JP4251829B2

JP4251829B2 - Battery and manufacturing method thereof

Info

Publication number: JP4251829B2
Application number: JP2002220094A
Authority: JP
Inventors: 和樹下園; 博之井上; 悦也藤阪
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 2002-07-29
Filing date: 2002-07-29
Publication date: 2009-04-08
Anticipated expiration: 2022-07-29
Also published as: JP2004063272A

Description

【０００１】
【発明の属する技術分野】
本発明は、電池およびその製造方法にかかり、特に、正・負極板の一方と封口体とを接続する集電体の構造の改善に関する。
【０００２】
【従来の技術】
一般に、ニッケル−水素化物蓄電池、ニッケル−カドミウム蓄電池などのアルカリ蓄電池は、発電要素を電池ケース内に収容し、電池ケースを一方極の端子として構成される。例えば図１０に一例を示すように、集電体として、集電体１０１と集電リード１０３を同一厚みで伸長させ、一体成形したものが提案されている。このような電池では、図１１に示すように、正極板８および負極板９の間にセパレータ１０を介在させ、これらを渦巻状に巻回して形成された発電要素を外装容器６としての金属製電池ケースに収納して集電リード板１０１を封口体に１箇所溶接した後、封口体１１を電池ケース６の開口部に絶縁ガスケットを介在させて装着する。そして、この発電要素を外装容器６としての金属製電池ケースに収納して集電リード板１０１を封口体に１箇所溶接した後、封口体１１を電池ケース６の開口部に絶縁ガスケットを介在させて装着することにより密閉して構成されている。細部については後述する。
【０００３】
特に、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、電池構成の中でも特に、発電要素と封口体の間を接続する集電体の電気抵抗が電池特性に大きな影響を与える。これらの用途ではしばしば大電流での充放電が要求されるので、極力内部抵抗を低減する必要がある。
しかしながら、上述したような集電リード板を用いて集電したアルカリ蓄電池では、集電リードを長く形成する必要があり、十分に満足できる程度に電池内部抵抗を低くすることはできなかった。
【０００４】
これに対し、集電リードにフープ状の特殊形状部品を使用し、この集電リードを集電板に溶接し、これを外装缶に挿入して電解液を注入した後、封口体の底面を集電リード部に接触させた状態で、電池の上下（封口板と缶底）から電流を流して集電リードと封口体とを溶接する方法も提案されている（特開２００１-１４３６８４号公報）。
【０００５】
この方法によれば前述の方法と同様集電リードの電流経路を増加させることが可能な上、封口体を閉じた状態で溶接することが可能である。このため、集電リードの長さを大幅に短縮することができ、その結果、内部抵抗が大幅に低減される。
【０００６】
しかしながらこの方法では、集電リードにフープ状の特殊形状部品を使用するため、加工が難しく、高価なものとなり、工業的にはコストの増加が非常に大きいという問題がある。また部品点数が増大するという問題もある。
【０００７】
さらにまた、集電板の一部を断面袋状に屈曲させてなる突起部を形成し、この突起部が電極対の接合面から離れる方向に突出して先端が電極端子部と連結されるようにしたものも提案されている（特開２００２-１５７９９２号公報）。
【０００８】
この構造では図１２（ａ）および（ｂ）に示すように、集電板７０は、ニッケル製の平板の折り曲げにより形成されており、円形状の平面部７３と集電板７０の中心位置からずれた位置に、集電板７０の中心軸を軸とする回転対象位置に袋状断面を有する二文字状に形成された突起部７１とで構成されている。７２は円板の中心孔であり、缶底の負極側の集電板と缶底とを溶接するための溶接棒を挿通するための孔である。
かかる構成によれば、一枚の平板を折り曲げ加工して形成されているため、部品点数が１つですむ上、集電板の平面部に集電された電流が突起部に流れ込むまでの平均距離が短いため、二次電池の内部抵抗を低減することができる。
【０００９】
【発明が解決しようとする課題】
しかしながら、折り曲げ加工によって形成されているため、肉厚は一定であり、前述したように、封口体と缶底との間に溶接電流を流して集電体と封口体とを直接溶接するいわゆる直接溶接法を用いる場合には、溶接領域の肉厚が他の領域と同程度に大きく、抵抗が小さく、十分に電流集中を生じさせにくいために、溶接を良好に行うことができないという問題がある。
【００１０】
また、二次電池としての使用時には、突起部を除く平面部７３が電極体の正の電極板の端部と接触して電流を集電する集電部を構成するわけであるが、折り曲げにより形成しようとすると突起部７１は円板表面を貫通するように形成される。このような形状では、突起部７１の周縁部が缶の環状溝と接触してしまうため、平面部７３の直径は電極体の外径近くまで広げられず、缶の環状溝の内径以下に小さくしなければならず、その分だけ集電に寄与する面積が低減されるため、集電抵抗の低減には限界があった。
このように、内部抵抗が十分に小さく、かつ製造が容易、特に直接溶接が容易でかつ信頼性の高い溶接状態を兼ね備えた電極を得るのは困難であった。
【００１１】
本発明は前記実情に鑑みてなされたものであって、部品点数が少なく、確実な溶接接続が可能で、内部抵抗の小さい電池を提供することを目的とする。
また、製造が容易で信頼性の高い電池の製造方法を提供することを目的とする。
【００１２】
【課題を解決するための手段】
上記目的を達成するため、本発明では、一方極の端子を兼ねる開口部を備えた外装容器と、前記開口部を密封する他方極の端子を兼ねる封口体と、前記外装容器内に収容される正極板および負極板を備えた電極体と、前記正極板または負極板の一方の前記封口体側に位置する端部と前記封口体とを集電体を介して接続する電池であって、前記集電体が、前記端部との接続面を構成する平坦部と、前記平坦部に一体的に形成され前記封口体側に突出するように成形された突起部とを備え、前記突起部の先端が前記平坦部よりも薄い肉薄部を形成するとともに、前記肉薄部が前記封口体との溶接領域を形成してなることを特徴とする。
【００１３】
かかる構成によれば、集電体が封口体と接続するための突起部と一体的に形成されているため、部品点数が少なく、組み立ても容易である。溶接領域を構成する集電体の先端部が他の領域よりも肉薄となっているため、封口体と缶底との間に溶接電流を流して集電体と封口体とを直接溶接法によって溶接する際、十分な電流集中による発熱を生じさせることができ、確実な溶接を行うことができる。また溶接領域が肉薄であるため、弾性度（可撓性）は高められ、封口体との接触性が高められ、確実な溶接が可能となる。
【００１４】
ここで、封口体装着後に溶接をする直接溶接法による場合、抵抗溶接により溶接部の強度を強くするためには、溶接電流の電流値とともに、溶接点に加わる加圧力も重要な要因となる。溶接点に溶接電流を流すと、溶接点では接触部分の金属がジュール熱により溶融して接合するが、溶接領域が肉薄であるため、十分な電流集中による発熱を得て溶融させることができる上、溶接領域は十分に加圧され得、溶融した金属が飛散する、所謂「溶接ちり」が発生するようなこともない。従って、溶接ちりに起因する電池短絡のおそれもなく、また溶接領域に内部欠陥が発生し、溶接強度が低下するようなこともない。
【００１５】
望ましくは、前記突起部の周縁は、平坦部で囲まれていることを特徴とする。
従って集電体の周縁部は平坦部となっており、平坦部の径を電極体の直径近くまで大きくできるため、集電効率が向上し、さらなる内部抵抗の低減を図ることが可能となる。
【００１６】
また望ましくは、前記突起部は、複数個配設されていることを特徴とする。
かかる構成によれば、複数箇所での溶接がなされ、確実な接続が可能となる上、電流経路も十分に多くかつ短くすることができる。
【００１７】
望ましくは、前記集電体は、その外周が前記外装容器の内側面に沿うように形成された金属板を打ち抜き加工することによって形成されており、前記正極板または負極板の一方の端部に接続しうるように裏面側に突出せしめられた複数の突起を具備してなる平坦部と、前記平坦部から突出せしめられ頂面が溶接領域となり得る肉薄部を持つ突起部とで構成されたことを特徴とする。
【００１８】
かかる構成によれば、集電体は、その外周が前記外装容器の内側面に沿うように形成された金属板で構成されているため、最大限に大きく集電領域を取ることができる。また金属板の打ち抜き加工によって形成されているため、極めて容易に形成可能であり、頂面の肉薄部も特別な加工を施すことなく容易に同時形成可能である。
【００１９】
また望ましくは、前記突起部は、平坦部よりも肉薄であるように構成すれば、直接溶接による溶接も確実に効率よく行うことができる。
【００２０】
また本発明の方法では、１枚の板状体を出発材料とし、打ち抜き成形加工により、平坦部と、前記平坦部から突出し、先端が前記平坦部よりも薄い肉薄部をもつように形成された突起部とを具備する集電体を形成する工程と、一方極の端子を兼ねる開口部を備えた外装容器内に、正極板および負極板を備えた電極体を配置する工程と、前記集電体を、正極板および負極板のうちの一方の開口部側の端部との接続面を形成するように、前記電極体上に載置し、前記端部と溶接する第１の溶接工程と、前記外装容器の前記開口部に他方極の端子を兼ねる封口体を配置し、前記封口体と前記外装容器との間に電流を流して前記突出部を、前記封口体に溶接する第２の溶接工程とを含むことを特徴とする。
【００２１】
かかる構成によれば、１枚の板状体を出発材料とし、打ち抜き成形加工により、集電体を形成しているため、打ち抜き金型を調整することにより、肉厚も極めて容易に調整することができる。また、平坦部と、前記平坦部から突出し、先端が前記平坦部よりも薄い肉薄部をもつように形成された突起部を持つ集電体を形成しているため、突起部を介して確実に接触性よく、集電体と封口体とが接触した状態となるように外装容器の開口部に封口体を配置することができる。従って、外装容器と封口体との間に溶接電流を流す、直接溶接法を用いる場合にも、肉薄部の存在により突起部が弾性をもつため、溶接時に接触部を加圧することが可能となる上、十分に電流集中を引き起こすことが可能となる。これにより、「溶接ちり」の発生を伴うことなく、集電体は封口体に良好に溶接されるようになる。
なおここで平坦部は、全体形状として平坦であればよく、ばりがでているものも含む。
【００２２】
【発明の実施の形態】
以下、本発明をニッケル−カドミウム蓄電池に適用した場合について図面を参照しつつ詳細に説明する。
（第１の実施の形態）
図１は、本実施形態による、打ち抜き加工により一体形成された集電体を装着したニッケル−カドミウム蓄電池の要部を示す斜視図、図２（ａ）および（ｂ）は、この集電体１の平面図および断面図である。この集電体は、ニッケルめっきのなされた厚み０．３ｍｍの鉄板からなり、平坦部２と、打ち抜き加工により高さ２．０ｍｍ程度に突出せしめられた突起部３とで構成されている。
【００２３】
この集電体は、ほぼ円板状をなすように形成され、突起部３を具備し、前記突起部の頂面が溶接領域となり得る肉薄領域４を構成したことを特徴とする。またこの平坦部には孔５が形成されている。そしてこの孔の周縁に裏面側に突出するようにばり５Ｂが形成され、このばりが正極板との溶接点を形成している。図３は電極体を外装容器としての電池ケース６に挿入して前記集電体１を介して封口体と溶接するときの状態を示す断面図である。さらに、図４は電池ケースに挿入された電極体が封口体に溶接されて完成したニッケル−カドミウム蓄電池を示す断面図である。
【００２４】
このニッケル−カドミウム蓄電池は、図４に示すように、鉄にニッケルめっきを施した有底筒状体の電池ケース６内に、ニッケル正極板８とカドミウム負極板９がセパレータ１０を介して巻回された電池要素が収容され、この上に上述の集電体１が載置され、封口体１１がこの集電体１の突起部３と直接溶接法によって溶接接続せしめられてなるものである。この封口体１１は底面に円形の下方突出部を形成した蓋体１２と、正極キャップ１３と、これら蓋体１２と正極キャップ１３との間に介在せしめられるスプリング１５と弁板１４とからなる弁体とで構成されており、この蓋体の中央にはガス抜き孔１６が形成されている。ここでニッケル正極板と集電体１との間は、封口体との溶接に先立ち、平坦部２に形成された孔５の周縁に裏面側に突出するようにばり５Ｂが形成され、このばりが正極板８との溶接点を形成している。一方電池ケース６の底部には円板状の負極集電体７が配設され、負極板９と溶接接続されている。またこの電池ケース６の開口部１７はかしめ加工によって封止がなされている。
【００２５】
次にこの集電体を用いて形成されるニッケル−カドミウム蓄電池について説明する。
【００２６】
１．電極体の作製
本実施形態のニッケル−カドミウム蓄電池は図３に示すように、ニッケル正極板８とカドミウム負極板９とを備えている。ニッケル正極板８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、カドミウム負極板９は、パンチングメタルからなる極板芯体の表面にカドミウム焼結多孔体を形成した後、化学含浸法により水酸化カドミウムを主体とする活物質を充填して作製されている。
【００２７】
これらのニッケル正極板８とカドミウム負極板９との間にセパレータ１０を介在させて渦巻状に巻回して渦巻状電極群を作製した。この渦巻状電極群の上端面には、ニッケル正極板８の極板芯体であるパンチングメタルの端部が露出し、また、下端面にはカドミウム負極板９の板芯体であるパンチングメタルの端部が露出している。そして、この渦巻状電極群の上端面に露出する正極芯体に多数の孔５を有する円板状の集電体１が溶接されるとともに、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集電体７が溶接される。
【００２８】
ここではまず、１枚の円形金属板（例えば、ニッケルめっきの鉄製で厚みが０．３ｍｍのもの）を打ち抜き加工により、図２（ａ）および（ｂ）に示すように成形し、孔５を多数個形成してなる平坦部２と、頂面が肉薄領域４を構成する突起部３をもつ集電体１を形成する。ここでこの集電体１は平坦部では０．３ｍｍの肉厚をもつが、突起部３では０．２５ｍｍと肉薄になっており、さらにその頂面では０．１５ｍｍとなっている。またこの平坦面にはスリットＳが形成され、導電経路が分断され、溶接電流が集中しやすいように構成される。
【００２９】
このように突起部が肉薄となっているため、可撓性、弾力性は高められ、わずかな位置ずれも吸収し得ることになり、集電体と封口体との溶接も容易で確実なものとなる。
また、集電体の平坦部２には孔５の裏面側に抜きばり５Ｂが形成され裏面に突出した溶接点を構成しており、これは同心円を成すように配列されている。
【００３０】
２．ニッケル−カドミウム蓄電池の作製
そして、この集電体１を用いてニッケル−カドミウム蓄電池を組み立てるに際しては、まず、上述の電極体を鉄にニッケルメッキを施した有底筒状の外装容器（底面の外面は負極外部端子となる）６内に収納し、電極体の中心部に形成された空間部に図示しない溶接電極を挿入して、カドミウム負極板９に溶接された負極集電体７を外装容器６の内底面にスポット溶接した。
【００３１】
この後、上述した突起部３が正極集電体としての集電体１の平坦部２の直径上に位置するように載置するとともに、平坦部２と正極板８とを前記抜きばり５Ｂからなる溶接点の位置でスポット溶接（第１溶接）した。
【００３２】
このようにして、集電体１の平坦部２と正極板８とを溶接した後、図２に示すように、外装容器６の上部内周側に防振リング（図示せず）を挿入し、外装容器６の外周側に溝入れ加工を施して防振リングの上端部に環状溝を形成した。
ついで、外装容器６内に３０質量％の水酸化カリウム（ＫＯＨ）水溶液からなる電解液を注入した後、この外装容器６の開口部の上部に、周縁に絶縁ガスケット１７を嵌着させた封口体１１を配置した。この場合、封口体１１の底面が集電体１の突起部３の先端である肉薄の溶接領域４と接触するように配置した。なお、封口体１１は、底面に円形状の下方突出部を形成してなる蓋体１２と、正極キャップ（正極外部端子）１３と、これら蓋体１２および正極キャップ１３間に介在されるスプリング１５と弁板１４とからなる弁体を備えており、蓋体１２の中央にはガス抜き孔１６が形成されている。
【００３３】
上述のように封口体を配置した後、正極キャップ（正極外部端子）１３の上面に一方の溶接電極Ｗ１を配置するとともに、外装容器６の底面（負極外部端子）の下面に他方の溶接電極Ｗ２を配置した。この後、これらの一対の溶接電極Ｗ１，Ｗ２間に２×１０⁶Ｎ／ｍ²の圧力を加えながら、これらの溶接電極Ｗ１，Ｗ２間に電池の放電方向に２０Ｖの電圧を印加し、３ＫＡの電流を時間約１０ｓｅｃの間、流す通電処理を施した。この通電処理により、封口体１１の底面と集電体１の突起部３の溶接領域４との接触部分が溶接（第２溶接）されて、溶接部が形成される。
【００３４】
上述したような溶接部を形成するためには、正極キャップ１３と外装容器６との間に所定の溶接電流を流して、封口体１１の底面と集電体１との接触部に、通電時の電流密度を増加させて、接触部のジュール熱の発生を大きくして赤熱し易い状態にする必要がある。
【００３５】
ここでは、一対の溶接電極Ｗ１，Ｗ２間に２×１０⁶Ｎ／ｍ²の圧力を印加しながら、これらの溶接電極Ｗ１，Ｗ２間に電圧を印加して、通電処理を施すことにより、電極体の高さ寸法にばらつきがあっても、あるいは集電体１の突起部３の溶接位置にばらつきがあっても、スリットおよび打ち抜き加工による肉薄化により可撓性を付与されているため、集電体１の溶接面と封口体１１の底面との間に接触点を形成することが可能となる。これにより、内部短絡の発生原因の１つとなる「溶接ちり」の発生を抑制できるとともに、内部欠陥のない溶接強度に優れた溶接部を形成することができるようになる。
【００３６】
ついで、電池ケース６の開口端縁１７を内方にかしめて電池を封口し、パンチにより加圧して、封口体１１を電池ケース６内に押し込み、嵌め成形を行い、図４に示すように、電池を形成した。
【００３７】
これにより、図４に示すように、公称容量２．４ＡｈのＳＣサイズの円筒形ニッケル−カドミウム蓄電池を作製した。
【００３８】
かかる構成によれば、１枚の円形金属板を打ち抜き加工により形成するのみで、容易に確実な溶接領域を形成することが可能となり、確実で信頼性の高い接続が可能となる。
また、平坦部２が電極と接続される集電体本体部、突起部３が封口体であり正極側端子と接続される集電リードの役割を果たすことができ、一体形成が可能であるため、接続抵抗の低減を図ることが可能となる。また図２（ｂ）に示すように頂面が肉薄となっているため、溶接電流を集中させることができ、また弾性をもち溶接領域に圧力が確実にかかるため、より確実な接続が可能となる。
【００３９】
（第２の実施の形態）
図５（ａ）は第２の実施の形態２の集電体を用いた電池の封口体装着前の要部を説明する斜視図、図５（ｂ）はこの断面図である。なお、第２の実施の形態に用いられる集電体１以外は第１の実施の形態と同様であり、第２の実施の形態においては、２つの突起部３ａ、３ｂが形成されたものである。この突起部は先端の溶接領域４がシャープなエッジ状をなしていることを特徴とする。
【００４０】
この突出部は肉薄になり、溶接電流が集中しやすくなっている上、突出部全体としても変形を生じ易い状況となっている。２つの突出部が形成されているため、電流経路が多数形成されることになり、内部抵抗がより低減される。
【００４１】
（第３の実施の形態）
図６（ａ）は第３の実施の形態の集電体を用いた電池の封口体装着前の要部を説明する斜視図、図６（ｂ）は断面図である。なお、第３の実施の形態に用いられる集電体１以外は第１および第２の実施の形態と同様であり、第３の実施の形態においては、突起部３を集電体１の中心を通る直線上を避けて形成したものである。
【００４２】
（第４の実施の形態）
図７（ａ）は第４の実施の形態の集電体を用いた電池の封口体装着前の要部を説明する斜視図、図７（ｂ）は断面図である。なお、第４の実施の形態に用いられる集電体１以外は第１乃至第３の実施の形態と同様であり、第４の実施の形態においては、突起部３ａ、３ｂをラウンド状に形成したものである。
【００４３】
この構成によれば、突起部３の肉厚を小さくしているため、溶接電流の集中により有効に加熱される。また突起部３は溶接工程で変形しやすく、電極体と封口体との距離を小さくすることができ、使用時の内部抵抗の低減を図ることが可能となる。
ここで突起部３の肉厚ｔ２は平坦部ｔ３の肉厚よりも小さく、突起部３の頂面の肉厚ｔ１は更に小さくなっている。（ｔ１＜ｔ２＜ｔ３）
加工は難しいが、ネック部の幅が小さくなるように突起部を形成することにより、平坦部２の減少を最小限に抑え、集電に寄与する領域を十分にとることが可能となる。
【００４４】
（第５の実施の形態）
図８（ａ）は第５の実施の形態の集電体を用いた電池の封口体装着前の要部を説明する斜視図、図８（ｂ）は断面図である。なお、第５の実施の形態に用いられる集電体１以外は第１乃至第４の実施の形態と同様であり、第４の実施の形態においては、突起部３の溶接領域４を構成する頂面が平坦となるように形成したものである。
【００４５】
この構成によれば、溶接に際して、安定となり、溶接位置を確実にすることが可能となる。
この場合も同様に溶接電流が集中しやすく、確実な直接溶接が可能となる。
【００４６】
（第６の実施の形態）
図９（ａ）は第６の実施の形態の集電体を用いた電池の封口体装着前の要部を説明する斜視図、図９（ｂ）は断面図である。なお、第６の実施の形態に用いられる集電体１以外は第１乃至第５の実施の形態と同様であり、第６の実施の形態においては、前記第５の実施の形態の突起部３の頂面に針状突起４Ｓを形成したものである。
この構成によれば、この針状突起４Ｓの存在により、より良好に溶接電流の集中を達成することが可能となる。
【００４７】
（比較例）
比較例として、図１０に、電池の封口体装着前の要部を説明する斜視図、図１１も溶接時の状態を示す断面図を示すような、従来例の集電体を用いた電池を作成した。なお、集電体１以外は第１乃至第６の実施の形態と同様であり、この比較例においては、集電体１０１とこの集電体１０１から導出された集電リード１０３とで構成されている。実施の形態と同様、ニッケル正極板とカドミウム負極板とをセパレータを介在させて巻回して得た発電要素の上下にこの集電体１０１と負極集電体とを溶接し、これを電池ケース６に収納し、この負極集電体を電池ケース６の内面に溶接する。
【００４８】
次いで図１１に示すように、集電体１０１から伸長する集電リード１０３の先端近傍を電極Ｗ３とＷ４とを用いて封口体１１の底面にスポット溶接した後、封口体１１を電池ケース６の開口部に絶縁ガスケットを介して配置し、電池ケースの開口端縁を内方に嵌めつけることにより、電池を封口して、公称容量２．４ＡｈのＳＣサイズのニッケル-カドミウム電池を組み立てる。
【００４９】
このようにして得られた比較例の電池と、前記第１の実施の形態の電池の各種放電電流に
おける放電時の作動電圧を測定した結果を図１３に示す。第１の実施の形態の電池の作動電圧を実線、比較例の電池の作動電圧を破線で示す。ここで測定は周囲温度２５℃において２．４Ａで７２分間充電した後、６０分間休止し、２，１０，２０，４０Ａの定電流で放電して電池電圧が０．８Ｖに達した時点で放電を停止するものである。
【００５０】
またこれらの電池の内部抵抗を測定した結果、本発明の実施の形態の電池は比較例の電池よりも約０．７ｍオーム程度内部抵抗が低くなっていることが確認された。
図１３の比較から、本発明の実施の形態の電池によれば、大電流放電時の作動電圧が比較電池よりも高くなっていることがわかる。
【００５１】
なお、上述した実施の形態においては、封口体を正極端子とし、外装容器を負極端子とした例について説明したが、封口体を負極端子とし、外装容器を正極端子としてもよい。この場合、正極集電体は電池外装容器の内底面に溶接され、封口体の底面は負極集電体に溶接されることとなる。
【００５２】
さらにまた、前記実施形態においては、電極体を外装容器に装着し集電体底面を正極板に溶接した後に、電解液を注入したが、固体電解質を用いる蓄電池の場合は、正極と負極との間に電解質を挟んだ状態で外装容器に装着し、集電体を溶接し、封着という手順をとることになる。
前記実施の形態では、集電体を正極板に溶接した後、封口体との溶接接続を行うようにしたが、同時に溶接してもよい。
【００５３】
なお、上述した実施の形態においては、正極板、負極板共に焼結式電極を用いたが、ペースト式電極など、非焼結式電極にも適用可能であることはいうまでもない。
【００５４】
また、上述した実施の形態においては、本発明をニッケル−カドミウム蓄電池に適用した例について説明したが、本発明はニッケル−カドミウム蓄電池に限らず、ニッケル−水素蓄電池等の他の蓄電池にも適用できることは明らかである。
【００５５】
【発明の効果】
以上説明してきたように、本発明の電池によれば、集電体の一部を突出させることにより、集電リード部を兼ねるようにし、集電体と封口体との電流経路を短くすると共に電流経路を多数に分岐させて集電経路の数を増大することにより、内部抵抗を低減し、作動電圧の向上をはかることが可能となる。
【００５６】
また集電体は打ち抜き加工により極めて容易に形成され、部品点数及び部品材料の低減と、加工工程の削減によりコストの低減を図ることが可能となる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態の集電体の封口体装着前の要部を説明する斜視図である。
【図２】本発明の第１の実施の形態の集電体の平面図および断面図である。
【図３】電極体を外装容器に挿入して図１の集電体を封口体と溶接する状態を示す断面図である。
【図４】本発明の第１の実施の形態の電池を示す断面図である。
【図５】本発明の第２の実施の形態の集電体の封口体装着前の要部を説明する斜視図である。
【図６】本発明の第３の実施の形態の集電体の封口体装着前の要部を説明する斜視図である。
【図７】本発明の第４の実施の形態の集電体の封口体装着前の要部を説明する斜視図である。
【図８】本発明の第５の実施の形態の集電体の封口体装着前の要部を説明する斜視図である。
【図９】本発明の第６の実施の形態の集電体の封口体装着前の要部を説明する斜視図である。
【図１０】従来例の電池における封口体装着前の要部を説明する斜視図である。
【図１１】従来例の電池における溶接時の状態を示す図である。
【図１２】他の従来例の電池の集電体を示す図である。
【図１３】本発明の実施の形態及び従来例の電池の作動電圧を示す比較図である。
【符号の説明】
１集電体、２平坦部、３突起部、４溶接領域、５孔、６外装ケース、７集電体、８正極板、９負極板、１０セパレータ、１１封口体、１２蓋体、１３正極キャップ、１４弁板、１５スプリング、１６ガス抜き孔
Ｗ１，Ｗ２…溶接電極、Ａ１，Ａ２…割型、Ｐ…パンチ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery and a method for manufacturing the same, and particularly relates to an improvement in the structure of a current collector that connects one of positive and negative electrode plates and a sealing body.
[0002]
[Prior art]
In general, alkaline storage batteries such as nickel-hydride storage batteries and nickel-cadmium storage batteries contain a power generation element in a battery case, and the battery case is configured as a terminal of one electrode. For example, as shown in FIG. 10, as a current collector, a current collector 101 and a current collector lead 103 that are extended with the same thickness and integrally molded have been proposed. In such a battery, as shown in FIG. 11, a separator 10 is interposed between a positive electrode plate 8 and a negative electrode plate 9, and a power generation element formed by winding them in a spiral shape is made of metal as an outer container 6. After being housed in the battery case and welding the current collector lead plate 101 to the sealing body at one location, the sealing body 11 is mounted on the opening of the battery case 6 with an insulating gasket interposed. The power generation element is housed in a metal battery case as the outer container 6 and the current collecting lead plate 101 is welded to the sealing body at one place, and then the sealing body 11 is interposed with an insulating gasket in the opening of the battery case 6. It is hermetically sealed by mounting. Details will be described later.
[0003]
In particular, when such an alkaline storage battery is used for an application that charges and discharges at a high rate, such as an electric tool or an electric vehicle, the current collector that connects between the power generation element and the sealing body, particularly in the battery configuration. Electrical resistance greatly affects battery characteristics. In these applications, charging / discharging with a large current is often required, so it is necessary to reduce the internal resistance as much as possible.
However, in the alkaline storage battery collected using the current collecting lead plate as described above, the current collecting lead needs to be formed long, and the internal resistance of the battery cannot be lowered to a sufficiently satisfactory level.
[0004]
On the other hand, a hoop-shaped special part is used for the current collecting lead, this current collecting lead is welded to the current collecting plate, this is inserted into an outer can and the electrolyte is injected, and then the bottom surface of the sealing body is removed. There has also been proposed a method in which a current is passed from the top and bottom of the battery (sealing plate and bottom of the can) in a state where the current collecting lead is in contact with the current collecting lead and the sealing body (Japanese Patent Laid-Open No. 2001-143684). ).
[0005]
According to this method, the current path of the current collecting lead can be increased as in the above-described method, and welding can be performed with the sealing body closed. For this reason, the length of the current collecting lead can be greatly shortened, and as a result, the internal resistance is greatly reduced.
[0006]
However, this method uses a hoop-shaped special-shaped component for the current collecting lead, so that processing is difficult and expensive, and there is a problem that the cost increase is very large industrially. There is also a problem that the number of parts increases.
[0007]
Furthermore, a protruding portion is formed by bending a part of the current collector plate into a cross-sectional bag shape, and the protruding portion protrudes in a direction away from the bonding surface of the electrode pair so that the tip is connected to the electrode terminal portion. This has also been proposed (Japanese Patent Laid-Open No. 2002-157992).
[0008]
In this structure, as shown in FIGS. 12A and 12B, the current collector plate 70 is formed by bending a flat plate made of nickel, and has a circular plane portion 73 and a current collector plate. 70 Current collector plate at a position deviated from the center position 70 And a protrusion 71 formed in a two-letter shape having a bag-like cross section at a position to be rotated about the central axis of the. Reference numeral 72 denotes a central hole of the disc, which is a hole for inserting a welding rod for welding the current collector plate on the negative electrode side of the can bottom to the can bottom.
According to such a configuration, since a single flat plate is formed by bending, only one part is required, and the average current collected in the flat portion of the current collector plate flows into the protrusion. Since the distance is short, the internal resistance of the secondary battery can be reduced.
[0009]
[Problems to be solved by the invention]
However, since it is formed by bending, the wall thickness is constant. As described above, a welding current is passed between the sealing body and the bottom of the can so that the current collector and the sealing body are directly welded. When using the welding method, the thickness of the welded area is as large as the other areas, the resistance is low, and there is a problem that welding cannot be performed satisfactorily because current concentration is difficult to occur. .
[0010]
In addition, when used as a secondary battery, the flat surface portion 73 excluding the protruding portion is in contact with the end portion of the positive electrode plate of the electrode body to constitute a current collecting portion that collects current. When trying to form, the protrusion 71 is formed so as to penetrate the disk surface. In such a shape, since the peripheral edge of the protrusion 71 comes into contact with the annular groove of the can, the diameter of the flat portion 73 is not expanded to the vicinity of the outer diameter of the electrode body, and is smaller than the inner diameter of the annular groove of the can. Since the area contributing to current collection is reduced by that amount, there is a limit to the reduction of current collection resistance.
As described above, it has been difficult to obtain an electrode that has a sufficiently small internal resistance and that is easy to manufacture, in particular, that is easily welded directly and has a highly reliable welding state.
[0011]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a battery having a small number of parts, capable of reliable welding connection and low internal resistance.
Another object of the present invention is to provide a battery manufacturing method that is easy to manufacture and highly reliable.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, an exterior container having an opening that also serves as a terminal of one electrode, a sealing body that also serves as a terminal of the other electrode that seals the opening, and the housing are accommodated in the exterior container. A battery that connects an electrode body including a positive electrode plate and a negative electrode plate, an end portion of one of the positive electrode plate or the negative electrode plate located on the sealing body side, and the sealing body through a current collector, The electric body includes a flat portion that constitutes a connection surface with the end portion, and a protruding portion that is integrally formed with the flat portion and is formed so as to protrude toward the sealing body, and the tip of the protruding portion is A thin portion thinner than the flat portion is formed, and the thin portion forms a welded region with the sealing body.
[0013]
According to such a configuration, since the current collector is formed integrally with the protrusion for connecting to the sealing body, the number of parts is small and assembly is easy. Since the tip of the current collector constituting the welding area is thinner than the other areas, a welding current is passed between the sealing body and the bottom of the can so that the current collector and the sealing body are directly welded. When welding, heat generation due to sufficient current concentration can be generated, and reliable welding can be performed. Further, since the weld region is thin, the elasticity (flexibility) is increased, the contact with the sealing body is increased, and reliable welding is possible.
[0014]
Here, in the case of the direct welding method in which welding is performed after the sealing body is mounted, in order to increase the strength of the welded portion by resistance welding, the pressure applied to the welding point is an important factor together with the current value of the welding current. When a welding current is passed through the welding point, the metal at the contact point is melted and joined by Joule heat at the welding point, but since the welding area is thin, heat can be obtained and melted by sufficient current concentration. The welding region can be sufficiently pressurized, and so-called “welding dust” in which molten metal scatters does not occur. Therefore, there is no fear of a battery short circuit due to welding dust, and internal defects are not generated in the welding region, and the welding strength is not reduced.
[0015]
Preferably, the peripheral edge of the protrusion is surrounded by a flat part.
Accordingly, the peripheral portion of the current collector is a flat portion, and the diameter of the flat portion can be increased to a value close to the diameter of the electrode body, so that the current collection efficiency is improved and the internal resistance can be further reduced.
[0016]
Desirably, a plurality of the protrusions are provided.
According to such a configuration, welding is performed at a plurality of locations, reliable connection is possible, and the number of current paths can be sufficiently increased and shortened.
[0017]
Preferably, the current collector is formed by punching a metal plate formed so that an outer periphery thereof is along an inner surface of the outer container, and is formed at one end portion of the positive electrode plate or the negative electrode plate. It was composed of a flat part having a plurality of protrusions protruded on the back surface side so as to be connected, and a protrusion part having a thin part that protrudes from the flat part and whose top surface can be a welding region. It is characterized by.
[0018]
According to such a configuration, the current collector is configured by the metal plate formed so that the outer periphery thereof is along the inner side surface of the outer container, and therefore, the current collecting region can be taken to the maximum. Moreover, since it is formed by punching a metal plate, it can be formed very easily, and the thin portion of the top surface can be easily formed simultaneously without any special processing.
[0019]
Desirably, if the protruding portion is configured to be thinner than the flat portion, welding by direct welding can be reliably and efficiently performed.
[0020]
Further, in the method of the present invention, a single plate-like body is used as a starting material, and is formed by punching to have a flat portion and a thin portion that protrudes from the flat portion and whose tip is thinner than the flat portion. A step of forming a current collector including a protrusion, a step of disposing an electrode body including a positive electrode plate and a negative electrode plate in an exterior container including an opening serving also as a terminal of one electrode, and the current collector A first welding step in which a body is placed on the electrode body and welded to the end so as to form a connection surface with the end on one opening side of the positive electrode plate and the negative electrode plate; A sealing member that also serves as a terminal of the other electrode is disposed in the opening of the outer container, and a current is passed between the sealing member and the outer container to weld the protruding portion to the sealing member. And a welding process.
[0021]
According to such a configuration, since the current collector is formed by punching and forming a single plate-like body as a starting material, the thickness can be adjusted very easily by adjusting the punching die. Can do. In addition, since the current collector has a flat portion and a protruding portion formed so as to protrude from the flat portion and have a thin portion whose tip is thinner than the flat portion, the current collector is surely inserted through the protruding portion. The sealing body can be disposed in the opening of the outer container so that the current collector and the sealing body are in contact with each other with good contact. Therefore, even when using a direct welding method in which a welding current is passed between the outer container and the sealing body, the protrusions have elasticity due to the presence of the thin portion, so that the contact portion can be pressurized during welding. In addition, it is possible to cause sufficient current concentration. As a result, the current collector is favorably welded to the sealing body without the occurrence of “welding dust”.
Here, the flat portion may be flat as a whole shape, and includes a portion having a flash.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention is nickel- cadmium The case where it applies to a storage battery is demonstrated in detail, referring drawings.
(First embodiment)
FIG. 1 is a perspective view showing a main part of a nickel-cadmium storage battery equipped with a current collector integrally formed by punching according to the present embodiment, and FIGS. 2 (a) and 2 (b) show the current collector 1. It is the top view and sectional drawing of these. The current collector is made of a nickel-plated iron plate having a thickness of 0.3 mm, and includes a flat portion 2 and a protruding portion 3 that protrudes to a height of about 2.0 mm by punching.
[0023]
This current collector is formed so as to have a substantially disk shape, and includes a protruding portion 3, and a thin region 4 in which the top surface of the protruding portion can be a welding region is characterized. A hole 5 is formed in the flat portion. A flash 5B is formed at the periphery of the hole so as to protrude to the back side, and this flash forms a welding point with the positive electrode plate. FIG. 3 is a cross-sectional view showing a state where the electrode body is inserted into a battery case 6 as an outer container and welded to the sealing body via the current collector 1. FIG. 4 is a cross-sectional view showing a nickel-cadmium storage battery completed by welding an electrode body inserted into a battery case to a sealing body.
[0024]
As shown in FIG. 4, this nickel-cadmium storage battery has a nickel positive electrode plate 8 and a cadmium negative electrode plate 9 wound through a separator 10 in a bottomed cylindrical battery case 6 in which nickel is plated on iron. The above-described current collector 1 is placed thereon, and the sealing body 11 is welded and connected to the protrusion 3 of the current collector 1 by a direct welding method. The sealing body 11 is a valve comprising a lid body 12 having a circular downward projecting portion on the bottom surface, a positive electrode cap 13, a spring 15 interposed between the lid body 12 and the positive electrode cap 13, and a valve plate 14. The gas vent hole 16 is formed in the center of the lid. Here, between the nickel positive electrode plate and the current collector 1, a flash 5B is formed on the periphery of the hole 5 formed in the flat portion 2 so as to protrude to the back side prior to welding with the sealing body. Forms a welding point with the positive electrode plate 8. On the other hand, a disc-shaped negative electrode current collector 7 is disposed at the bottom of the battery case 6 and is connected to the negative electrode plate 9 by welding. The opening 17 of the battery case 6 is sealed by caulking.
[0025]
Next, a nickel-cadmium storage battery formed using this current collector will be described.
[0026]
1. Production of electrode body
As shown in FIG. 3, the nickel-cadmium storage battery of the present embodiment includes a nickel positive electrode plate 8 and a cadmium negative electrode plate 9. The nickel positive electrode plate 8 is formed by forming a nickel sintered porous body on the surface of an electrode plate core made of punching metal, and then filling the nickel sintered porous body with an active material mainly composed of nickel hydroxide by a chemical impregnation method. It has been made. On the other hand, the cadmium negative electrode plate 9 is prepared by forming a cadmium sintered porous body on the surface of an electrode plate core made of punching metal and then filling an active material mainly composed of cadmium hydroxide by a chemical impregnation method. .
[0027]
A separator 10 was interposed between the nickel positive electrode plate 8 and the cadmium negative electrode plate 9 to form a spiral electrode group. The end of the punching metal, which is the electrode core of the nickel positive electrode plate 8, is exposed at the upper end surface of the spiral electrode group, and the punching metal, which is the plate core of the cadmium negative electrode plate 9, is exposed at the lower end surface. The edge is exposed. And the disc-shaped collector 1 which has many holes 5 is welded to the positive electrode core body exposed to the upper end surface of this spiral electrode group, and many openings are opened to the negative electrode core body exposed to the lower end surface. The disc-shaped negative electrode current collector 7 is welded.
[0028]
Here, first, a circular metal plate (for example, nickel-plated iron having a thickness of 0.3 mm) is formed by punching as shown in FIGS. 2 (a) and 2 (b), and the hole 5 is formed. A current collector 1 having a large number of flat portions 2 and protrusions 3 whose top surfaces form thin regions 4 is formed. Here, the current collector 1 has a thickness of 0.3 mm at the flat portion, but is as thin as 0.25 mm at the protrusion 3 and further 0.15 mm at the top surface. Further, a slit S is formed on the flat surface, the conductive path is divided, and the welding current is easily concentrated.
[0029]
Since the protrusions are thin in this way, flexibility and elasticity are improved, and even slight misalignment can be absorbed, and welding between the current collector and the sealing body is easy and reliable. It becomes.
Further, the flat portion 2 of the current collector is formed with a punch 5B on the back side of the hole 5 to form a welding point protruding on the back side, which is arranged to form a concentric circle.
[0030]
2. Preparation of nickel-cadmium storage battery
When assembling a nickel-cadmium storage battery using the current collector 1, first, a bottomed cylindrical outer container in which the above electrode body is nickel-plated on iron (the outer surface of the bottom surface becomes a negative external terminal). ) Housed in 6, a welding electrode (not shown) is inserted into the space formed at the center of the electrode body, and the negative electrode current collector 7 welded to the cadmium negative electrode plate 9 is spotted on the inner bottom surface of the outer container 6. Welded.
[0031]
Thereafter, the protrusion 3 described above is placed so as to be positioned on the diameter of the flat portion 2 of the current collector 1 as the positive electrode current collector, and the flat portion 2 and the positive electrode plate 8 are removed from the punch 5B. Spot welding (first welding) was performed at the position of the welding point.
[0032]
After the flat portion 2 of the current collector 1 and the positive electrode plate 8 are welded in this way, as shown in FIG. The outer peripheral side of the outer casing 6 was grooved to form an annular groove at the upper end of the vibration isolation ring.
Next, a sealing body in which an electrolytic solution made of a 30% by mass potassium hydroxide (KOH) aqueous solution was injected into the outer container 6 and then an insulating gasket 17 was fitted to the upper periphery of the opening of the outer container 6. 11 was placed. In this case, the sealing body 11 is disposed so that the bottom surface of the sealing body 11 is in contact with the thin welded region 4 that is the tip of the protrusion 3 of the current collector 1. The sealing body 11 includes a lid body 12 formed with a circular downward projecting portion on the bottom surface, a positive electrode cap (positive electrode external terminal) 13, and a spring 15 interposed between the lid body 12 and the positive electrode cap 13. And a valve plate 14, and a gas vent hole 16 is formed in the center of the lid 12.
[0033]
After arranging the sealing body as described above, one welding electrode W1 is arranged on the upper surface of the positive electrode cap (positive electrode external terminal) 13, and the other welding electrode W2 is arranged on the lower surface of the bottom surface (negative electrode external terminal) of the outer casing 6. Arranged. Thereafter, 2 × 10 2 between the pair of welding electrodes W1, W2. ⁶ N / m ² A voltage of 20 V was applied between the welding electrodes W1 and W2 in the discharge direction of the battery while applying a pressure of 3 mm, and an energization process was performed in which a 3 KA current was applied for about 10 seconds. By this energization process, the contact portion between the bottom surface of the sealing body 11 and the welding region 4 of the projection 3 of the current collector 1 is welded (second welding) to form a welded portion.
[0034]
In order to form the welded portion as described above, a predetermined welding current is passed between the positive electrode cap 13 and the outer container 6, and the contact portion between the bottom surface of the sealing body 11 and the current collector 1 is energized. Therefore, it is necessary to increase the generation of Joule heat at the contact portion to make it easy to red heat.
[0035]
Here, between the pair of welding electrodes W1, W2, 2 × 10 ⁶ N / m ² By applying a voltage between the welding electrodes W1 and W2 while applying the pressure of and applying an energization treatment, even if the height dimension of the electrode body varies, or the protrusion of the current collector 1 Even if there is variation in the welding position of 3, contact points are formed between the welded surface of the current collector 1 and the bottom surface of the sealing body 11 because flexibility is provided by thinning by slitting and punching. It becomes possible to do. As a result, it is possible to suppress the occurrence of “welding dust” that is one of the causes of the occurrence of an internal short circuit, and to form a welded portion that has no internal defects and has excellent welding strength.
[0036]
Next, the opening edge 17 of the battery case 6 is caulked inwardly, the battery is sealed, pressed by a punch, the sealing body 11 is pushed into the battery case 6, and the fitting is performed, as shown in FIG. A battery was formed.
[0037]
As a result, as shown in FIG. 4, an SC-sized cylindrical nickel-cadmium storage battery having a nominal capacity of 2.4 Ah was produced.
[0038]
According to such a configuration, it is possible to easily form a reliable welding region by simply forming a single circular metal plate by punching, and a reliable and reliable connection is possible.
Also, the flat portion 2 can act as a current collector main body connected to the electrode, and the protrusion 3 can serve as a current collector lead that is a sealing body and connected to the positive terminal, and can be integrally formed. Therefore, it is possible to reduce the connection resistance. Moreover, since the top surface is thin as shown in FIG. 2 (b), the welding current can be concentrated, and since the pressure is applied to the welding region with elasticity, a more reliable connection is possible. Become.
[0039]
(Second Embodiment)
FIG. 5A is a perspective view for explaining a main part of the battery using the current collector of the second embodiment before the sealing body is mounted, and FIG. 5B is a sectional view thereof. Note that, except for the current collector 1 used in the second embodiment, the second embodiment is the same as the first embodiment. In the second embodiment, two protrusions 3a and 3b are formed. is there. This protrusion is characterized in that the weld region 4 at the tip has a sharp edge shape.
[0040]
The protruding portion is thin, the welding current is easily concentrated, and the entire protruding portion is easily deformed. Since two protrusions are formed, a large number of current paths are formed, and the internal resistance is further reduced.
[0041]
(Third embodiment)
FIG. 6A is a perspective view for explaining a main part of the battery using the current collector of the third embodiment before the sealing body is mounted, and FIG. 6B is a cross-sectional view. Note that, except for the current collector 1 used in the third embodiment, the present embodiment is the same as the first and second embodiments. In the third embodiment, the protrusion 3 is the center of the current collector 1. It was formed avoiding the straight line passing through.
[0042]
(Fourth embodiment)
FIG. 7A is a perspective view for explaining a main part of the battery using the current collector of the fourth embodiment before the sealing body is mounted, and FIG. 7B is a cross-sectional view. Note that, except for the current collector 1 used in the fourth embodiment, it is the same as the first to third embodiments. In the fourth embodiment, the protrusions 3a and 3b are formed in a round shape. It is what.
[0043]
According to this structure, since the thickness of the projection part 3 is made small, it is heated effectively by the concentration of the welding current. Further, the protrusion 3 is easily deformed in the welding process, the distance between the electrode body and the sealing body can be reduced, and the internal resistance during use can be reduced.
Here, the thickness t2 of the protruding portion 3 is smaller than the thickness of the flat portion t3, and the thickness t1 of the top surface of the protruding portion 3 is further reduced. (T1 <t2 <t3)
Although it is difficult to process, by forming the protruding portion so that the width of the neck portion is reduced, it is possible to minimize the reduction of the flat portion 2 and to take a sufficient area contributing to current collection.
[0044]
(Fifth embodiment)
FIG. 8A is a perspective view for explaining a main part of the battery using the current collector of the fifth embodiment before the sealing body is mounted, and FIG. 8B is a cross-sectional view. Note that, except for the current collector 1 used in the fifth embodiment, it is the same as the first to fourth embodiments, and in the fourth embodiment, the welding region 4 of the protrusion 3 is configured. The top surface is formed to be flat.
[0045]
According to this configuration, the welding is stable and the welding position can be ensured.
In this case as well, the welding current is easily concentrated, and reliable direct welding is possible.
[0046]
(Sixth embodiment)
FIG. 9A is a perspective view for explaining a main part of the battery using the current collector of the sixth embodiment before the sealing body is mounted, and FIG. 9B is a cross-sectional view. Note that, except for the current collector 1 used in the sixth embodiment, the present embodiment is the same as the first to fifth embodiments. In the sixth embodiment, the protrusions of the fifth embodiment are the same. 3, a needle-like protrusion 4S is formed on the top surface.
According to this configuration, the presence of the needle-like protrusions 4S can achieve better welding current concentration.
[0047]
(Comparative example)
As a comparative example, FIG. 10 is a perspective view for explaining a main part of the battery before the sealing body is mounted, and FIG. 11 is a cross-sectional view showing a state at the time of welding. Created. Note that the components other than the current collector 1 are the same as those in the first to sixth embodiments. In this comparative example, the current collector 101 and the current collector lead 103 led out from the current collector 101 are used. ing. As in the embodiment, the current collector 101 and the negative electrode current collector are welded to the top and bottom of a power generation element obtained by winding a nickel positive electrode plate and a cadmium negative electrode plate with a separator interposed therebetween, and this is connected to a battery case 6. The negative electrode current collector is welded to the inner surface of the battery case 6.
[0048]
Next, as shown in FIG. 11, the vicinity of the tip of the current collecting lead 103 extending from the current collector 101 is spot welded to the bottom surface of the sealing body 11 using electrodes W3 and W4, and then the sealing body 11 is attached to the battery case 6. The battery is sealed by placing the opening through an insulating gasket and fitting the opening edge of the battery case inward to assemble an SC-sized nickel-cadmium battery having a nominal capacity of 2.4 Ah.
[0049]
Various discharge currents of the battery of the comparative example thus obtained and the battery of the first embodiment were used.
FIG. 13 shows the result of measuring the operating voltage during discharging. The operating voltage of the battery of the first embodiment solid line The operating voltage of the battery of the comparative example Broken line It shows with. Here, the measurement is performed at an ambient temperature of 25 ° C. and charged at 2.4 A for 72 minutes, then stopped for 60 minutes, discharged at a constant current of 2, 10, 20, 40 A, and discharged when the battery voltage reaches 0.8V. Is to stop.
[0050]
Further, as a result of measuring the internal resistance of these batteries, it was confirmed that the battery of the embodiment of the present invention had a lower internal resistance by about 0.7 mΩ than the battery of the comparative example.
From the comparison of FIG. 13, it can be seen that, according to the battery of the embodiment of the present invention, the operating voltage at the time of large current discharge is higher than that of the comparative battery.
[0051]
In the above-described embodiment, an example in which the sealing body is a positive electrode terminal and the outer container is a negative electrode terminal has been described. However, the sealing body may be a negative electrode terminal and the outer container may be a positive electrode terminal. In this case, the positive electrode current collector is welded to the inner bottom surface of the battery outer casing, and the bottom surface of the sealing body is welded to the negative electrode current collector.
[0052]
Furthermore, in the above embodiment, the electrolytic solution is injected after the electrode body is mounted on the outer container and the current collector bottom surface is welded to the positive electrode plate. However, in the case of a storage battery using a solid electrolyte, the positive electrode and the negative electrode It is attached to the outer container with the electrolyte sandwiched therebetween, the current collector is welded, and sealing is performed.
In the above embodiment, the current collector is welded to the positive electrode plate and then welded to the sealing body. However, the current collector may be welded simultaneously.
[0053]
In the above-described embodiment, the sintered electrode is used for both the positive electrode plate and the negative electrode plate. However, it goes without saying that the present invention can also be applied to a non-sintered electrode such as a paste electrode.
[0054]
Moreover, in embodiment mentioned above, although the example which applied this invention to the nickel cadmium storage battery was demonstrated, this invention is applicable not only to a nickel cadmium storage battery but other storage batteries, such as a nickel hydride storage battery. Is clear.
[0055]
【The invention's effect】
As described above, according to the battery of the present invention, by projecting a part of the current collector, the current collector leads to serve as a current collecting lead portion, and the current path between the current collector and the sealing body is shortened. By increasing the number of current collecting paths by branching a large number of current paths, the internal resistance can be reduced and the operating voltage can be improved.
[0056]
In addition, the current collector is very easily formed by punching, and the cost can be reduced by reducing the number of parts and parts material and by reducing the number of processing steps.
[Brief description of the drawings]
FIG. 1 is a perspective view for explaining a main part of a current collector according to a first embodiment of the present invention before mounting a sealing body.
FIG. 2 is a plan view and a cross-sectional view of a current collector according to a first embodiment of the present invention.
3 is a cross-sectional view showing a state in which an electrode body is inserted into an outer container and the current collector of FIG. 1 is welded to a sealing body.
FIG. 4 is a cross-sectional view showing the battery according to the first embodiment of the present invention.
FIG. 5 is a perspective view for explaining a main part of the current collector of the second embodiment of the present invention before the sealing body is mounted.
FIG. 6 is a perspective view for explaining a main part of the current collector according to the third embodiment of the present invention before the sealing body is mounted.
FIG. 7 is a perspective view for explaining a main part of the current collector according to the fourth embodiment of the present invention before the sealing body is mounted.
FIG. 8 is a perspective view for explaining a main part of the current collector of the fifth embodiment before the sealing body is mounted.
FIG. 9 is a perspective view illustrating a main part of a current collector according to a sixth embodiment of the present invention before the sealing body is mounted.
FIG. 10 is a perspective view for explaining a main part of a conventional battery before the sealing body is mounted.
FIG. 11 is a diagram showing a state during welding in a conventional battery.
FIG. 12 is a diagram showing a current collector of a battery according to another conventional example.
FIG. 13 is a comparison diagram showing operating voltages of the battery according to the embodiment of the present invention and the conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Current collector, 2 flat part, 3 protrusion part, 4 welding area, 5 hole, 6 exterior case, 7 current collector, 8 positive electrode plate, 9 negative electrode plate, 10 separator, 11 sealing body, 12 lid body, 13 positive electrode Cap, 14 Valve plate, 15 Spring, 16 Gas vent
W1, W2 ... welding electrode, A1, A2 ... split mold, P ... punch

Claims

An exterior container having an opening serving also as a terminal of one electrode; a sealing body serving also as a terminal of the other electrode that seals the opening; and an electrode body including a positive electrode plate and a negative electrode plate accommodated in the exterior container; A battery for connecting an end located on one side of the sealing body of the positive electrode plate or the negative electrode plate and the sealing body via a current collector,
The current collector includes a flat portion that forms a connection surface with the end portion, and a protrusion portion that is integrally formed with the flat portion and protrudes toward the sealing body, and a tip end of the protrusion portion is the flat portion. A battery characterized in that a thinner thin part is formed and the thin part forms a welded region with the sealing body.

The current collector is formed by punching a metal plate formed so that an outer periphery thereof is along the inner surface of the outer container, and can be connected to one end of the positive electrode plate or the negative electrode plate. A flat portion comprising a plurality of protrusions projected on the back surface side, and a protrusion having a thin portion that protrudes from the flat portion and whose top surface can be a welding region. Item 6. The battery according to Item 1.

The battery according to claim 1, wherein the protruding portion is thinner than the flat portion.

A collection comprising a flat plate as a starting material, and a projecting portion formed by stamping and forming so as to protrude from the flat portion and have a thin portion whose tip is thinner than the flat portion. Forming an electric body;
A step of disposing an electrode body provided with a positive electrode plate and a negative electrode plate in an outer container provided with an opening serving also as a terminal of one electrode;
The current collector is placed on the electrode body so as to form a connection surface with an end portion on one opening side of the positive electrode plate and the negative electrode plate, and is welded to the end portion. Welding process;
A second weld that arranges a sealing body that also serves as a terminal of the other electrode in the opening of the outer container, and causes a current to flow between the sealing body and the outer container to weld the protrusion to the sealing body. A process for producing a battery comprising the steps of: