１が電池ケース３内に収納して固定されたならば、図３および図４に示すように、電池ケース３内の電極体１における正極集電体１０に前記リード部材２が溶接により固着される。この溶接に際しては、図１に矢印で示すように、リード部材２の左右一対ずつの接続突片２８を正極集電体１０の２つの膨出受部１８の各々の両端部分に上方からそれぞれ嵌め込むようにして、左右両側の支持突片２４を正極集電体１０の本体平板部１２上に載置する。つぎに、リード部材２に正極集電体１０に向け押圧力を付与した状態で、図４（ａ）に示す４つの接続突片２８の外面に形成された溶接用突起３０に、ガス抜き孔２９を通じてレーザ光を照射してレーザ溶接を行う。これにより、リード部材２は、４つの接続突片２８が２つの膨出受部１８にそれぞれ溶接されることにより、正極集電体１０に電気的接続状態で固着される。
【００２９】
上記リード部材２を正極集電体１０にレーザ溶接する際には、４つの接続突片２８が２つの膨出受部１８に確実に密接している。すなわち、上述の正極集電体１０を電極群９に抵抗溶接した際に本体平板部１２に変形が生じた場合であっても、膨出受部１８は、本体平板部１２に対し上方へ膨出する配置に屈曲形成されて変形の生じ難い状態に設けられているから、元の形状を確実に保持し続ける。一方、各接続突片２８は、支持突片２４から段差部２７を介し突設されて、変形可能な弾力性を有しているから、リード部材２が正極集電体１０上に押し付けられたときに、各接続突片２８は自体の僅かな変形を伴いながら膨出受部１８に確実に密接される。このように、４つの接続突片２８は２つの膨出受部１８に対し面接触で確実に密接するので、リード部材２と正極集電体１０との溶接部には良好で安定した溶接品質を常に確保することができる。
【００３０】
しかも、膨出受部１８は、本体平板部１２が溶接されている電極群９の端面から段差部２７の高さｈ分だけ離間しているので、上記レーザ溶接時にレーザ光が接続突片２８および膨出受部１８を貫通するといった事態が万一生じた場合であっても、電極群９に熱的ダメージを与えるといった不具合の発生が防止される。なお、リード部材２と正極集電体１０とは、上記レーザ溶接に代えて、抵抗溶接またはビーム溶接によって相互に固着してもよく、その場合にも、上述したレーザ溶接の場合の効果とほぼ同様の効果を得ることができる。
【００３１】
このようにして電池ケース３内に収納固定されている電極体１に対しリード部材２が溶接により電気的接続状態に取り付けられたならば、続いて、所要量の電解液が、リード部材２のガス抜き孔２９および正極集電体１０の注液孔１３を通じて電極体１の中央の空間部分に注入される。そののち、図５および図６に示すように、封口体３１が、その周縁に絶縁ガスケット３２を嵌着させた配置で、リード部材２に対し溶接により電気的接続状態に取り付けられる。
【００３２】
前記封口体３１は、電池ケース３の開口部を封口するための蓋板３３と、この蓋板３３の上面に溶接により固着されて正極外部端子となる正極キャップ３４と、蓋板３３と正極キャップ３４とで囲まれた弁室内に収容された弁体３７とを備えて構成されている。蓋板３３の中央部には、ガスを前記弁室内に導入するためのガス導入孔３８が穿設されており、正極キャップ３４には、３個のガス排出用切欠き３９と、この各ガス排出用切欠き３９に連通して外周縁まで延びる溶接用切欠き４０とが形成されている。
【００３３】
上記封口体３１をリード部材２に溶接するに際しては、封口体３１が、その周縁に絶縁ガスケット３２を嵌着させた配置で電池ケース３内に開口部から挿入されてリード部材２上に載置され、その封口体３１に対しリード部材２に向けた方向に押圧力を付与した状態で、正極キャップ３４の各溶接用切欠き４０内を通してレーザ光を蓋板３３に照射することにより、封口体３１側からこの封口体３１の蓋板３３とリード部材２の平板部２２とをレーザ溶接する。
【００３４】
上記レーザ溶接時には、封口体３１に加えられる押圧力により、リード部材２が、これの両側の側面部２３の屈曲部２３ａが僅かに屈曲する状態に弾性変形されて、この側面部２３の弾性変形による復元力によってリード部材２の平板部２２が封口体３１の蓋板３３に押し付けられて面接触で確実に密接される。この互いに面接触で密接された平板部２２と蓋板３３とがレーザ溶接されるので、その溶接部には常に安定した溶接品質を確保することができる。なお、上記レーザ溶接に代えて、ビーム溶接を行ってもよく、その場合においても、上記レーザ溶接の場合と同様の効果を得ることができる。
【００３５】
さらに、上記実施の形態の蓄電池では、リード部材２の平板部２２と封口体３１の蓋板３３とを抵抗溶接しても、従来の蓄電池におけるリード部と封口体との溶接時に発生した「溶接ちり」が生じない。すなわち、抵抗溶接は、溶接点に電流を流すことによって溶接点の接触部分の金属をジュール熱により溶融させて相互に接合するので、溶接すべき双方の金属が溶接点で密接されていないと、溶融した金属が飛散する現象である、所謂「溶接ちり」が発生する。図８および図９に示した従来の蓄電池では、リード部５７，５８と封口体とが線接触であるとともに、リード部５７，５８がいずれも筒状であって弾性を有していないことから、相互に確実な密接状態となり難いので、上記「溶接ちり」が発生し易い。
【００３６】
これに対し、この実施の形態の蓄電池では、上述したように、溶接すべきリード部材２の平板部２２と封口体３１の蓋板３３とを面接触で確実な密接状態とすることができるので、「溶接ちり」の発生を招くことなく抵抗溶接でき、強い溶接強度を有する良好な溶接品質の溶接部を確実に形成することができる。これは、上述したリード部材２を正極集電体１０に抵抗溶接する場合においても同様であり、膨出受部１８と接続突片２８とを確実に密接させることができるから、「溶接ちり」が生じることがない。
【００３７】
最後に、図７に示すように、電池ケース３の開口周縁部が内方にかしめ加工される。このかしめ加工時には、電池ケース３における内方に折り曲げられる開口縁部により、封口体３１が絶縁ガスケット３２を介して環状支持部２１上に押し付けられる状態となるまで押し込められ、リード部材２は、上述の電池ケース３の内方に押し込められる封口体３１により加圧されることにより、両側面部２３の屈曲部２３ａが内方に屈曲されて、高さが低くなる。これにより、封口体３１は、電池ケース３における内方に折り曲げられた開口周縁部と環状支持部２１との間にかしめ固定され、且つ圧縮された絶縁ガスケット３２によって電池ケース３の開口部が密閉されて、所要の蓄電池が出来上がる。この蓄電池では、リード部材２のかしめ加工時の弾性変形による復元力により、リード部材２と正極集電体１０および封口体３１との接続状態を、外部圧力を受けた場合にも安定に保持し続けることができるものとなる。
【００３８】
また、この実施の形態の蓄電池では、封口体３１を電池ケース３内に挿入したのちに、封口体３１とリード部材２との溶接工程に先立って、電池ケース３の開口周縁部をかしめ加工するように工程を変更しても、封口体３１とリード部材２との溶接部に良好な溶接品質を常に確保することが可能である。すなわち、リード部材２は、電池ケース３の開口縁部がかしめ加工されることによって両側面部２３の屈曲部２３ａが弾性変形されるから、その両側面部２３の復元力によって平板部２２が封口体３１の蓋板３３に押し付けられて密接する。そのため、封口体３１側から封口体３１とリード部材２とをレーザ溶接またはビーム溶接する際には、封口体３１に対しリード部材２に向けた押圧力を付与しなくてもよいから、溶接作業が容易になるとともに、その溶接部には常に安定した溶接品質を確保することができる。
【００３９】
この実施の形態の蓄電池は、電池として機能したときの通電電流が、正極集電体１０から封口体３１に向けてリード部材２の両側面部２３に沿った２経路に分かれて流れるから、正極集電体１０と封口体３１との間の集電距離はリード部材２の一方の側面部２３の長さとなり、リード部材２での電圧降下をほぼ半分に低減させることが可能となる。このため、リード部材２は、厚みの小さな金属板を用いて形成しても、その断面積が両方の側面部２３の和の比較的大きな値となり、さらに、側面部２３の高さは正極集電体１０と封口体３１との配設間隔よりも僅かに大きくすれば足りるから、電流の通電経路も短くなる。これにより、上記蓄電池は、リード部材２での電圧降下が小さくなることから、電池内部抵抗が著しく低減されて、高率放電性能に優れたものとなる。しかも、上記蓄電池は、リード部材２を厚みの小さな基材で形成できるから、電池ケース３の開口周縁部のかしめ加工を容易に行うことができ、製造が容易となる。
【００４０】
また、上記蓄電池は、振動や衝撃が加わったときに、これらによる外部圧力を、リード部材２の弾性を有する側面部２３および接続突片２８の僅かな弾性変形によって吸収することができ、耐振性に優れた信頼性の高いものとなる。
【００４１】
【発明の効果】
以上のように、本発明の蓄電池によれば、リード部の複数の接続突片と集電体とが面接触で溶接され、且つ封口体とリード部の平板部とが面接触で溶接され、しかも、リード部材と封口体との溶接時には、封口体に加えられる押圧力により、リード部材の側面部の屈曲部が僅かに屈曲する状態に弾性変形するので、この側面部の弾性変形による復元力によってリード部材の平板部が封口体に押し付けられて面接触で確実に密接されるから、その溶接部には常に安定した溶接品質を確保することができる。また、電池として機能したときの通電電流が、集電体から封口体に向けてリード部材の両側面部に沿った２経路に分かれて流れるから、電流の通電経路が短くなってリード部材での電圧降下が小さくなり、電池内部抵抗が著しく低減されて、高率放電性能に優れたものとなる。しかも、この蓄電池は、リード部材を厚みの小さな基材で形成できるから、電池ケースの開口周縁部のかしめ加工を容易に行うことができ、製造が容易となる。また、この蓄電池は、振動や衝撃が加わったときに、これらによる外部圧力を、リード部材の弾性を有する側面部の僅かな弾性変形によって吸収することができ、耐振性に優れて信頼性が向上する。
【００４２】
【図面の簡単な説明】
【図１】本発明の一実施の形態に係る蓄電池における電極体とリード部材を示す分解斜視図。
【図２】（ａ），（ｂ）は同上の蓄電池における電極体を電池ケース内に収納して固定した状態の平面図および縦断面図。
【図３】同上の蓄電池における電極体にリード部材を取り付けた状態の斜視図。
【図４】（ａ），（ｂ）は同上の蓄電池における電池ケース内に収納して固定した電極体にリード部材を取り付けた状態を示す平面図および縦断面図。
【図５】同上の蓄電池におけるリード部を取り付けた電極群と封口体とを示す分解斜視図。
【図６】（ａ），（ｂ）は同上の蓄電池における電池ケースの開口縁部をかしめ加工する前の状態を示す平面図および縦断面図。
【図７】（ａ），（ｂ）は同上の蓄電池の完成状態を示す平面図および縦断面図。
【図８】従来の蓄電池における電極体とリード部を示す斜視図。
【図９】（ａ），（ｂ）は従来の他の蓄電池における電極体の正極集電体上にリード部を接続した状態の平面図および側面図。
【符号の説明】
１電極体
２リード部材
３電池ケース
４正極板
７負極板
８セパレータ
９電極群
１０正極集電体（集電体）
１３注液孔
１８膨出受部
２２平板部
２３側面部
２３ａ屈曲部
２７段差部
２８接続突片
３１封口体
３２絶縁ガスケット
３３蓋板
３４正極キャップ（キャップ）
３７弁体
４０溶接用切欠き[0001]
BACKGROUND OF THE INVENTION
According to the present invention, an electrode body is housed in a battery case that also serves as a terminal of one electrode, and a current collector that is connected to either end of the positive or negative electrode plate serves as a terminal of the other electrode Having a configuration connected to the body Storage battery It is about.
[0002]
[Prior art]
In general, alkaline storage batteries such as nickel-hydrogen storage batteries and nickel-cadmium storage batteries have a positive electrode plate and / or a negative electrode plate of an electrode group in which a positive electrode plate and a negative electrode plate are spirally wound with a separator interposed therebetween. After connecting the current collector to the end to form an electrode body, housing this electrode body in the battery case, and connecting the tip of the lead portion led out from the current collector to the sealing body by welding, The battery case is hermetically sealed by attaching a sealing body to the opening of the battery case with an insulating gasket interposed therebetween and caulking the opening peripheral edge of the battery case inward. When such an alkaline storage battery is used for applications such as electric tools and electric vehicles that charge and discharge at a high rate, a lead for connecting the current collector and the sealing body particularly to each other in the battery configuration. The electric resistance in the area has a great influence on the battery characteristics. That is, when the electrical resistance at the lead portion is large, discharging with a large current causes a large voltage drop due to the electrical resistance at the lead portion, resulting in a problem that the battery voltage decreases.
[0003]
Therefore, conventionally, it has been proposed to reduce the electrical resistance at the lead portion by forming a lead portion by using a plurality of current collecting components or by increasing the thickness of the current collecting component (Patent No. 1). No. 2762599). However, when the current collecting parts constituting the lead part are plural, not only the number of parts is increased and the cost is increased, but also the lead part becomes inflexible. Welding becomes difficult, and it becomes difficult to bend the lead portion when the sealing body is inserted into the opening of the battery case, resulting in poor productivity. Further, if the thickness of the current collecting parts constituting the lead portion is increased, an invalid current is increased in the welding current when resistance welding is performed, and the weldability of the sealing body is deteriorated. It becomes difficult to bend the lead portion when inserting into the cable, resulting in poor productivity.
[0004]
On the other hand, when welding the lead portion to the sealing body, first, the sealing body is brought into contact with the lead portion that stands vertically from the current collector, and the lead is applied to the sealing body while pressing the welding electrode against the side surface of the lead portion. The part is resistance welded. In general, the use of a lead portion having a large thickness reduces the specific resistance and reduces the battery internal resistance. However, after the lead part is welded to the sealing body, it is necessary to bend the lead part when the sealing body is attached to the opening of the battery case. In order to insert this sealing body into the battery case suitably It is necessary to use a long and thin lead part. However, since the resistance of the lead portion is proportional to the length and inversely proportional to the cross-sectional area, the long and thin lead portion has a large specific resistance. Therefore, a storage battery using such a lead portion has a battery internal resistance. It will be a big thing.
[0005]
Therefore, conventionally, a connection method has been proposed in which the current collecting path from the electrode body to the sealing body is shortened to reduce the internal resistance of the battery (see JP-A-10-261397). In this case, after the electrode body is stored in the battery case, the opening of the battery case is sealed by caulking while the lower surface of the sealing body is in contact with the lead portion welded to the current collector of the electrode body, After that, the contact portion between the lead portion and the sealing body is welded by increasing the current between the battery case and the sealing body. As a result, it is not necessary to bend the lead part, so even with a short lead part, it is possible to easily attach the sealing body to the opening of the battery case, shortening the current collection distance and reducing the battery internal resistance. Can be reduced.
[0006]
However, in the above-described welding method between the current collector and the sealing body, when there is a manufacturing variation in the height of the electrode body accommodated in the battery case, the lead portion is reliably brought into contact with the sealing body. There is a problem that it is impossible to perform welding with stable welding quality. Moreover, if the lead part is merely brought into contact with the sealing body, the weld strength and weld quality at the weld point after welding may be inferior, and the product yield may be deteriorated.
[0007]
Storage batteries disclosed in Japanese Patent Application Laid-Open Nos. 13-143684 and 13-155710 are known to solve the above-described problems. In the former storage battery, as shown in FIG. 8, a positive electrode current collector 53 and a negative electrode current collector 54 are welded to upper and lower ends of an electrode group 52 wound in a spiral shape to form an electrode body 51. After the body 51 is housed in a battery case (not shown), the lead portion 57 integrally including the cylindrical body 57a and the pair of wing portions 57b is placed on the positive electrode current collector 53. The pair of wings 57b are welded to the positive electrode current collector 53, and then the bottom surface of the sealing body (not shown) is brought into contact with the peripheral side surface of the cylindrical body 57a, so that the pair of welding electrodes are connected to the sealing body and the battery case. The positive electrode current collector 53 and the sealing body are connected via the cylindrical lead part 57 by welding the contact portion between the sealing body and the cylindrical body 57a.
[0008]
On the other hand, as shown in the plan view and the side view of FIGS. 9A and 9B, the latter storage battery has a positive electrode current collector 53 and a negative electrode current collector at the upper and lower ends of the spirally wound electrode group 52. (Not shown) are each welded to form an electrode body 51. After this electrode body 51 is housed in a battery case (not shown), a positive electrode current collector 53 and a sealing body (not shown) However, they are configured to be connected to each other by a lead portion 58 formed of a drum-shaped cylindrical body 59 whose central portion in the length direction is recessed. The lead portion 58 includes flange portions 60 and 61 in which wide portions 60a and 61a and narrow portions 60b and 61b are alternately formed at the upper and lower end portions of the drum-shaped cylinder 59, and the wide portion 60a and the narrow portion are narrow. The portion 61b is disposed so as to overlap each other with a space therebetween, and the narrow portion 60b and the wide portion 61a are disposed so as to overlap each other with a space therebetween.
[0009]
In the former storage battery, since the lead portion 57 is formed of a cylindrical body 57a having a hollow portion, the current when functioning as a battery flows in two paths along the peripheral side wall of the cylindrical body 57a. Since the voltage drop at the lead portion 57 can be reduced by half compared to the case of using a single strip-shaped lead plate, it is necessary to increase the thickness of the cylindrical body 57a of the lead portion 57. There are no advantages. On the other hand, in the latter storage battery, the cross-sectional area of the lead portion 58 (the circumferential length of the cylindrical body × the thickness of the base material of the cylindrical body) is increased, and the length of the lead portion 58 can be shortened. There is an advantage that the electrical resistance is reduced.
[0010]
[Problems to be solved by the invention]
However, in any of the above-described storage batteries, the lead portions 57 and 58 are cylindrical, and the cylindrical lead portions 57 and 58 are arranged horizontally or vertically, so that the positive electrode current collector 53 and the sealing body are arranged. Since the lead portions 57 and 58 and the sealing body and the current collector 53 are both in line contact with each other, for example, it is difficult to uniformly generate heat when resistance welding is performed. Since it is difficult to bring the lead portions 57 and 58 and the sealing body into sufficient pressure contact, so-called “welding dust”, which is a phenomenon in which molten metal scatters, occurs, which causes a short circuit of the battery. There is a risk. Further, when the current collector 53 is resistance-welded to the electrode group 52, when a welding current is passed through the electrode group 52, the welding current tends to become unstable due to manufacturing variations of the electrode group 52. Therefore, in the storage battery having the above configuration, it is particularly difficult to weld the lead portion 57 and the sealing body while always maintaining stable welding quality. Furthermore, when the positive electrode current collector 53 and the lead portions 57 and 58 are welded, the electrode group 52 may be thermally damaged.
[0011]
Therefore, the present invention has been made in view of the above-described conventional problems. The lead member can be welded to the current collector and the sealing body while always ensuring stable welding quality, and the internal resistance of the battery is reduced. It has a configuration that can Storage battery Is intended to provide.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a storage battery according to the present invention comprises a bottomed cylindrical battery case that also serves as one electrode, and an electrode group in which a positive electrode plate and a negative electrode plate are stacked with a separator interposed therebetween. A current collector is connected to at least one end, an electrode body housed in the battery case, a sealing body serving also as the other electrode that seals the opening of the battery case with an insulating gasket interposed therebetween, A lead member that is interposed between and connected to the current collector and the sealing body, and the lead member is connected to the sealing body by welding; and A pair of side surfaces extending in the same direction from opposite sides and having an inwardly bent portion in the middle and having a cross-sectional shape in the shape of a cross, and projecting inwardly from the front end portions of the both side surfaces, respectively. Multiple connection protrusions connected by welding to the electrical body The provided integrally has a substantially rectangular cross-section In the storage battery, the lead member includes a pair of support protrusions that are bent in the orthogonal direction inside from the front ends of the pair of side surface portions, and between the end portions of the support protrusions and the connection protrusions. And the step of projecting the connection projecting piece in an inwardly recessed arrangement with respect to the support projecting piece, and the current collector has a liquid injection hole provided in the center part, A pair of bulge receiving portions that are bent so as to bulge to the same height as the stepped portion from the opposite sides of the liquid injection hole to the lead member side, and each of the pair of bulge receiving portions Two connecting protrusions are overlapped on both sides of each other and welded to each other It is characterized by that.
[0013]
In this storage battery, the plurality of connecting protrusions of the lead portion and the current collector are welded by surface contact, and the sealing body and the flat plate portion of the lead portion are welded by surface contact, and the lead member and the sealing body are At the time of welding, due to the pressing force applied to the sealing member, the bent portion of the side surface portion of the lead member is elastically deformed into a slightly bent state. Therefore, the flat plate portion of the lead member is sealed by the restoring force due to the elastic deformation of the side surface portion. Therefore, stable welding quality can always be ensured for the welded portion. In addition, since the energization current when functioning as a battery flows in two paths along the side surfaces of the lead member from the current collector to the sealing body, the current energization path is shortened and the voltage at the lead member is reduced. The drop is reduced, the battery internal resistance is remarkably reduced, and the high rate discharge performance is excellent. In addition, in this storage battery, the lead member can be formed of a base material having a small thickness, so that the caulking process of the opening peripheral portion of the battery case can be easily performed, and the manufacture becomes easy. In addition, this storage battery can absorb external pressure due to vibrations and shocks by slight elastic deformation of the side part having elasticity of the lead member, and has excellent vibration resistance and improved reliability. To do.
[0014]
[0015]
Also above According to the configuration, even when the current collector is subjected to resistance welding, for example, when the current collector is deformed to the electrode group, the bulge receiving portion is provided in a state in which it is bent and hardly deformed. So keep the original shape reliably. On the other hand, since each connection protrusion protrudes from the support protrusion through the stepped portion and has a deformable elasticity, when each lead member is pressed against the current collector, each connection protrusion It is surely brought into close contact with the bulging receiving part with a slight deformation of itself. In this way, the four connecting protrusions are surely brought into close contact with the two bulging receiving portions by surface contact, so that a good and stable welding quality is always ensured in the welded portion between the lead member and the current collector. Can do.
[0016]
In the above invention, the sealing body is surrounded by a lid plate that seals the opening of the battery case, a cap that is fixed to the central portion of the lid plate and serves as an external terminal of the other electrode, and the lid plate and the cap. It is preferable that the cover plate and the lead member are connected and fixed to each other by laser welding or electron beam welding through the welding notch of the cap. . According to this configuration, since the lid plate of the sealing body and the lead member are connected and fixed to each other by laser welding or electron beam welding, there is no possibility of occurrence of “welding dust” like resistance welding.
[0017]
In the above invention, the lead member is in a state in which the bent portions of the pair of side surface portions are bent by receiving pressure from a sealing body pushed into the inner side of the battery case at the time of caulking inward of the opening peripheral portion of the battery case. It can be set as the structure currently elastically deformed. According to this configuration, the connection state between the lead member, the current collector, and the sealing body can be maintained stably even when external pressure is applied, due to the restoring force due to the elastic deformation of the lead member.
[0018]
[0019]
[0020]
[0021]
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in the order of manufacturing steps with reference to the drawings. FIG. 1 is an exploded perspective view showing an electrode body 1 and a lead member 2 in a storage battery according to an embodiment of the present invention. FIGS. 2 (a) and 2 (b) show the electrode body 1 in the storage battery in a battery case 3, respectively. It is the top view and longitudinal cross-sectional view which show the state accommodated and fixed. As shown in FIG. 2 (b), the electrode assembly 1 has positive electrode collectors on the upper and lower end surfaces of an electrode group 9 formed by winding a positive electrode plate 4 and a negative electrode plate 7 with a separator 8 interposed therebetween. The electric body 10 and the negative electrode current collector 11 are each attached by welding. The positive electrode current collector 10 and the negative electrode current collector 11 are welded to the positive and negative electrode cores of the positive and negative electrode plates 4 and 7 exposed at the upper end surface and the lower end surface of the electrode group 9, respectively. The lead member 2 is interposed between the electrode body 1 and a sealing body, which will be described later, and connects them to each other by welding. Details of the lead member 2 will be described later.
[0023]
As shown in FIG. 1, the positive electrode current collector 10 has a rectangular liquid injection hole 13 formed at the center of a disc-shaped main body flat plate portion 12 corresponding to the end face shape of the electrode group 9, and the liquid injection Six rectangular cutouts 14 reaching the outer peripheral edge from the vicinity of the hole 13 are formed in a radial arrangement at equal intervals. Ribbed protrusions 17 are formed at opposite edges of each notch 14 by being bent in one direction (downward in the figure).
[0024]
When welding the positive electrode current collector 10 to the electrode group 9, the positive electrode current collector 10 is placed on the end surface of the electrode group 9 with the rib-like protrusions 17 facing the electrode group 9, The welding electrode is applied to both side portions of the main body flat plate portion 12 with the notch portion 14 interposed therebetween, and electricity is applied. During this welding, there is little welding current flowing in the main body flat plate portion 12 outside the rib-like projection piece 17 and most of the welding current is concentrated on the rib-like projection piece 17, so the rib-like projection piece 17 and the upper end portion of the positive electrode plate 4 At each point where the positive electrode core exposed at the crossing point, the rib-like protrusions 17 melt in a state of biting into the positive electrode core, and this portion is strongly welded. Thereby, when it is set as a storage battery, an internal resistance becomes low, it becomes possible to take out a large current, and the effect that a discharge capacity becomes high is acquired.
[0025]
Further, the positive electrode current collector 10 is formed by bending a pair of bulge receiving portions 18 bulging upward in a rectangular shape on two opposite sides of the rectangular liquid injection hole 13. As shown by the arrows in FIG. 1, the pair of bulge receiving portions 18 are welded in a state where the four connection protrusions 28 of the lead member 2 are overlapped. Is welded to the positive electrode current collector 10 after the electrode body 1 is housed and fixed in the battery case 3.
[0026]
That is, the electrode body 1 formed by welding the positive and negative electrode current collectors 10 and 11 to both end faces of the spiral electrode group 9 described above is placed in a bottomed cylindrical metal battery case 3 that also serves as the positive electrode. After that, one welding electrode is pressed from the liquid injection hole 13 of the positive electrode current collector 10 through the central space of the electrode group 9 and pressed against the negative electrode current collector 11, and the other welding electrode is connected to the battery. The negative electrode current collector 11 is spot welded to the bottom surface of the battery case 3 by being pressed against the outer surface of the case 3 and energized. Subsequently, as shown in FIG. 2B, the insulating ring 19 is fitted on the inner peripheral surface of the battery case 3 and placed on the positive electrode current collector 10. In this state, the battery case 3 is subjected to grooving processing on the outer peripheral surface thereof, and an annular groove 20 is formed at a location near the upper side of the insulating ring 19. As a result, the electrode body 1 is fixed in the battery case 3 via the insulating ring 19 by the annular support portion 21 bulged inward of the battery case 3 by forming the annular groove 20.
[0027]
Here, the lead member 2 will be described. As shown in FIG. 1, the lead member 2 includes a flat plate portion 22 for connection to a sealing body, which will be described later, and a pair of side surface portions 23 that are bent in the same orthogonal direction from opposite sides of the flat plate portion 22. A pair of support protrusions 24 bent from the both side surface portions 23 toward the inner orthogonal direction, and the support protrusions from both end portions of the both support protrusions 24 via stepped portions 27, respectively. The cross-sectional shape is formed in a substantially rectangular shape, including a total of four connecting protrusions 28 that are integrally protruded in an inwardly recessed arrangement with respect to 24. The step portion 27 is set to the same height h as the bulging receiving portion 18 of the positive electrode current collector 10. Further, the side surface portions 23 are provided with a bent portion 23a in the central portion, are formed in a cross-sectional shape constricted inwardly, and have elasticity that can be deformed in the vertical direction. The connecting protrusions 28 arranged on each side are opposed to each other with a gap at each tip. A gas vent hole 29 is formed in the central portion of the flat plate portion 22.
[0028]
If the electrode body 1 is housed and fixed in the battery case 3 as shown in FIG. 2, the positive electrode current collector 10 in the electrode body 1 in the battery case 3 is connected to the positive electrode current collector 10 in the battery case 3 as shown in FIGS. The lead member 2 is fixed by welding. In this welding, as shown by arrows in FIG. 1, a pair of left and right connecting protrusions 28 of the lead member 2 are respectively fitted to both end portions of the two bulging receiving portions 18 of the positive electrode current collector 10 from above. The left and right support protrusions 24 are placed on the main plate 12 of the positive electrode current collector 10. Next, in a state where a pressing force is applied to the lead member 2 toward the positive electrode current collector 10, a gas vent hole is formed in the welding projection 30 formed on the outer surface of the four connection projection pieces 28 shown in FIG. Laser welding is performed by irradiating a laser beam through 29. Accordingly, the lead member 2 is fixed to the positive electrode current collector 10 in an electrically connected state by welding the four connection protrusions 28 to the two bulging receiving portions 18 respectively.
[0029]
When the lead member 2 is laser-welded to the positive electrode current collector 10, the four connection protrusions 28 are securely in close contact with the two bulging receiving portions 18. That is, even when the main plate 12 is deformed when the positive electrode current collector 10 is resistance-welded to the electrode group 9, the bulging receiving portion 18 bulges upward with respect to the main plate 12. Since it is bent and formed in the position where it comes out, it is provided in a state where deformation is difficult to occur. On the other hand, each connection protrusion 28 protrudes from the support protrusion 24 via the step portion 27 and has a deformable elasticity, so that the lead member 2 is pressed onto the positive electrode current collector 10. Sometimes, each connection protrusion 28 is surely brought into close contact with the bulging receiving portion 18 with a slight deformation of itself. As described above, the four connection protrusions 28 are in close contact with the two bulging receiving portions 18 by surface contact, so that a good and stable welding quality is provided at the welded portion between the lead member 2 and the positive electrode current collector 10. Can always be ensured.
[0030]
In addition, since the bulging receiving portion 18 is separated from the end face of the electrode group 9 to which the main body flat plate portion 12 is welded by the height h of the stepped portion 27, the laser beam is connected to the connecting projection piece 28 during the laser welding. Even when a situation such as penetrating the bulging receiving portion 18 occurs, it is possible to prevent the occurrence of a malfunction such as thermal damage to the electrode group 9. The lead member 2 and the positive electrode current collector 10 may be fixed to each other by resistance welding or beam welding instead of the above laser welding, and in this case, the effect of the laser welding described above is almost the same. Similar effects can be obtained.
[0031]
If the lead member 2 is attached in an electrically connected state by welding to the electrode body 1 housed and fixed in the battery case 3 in this manner, then a required amount of the electrolyte is applied to the lead member 2. It is injected into the central space portion of the electrode body 1 through the gas vent hole 29 and the liquid injection hole 13 of the positive electrode current collector 10. After that, as shown in FIGS. 5 and 6, the sealing body 31 is attached to the lead member 2 in an electrically connected state by welding with an insulating gasket 32 fitted to the periphery thereof.
[0032]
The sealing body 31 includes a cover plate 33 for sealing the opening of the battery case 3, a positive electrode cap 34 which is fixed to the upper surface of the cover plate 33 by welding and serves as a positive electrode external terminal, and the cover plate 33 and the positive electrode cap. 34 and a valve body 37 accommodated in a valve chamber surrounded by. A gas introduction hole 38 for introducing gas into the valve chamber is formed in the central portion of the cover plate 33. The positive electrode cap 34 has three gas discharge notches 39 and each gas. A welding notch 40 is formed which communicates with the discharge notch 39 and extends to the outer peripheral edge.
[0033]
When the sealing body 31 is welded to the lead member 2, the sealing body 31 is inserted into the battery case 3 from the opening in an arrangement in which an insulating gasket 32 is fitted on the periphery thereof and placed on the lead member 2. The sealing body 31 is irradiated with a laser beam through each welding notch 40 of the positive electrode cap 34 in a state in which a pressing force is applied to the sealing body 31 in the direction toward the lead member 2. The lid plate 33 of the sealing body 31 and the flat plate portion 22 of the lead member 2 are laser-welded from the 31 side.
[0034]
At the time of laser welding, the lead member 2 is elastically deformed by the pressing force applied to the sealing body 31 so that the bent portions 23a of the side surface portions 23 on both sides thereof are slightly bent. The flat plate portion 22 of the lead member 2 is pressed against the lid plate 33 of the sealing body 31 by the restoring force due to the above, and is securely brought into close contact with the surface contact. Since the flat plate portion 22 and the cover plate 33 which are brought into close contact with each other are laser-welded, it is possible to always ensure stable welding quality at the welded portion. In addition, it may replace with the said laser welding and may perform beam welding, and the effect similar to the case of the said laser welding can be acquired also in that case.
[0035]
Furthermore, in the storage battery of the above embodiment, even if the flat plate portion 22 of the lead member 2 and the lid plate 33 of the sealing body 31 are resistance-welded, the “welding” that occurs during welding of the lead portion and the sealing body in the conventional storage battery is performed. "Dust" does not occur. That is, in resistance welding, since the metal at the contact point of the welding point is melted by Joule heat by flowing an electric current through the welding point, the two metals to be welded are not in close contact at the welding point. So-called “welding dust” is generated, which is a phenomenon in which molten metal is scattered. In the conventional storage battery shown in FIGS. 8 and 9, the lead portions 57 and 58 and the sealing body are in line contact, and the lead portions 57 and 58 are both cylindrical and have no elasticity. The above-mentioned “welding dust” is likely to occur because it is difficult to be surely brought into close contact with each other.
[0036]
On the other hand, in the storage battery of this embodiment, as described above, the flat plate portion 22 of the lead member 2 to be welded and the lid plate 33 of the sealing body 31 can be brought into a reliable close state by surface contact. Therefore, resistance welding can be performed without causing the occurrence of “welding dust”, and a weld portion with good welding quality having strong welding strength can be reliably formed. This is the same in the case of resistance welding the lead member 2 described above to the positive electrode current collector 10, and the bulging receiving portion 18 and the connecting projection piece 28 can be reliably brought into close contact with each other. Will not occur.
[0037]
Finally, as shown in FIG. 7, the opening periphery of the battery case 3 is caulked inward. At the time of this caulking process, the opening edge portion of the battery case 3 bent inward is pushed in until the sealing body 31 is pressed onto the annular support portion 21 via the insulating gasket 32, and the lead member 2 is By being pressurized by the sealing body 31 pushed inward of the battery case 3, the bent portions 23a of the side surface portions 23 are bent inward, and the height is lowered. As a result, the sealing body 31 is caulked and fixed between the peripheral edge portion of the opening bent inward in the battery case 3 and the annular support portion 21, and the opening portion of the battery case 3 is hermetically sealed by the compressed insulating gasket 32. The required storage battery is completed. In this storage battery, the connection state between the lead member 2, the positive electrode current collector 10 and the sealing body 31 is stably maintained even when external pressure is applied, by the restoring force due to elastic deformation during caulking of the lead member 2. It can be continued.
[0038]
Further, in the storage battery of this embodiment, after the sealing body 31 is inserted into the battery case 3, the opening peripheral portion of the battery case 3 is caulked before the sealing process of the sealing body 31 and the lead member 2. Thus, even if the process is changed, it is possible to always ensure good welding quality at the welded portion between the sealing body 31 and the lead member 2. That is, the lead member 2 is elastically deformed by bending the opening edge portion of the battery case 3 so that the bent portion 23 a of the side surface portion 23 is elastically deformed. Therefore, the flat plate portion 22 is sealed by the restoring force of the side surface portion 23. The lid plate 33 is pressed against and closely contacts. Therefore, when the sealing body 31 and the lead member 2 are laser-welded or beam-welded from the sealing body 31 side, it is not necessary to apply a pressing force toward the lead member 2 to the sealing body 31. As a result, it is possible to ensure stable welding quality at the welded portion.
[0039]
In the storage battery of this embodiment, the energizing current when functioning as a battery flows in two paths along the side surface portions 23 of the lead member 2 from the positive electrode current collector 10 toward the sealing body 31. The current collection distance between the electric body 10 and the sealing body 31 is the length of one side surface portion 23 of the lead member 2, and the voltage drop at the lead member 2 can be reduced to almost half. For this reason, even if the lead member 2 is formed using a metal plate having a small thickness, the cross-sectional area thereof is a relatively large value of the sum of both the side portions 23, and the height of the side portion 23 is the positive electrode collector. Since it is sufficient to make it slightly larger than the arrangement interval between the electric body 10 and the sealing body 31, the current supply path is also shortened. Thereby, since the voltage drop in the lead member 2 becomes small, the battery internal resistance is remarkably reduced, and the storage battery has excellent high rate discharge performance. And since the said storage battery can form the lead member 2 with a base material with small thickness, the opening peripheral part of the battery case 3 can be easily crimped, and manufacture becomes easy.
[0040]
The storage battery can absorb external pressure caused by vibration and shock by slight elastic deformation of the side surface portion 23 and the connecting projection piece 28 having elasticity of the lead member 2, and vibration resistance. Excellent reliability with high reliability.
[0041]
【The invention's effect】
As described above, according to the storage battery of the present invention, the plurality of connecting protrusions of the lead portion and the current collector are welded in surface contact, and the sealing body and the flat plate portion of the lead portion are welded in surface contact. Moreover, when the lead member and the sealing body are welded, the bending force of the side surface portion of the lead member is elastically deformed by the pressing force applied to the sealing body, so that the restoring force due to the elastic deformation of the side surface portion. Thus, the flat plate portion of the lead member is pressed against the sealing body and is securely brought into close contact with the surface contact, so that stable weld quality can always be ensured in the welded portion. In addition, since the energization current when functioning as a battery flows in two paths along the side surfaces of the lead member from the current collector to the sealing body, the current energization path is shortened and the voltage at the lead member is reduced. The drop is reduced, the battery internal resistance is remarkably reduced, and the high rate discharge performance is excellent. In addition, in this storage battery, the lead member can be formed of a base material having a small thickness, so that the caulking process of the opening peripheral portion of the battery case can be easily performed, and the manufacture becomes easy. In addition, this storage battery can absorb external pressure due to vibrations and shocks by slight elastic deformation of the side part having elasticity of the lead member, and has excellent vibration resistance and improved reliability. To do.
[0042]
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing an electrode body and a lead member in a storage battery according to an embodiment of the present invention.
FIGS. 2A and 2B are a plan view and a longitudinal sectional view showing a state where an electrode body in the above storage battery is housed in a battery case and fixed. FIG.
FIG. 3 is a perspective view showing a state in which a lead member is attached to an electrode body in the above storage battery.
4A and 4B are a plan view and a longitudinal sectional view showing a state in which a lead member is attached to an electrode body housed and fixed in a battery case in the above storage battery.
FIG. 5 is an exploded perspective view showing an electrode group to which a lead portion is attached and a sealing body in the above storage battery.
FIGS. 6A and 6B are a plan view and a longitudinal sectional view showing a state before the opening edge portion of the battery case in the storage battery is caulked. FIG.
7A and 7B are a plan view and a longitudinal sectional view showing a completed state of the storage battery of the above.
FIG. 8 is a perspective view showing an electrode body and a lead portion in a conventional storage battery.
FIGS. 9A and 9B are a plan view and a side view showing a state in which a lead portion is connected to a positive electrode current collector of an electrode body in another conventional storage battery.
[Explanation of symbols]
1 Electrode body
2 Lead material
3 Battery case
4 Positive electrode plate
7 Negative electrode plate
8 Separator
9 Electrode group
10 Positive current collector (current collector)
13 Injection hole
18 Swelling receiving part
22 Flat plate
23 Side
23a Bent part
27 steps
28 Connection protrusion
31 Sealing body
32 Insulation gasket
33 Cover plate
34 Positive electrode cap (cap)
37 Disc
40 Notch for welding

Claims

A bottomed cylindrical battery case that doubles as one pole,
A current collector is connected to at least one end of an electrode group in which a positive electrode plate and a negative electrode plate are stacked with a separator interposed therebetween, and an electrode body housed in the battery case;
A sealing body serving also as the other electrode for sealing the opening of the battery case with an insulating gasket interposed therebetween;
A lead member interposed between the current collector and the sealing body and connected to each other;
The lead member has a plate-like cross-sectional shape that extends in the same direction from both sides of the flat plate portion that is connected to the sealing body by welding and has an inwardly bent portion in the middle portion. A pair of side surface portions and a plurality of connection projecting pieces protruding inward from the front end portions of the both side surface portions and connected to the current collector by welding are integrally provided, and have a substantially rectangular cross-sectional shape. Storage battery,
The lead member is provided between a pair of support protrusions that are bent in the orthogonal direction inside from the front ends of the pair of side surface portions, and is provided between both end portions of the support protrusions and the connection protrusion. A stepped portion for projecting the projecting protrusion in an inwardly recessed arrangement with respect to the support projecting piece,
The current collector has a liquid injection hole provided in a central portion, and a pair of bulges formed so as to bulge from the opposite sides of the liquid injection hole to the lead member side at the same height as the stepped portion. And a reception part,
A storage battery , wherein two connection projection pieces are overlapped in a fitted state and welded to each other on both sides of each of the pair of bulge receiving portions .

The sealing body is accommodated in an inner space surrounded by a lid plate that seals the opening of the battery case, a cap that is fixed to the center portion of the lid plate and serves as an external terminal of the other electrode, and the lid plate and the cap. A valve body,
The storage battery according to claim 1 , wherein the lid plate and the lead member are connected and fixed to each other by laser welding or electron beam welding through a notch for welding of the cap.

The lead member is elastically deformed in such a manner that the bent portions of the pair of side surface portions are bent by receiving pressure from a sealing body that is pushed into the inner side of the battery case during caulking to the inner periphery of the opening peripheral portion of the battery case. The storage battery according to claim 1 or 2 .