JP4244580B2

JP4244580B2 - Sealed battery

Info

Publication number: JP4244580B2
Application number: JP2002212033A
Authority: JP
Inventors: 幸宏五反田; 武史乾; 康弘鈴木; 敏之清水; 俊哉桑村; 哲也矢野
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2002-07-22
Filing date: 2002-07-22
Publication date: 2009-03-25
Anticipated expiration: 2022-07-22
Also published as: JP2004055372A

Description

【０００１】
【発明の属する技術分野】
本発明は、発電要素を収容した電池ケースの開口部を閉塞すると共に、内部にＰＴＣ素子が配置された封口板を備え、この封口板における耐漏液性を向上させた密閉型電池に関する。
【０００２】
【従来の技術】
密閉型電池は、高容量を有することから携帯機器の電源に加え、幅広い分野で使用されている。特に、リチウム若しくはその合金からなる負極、非水電解液を用いた密閉型電池（以下、非水電解液電池）は、長期間の保存、使用に対して電池特性の劣化を極めて小さく、且つ使用可能な温度範囲が広いことから、前記機器の電源だけでなく、ガスメータの電源、車載用緊急通報システムの電源といった高い信頼性が容易される分野では必要不可欠な電池である。
【０００３】
非水電解液電池は、上述のように高いエネルギー密度を有しており、電池の異状放電、短絡等に起因する安全性の低下を回避するために、ＰＴＣ素子、及び防爆機能を封口板に備えている。この封口板は、一方の極板に電気的に接続された皿板上に、安全弁膜、ＰＴＣ素子及びキャップ状の端子板を載置した形態としている。
【０００４】
電池の内圧が上昇した場合には、封口板のガス抜き孔の間に配された安全弁膜が上方に膨れ上がる。そして、安全弁膜が所定以上に膨れあがると、キャップ状端子板内側に安全弁膜に対向して備えられた切刃が、安全弁膜を破断し、通気路を形成することで、電池内のガスは安全弁膜の破断部を通り抜け、ＰＴＣ素子、キャップ状端子板の各ガス抜き孔を通って、電池外部に排出される。
【０００５】
また、電池内の温度が上昇した場合には、ＰＴＣ素子の抵抗値が増大し絶縁体として機能して、キャップ状端子板から電池内にそれ以上の電流が流れ込まないようにされている。
【０００６】
【発明が解決しようとする課題】
上述のような構成を有する封口板は、その製造工程で安全弁膜、ＰＴＣ素子、キャップ状端子板が載置された皿板をシーマ等によりカシメて一体化している。しかし、カシメ時に、皿板は偏心等の不良を起こし易く、また生産性の低下を招いてしまう。さらにカシメ状態の不良は、高温保存時の際に耐漏液性を低下させる主因となっていた。
【０００７】
そこで、本発明者らは、皿板、安全弁膜、ＰＴＣ素子及びキャップ状端子板を載置した封口板を電池ケースの開口部に配置した後、電池ケースの封口により封口板の要素を固定、保持する構成を採用することで、組立工程の容易化、簡素化をはかると同時に、封口板の耐漏液性を向上させることを提案した。
【０００８】
この提案に基づく封口板を用いた密閉型電池は、バックアップ用電源の用途として長期間にわたって保存、或いは使用される使用様態、特に高温環境下で長期間保存される使用様態では、皿板上に載置された各要素の積層面間に電解液が侵入することがあり、さらに侵入した電解液がキャップ状端子板のガス抜き孔から電解液が漏液することがあった。
【０００９】
本発明の目的は、上述のような封口板の積層面を介した漏液の発生を防止する封口板を備えるものであり、高い信頼性を有するだけでなく、電池特性の劣化も抑制した密閉型電池を提供することにある。
【００１０】
【課題を解決するための手段】
上記の目的を達成するために、本願の第１の発明に係る密閉型電池は、正極と負極とセパレータおよび電解液からなる発電要素を正、負いずれか一方極の端子を兼ねる電池ケースに収容し、この電池ケースの開口部を他方極の端子をなす封口板で閉塞した構成を有し、さらに前記封口板は、中央部に凸部を有し、かつその上面または側面部にガス抜き孔を設けたキャップ状端子板、このキャップ状端子板の下側に配置され、中央部にガス抜き孔を設けたＰＴＣ素子、前記発電要素の一方の電極に接続され、中央部にガス抜き孔を有する皿板、この皿板のガス抜き孔を閉塞し、電池の内圧上昇時に膨脹、破断する機能を有し、前記皿板とＰＴＣ素子との間に配される金属製の安全弁膜を備えてなり、前記キャップ状端子板、ＰＴＣ素子、安全弁膜、及び皿板の要素が隣接する他の要素に対して積層面全体を溶着、あるいはガス抜き孔の周縁を取り囲む様に連続した溶接にて一体化する点、且つこの溶接、或いは溶着が施された部位を液密とする点に特徴を有する。
【００１１】
このような構成を有する電池は、皿板状に載置された安全弁膜、ＰＴＣ素子、キャップ状端子板の各積層面、すなわち隣接する要素との接触面に、ハンダ等を用いた溶着、あるいは抵抗溶接やレーザー溶接等の溶接手段により溶着／溶接部位を形成している。これらの部位は、積層面全体を溶着部位とすること、或いは接触面の全周にわたる溶接部位、例えば少なくとも一畝の連続した溶接部位とすることで、液密とされる。これにより、封口板を構成する要素は電気的に接続されているだけでなく、液密性が付与されることで、積層面間への電解液の侵入を阻止し、封口板を介した漏液の発生を確実に抑制するものである。
【００１２】
また、本願の第２の発明に係る封口板は、中央部に凸部を有し、かつその上面または側面部にガス抜き孔を設けたキャップ状端子板、このキャップ状端子板の下側に配置され、中央部にガス抜き孔を設けたＰＴＣ素子、前記発電要素の一方の電極に接続され、中央部にガス抜き孔を有する皿板、この皿板のガス抜き孔を閉塞し、電池の内圧上昇時に膨脹、破断する機能を有し、前記皿板とＰＴＣ素子との間に配される金属と樹脂とのラミネート材からなる安全弁膜を備えてなり、前記ＰＴＣ素子が前記キャップ状端子板及び皿板に対して積層面全体を溶着、あるいはガス抜き孔の周縁を取り囲む様に連続した溶接にて一体化される点、前記安全弁膜が前記ＰＴＣ素子及び皿板に対して積層面全体に接着される点、及び前記溶接／溶着が施された部位、及び接着が施された部位が液密とされる点に特徴を有する。
【００１３】
この第２の発明は、安全弁膜に樹脂ラミネートされた金属薄板を用いており、ＰＴＣ素子及び皿板で安全弁膜を挟持した形態となっている。安全弁膜は、表面に樹脂ラミネート層が形成されることから、安全弁膜と皿板及びＰＴＣ素子との積層面は接着により一体化される。接着には、耐有機電解液性を優れ、樹脂及びＰＴＣ素子の主面に配される金属部位、及び皿板との接着性に優れた材料が用いられる。この材料としては、エポキシ系やアクリル系（ホットメルト）接着剤が好ましい。また、安全弁膜は、樹脂ラミネート層の存在により、導電性を有しておらず、通電経路とならない。そこで、導電性を確保するために、ＰＴＣ素子と皿板とを電気的に接続している。
【００１４】
一方、ＰＴＣ素子は、キャップ状端子板、及び皿板に対してハンダや導電性接着剤等を用いた溶着、あるいは抵抗溶接やレーザー溶接等の手段により溶接されることで、電気的な接続を行うと共に、封口板に液密性を付与している。
【００１５】
このような構成によれば、通電経路となる部位の積層面は、溶着或いは溶着部位を形成し、ＰＴＣ素子とキャップ状端子板及び皿板を一体化しており、且つ樹脂部位と金属部位とを接続する安全弁膜と皿板及びＰＴＣ素子との接続部位は、接着により一体化されるために耐漏液性が向上する。さらに通電経路となる部位は溶接、溶着にて電気伝導性を向上させ、通電経路以外の部位を接着剤にて一体化することで、生産性を改善している。
【００１６】
また、本願発明に係る上記の各密閉型電池は、前記溶着にクリームハンダを用いるのが好ましい。クリームハンダは、皿板、安全弁膜、ＰＴＣ素子、キャップ状端子板の積層面に塗布される。そして、皿板状に各要素を配置した後、電気炉や高周波炉等に挿入することでクリームハンダを溶融し、封口板を加圧することで各要素の一体化がなされる。この製造法は、従来の封口板の組立工程と比較すると、クリームハンダの塗布工程、及び塗布されたクリームハンダを溶融させる工程が増加している。しかし、工数の増加が最少に抑えられており、生産の悪化を招くものではない。また、クリームハンダを溶融させる工程において、ＰＴＣ素子へヒートショックが付加され、ＰＴＣ素子の抵抗値を下げる効果も得られる。
【００１７】
作製された封口板は、クリームハンダによる溶着部位が各要素の積層面間に形成されることで、要素間の接触抵抗が減少しており、従来構成の封口板に比して放電特性を改善する効果も奏する。また、各要素の積層面全体にクリームハンダを塗布することで、溶接部位の面積が最大化され、封口板の液密性を大幅に向上させる効果も得られる。
【００１８】
【発明の実施の形態】
以下、本願発明の実施形態を説明する。この実施形態は、上述した第１及び第２の発明を具現化した一例を示したものであり、以下の記載内容に限定するものではない。
【００１９】
（第１の実施形態）
第１の実施形態に係る密閉型電池の封口板は、中央部に凸部を有し、上面または側面部にガス抜き孔を設けたキャップ状端子板、このキャップ状端子板の下側に配置され、中央部にガス抜き孔を設けたＰＴＣ素子、前記発電要素の一方の電極に接続され、中央部にガス抜き孔を有する皿板、この皿板のガス抜き孔を閉塞し、電池の内圧上昇時に膨脹、破断する機能を有し、前記皿板とＰＴＣ素子との間に配される金属製の安全弁膜を備える。
【００２０】
皿板は、シート状の鋼板をプレス加工することで所定形状に打ち抜き、中央部に円形或いは方形状のガス抜き孔を打ち抜くことで作成される。さらにプレス加工を施し、中央部を電池ケース側に突出させ、平坦面を形成した形状としても良い。皿板の外周形状は、電池ケースの封口部形状に応じて設定され、厚み方向の形状は封口部位の形状等の種々因子を考慮し、決定される。皿板の下面は、電池ケースの開口部に配置される際に、ケースに収容された正負極板の何れか一方から延出された接続リードを接続する。この時、前記平坦面を形成した皿板では、前記平坦面と皿板の上部に配置される安全弁膜との間に間隙が存在し、接続リードを溶接する際の安全弁膜への熱影響、応力付加の影響を回避できる。
【００２１】
安全弁膜は、金属薄板、好ましくはアルミニウム箔からなり、電池の内圧上昇にともなって、上方に膨れる。この時、キャップ状端子板の内頂部に切刃を設けた構成では、切刃によって安全膜が破断され、未設置の構成では、安全弁膜の破断強度を調整することで、電池内圧が所定値以上に上昇しない。また、ＰＴＣ素子は、上述した皿板と同様に封口部の形状に応じた外周形状に打ち抜かれ、中央部に円形或いは方形状のガス抜き孔を形成し、ドーナツ状とされる。ＰＴＣ素子は導電性高分子材料の表裏面に金属薄板を一体化した構造を有しており、封口板の他の要素に対して溶着、及び溶接による接続が可能である。
【００２２】
キャップ状端子板は、中央部に凸部を有し、上面または側面部にガス抜き孔を設けた形態である。この端子板は、ステンレス鋼板等をプレス加工にて所定の外観形状に打ち抜いた後、さらに中央部を突出させるようにプレス加工を施している。凸部は、封口板の様態に完成した際に、皿板及びＰＴＣ素子の中央部に形成したガス抜き孔と連通する様に形状を規定している。また、安全弁膜を切刃にて破断させる構成を採用した場合には、凸部の頂面の一部を、先端が鋭利な形状で折り曲げることで切刃が形成される。
【００２３】
上述の様に形成された封口板の各要素は、皿板上に安全弁膜、ＰＴＣ素子及びキャップ状端子板を載置し、以下に記す方法にて一体化される。
【００２４】
第１の方法としては、抵抗溶接を用いた方法である。この方法としては、先ず皿板上に安全弁膜を配置し、両者を抵抗溶接にて一体化する。この抵抗溶接は皿板の中央部に形成されたガス抜き孔の周縁を取り囲む様に連続した溶接部位を形成する。引き続いて、安全弁体上にＰＴＣ素子を配置し、上記と同様に抵抗溶接を実施する。この時、安全弁体と皿板は既に抵抗溶接により一体化されており、抵抗溶接による電流はＰＴＣ素子と安全弁体との積層面に集中する。この電流集中により生じた発熱にて、ＰＴＣ素子と安全弁膜の溶接がなされる。同様にＰＴＣ素子とキャップ状端子板の間にて抵抗溶接を施すことで接合がなされる。作製された封口板は、各要素の積層面が抵抗溶接にて一体化されており、溶接部位が封口板の外周から中央のガス抜き孔への連通を断っているので、液密性を獲得できる。
【００２５】
上記の作製方法に代えて、ＰＴＣ素子とキャップ状封口板を予め一体化しておき、安全弁膜及び皿板と一体化する方法を採用しても良く、各要素を一体化するのであれば、その順序は問わない。また、安全弁膜と皿板との界面は、安全弁膜によって外部との連通が遮断されていることから、導電性のみを確保する構成としても良い。
【００２６】
第２の方法としては、レーザー溶接を用いた方法である。この方法では、レーザー溶接が各要素の積層面の外周縁、或いはガス抜き孔の内周縁に沿って施される。このため、同一径を有する要素を重ね合わせた場合、積層面の縁部は両者の側面部分となる。ＰＴＣ素子の金属部分、及び安全弁膜は極薄に形成されていることから、側面方向からのレーザー溶接は生産の悪化を来す虞がある。そこで、接続される要素の外周縁、若しくは内周縁の径を相違させることで、前記縁部を一方の要素の積層面上に露呈させ、この部位にレーザー溶接を施すことで、要素を一体化できる。
【００２７】
第３の方法としては、クリームハンダを用いる方法である。この方法では、クリームハンダを要素の積層面に塗布した状態で各要素を積層し、加熱及び加圧を施すことによって一体化を行う。
【００２８】
本実施形態では、封口板を構成する要素を溶着、溶接する方法として上述した３つの手法を個別に説明した。これらの方法に加えて、超音波や高周波溶着による方法、導電性を有する接着剤（銀系導電性接着剤、Ｎｉ系導電性接着剤）を用いる方法や、導電性ペーストや拡散接合による方法を採用しても良い。さらに、要素毎に異なる一体化方法を用いても良い。
【００２９】
このように本実施形態に係る封口板は、積層面に液密性を有する。このため、封口板への電解液の侵入を阻止し、封口板を介した漏液の発生を確実に抑制することで、高温保存時などにおける電池の耐漏液性を大幅に向上させることができる。
【００３０】
（第２の実施形態）
第２の実施形態に係る密閉型電池の封口板は、キャップ状端子板、ＰＴＣ素子、皿板に加え、皿板のガス抜き孔を閉塞し、電池の内圧上昇時に膨脹、破断する機能を有し、皿板とＰＴＣ素子との間に配される金属と樹脂とのラミネート材からなる安全弁膜を備える。キャップ状端子、ＰＴＣ素子及び皿板は、第１の実施形態にて適用されるものとほぼ同一であり、その詳細な説明は省略する。本実施形態におけるＰＴＣ素子は、前記キャップ状端子板及び皿板に対して溶着、あるいは溶接にて一体化される。一方、安全弁膜は、ＰＴＣ素子及び皿板に対して接着される。そして、これら溶接／溶着が施された部位、及び接着が施された部位を設けることで、封口板を介した漏液の発生が抑制される。
【００３１】
安全弁膜は、皿板及びＰＴＣ素子に接する面に接着層を形成し、これらを一体化することで作製される。接着層には、耐有機電解液性に加えて、金属及びラミネート層を形成する樹脂との接着性に優れることが要求される。接着層を形成する接着の例としては、２液混合型のエポキシ樹脂、アクリル系のホットメルト接着剤等が用いられる。
【００３２】
一方、ＰＴＣ素子と皿板及びキャップ状端子板との溶着／溶接は、第１の実施形態と同様の接合方法が適用される。特にクリームハンダを使用する方法では、接着層がハンダ溶融時の熱影響を受け易いことから、耐熱性の低い接着剤を使用する場合には、予め一体化を施しておくのが好ましい。また、熱硬化形の接着剤を用いる場合には、クリームハンダの溶融工程おいて接着層の硬化もなされる。このため、工程の簡素化に加え、一体化が確実になされ、封口板の耐漏液性を一層向上させるものである。
【００３３】
また、安全弁膜は表面をラミネート層が形成されているために、皿板とＰＴＣ素子との導電性を確保する必要がある。そこで、皿板及びＰＴＣ素子に比べて安全弁膜を小径とし、その外周に導電性を確保するためのスペーサーを配置し、一体化することで導電性は確保される。このスペーサーは、キャップ状端子板とＰＴＣ素子との一体化と同様に、第１の実施形態と同様の接合方法が適用される。
【００３４】
さらに、前記のスペーサーに代えて、皿板に突起を形成し、ＰＴＣ素子との導電性を確保する構成として良い。この構成は、皿板の主面にＰＴＣ素子側に突出した円錐状の突起部が設け、突起によりＰＴＣ素子との導電性を確保するものである。この突起は、ガス抜き孔の周縁に沿って、且つ等間隔をおいて設けられた３個以上の円錐状の突起や、複数個の円弧形の突条を設け、突条が円を描く形状とされる。この突起を介して、ＰＴＣ素子と皿板との抵抗溶接を実施することで、両者の一体化がなされる。
【００３５】
【実施例】
以下、本発明の実施例について図面を参照しながら説明する。
【００３６】
図１は、本発明に係る密閉型電池の部分断面図である。本発明に係る電池の主たる要素である封口板は、皿板７、安全弁膜６、ＰＴＣ素子４、キャップ状端子板１の順で載置された構成を有しており、電池ケース１０の開口部に配されている。図１から明らかなように、封口板はガスケット８を介してカシメ固定されており、電池ケースを封口している。また、電池ケース１０に収容された発電要素の一方極の極板に接続される。本実施例では、正極板に接続されたリード板９は、皿板７の底面に溶接されている。キャップ状端子板１はガス抜き孔２を有している。本実施例では、このガス抜き孔２はキャップ状端子板１の凸部３の上面から側面にかけた部位に形成されたものを用いた。
【００３７】
この封口板は、皿板７、安全弁膜６、ＰＴＣ素子４、キャップ状端子板１の各積層面の全体に、クリームハンダを塗布した後、これを溶融させた状態で、封口板の厚み方向に加圧を施することで得られたものである。得られた封口板は、溶着部位５を介して隣接する要素と接合されており、且つ溶着部位５が積層面の全体に形成されることから、ガスケット８を介して封口板へ達した電解液が、積層面に侵入するのを抑制している。
【００３８】
上記の構成を有する封口板を使用し、正極に二酸化マンガン、負極に金属リチウムを用いた円筒形の非水電解液電池を作製した（電池Ａ）。また、比較例として、各要素の一体がなされていない従来構成の封口板を用いた非水電解液電池を作製した（電池Ｂ）。尚、作製個数は、３００個ずつとした。
【００３９】
作製された電池の耐漏液性を検討するために、高温環境下における保存試験を実施した。試験条件は、８５℃の高温環境下に１ヶ月間とし、保存後における漏液の発生有無を顕微鏡による目視検査を行った。その結果を（表１）に示す。
【００４０】
【表１】

【００４１】
（表１）に示したように、高温保存時における耐漏液性を向上させることができた。
【００４２】
【発明の効果】
以上のように、本発明の封口板は、電池の高温保存時における耐漏液性を向上させることができるものであり、その工業的価値は大なるものである。
【図面の簡単な説明】
【図１】本実施例における封口板を備えた電池の部分断面図
【符号の説明】
１キャップ状端子板
２ガス抜き孔
３凸部
４ＰＴＣ素子
５溶着部位
６安全弁膜
７皿板
８絶縁パッキング
９リード板[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sealed battery that includes a sealing plate that closes an opening of a battery case that houses a power generation element and in which a PTC element is disposed, and has improved leakage resistance in the sealing plate.
[0002]
[Prior art]
Since the sealed battery has a high capacity, it is used in a wide range of fields in addition to the power source of portable devices. In particular, a negative electrode made of lithium or an alloy thereof, and a sealed battery using a non-aqueous electrolyte (hereinafter referred to as a non-aqueous electrolyte battery) have extremely small deterioration in battery characteristics with respect to long-term storage and use. Since the possible temperature range is wide, it is an indispensable battery in fields where high reliability such as a power source of a gas meter and a power source of an in-vehicle emergency call system is facilitated in addition to the power source of the device.
[0003]
The non-aqueous electrolyte battery has a high energy density as described above, and a PTC element and an explosion-proof function are used as a sealing plate in order to avoid a decrease in safety due to abnormal discharge, short circuit, etc. of the battery. I have. The sealing plate is configured such that a safety valve membrane, a PTC element, and a cap-shaped terminal plate are placed on a plate plate electrically connected to one electrode plate.
[0004]
When the internal pressure of the battery rises, the safety valve membrane disposed between the vent holes of the sealing plate swells upward. When the safety valve membrane swells more than a predetermined amount, the cutting blade provided inside the cap-shaped terminal plate facing the safety valve membrane breaks the safety valve membrane and forms a ventilation path, so that the gas in the battery is It passes through the ruptured portion of the safety valve membrane, passes through the vent holes of the PTC element and cap-shaped terminal plate, and is discharged to the outside of the battery.
[0005]
Further, when the temperature in the battery rises, the resistance value of the PTC element increases and functions as an insulator so that no more current flows from the cap-shaped terminal plate into the battery.
[0006]
[Problems to be solved by the invention]
In the sealing plate having the above-described configuration, the plate on which the safety valve membrane, the PTC element, and the cap-shaped terminal plate are placed is caulked and integrated with a seamer or the like in the manufacturing process. However, at the time of crimping, the plate tends to cause defects such as eccentricity, and the productivity is lowered. Further, the poor caulking state has been a major cause of reducing the liquid leakage resistance during high temperature storage.
[0007]
Therefore, the present inventors placed a sealing plate on which the dish plate, safety valve membrane, PTC element and cap-shaped terminal plate are placed in the opening of the battery case, and then fixed the element of the sealing plate by the sealing of the battery case. By adopting the holding structure, it was proposed to improve the leakage resistance of the sealing plate while facilitating and simplifying the assembly process.
[0008]
A sealed battery using a sealing plate based on this proposal is stored on a plate in a use state in which it is stored or used for a long period of time as a backup power source, particularly in a use state in which it is stored for a long time in a high temperature environment. In some cases, the electrolytic solution may invade between the laminated surfaces of the mounted elements, and the electrolytic solution that has entered may leak from the vent hole of the cap-shaped terminal plate.
[0009]
An object of the present invention is to provide a sealing plate that prevents the occurrence of liquid leakage through the laminated surface of the sealing plate as described above, and not only has high reliability, but also hermetically sealed with suppressed deterioration of battery characteristics. It is to provide a type battery.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a sealed battery according to the first invention of the present application houses a power generation element composed of a positive electrode, a negative electrode, a separator, and an electrolytic solution in a battery case that serves as either a positive or negative terminal. The opening of the battery case is closed with a sealing plate that forms a terminal of the other electrode, and the sealing plate has a convex portion at the center and a gas vent hole on the upper surface or side surface thereof. A cap-shaped terminal board provided with a PTC element disposed on the lower side of the cap-shaped terminal board and provided with a gas venting hole in the central part, connected to one electrode of the power generating element, and having a gas venting hole in the central part A plate having a metal safety valve that closes the vent hole of the plate and expands and breaks when the internal pressure of the battery rises, and is provided between the plate and the PTC element. The cap-shaped terminal plate, PTC element, safety valve , And a point of integrating the entire laminate surface to the other element components of the dish plate adjacent welding or by peripheral continuous welded so as to surround the vent hole, and welding, or welding is applied It is characterized in that the part is liquid-tight.
[0011]
The battery having such a structure is welded using solder or the like on each laminated surface of the safety valve membrane, the PTC element, and the cap-shaped terminal plate placed in a dish plate shape, that is, a contact surface with an adjacent element, or The welding / welding site is formed by welding means such as resistance welding or laser welding. These parts are liquid-tight by setting the entire laminated surface as a welding part, or by making a welding part over the entire circumference of the contact surface, for example, at least one continuous welding part. As a result, not only the elements constituting the sealing plate are electrically connected, but also liquid-tightness is imparted, thereby preventing the electrolyte from entering between the laminated surfaces and causing leakage through the sealing plate. The generation of liquid is surely suppressed.
[0012]
Further, the sealing plate according to the second invention of the present application is a cap-shaped terminal plate having a convex portion at the center portion and provided with a vent hole on the upper surface or side surface portion thereof, on the lower side of the cap-shaped terminal plate. PTC element having a vent hole in the central part, connected to one electrode of the power generation element, a dish plate having a gas vent hole in the central part, closing the gas vent hole of the dish plate, It has a function of expanding and breaking when the internal pressure rises, and comprises a safety valve film made of a laminate material of a metal and a resin disposed between the dish plate and the PTC element, and the PTC element is the cap-shaped terminal plate And the whole laminated surface is welded to the plate, or integrated by continuous welding so as to surround the periphery of the vent hole, and the safety valve membrane is formed on the whole laminated surface to the PTC element and the plate. The point to be bonded and the welding / welding is performed Sites, and sites that adhesive is applied is characterized in that it is liquid-tight.
[0013]
The second invention uses a thin metal plate laminated with a resin on the safety valve membrane, and the safety valve membrane is sandwiched between the PTC element and the dish plate. Safety valve membrane, since the resin Ramine coat layer is formed on the surface, the laminated surface of the safety valve membrane and the dish plate and the PTC element are integrated by bonding. For the adhesion, a material excellent in organic electrolyte resistance and having excellent adhesion to the resin and the metal portion disposed on the main surface of the PTC element and the dish plate is used. This material is preferably an epoxy or acrylic (hot melt) adhesive. In addition, the safety valve membrane does not have conductivity due to the presence of the resin laminate layer, and does not serve as an energization path. Therefore, in order to ensure conductivity, the PTC element and the plate are electrically connected.
[0014]
On the other hand, the PTC element is electrically connected to the cap-shaped terminal plate and the plate by welding using solder, conductive adhesive, or the like, or resistance welding or laser welding. As well as providing liquid-tightness to the sealing plate.
[0015]
According to such a configuration, the laminated surface of the site serving as the energization path forms a weld or weld site, integrates the PTC element, the cap-shaped terminal plate, and the dish plate, and connects the resin site and the metal site. Since the connecting parts of the safety valve membrane to be connected to the dish plate and the PTC element are integrated by adhesion, the leakage resistance is improved. Furthermore, the site | part used as an electricity supply path improves electrical conductivity by welding and welding, and improves productivity by integrating parts other than an electricity supply path | route with an adhesive agent.
[0016]
Each of the sealed batteries according to the present invention preferably uses cream solder for the welding. The cream solder is applied to the laminated surface of the dish plate, the safety valve membrane, the PTC element, and the cap-shaped terminal plate. And after arrange | positioning each element in the shape of a plate, it inserts into an electric furnace, a high frequency furnace, etc., a cream solder is fuse | melted and each element is integrated by pressurizing a sealing board. In this manufacturing method, the cream solder application process and the process of melting the applied cream solder are increased as compared with the conventional sealing plate assembly process. However, the increase in man-hours is kept to a minimum and does not cause deterioration of production. Further, in the process of melting the cream solder, a heat shock is applied to the PTC element, and the effect of lowering the resistance value of the PTC element can be obtained.
[0017]
The produced sealing plate has a welded area formed by cream solder between the laminated surfaces of each element, reducing the contact resistance between the elements and improving the discharge characteristics compared to the sealing plate of the conventional configuration. The effect to do. Further, by applying cream solder to the entire laminated surface of each element, the area of the welded portion is maximized, and the effect of greatly improving the liquid tightness of the sealing plate can be obtained.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described. This embodiment shows an example that embodies the first and second inventions described above, and is not limited to the following description.
[0019]
(First embodiment)
The sealing plate of the sealed battery according to the first embodiment is a cap-shaped terminal plate having a convex portion at the center and provided with a vent hole on the upper surface or the side surface, and is disposed below the cap-shaped terminal plate. A PTC element having a vent hole in the center, a dish plate connected to one electrode of the power generation element and having a vent hole in the center part, closing the vent hole in the dish plate, It has a function of expanding and breaking when raised, and includes a metal safety valve membrane disposed between the plate and the PTC element.
[0020]
The dish plate is created by punching a sheet-shaped steel plate into a predetermined shape by pressing and punching a circular or rectangular gas vent hole in the center. Furthermore, it is good also as a shape which gave press work and protruded the center part to the battery case side, and formed the flat surface. The outer peripheral shape of the plate is set according to the shape of the sealing part of the battery case, and the shape in the thickness direction is determined in consideration of various factors such as the shape of the sealing part. When the lower surface of the dish plate is disposed in the opening of the battery case, the connection lead extending from one of the positive and negative electrode plates accommodated in the case is connected. At this time, in the dish plate formed with the flat surface, there is a gap between the flat surface and the safety valve film disposed on the upper part of the dish plate, the thermal effect on the safety valve film when welding the connection lead, The effect of applying stress can be avoided.
[0021]
The safety valve membrane is made of a thin metal plate, preferably aluminum foil, and swells upward as the internal pressure of the battery increases. At this time, in the configuration in which the cutting blade is provided on the inner top portion of the cap-shaped terminal plate, the safety membrane is broken by the cutting blade, and in the configuration in which the cutting blade is not installed, the internal pressure of the battery is set to a predetermined value by adjusting the breaking strength of the safety valve membrane. It will not rise any more. In addition, the PTC element is punched into an outer peripheral shape corresponding to the shape of the sealing portion in the same manner as the above-described dish plate, and a circular or rectangular gas vent hole is formed in the central portion to form a donut shape. The PTC element has a structure in which a thin metal plate is integrated on the front and back surfaces of a conductive polymer material, and can be connected to other elements of the sealing plate by welding and welding.
[0022]
A cap-shaped terminal board has a convex part in the center part, and is a form which provided the vent hole in the upper surface or the side part. This terminal board is subjected to press work so that a central portion protrudes after a stainless steel plate or the like is punched into a predetermined external shape by press work. The convex portion defines the shape so as to communicate with the vent hole formed in the central portion of the dish plate and the PTC element when completed in the form of a sealing plate. Moreover, when the structure which fractures | ruptures a safety valve membrane with a cutting blade is employ | adopted, a cutting blade is formed by bend | folding a part of top surface of a convex part in the shape where the front-end | tip is sharp.
[0023]
The elements of the sealing plate formed as described above are integrated by a method described below by placing a safety valve membrane, a PTC element, and a cap-shaped terminal plate on a dish plate.
[0024]
The first method is a method using resistance welding. As this method, first, a safety valve membrane is disposed on a plate, and both are integrated by resistance welding. In this resistance welding, a continuous welded portion is formed so as to surround the periphery of the gas vent hole formed in the central portion of the plate. Subsequently, a PTC element is disposed on the safety valve body, and resistance welding is performed in the same manner as described above. At this time, the safety valve body and the plate are already integrated by resistance welding, and the current due to resistance welding is concentrated on the laminated surface of the PTC element and the safety valve body. The PTC element and the safety valve membrane are welded by the heat generated by the current concentration. Similarly, joining is performed by performing resistance welding between the PTC element and the cap-shaped terminal plate. The produced sealing plate has a laminated surface of each element integrated by resistance welding, and the welded part cuts off the communication from the outer periphery of the sealing plate to the central vent hole, thus obtaining liquid tightness it can.
[0025]
Instead of the above manufacturing method, the PTC element and the cap-shaped sealing plate may be integrated in advance, and a method of integrating with the safety valve membrane and the dish plate may be adopted. The order does not matter. In addition, since the interface between the safety valve membrane and the dish plate is blocked from communication with the outside by the safety valve membrane, only the conductivity may be secured.
[0026]
The second method is a method using laser welding. In this method, laser welding is performed along the outer peripheral edge of the laminated surface of each element or the inner peripheral edge of the vent hole. For this reason, when the element which has the same diameter is piled up, the edge part of a lamination | stacking surface turns into a side part of both. Since the metal portion of the PTC element and the safety valve membrane are formed extremely thin, laser welding from the side surface direction may cause deterioration in production. Therefore, by making the diameter of the outer peripheral edge or inner peripheral edge of the connected elements different, the edge is exposed on the laminated surface of one element, and laser welding is applied to this part, thereby integrating the elements it can.
[0027]
The third method is a method using cream solder. In this method, each element is laminated in a state where cream solder is applied to the laminated surface of the elements, and integration is performed by applying heat and pressure.
[0028]
In the present embodiment, the three methods described above are individually described as methods for welding and welding the elements constituting the sealing plate. In addition to these methods, a method using ultrasonic waves or high-frequency welding, a method using a conductive adhesive (silver-based conductive adhesive, Ni-based conductive adhesive), a method using conductive paste or diffusion bonding, etc. It may be adopted. Furthermore, different integration methods may be used for each element.
[0029]
Thus, the sealing board which concerns on this embodiment has liquid-tightness on a lamination surface. For this reason, the leakage resistance of the battery during high-temperature storage can be greatly improved by preventing the electrolyte from entering the sealing plate and reliably suppressing the occurrence of leakage through the sealing plate. .
[0030]
(Second Embodiment)
The sealing plate of the sealed battery according to the second embodiment has a function of expanding and breaking when the internal pressure of the battery is increased in addition to the cap-shaped terminal plate, the PTC element, and the dish plate, closing the gas vent hole of the dish plate. And a safety valve membrane made of a laminate material of a metal and a resin disposed between the dish plate and the PTC element. The cap-shaped terminal, the PTC element, and the plate are almost the same as those applied in the first embodiment, and detailed description thereof is omitted. The PTC element in this embodiment is integrated by welding or welding to the cap-shaped terminal plate and the plate. On the other hand, the safety valve membrane is bonded to the PTC element and the dish plate. And the generation | occurrence | production of the liquid leakage through a sealing board is suppressed by providing the site | part to which these welding / welding was given, and the site | part to which adhesion | attachment was given.
[0031]
The safety valve membrane is manufactured by forming an adhesive layer on the surface in contact with the plate and the PTC element and integrating them. The adhesive layer is required to have excellent adhesion to the metal and the resin that forms the laminate layer, in addition to the organic electrolyte resistance. As an example of adhesion for forming the adhesive layer, a two-component mixed epoxy resin, an acrylic hot melt adhesive, or the like is used.
[0032]
On the other hand, the welding method similar to that of the first embodiment is applied to the welding / welding of the PTC element, the plate, and the cap-shaped terminal plate. In particular, in the method using cream solder, since the adhesive layer is easily affected by heat when the solder is melted, it is preferable to perform integration in advance when using an adhesive having low heat resistance. Further, when a thermosetting adhesive is used, the adhesive layer is also cured in the cream solder melting step. For this reason, in addition to simplification of the process, the integration is ensured, and the leakage resistance of the sealing plate is further improved.
[0033]
Moreover, since the safety valve membrane has a laminate layer formed on its surface, it is necessary to ensure the conductivity between the plate and the PTC element. Thus, the safety valve membrane has a smaller diameter than that of the plate and the PTC element, and a spacer for ensuring conductivity is disposed on the outer periphery of the safety valve membrane so as to ensure the conductivity. For this spacer, the same joining method as in the first embodiment is applied, as in the case of integration of the cap-shaped terminal plate and the PTC element.
[0034]
Furthermore, it is good also as a structure which replaces with the said spacer and forms a protrusion in a saucer plate and ensures electroconductivity with a PTC element. In this configuration, a conical projection protruding to the PTC element side is provided on the main surface of the plate, and the conductivity with the PTC element is ensured by the projection. The protrusions are provided with three or more conical protrusions and a plurality of arc-shaped protrusions provided at equal intervals along the periphery of the gas vent hole, and the protrusions draw a circle. Shaped. The PTC element and the dish plate are subjected to resistance welding via the protrusions, so that both are integrated.
[0035]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0036]
FIG. 1 is a partial cross-sectional view of a sealed battery according to the present invention. The sealing plate, which is the main element of the battery according to the present invention, has a configuration in which the plate 7, the safety valve membrane 6, the PTC element 4, and the cap-shaped terminal plate 1 are placed in this order. It is arranged in the department. As is clear from FIG. 1, the sealing plate is caulked and fixed via the gasket 8 to seal the battery case. Further, it is connected to one electrode plate of the power generation element housed in the battery case 10. In the present embodiment, the lead plate 9 connected to the positive electrode plate is welded to the bottom surface of the dish plate 7. The cap-shaped terminal board 1 has a gas vent hole 2. In the present embodiment, the gas vent hole 2 is formed in a portion extending from the upper surface to the side surface of the convex portion 3 of the cap-shaped terminal board 1.
[0037]
The sealing plate is formed by applying cream solder to the entire laminated surface of the plate 7, the safety valve membrane 6, the PTC element 4, and the cap-shaped terminal plate 1, and then melting it in the thickness direction of the sealing plate. It was obtained by applying pressure to the. The obtained sealing plate is joined to an adjacent element via the welded portion 5 and the welded portion 5 is formed on the entire laminated surface, so that the electrolyte solution that has reached the sealing plate via the gasket 8 However, it has suppressed that it penetrate | invades into a lamination | stacking surface.
[0038]
Using the sealing plate having the above-described configuration, a cylindrical non-aqueous electrolyte battery using manganese dioxide for the positive electrode and metallic lithium for the negative electrode was produced (battery A). In addition, as a comparative example, a nonaqueous electrolyte battery using a sealing plate having a conventional configuration in which each element is not integrated was manufactured (battery B). In addition, the production number was 300 pieces each.
[0039]
In order to examine the leakage resistance of the fabricated battery, a storage test was conducted in a high temperature environment. The test conditions were one month in a high temperature environment of 85 ° C., and the presence or absence of leakage after storage was visually inspected with a microscope. The results are shown in (Table 1).
[0040]
[Table 1]

[0041]
As shown in (Table 1), the liquid leakage resistance during high temperature storage could be improved.
[0042]
【The invention's effect】
As described above, the sealing plate of the present invention can improve the leakage resistance when the battery is stored at high temperatures, and its industrial value is great.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view of a battery provided with a sealing plate in this embodiment.
DESCRIPTION OF SYMBOLS 1 Cap-shaped terminal board 2 Gas vent hole 3 Convex part 4 PTC element 5 Welding part 6 Safety valve membrane 7 Dish board 8 Insulation packing 9 Lead board

Claims

A power generation element composed of a positive electrode, a negative electrode, a separator, and an electrolyte is housed in a battery case that serves as either a positive or negative terminal, and the battery case is closed with a sealing plate that forms a terminal of the other electrode. A battery,
The sealing plate is a cap-shaped terminal plate having a convex portion at the center and provided with a gas vent on the upper surface or side surface thereof, and is disposed below the cap-shaped terminal plate. PTC element provided with a plate plate connected to one electrode of the power generation element and having a vent hole in the center, and the function of expanding and breaking when the internal pressure of the battery is increased by closing the vent hole of the plate plate having a metal safety valve membrane arranged between the said dish plate and the PTC element as an element, the cap-shaped terminal plate, PTC element, laminated to other elements adjacent safety valve membrane, and dish plate A sealed battery characterized in that the whole surface is welded or integrated by continuous welding so as to surround the periphery of the vent hole , and the welded or welded portion is liquid-tight.

A power generation element composed of a positive electrode, a negative electrode, a separator, and an electrolyte is housed in a battery case that serves as either a positive or negative terminal, and the battery case is closed with a sealing plate that forms a terminal of the other electrode. A battery,
The sealing plate is a cap-shaped terminal plate having a convex portion at the center and provided with a gas vent on the upper surface or side surface thereof, and is disposed below the cap-shaped terminal plate. PTC element provided with a plate plate connected to one electrode of the power generation element and having a vent hole in the center, and the function of expanding and breaking when the internal pressure of the battery is increased by closing the vent hole of the plate plate And a safety valve membrane made of a laminate material of a metal and a resin disposed between the dish plate and the PTC element. The PTC element has an entire laminated surface with respect to the cap-shaped terminal plate and the dish plate. It is integrated by welding or continuous welding so as to surround the periphery of the vent hole, and the safety valve membrane is bonded to the entire laminated surface with respect to the PTC element and the plate, and the welded and welded portion is applied. , And the part where the adhesive is applied is liquid-tight Sealed battery, characterized in that.

The sealed battery according to claim 1, wherein the welding is performed with cream solder.