JP4202539B2

JP4202539B2 - Manufacturing method of sealed battery

Info

Publication number: JP4202539B2
Application number: JP20304699A
Authority: JP
Inventors: 昌浩加藤; 克久本間; 雄二小口; 税萩原; 正治山中
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 1998-08-13
Filing date: 1999-07-16
Publication date: 2008-12-24
Anticipated expiration: 2019-07-16
Also published as: JP2000123822A

Description

【０００１】
【発明の属する技術分野】
本発明は、密閉電池および密閉電池の製造方法に関し、特に電解液の注入孔を封止する構造を改良した密閉電池およびその製造方法に係わる。
【０００２】
【従来の技術】
従来、この種の密閉電池、例えば角型密閉電池は次のような構造を有する。
【０００３】
（１）有底角筒形の金属製外装缶と、この外装缶内に収納された発電要素と、前記外装缶の開口部から注入された電解液と、前記外装缶の上端開口部に溶接により接合され、ハーメティックシールにより絶縁された電極端子を有する金属製蓋体とを備えた密閉電池。
【０００４】
（２）有底角筒形の外装缶と、この外装缶内に収納された発電要素と、前記外装缶の開口部に溶接により接合され、ハーメティックシールにより絶縁された電極端子および電解液の注入孔を有する金属板材からなる蓋体と、前記蓋体の注入孔を通して前記外装缶内に注入された電解液と、前記注入孔に差し込まれ、ろう付けまたは抵抗溶接により接合された球形状または釘形の栓体とを備えた密閉電池。
【０００５】
しかしながら、前述した（１）の構造を有する角型密閉電池では外装缶の上端開口部に蓋体を溶接する際、前記外装缶内に既に電解液が収容され、電解液が蒸発された雰囲気下でなされる。このため、前記外装缶と前記蓋体との溶接箇所に電解液蒸気が付着して溶接不良が生じて密閉性が著しく低下される。
【０００６】
前記（２）の構造を有する角型密閉電池では、前記栓体を電解液が付着されている注入孔に差し込み、抵抗溶接またはろう付けを行なう。このため、前記電解液の蒸発により前記栓体の接合不良を招く恐れがある。また、軽量化を図る目的で前記蓋体をアルミニウムにより形成する場合、前記栓体をろう付けや抵抗溶接により前記蓋体の注入孔に接合することが困難になる。
【０００７】
なお、注入孔を外装缶の底面や側面に設けた密閉電池においても、部位が異なるだけで、他の構成が変わらないため注入孔を蓋体に設けた電池と同様な問題が起こる。
【０００８】
また、角型の密閉電池のみならず、円筒型の密閉電池においても、前記（１）の技術では角型と同様な理由から溶接不良が生じて密閉性が低下する。前記（２）の技術では、角型と同様な理由から接合不良が起こったり、接合自体が困難になる。
【０００９】
【発明が解決しようとする課題】
本発明は、外装缶の開口部に蓋体を気密に接合またはカシメを行なった電池ケースを有し、かつ前記電池ケースの注入孔を金属封止部材で気密に封止した構造の密閉電池およびその製造方法を提供しようとするものである。
【００１０】
【課題を解決するための手段】
本発明に係る密閉電池の製造方法は、アルミニウム系金属からなる外装缶内にセパレータを挟んで対峙された正極および負極を有する発電要素を収納する工程；
前記外装缶の開口部にアルミニウム系金属からなる蓋体を溶接により接合して電池ケースを作製する工程；
前記電池ケース内に電解液をそのケースに開口された注入孔を通して注入する工程；
前記注入孔を含む前記電池ケースにアルミニウム系金属板材を配置する工程；
一端側に円筒部を有し、その円筒部の先端面に複数の突起が形成された円柱状ホーンを用意する工程；および
前記円柱状ホーンの前記円筒部の先端面を前記金属板材に対してその円筒部が前記注入孔を包囲するように当接させ、このホーンを通して前記金属板材に超音波を付与して前記金属板材を前記電池ケースに溶接すると共に前記円筒部の外縁に沿って前記金属板材を溶断することにより円板状の封止部材を前記電池ケースに接合して前記注入孔を気密封止する工程；
を具備したことを特徴とするものである。
【００１６】
【発明の実施の形態】
以下、本発明に係わる密閉電池を角型密閉電池を例として図面を参照して詳細に説明する。ここで、角型とは外装缶を発電要素を含む面で切断したときの形状が長方形であることを意味するが、コーナ部においてアールが付けられることを許容するものである。
【００１７】
図１１は、本発明に係わる密閉電池、例えば角型密閉リチウムイオン二次電池を示す斜視図である。
【００１８】
角型の電池ケース１は、例えばアルミニウム系金属からなる有底矩形筒状をなす外装缶２の開口部にアルミニウム系金属からなる蓋体３を例えばレーザ溶接により気密に接合した構造を有する。前記外装缶２は、例えば正極端子を兼ね、底部内面に絶縁フィルム４が配置されている。
【００１９】
発電要素である電極体５は、前記電池ケース１の外装缶２内に収納されている。前記電極体５は、例えば負極６とセパレータ７と正極８とを前記正極８が最外周に位置するように渦巻状に捲回した後、扁平状にプレス成形することにより作製される。中心付近にリード取出穴を有する例えば合成樹脂からなるスペーサ９は、前記外装缶２内の前記電極体５上に配置されている。
【００２０】
前記蓋体３の中心付近には、負極端子の取出し穴１０が開口されている。注入孔１１は、前記取出し穴１０から離れた前記蓋体３の箇所に開口されている。電解液は、前記注入孔１１を通して前記外装缶２内に注入されている。負極端子１２は、前記蓋体３の穴１０にガラス製または樹脂製の絶縁材１３を介してハーメティクシールされている。前記負極端子１２の下端面には、リード１４が接続され、かつこのリード１４の他端は前記電極体５の負極６に接続されている。
【００２１】
上部側絶縁紙１７は、前記蓋体３の外表面全体に被覆されている。スリット１８を有する下部側絶縁紙１９は、前記外装缶２の底面に配置されている。二つ折りされたＰＴＣ（Positive Thermal Coefficient）素子２０は、一方の面が前記外装缶２の底面と前記下部側絶縁紙１９の間に介装され、かつ他方の面が前記スリット１８を通して前記絶縁紙１９の外側に延出されている。外装チューブ２１は、前記外装缶２側面から上下面の絶縁紙１７、１９の周辺まで延出するように配置され、前記上部側絶縁紙１７および下部側絶縁紙１９を前記外装缶２に固定している。このような外装チューブ２１の配置により、外部に延出された前記ＰＴＣ素子２０の他方の面が前記下部側絶縁紙１９の底面に向けて折り曲げられる。
【００２２】
前記電池ケースの材質であるアルミニウム系金属としては、例えば純アルミニウム、０．０５重量％以下のＭｇおよび０．２重量％以下のＣｕを含むアルミニウム合金を挙げることができる。このようなアルミニウム系金属としては、例えばＪＩＳの合金番号でＡ１０５０、Ａ１１００、Ａ１２００、Ａ３００３等を挙げることができる。ただし、電池ケースはアルミニウム系金属の他にステンレスまたは鉄を用いることを許容する。
【００２３】
前記電池ケースをアルミニウム系金属により作った場合には、その厚さを０．５ｍｍ以上、より好ましくは１ｍｍ以上にすることが望ましい。電池ケースの厚さを０．５ｍｍ未満にすると、強度が低下して外装缶に収納された発電要素を十分に保護することが困難になる。
【００２４】
前記電池ケースを鉄またはステンレスにより作った場合には、その厚さを０．２ｍｍ以上、より好ましくは１ｍｍ以上にすることが望ましい。電池ケースの厚さを０．２ｍｍ未満にすると、強度が低下して外装缶に収納された発電要素を十分に保護することが困難になる。
【００２５】
前記電池ケースを構成する外装缶と蓋体は、レーザ溶接により接合する場合に限らず、カシメにより接合してもよい。
【００２６】
前記負極、セパレータ、正極および電解液は、密閉電池がリチウムイオン二次電池の場合、次のような形態のものが用いられる。
【００２７】
前記負極は、例えばリチウムイオンが出し入れされる炭素質物質を含むペーストをアルミニウム薄板のような集電体の両面に保持させた構造を有する。
【００２８】
前記正極は、例えばリチウムニッケル酸化物、リチウムコバルト酸化物、リチウムマンガン酸化物のような活物質を含むペーストを銅薄板のような集電体の両面に保持させた構造を有する。
【００２９】
前記セパレータとしては、例えばポリプロピレンのような合成樹脂からなる多孔性フィルムが用いられる。
【００３０】
前記電解液としては、例えば過塩素酸リチウム、ホウフッ化リチウム、六フッ化リチウム、六フッ化燐リチウム等の電解質をエチレンカーボネート、プロピレンカーボネートのような有機溶媒で溶解したもの等が用いられる。
【００３１】
次に、前記蓋体３の注入孔を封止するための３つの形態を詳細に説明する。
【００３２】
封止形態（１）
図２は、図１１の二次電池の蓋体を示す上面図、図３は図２のIII−III線に沿う拡大断面図。
【００３３】
例えば金属円板からなる封止部材１５は、前記蓋体３の前記注入孔１１を通して電解液を注入した後において前記注入孔１１周囲の前記蓋体３に対して超音波溶接により接合され、前記注入孔１１を気密封止している。すなわち、前記封止部材１５は図２および図３に示すように前記注入孔１１を囲むように形成されたドーナツ状の超音波溶接部１６により前記蓋体３に対して接合されている。
【００３４】
前記封止部材の材質であるアルミニウム系金属としては、例えば純アルミニウム、０．０５重量％以下のＭｇおよび０．２重量％以下のＣｕを含むアルミニウム合金を挙げることができる。このようなアルミニウム系金属としては、例えばＪＩＳの合金番号でＡ１０５０、Ａ１１００、Ａ１２００、Ａ３００３等を挙げることができる。特に、前記封止部材の材質は焼きなましにより調質された最も軟質のアルミニウムのＯ材であることが好ましい。このようなアルミニウムのＯ材からなる封止部材は、超音波溶接性が高いために前記電池ケース（例えば蓋体）に良好に接合することが可能になる。
【００３５】
前記金属板材からなる封止部材は、その溶接しろ部分の厚さを０．０８〜０．３０ｍｍにすることが好ましい。前記封止部材の溶接しろ部分の厚さを０．０８ｍｍ未満にすると、前記封止部材による前記電池ケース（例えば蓋体）に開口された注入孔の気密封止が困難になる。一方、前記封止部材の溶接しろ部分の厚さが０．３０ｍｍを超えるとこの封止部材を電池ケース（例えば蓋体）に良好に超音波溶接することが困難になる。このため、前記封止部材による前記注入孔の気密封止性が損なわれる恐れがある。より好ましい前記封止部材の厚さは、０．１０〜０．２５ｍｍである。
【００３６】
封止形態（２）
図５は、図１１の二次電池の蓋体を示す上面図、図６は図５の要部断面図、図７は鋲形状の封止部材を蓋体の注入孔に圧入する状態を示す斜視図である。なお、前述した図２、図３と同様な部材は同符号を付して説明を省略する。
【００３７】
金属製の円板４１の中心付近に金属製突出棒４２（突出部）を取着するか、もしくは前記円板４１をプレス加工して形成した鋲形状をなす封止部材１５における前記突出棒４２は、蓋体３の注入孔１１内に圧入して前記注入孔１１を気密封止すると共に前記封止部材１５の前記円板４１を前記蓋体３表面に当接させている。前記円板４１と前記蓋体３は、溶接、例えばスポット溶接された複数、例えば４つの溶接部４３を有し、これらの溶接部４３により前記封止部材１５と前記蓋体３とを接合している。
【００３８】
前記封止部材は、例えば鉄またはステンレスから作られる。ただし、前記蓋体をアルミニウム系金属から作った場合、前記封止部材も同様なアルミニウム系金属から作ることによって密閉電池をより軽量化することが可能になる。
【００３９】
前記封止部材の円板は、０．１ｍｍ以上の厚さを有することが好ましい。この円板の厚さを０．１ｍｍ未満にすると、前記封止部材による前記注入孔の気密封止が困難になる。
【００４０】
図7に示すように前記封止部材１５の突出棒４２の外径（φ₁）は、前記蓋体３の注入孔１１の内径（φ₂）より０．０２〜０．１ｍｍ大きいことが好ましい。この寸法差を０．０２ｍｍ未満にすると、前記封止部材により前記注入孔を良好に気密封止することが困難になる恐れがある。一方、前記寸法差が０．１ｍｍを超えると、前記封止部材の突出棒を前記蓋体の注入孔への挿入と、気密保持が困難になる。
【００４１】
前記封止部材の突出棒を前記蓋体の注入孔に圧入する時の力は、５〜１２ｋｇｆにすることが好ましい。
【００４２】
前記封止部材の突出棒は、先端をテーパ状にすることが好ましい。
【００４３】
前記封止部材の円板と蓋体との溶接は、例えば抵抗溶接、レーザ溶接または超音波溶接が用いられる。超音波溶接を適用する場合には、アルミニウム系金属から作られた前記蓋体および封止部材が用いられる。このようなアルミニウム系金属としては、例えばＪＩＳの合金番号でＡ１０５０、Ａ１１００、Ａ１２００、Ａ３００３等を挙げることができる。
【００４４】
なお、封止部材の円板と蓋体との溶接はスポット溶接に限らず、蓋体の注入孔を囲むように例えば円環状の溶接部を形成してもよい。
【００４５】
封止形態（３）
図８は、図１１の二次電池の蓋体を示す上面図、図９は図８の要部断面図である。なお、前述した図２、図３と同様な部材は同符号を付して説明を省略する。
【００４６】
金属製の円板４１の中心付近に金属製突出棒４２（突出部）を取着するか、もしくは前記円板４１をプレス加工して形成した鋲形状をなす封止部材１５における前記突出棒４２は、蓋体３の注入孔１１内に挿入されて前記円板４１を前記蓋体３表面に当接させている。前記円板４１と前記蓋体３は、前記注入孔１１を囲むように溶接された例えば円環状の溶接部４４を有し、この溶接部４４により前記封止部材１５を前記蓋体３に接合すると共に、前記注入孔１１を気密封止している。
【００４７】
前記封止部材は、例えば鉄またはステンレスから作られる。ただし、前記蓋体をアルミニウム系金属から作った場合、前記封止部材も同様なアルミニウム系金属から作ることによって密閉電池をより軽量化することが可能になる。
【００４８】
前記封止部材の円板は、０．１ｍｍ以上の厚さを有することが好ましい。この円板の厚さを０．１ｍｍ未満にすると、前記封止部材による前記注入孔の気密封止が困難になる。
【００４９】
前記封止部材の円板と蓋体との溶接は、例えば抵抗溶接、レーザ溶接または超音波溶接が用いられる。例えば後述する図４に示すホーン３３を用いた超音波溶接を適用する場合には、アルミニウム系金属から作られた前記蓋体および封止部材が用いられる。このようなアルミニウム系金属としては、例えばＪＩＳの合金番号でＡ１０５０、Ａ１１００、Ａ１２００、Ａ３００３等を挙げることができる。
【００５０】
次に、前述した密閉電池の製造方法を説明する。
【００５１】
まず、アルミニウム系金属からなる有底角形の外装缶２内の底面に絶縁紙４を配置し、この中に発電要素（例えば正極８および負極６をセパレータ７を挟んで渦巻き状に捲回し、扁平状に成形した電極体５）を収納する。つづいて、前記外装缶２内の前記電極体５上に中心付近にリード取出し穴を有するスペーサ９を配置した後、前記外装缶２の上端開口部にアルミニウム系金属からなる蓋体３を例えばレーザ溶接により気密に接合して内部に電極体５が収納された電池ケース１を組み立てる。なお、前記蓋体３は絶縁材１３を介してハーメティックシールされた電極端子（負極端子１２）および電解液の注入孔１１を有する。
【００５２】
次いで、前記外装缶２内に電解液を前記蓋体３の注入孔１１を通して注入した後、この注入孔を気密封止する。つづいて、前記蓋体３表面に絶縁紙１７を位置させ、かつ前記外装缶２の底部外面にスリット１８を有する絶縁紙１９を配置すると共に、この絶縁紙１８に二つ折りされたＰＴＣ素子２０を配置し、前記外装缶２を含む全体を外装チューブ２１に入れ、このチューブ２１を熱収縮する。これにより上部側の絶縁紙１７は前記蓋体３に、下部側の絶縁紙１９およびＰＴＣ素子２０は前記外装缶２の底部に、それぞれ固定され、例えば前述した図１に示す構造の角型密閉リチウムイオン二次電池のような角型密閉電池が製造される。
【００５３】
前述した密閉電池の製造において、蓋体の注入孔の封止は次の３つの方法によりなされる。
【００５４】
封止方法（１）
前記外装缶２内に電解液を前記蓋体３の注入孔１１を通して注入した後、前記外装缶２を支持固定し、前記注入孔１１を含む前記蓋体３の外表面に長尺のアルミニウム系金属板材を捲回したフープからアルミニウム系金属板材を配置する。つづいて、図４の（Ａ），（Ｂ）に示す下端付近に円筒部３１を有し、かつ前記円筒部３１下面に多数の突起（例えばピラミッド形の突起）３２が形成された円柱状ホーン３３を備えた超音波溶接装置を用いて前記金属板材を超音波溶接すると共に溶断することにより円板状の封止部材１５を前記蓋体３に接合する。詳述すると、前記ホーン３３の円筒部３１下面を前記金属板材の所定位置に当接させた後、図示しない超音波振動部材により前記ホーン３３を超音波振動させることにより前記円柱状ホーン３３の当接箇所に超音波溶接部が形成されるとともに、そのホーン３３の外周縁で前記板材を溶断することにより円板状の封止部材１５を前記蓋体３に接合するとともに、前記注入孔１１を気密封止する。つまり、前述した図２および図３に示すように円板状の封止部材１５が前記注入孔１１を囲むように形成されたドーナツ状の超音波溶接部１６により前記蓋体３に対して接合される。
【００５５】
前記超音波溶接において、前記ホーン３３における円筒部３１下面に多数の突起３２を形成することにより前記ホーン３３が前記金属板材に対して効果的に食い込み、溶断により形成された円板状の封止部材１５から前述した図２および図３に示すように蓋体３に向かって深い超音波溶接部１６が形成され、前記蓋体３の注入孔１１を良好に気密封止することが可能になる。なお、前記突起３２はその数を多くするほど効果が大きくなる。
【００５６】
また、図４に示す円柱状ホーン３３の円筒部３１の外周縁のアール（Ｒ₁）を０．２以下と急峻にし、同円筒部３１の内周縁のアール（Ｒ₂）を０．５以上と緩慢にすることが好ましい。このような形状のホーン３３を用いることによって、このホーン３３の円筒部３１を前記金属板材に当接させて超音波振動を付与する際、前記円筒部３１の外周縁がカッターの役目をなし、前記アルミニウム系金属板材を容易に溶断して前記円筒部３１と同様な外形寸法を持つ封止部材を蓋体に接合できるとともに、前記円筒部３１の内周縁で溶断されるのを防止することが可能になる。
【００５７】
封止方法（２）
金属製円板４１の中心付近に金属製突出棒４２を固定した鋲形状をなす封止部材１５を用意し、この封止部材１５の突出棒４２を電解液注入後の前記注入孔１１に圧入して前記注入孔１１を気密封止すると共に、前記平板４１を前記蓋体３表面に当接させた後、前記平板４１と前記蓋体３を例えばスポット溶接して４つの溶接部４３により前記封止部材１４を前記蓋体３に接合する。
【００５８】
封止方法（３）
金属製円板４１の中心付近に金属製突出棒４２を形成した鋲形状をなす封止部材１５を用意し、この封止部材１５の突出棒４２を電解液注入後の前記注入孔１１に挿入して前記平板４１を前記蓋体３表面に当接させた後、前記平板４１と前記蓋体３を前記注入孔を囲むように溶接して例えば円環状の溶接部４４を形成し、前記封止部材１４を前記蓋体３に接合すると共に、前記注入孔１１を気密封止する。
【００５９】
なお、本発明に係わる密閉電池において注入孔は電池ケース1の蓋体3に開口される場合に限らない。例えば、図１０に示すように外装缶２の側面に注入孔１１を開口し、この注入孔１１を含む外装缶２の側面に封止蓋１５を超音波溶接により接合してもよい。また、電池ケースの外装缶の底面に注入孔を開口し、この注入孔を含む外装缶の底面に封止蓋を超音波溶接により接合してもよい。
【００６０】
また、本発明に係わる密閉電池において外装缶２と電極体５との電気的接合は、図１に示す構造にしてもよい。すなわち、電極体５の最外周をセパレータ７とし、その代わりに電極体５から正極リード２２を蓋体３の側に設けて、蓋体３における電極体５側の面に対して正極リード２２を溶接によって接合する。このようにすれば、蓋体３と外装缶２とは溶接によって電気的に接合されるので、蓋体３を介して間接的に外装缶２と電極体５とを電気的に接合することができる。
【００６１】
さらに、前述した密閉電池において電極体を外装缶に収納する際にその負極が外側に位置するようにして外装缶を負極端子とし、蓋体にハーメティクシールされた電極端子を正極端子とする構造にしてもよい。
【００６２】
本発明に係わる密閉電池は角型の密閉電池に限らず、形状が異なるだけで電池としての基本構成が変わらない円筒型等の密閉電池にも同様に適用することができる。
【００６３】
以上説明した本発明に係わる密閉電池は、注入孔を通して電解液を注入した後において、アルミニウム系金属からなる封止部材を前記注入孔周囲のアルミニウム系金属からなる電池ケース（例えば蓋体）に対して超音波溶接により接合した構成を有する。
【００６４】
このような構成によれば、電池ケースおよび封止部材が比較的軟質のアルミニウム系金属により作られているため、それら部材を溶接条件が安定した超音波溶接により容易に接合することができる。特に、封止部材の材質として焼きなましにより調質された最も軟質のアルミニウムのＯ材を用いれば、電池ケースに対してより一層良好な超音波溶接を実現できる。その上、前記注入孔を封止する前記封止部材の溶接しろ部分の厚さを０．０８〜０．３０ｍｍにすることによって、より一層信頼性の高い超音波溶接を実現できる。
【００６５】
また、前記注入孔内面に電解液が付着していても、超音波溶接箇所である前記注入孔周辺の電池ケース（例えば蓋体）外面には電解液が存在しないため、前記電解液による溶接への影響を受けることなく前記注入孔を含む前記蓋体に封止部材を良好に超音波溶接することができる。
【００６６】
したがって、電池ケースに開口された電解液の注入孔を封止部材によって良好に気密封止した軽量の密閉電池を得ることができる。特に、前記封止部材と前記注入孔周囲の前記電池ケースとの超音波溶接部の形状をドーナツ状にすることによって、前記注入孔をより一層良好に気密封止することが可能になる。
【００６７】
本発明の方法によれば、アルミニウム系金属からなる外装缶内にセパレータを挟んで対峙された正極および負極を有する発電要素を収納する工程と、前記外装缶の開口部にアルミニウム系金属からなる蓋体を溶接により接合して電池ケースを作製する工程と、前記電池ケースに電解液を注入するための注入孔を開口する工程と、前記電池ケース内に電解液を前記注入孔を通して注入する工程と、前記注入孔を含む前記電池ケースにアルミニウム系金属板材を配置した後、先端面に多数の突起が形成された円筒部を一端側に有する円柱状ホーンにおける前記円筒部の先端面を前記金属板材にその円筒部が前記注入孔を包囲するように当接させ、このホーンを通して前記金属板材に超音波を付与して溶接すると共に前記円筒部の外縁に沿って溶断することにより円板状の封止部材を前記電池ケースに接合して前記注入孔を気密封止する工程とを具備することによって、電池ケースに開口された電解液の注入孔を封止部材によって良好に気密封止した軽量の密閉電池を容易に製造することができる。
【００６８】
本発明に係わる別の密閉電池は、金属製平板の中心付近に金属製突出棒を形成した鋲形状をなす封止部材を用いて、この突出棒を電解液の注入後の注入孔に圧入して前記注入孔を気密封止すると共に、前記平板を前記ケース表面に当接させ、かつ前記平坦と前記ケースとを溶接して前記ケースに接合した構成を有する。
【００６９】
このような構成によれば、前記封止部材の突出棒を前記電池ケース（例えば蓋体）の注入孔に挿入し、前記電池ケース表面に当接された記封止部材の平板とを溶接することによって、電池ケースに開口された電解液の注入孔を封止部材によって極めて良好に気密封止した密閉電池を得ることができる。
【００７０】
特に、前記注入孔の径に比べて０．０２〜０．１ｍｍ大きな外径を持つ突出棒を有する前記封止部材を用いることによって、前記注入孔をより一層良好に気密封止することが可能になる。
【００７１】
本発明の別の方法によれば、金属からなる外装缶内にセパレータを挟んで対峙された正極および負極を有する発電要素を収納する工程と、前記外装缶のの開口部に金属からなる蓋体を溶接もしくはカシメにより気密に固定して電池ケースを作製する工程と、前記電池ケースに電解液を注入するための注入孔を開口する工程と、前記電池ケース内に電解液を前記注入孔を通して注入する工程と、金属製平板の中心付近に金属製突出棒を形成した鋲形状をなす封止部材を用意し、この封止部材の突出棒を前記注入孔に挿入して前記注入孔を気密封止すると共に、前記平板を前記ケース表面に当接させた後、前記平板と前記ケースとを溶接する工程とを具備することによって、電池ケースに開口された電解液の注入孔を封止部材によって極めて良好に気密封止した密閉電池を製造できる。
【００７２】
本発明に係わるさらに別の密閉電池は、金属製平板の中心付近に金属製突出棒を形成した鋲形状をなす封止部材を用い、この突出棒を電池ケース（例えば蓋体）の注入孔に挿入して前記平板を前記ケース表面に当接させ、かつ前記平板と前記ケースとを前記注入孔を囲むように溶接して前記ケースに接合されることにより前記注入孔を気密封止した構成を有する。
【００７３】
このような構成によれば、前記封止部材の突出棒を前記電池ケース（例えば蓋体）の注入孔に挿入することによって、前記封止部材を前記注入孔を含む電池ケースに簡単に位置決めできるとともに、前記電池ケース表面に当接された記封止部材の平板とを前記注入孔を囲むように溶接する際に前記封止部材の位置ずれを防止できるため、電池ケースに開口された電解液の注入孔を封止部材によって極めて良好にに気密封止した密閉電池を得ることができる。
【００７４】
本発明のさらに別の方法によれば、金属からなる外装缶内にセパレータを挟んで対峙された正極および負極を有する発電要素を収納する工程と、前記外装缶のの開口部に金属からなる蓋体を溶接もしくはカシメにより気密に固定して電池ケースを作製する工程と、前記電池ケースに電解液を注入するための注入孔を開口する工程と、前記電池ケース内に電解液を前記注入孔を通して注入する工程と、金属製平板の中心付近に金属製突出棒を形成した鋲形状をなす封止部材を用意し、この封止部材の突出棒を前記注入孔に挿入して前記平板を前記ケース表面に当接させた後、前記平板と前記ケースとを前記注入孔を囲むように溶接して前記注入孔を気密封止する工程とを具備することによって、電池ケースに開口された電解液の注入孔を封止部材によって極めて良好に気密封止した密閉電池を製造できる。
【００７５】
【実施例】
以下、本発明の好ましい実施例を前述した図１１、図２、図３に示す角型密閉電池を参照して詳細に説明する。
【００７６】
（実施例１）
まず、アルミニウム（ＪＩＳ合金番号Ａ３００３）からなる有底角筒形の外装缶２内の底面に絶縁紙４を配置し、この中に正極８および負極６をセパレータ７を挟んで渦巻き状に捲回し、扁平状に成形した電極体５を収納した。つづいて、前記外装缶２内の前記電極体５上の中心付近にリード取出し穴を有するスペーサ９を配置した後、アルミニウム（ＪＩＳ合金番号Ａ３００３）からなる厚さ１．０ｍｍの蓋体３を前記外装缶２の上端開口部にレーザ溶接により気密に接合した。なお、前記蓋体３には絶縁材１３を介してハーメティクシールされた負極端子１２および電解液の注入孔１１（孔径２．０ｍｍ）を有する。
【００７７】
次いで、前記外装缶２内に六フッ化燐リチウムの電解質をエチレンカーボネートとメチルエチルカーボネートで溶解した非水溶媒系電解液を前記蓋体３の注入孔１１を通して注入した。つづいて、幅６ｍｍ、厚さ０．０５ｍｍのアルミニウム（ＪＩＳ合金番号Ａ３００３で焼きなましを行なったＯ材）からなる長尺板材のフープから引き出した板材を前記注入孔１１を含む前記蓋体３の外表面に配置した。
【００７８】
次いで、前述した図３に示す円柱状ホーン３３を備えた超音波溶接装置を用意した。この円柱状ホーン３３は、下端付近に外径４．５ｍｍ、内径３．０ｍｍで、外周のエッジＲ₁が０．２、内周のエッジＲ₂が０．５の円筒部３１を有し、かつ前記円筒部３１下面に高さ０．０５ｍｍ、ピッチ０．２ｍｍの多数のピラミッド形突起３２が形成されている。前記円柱状ホーン３３の円筒部３１下面の多数の突起３２を前記蓋体３のアルミニウム板材の所定位置に当接させて食い込ませた後、図示しない超音波振動部材により前記ホーン３３を超音波振動させることにより前記円柱状ホーン３３の当接箇所に図２に示すように外径４．５ｍｍ、内径３．０ｍｍのドーナツ状の超音波溶接部１６を形成するとともに、そのホーン３３の外周縁のカッター作用により前記板材を溶断することにより外径寸法が４．５ｍｍの円板状の封止部材１５を前記蓋体３に接合して前記注入孔１１を塞いだ。この時の超音波溶接条件は、振幅１８μｍ、加圧力２．５ｋｇｆ／ｃｍ2、エネルギー０．７０Ｊとした。
【００７９】
次いで、前記蓋体３表面に絶縁紙１７を配置し、かつ前記外装缶２の底部外面にスリット１８を有する絶縁紙１９を配置すると共に、この絶縁紙１９に二つ折りされたＰＴＣ素子２０を配置した。前記外装缶２を含む全体を外装チューブ２１に入れ、このチューブ２１を熱収縮することにより上部側の絶縁紙１７を前記蓋体３に、下部側の絶縁紙１９およびＰＴＣ素子２０を前記外装缶２の底部に固定することにより前述した図１１に示す構造の角型密閉リチウムイオン二次電池を製造した。
【００８０】
（実施例２〜６）
幅６ｍｍで下記表１に示す厚さのアルミニウムのＯ材からなる長尺板材を用い、実施例１と同様な形状のホーンを有する超音波溶接装置による超音波溶接条件を振幅１８μｍ、加圧力１．０〜３．０ｋｇｆ／ｃｍ2、エネルギー０．４〜０．７５Ｊとした以外、実施例１と同様な方法により封止部材を電池ケースの注入孔を含む蓋体に超音波溶接し、前述した図１１に示す構造の５種の角型密閉リチウムイオン二次電池を製造した。
【００８１】
得られた実施例１〜６の各二次電池１００個について、電解液の漏れ等を起こさない良品の割合を調べた。その結果を下記表１に示す。
【００８２】
【表１】

【００８３】
前記表１から明らかなように厚さが０．０８〜０．３０ｍｍの封止部材を有する二次電池は、極めて高い良品率を有することがわかる。
【００８４】
（参照例１）
実施例１と同様に外装缶に電極体を収納し、外装缶に注入孔が開口された蓋体をレーザ溶接により気密に接合した後、電解液を前記注入孔を通して注入した。つづいて、外径２．０８ｍｍ弱の突出棒を有し、円板の厚さが０．１５ｍｍの鋲状封止部材を用い、この封止部材の突出棒を前記電池ケースの蓋体の注入孔（孔径；２．０ｍｍ）に挿入するとともに前記円板を前記蓋体表面に当接させた。この後、前記円板と前記蓋体とをスポット溶接することにより前述した図１１，図５，図６に示す構造角型密閉リチウムイオン二次電池を製造した。
【００８５】
（参照例２，３）
まず、厚さが０．１５ｍｍの円板中心付近に外径２．０ｍｍ弱の突出棒を形成した鋲状封止部材を用い、実施例１と同様に電極体の収納、電解液の注入後の電池ケースの蓋体の注入孔（孔径；２．０ｍｍ）に前記封止部材の突出棒を挿入した。この後、実施例１と同様な下部付近に円筒部を有するホーンを備えた超音波溶接装置、および外径４．５ｍｍ、外周のエッジが０．２で、かつ円形下面に高さ０．０５ｍｍ、ピッチ０．２ｍｍの多数のピラミッド形突起が形成された全体が円柱状をなすホーンを備えた超音波溶接装置により振幅１８μｍ、加圧力２．０ｋｇｆ／ｃｍ2、エネルギー０．６Ｊの超音波溶接条件で超音波溶接することにより前述した図１１，図８，図９に示す構造の２種の角型密閉リチウムイオン二次電池を製造した。
【００８６】
得られた参照例１〜３の各二次電池１００個について、電解液の漏れ等を起こさない良品の割合を調べた。その結果を下記表２に示す。
【００８７】
【表２】

【００８８】
前記表２から明らかなように鋲状封止部材を用いて電池ケースの注入孔を含む蓋体に溶接した参照例１〜３の二次電池は、いずれも極めて高い良品率を有することがわかる。
【００８９】
【発明の効果】
以上詳述したように、本発明によれば外装缶の開口部に蓋体を気密に接合またはカシメを行なった電池ケースを有し、かつ前記電池ケースの注入孔を金属封止部材で気密に封止した信頼性の高い密閉電池およびその製造方法を提供できる。
【図面の簡単な説明】
【図１】本発明に係わる角型密閉リチウムイオン二次電池のさらに別の形態を示す部分切欠斜視図。
【図２】図１の二次電池の蓋体を示す図。
【図３】図２のIII−III線に沿う断面図。
【図４】超音波溶接装置に組込まれるホーンを示す図。
【図５】本発明に係わる別の密閉型電池における蓋体を示す図。
【図６】図５の要部断面図。
【図７】図５の要部斜視図。
【図８】本発明に係わるさらに別の密閉型電池における蓋体を示す図。
【図９】図８の要部断面図。
【図１０】本発明に係わる角型密閉リチウムイオン二次電池の別の形態示す側面図。
【図１１】本発明に係わる密閉型電池の一例である角型密閉リチウムイオン二次電池を示す部分切欠斜視図。
【符号の説明】
１…電池ケース、２…外装缶、３…蓋体、５…電極体、１１…注入孔、１５…封止部材、１６…超音波溶接部、２０…ＰＴＣ素子、２１…外装チューブ、３１…円筒部、３２…突起、３３…ホーン、４１…円板、４２…突出棒、４３，４４…溶接部。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sealed battery and a manufacturing method of the sealed battery, and more particularly to a sealed battery having an improved structure for sealing an injection hole for an electrolyte and a manufacturing method thereof.
[0002]
[Prior art]
Conventionally, this type of sealed battery, such as a square sealed battery, has the following structure.
[0003]
(1) A bottomed rectangular tube-shaped metal outer can, a power generation element housed in the outer can, an electrolyte injected from an opening of the outer can, and an upper end opening of the outer can And a metal lid having an electrode terminal joined by a hermetic seal and insulated by a hermetic seal.
[0004]
(2) Bottomed rectangular tube-shaped outer can, power generation element housed in the outer can, electrode terminal and electrolyte solution joined to the opening of the outer can by welding and insulated by a hermetic seal A lid made of a metal plate material having an injection hole, an electrolyte injected into the outer can through the injection hole of the lid, and a spherical shape inserted into the injection hole and joined by brazing or resistance welding Or a sealed battery with a nail-shaped plug.
[0005]
However, in the rectangular sealed battery having the structure of (1) described above, when the lid is welded to the upper end opening of the outer can, the electrolytic solution is already contained in the outer can and the electrolyte is evaporated. Made in For this reason, electrolyte solution vapor adheres to the welding location of the said outer can and the said cover body, a poor welding arises, and sealing performance falls remarkably.
[0006]
In the rectangular sealed battery having the structure (2), the plug is inserted into an injection hole to which an electrolytic solution is attached, and resistance welding or brazing is performed. For this reason, there exists a possibility of causing the joining defect of the said plug by evaporation of the said electrolyte solution. Further, when the lid is formed of aluminum for the purpose of reducing the weight, it is difficult to join the stopper to the injection hole of the lid by brazing or resistance welding.
[0007]
Even in a sealed battery in which the injection hole is provided on the bottom and side surfaces of the outer can, the same problem as in the battery in which the injection hole is provided in the lid occurs because the other parts are not changed except for the site.
[0008]
Further, not only in the rectangular sealed battery but also in the cylindrical sealed battery, the technique (1) causes poor welding due to the same reason as the rectangular type, and the sealing performance is lowered. In the technique (2), a bonding failure occurs for the same reason as that of the square shape, or the bonding itself becomes difficult.
[0009]
[Problems to be solved by the invention]
The present invention includes a sealed battery having a battery case in which a lid is airtightly joined or crimped to an opening of an outer can, and an injection hole of the battery case is hermetically sealed with a metal sealing member, and The manufacturing method is intended to be provided.
[0010]
[Means for Solving the Problems]
  In the present inventionThe method for producing such a sealed battery includes a step of housing a power generation element having a positive electrode and a negative electrode facing each other with a separator sandwiched in an outer can made of an aluminum-based metal;
  A step of producing a battery case by joining a lid made of an aluminum-based metal to the opening of the outer can by welding;
  Injecting an electrolyte into the battery case through an injection hole opened in the case;
  Disposing an aluminum-based metal plate in the battery case including the injection hole;
  Providing a columnar horn having a cylindrical portion on one end side and having a plurality of protrusions formed on a tip surface of the cylindrical portion; and
  The tip of the cylindrical portion of the columnar horn is brought into contact with the metal plate so that the cylindrical portion surrounds the injection hole, and ultrasonic waves are applied to the metal plate through the horn to provide the metal plate. Welding the metal plate material along the outer edge of the cylindrical portion and joining the disk-shaped sealing member to the battery case to hermetically seal the injection hole;
It is characterized by comprising.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a sealed battery according to the present invention will be described in detail with reference to the drawings, taking a square sealed battery as an example. Here, the square shape means that the shape when the outer can is cut along the surface including the power generation element is rectangular, but it is allowed to be rounded at the corner.
[0017]
  Figure11These are the perspective views which show the sealed battery concerning this invention, for example, a square-shaped sealed lithium ion secondary battery.
[0018]
The rectangular battery case 1 has a structure in which a lid 3 made of an aluminum-based metal is air-tightly joined, for example, by laser welding to an opening of an outer can 2 having a bottomed rectangular cylindrical shape made of an aluminum-based metal. The outer can 2 also serves as a positive electrode terminal, for example, and an insulating film 4 is disposed on the inner surface of the bottom.
[0019]
The electrode body 5 that is a power generation element is housed in the outer can 2 of the battery case 1. The electrode body 5 is produced, for example, by winding the negative electrode 6, the separator 7, and the positive electrode 8 in a spiral shape so that the positive electrode 8 is located on the outermost periphery, and then press-molding it into a flat shape. A spacer 9 made of, for example, synthetic resin having a lead extraction hole near the center is disposed on the electrode body 5 in the outer can 2.
[0020]
In the vicinity of the center of the lid 3, an extraction hole 10 for a negative electrode terminal is opened. The injection hole 11 is opened at a location of the lid 3 away from the extraction hole 10. The electrolytic solution is injected into the outer can 2 through the injection hole 11. The negative electrode terminal 12 is hermetically sealed in the hole 10 of the lid 3 via an insulating material 13 made of glass or resin. A lead 14 is connected to the lower end surface of the negative electrode terminal 12, and the other end of the lead 14 is connected to the negative electrode 6 of the electrode body 5.
[0021]
The upper insulating paper 17 is covered on the entire outer surface of the lid 3. The lower insulating paper 19 having the slits 18 is disposed on the bottom surface of the outer can 2. The PTC (Positive Thermal Coefficient) element 20 folded in half has one surface interposed between the bottom surface of the outer can 2 and the lower insulating paper 19 and the other surface through the slit 18 to the insulating paper. 19 is extended to the outside. The outer tube 21 is disposed so as to extend from the side surface of the outer can 2 to the periphery of the upper and lower

insulating papers

17 and 19, and fixes the upper insulating paper 17 and the lower insulating paper 19 to the outer can 2. ing. With such an arrangement of the outer tube 21, the other surface of the PTC element 20 extending to the outside is bent toward the bottom surface of the lower insulating paper 19.
[0022]
Examples of the aluminum-based metal that is a material of the battery case include an aluminum alloy containing pure aluminum, 0.05 wt% or less Mg and 0.2 wt% or less Cu. As such an aluminum-based metal, for example, A1050, A1100, A1200, A3003 and the like can be given as JIS alloy numbers. However, the battery case allows the use of stainless steel or iron in addition to the aluminum-based metal.
[0023]
When the battery case is made of an aluminum-based metal, the thickness is desirably 0.5 mm or more, more preferably 1 mm or more. If the thickness of the battery case is less than 0.5 mm, the strength is lowered and it is difficult to sufficiently protect the power generation element stored in the outer can.
[0024]
When the battery case is made of iron or stainless steel, the thickness is desirably 0.2 mm or more, more preferably 1 mm or more. When the thickness of the battery case is less than 0.2 mm, the strength is reduced and it is difficult to sufficiently protect the power generation element stored in the outer can.
[0025]
The outer can and the lid constituting the battery case are not limited to being joined by laser welding, but may be joined by caulking.
[0026]
When the sealed battery is a lithium ion secondary battery, the negative electrode, the separator, the positive electrode, and the electrolyte are used in the following forms.
[0027]
The negative electrode has a structure in which, for example, a paste containing a carbonaceous material into and out of lithium ions is held on both surfaces of a current collector such as an aluminum thin plate.
[0028]
The positive electrode has a structure in which a paste containing an active material such as lithium nickel oxide, lithium cobalt oxide, or lithium manganese oxide is held on both surfaces of a current collector such as a copper thin plate.
[0029]
As the separator, for example, a porous film made of a synthetic resin such as polypropylene is used.
[0030]
As the electrolytic solution, for example, an electrolyte such as lithium perchlorate, lithium borofluoride, lithium hexafluoride, or lithium hexafluorophosphate dissolved in an organic solvent such as ethylene carbonate or propylene carbonate is used.
[0031]
Next, three forms for sealing the injection hole of the lid 3 will be described in detail.
[0032]
  Sealing form (1)
  Figure 211The top view which shows the cover body of the secondary battery of FIG. 3, FIG. 3 is an expanded sectional view which follows the III-III line | wire of FIG.
[0033]
For example, the sealing member 15 made of a metal disk is joined to the lid 3 around the injection hole 11 by ultrasonic welding after injecting the electrolytic solution through the injection hole 11 of the lid 3. The injection hole 11 is hermetically sealed. That is, the sealing member 15 is joined to the lid 3 by a donut-shaped ultrasonic weld 16 formed so as to surround the injection hole 11 as shown in FIGS.
[0034]
Examples of the aluminum-based metal that is the material of the sealing member include an aluminum alloy containing pure aluminum, 0.05 wt% or less Mg and 0.2 wt% or less Cu. As such an aluminum-based metal, for example, A1050, A1100, A1200, A3003 and the like can be given as JIS alloy numbers. In particular, the material of the sealing member is preferably the softest aluminum O material tempered by annealing. Since the sealing member made of the aluminum O material has high ultrasonic weldability, it can be satisfactorily bonded to the battery case (for example, the lid).
[0035]
The sealing member made of the metal plate preferably has a weld margin of 0.08 to 0.30 mm. When the thickness of the welding portion of the sealing member is less than 0.08 mm, it becomes difficult to hermetically seal the injection hole opened in the battery case (for example, the lid) by the sealing member. On the other hand, when the thickness of the welding portion of the sealing member exceeds 0.30 mm, it becomes difficult to satisfactorily ultrasonically weld the sealing member to a battery case (for example, a lid). For this reason, there exists a possibility that the airtight sealing performance of the said injection hole by the said sealing member may be impaired. A more preferable thickness of the sealing member is 0.10 to 0.25 mm.
[0036]
  Sealing form (2)
  FIG.11FIG. 6 is a cross-sectional view of the main part of FIG. 5, and FIG. 7 is a perspective view showing a state in which a hook-shaped sealing member is press-fitted into the injection hole of the lid. Note that members similar to those in FIGS. 2 and 3 described above are denoted by the same reference numerals and description thereof is omitted.
[0037]
The protruding bar 42 in the sealing member 15 having a bowl shape formed by attaching a metal protruding bar 42 (protruding part) near the center of the metal disk 41 or pressing the disk 41. Is press-fitted into the injection hole 11 of the lid 3 to hermetically seal the injection hole 11, and the disk 41 of the sealing member 15 is brought into contact with the surface of the lid 3. The disc 41 and the lid 3 have a plurality of, for example, four welds 43 that are welded, for example, spot welded, and join the sealing member 15 and the lid 3 by these welds 43. ing.
[0038]
The sealing member is made of, for example, iron or stainless steel. However, when the lid is made of an aluminum-based metal, the sealed battery can be made lighter by making the sealing member from the same aluminum-based metal.
[0039]
The disk of the sealing member preferably has a thickness of 0.1 mm or more. When the thickness of the disk is less than 0.1 mm, it becomes difficult to hermetically seal the injection hole with the sealing member.
[0040]
As shown in FIG. 7, the outer diameter (φ of the protruding rod 42 of the sealing member 15₁) Is the inner diameter (φ of the injection hole 11 of the lid 3.₂) Is preferably 0.02 to 0.1 mm larger than. If the dimensional difference is less than 0.02 mm, it may be difficult to hermetically seal the injection hole with the sealing member. On the other hand, when the dimensional difference exceeds 0.1 mm, it becomes difficult to insert the protruding rod of the sealing member into the injection hole of the lid and to keep the airtight.
[0041]
The force when the projecting rod of the sealing member is press-fitted into the injection hole of the lid is preferably 5 to 12 kgf.
[0042]
The protruding rod of the sealing member preferably has a tapered tip.
[0043]
For example, resistance welding, laser welding, or ultrasonic welding is used for welding the disk of the sealing member and the lid. When applying ultrasonic welding, the lid body and the sealing member made of an aluminum-based metal are used. As such an aluminum-based metal, for example, A1050, A1100, A1200, A3003 and the like can be given as JIS alloy numbers.
[0044]
The welding of the sealing member disk and the lid is not limited to spot welding, and for example, an annular welded portion may be formed so as to surround the injection hole of the lid.
[0045]
  Sealing form (3)
  Figure 811The top view which shows the cover body of the secondary battery of this, FIG. 9 is principal part sectional drawing of FIG. Note that members similar to those in FIGS. 2 and 3 described above are denoted by the same reference numerals and description thereof is omitted.
[0046]
The protruding bar 42 in the sealing member 15 having a bowl shape formed by attaching a metal protruding bar 42 (protruding part) near the center of the metal disk 41 or pressing the disk 41. Is inserted into the injection hole 11 of the lid 3 to bring the disk 41 into contact with the surface of the lid 3. The disc 41 and the lid 3 have, for example, an annular welded portion 44 welded so as to surround the injection hole 11, and the sealing member 15 is joined to the lid 3 by the welded portion 44. In addition, the injection hole 11 is hermetically sealed.
[0047]
The sealing member is made of, for example, iron or stainless steel. However, when the lid is made of an aluminum-based metal, the sealed battery can be made lighter by making the sealing member from the same aluminum-based metal.
[0048]
The disk of the sealing member preferably has a thickness of 0.1 mm or more. When the thickness of the disk is less than 0.1 mm, it becomes difficult to hermetically seal the injection hole with the sealing member.
[0049]
  For example, resistance welding, laser welding, or ultrasonic welding is used for welding the disk of the sealing member and the lid. For exampleTo be described laterWhen ultrasonic welding using the horn 33 shown in FIG. 4 is applied, the lid body and the sealing member made of an aluminum-based metal are used. As such an aluminum-based metal, for example, A1050, A1100, A1200, A3003 and the like can be given as JIS alloy numbers.
[0050]
Next, a method for manufacturing the above-described sealed battery will be described.
[0051]
First, the insulating paper 4 is disposed on the bottom surface of the bottomed rectangular outer can 2 made of an aluminum-based metal, and a power generation element (for example, the positive electrode 8 and the negative electrode 6 is wound in a spiral shape with the separator 7 interposed therebetween, and is flattened. A shaped electrode body 5) is accommodated. Subsequently, after arranging a spacer 9 having a lead extraction hole in the vicinity of the center on the electrode body 5 in the outer can 2, a lid 3 made of an aluminum-based metal is attached to the upper end opening of the outer can 2 by, for example, a laser. A battery case 1 in which the electrode body 5 is housed in an airtight manner by welding is assembled. The lid 3 has an electrode terminal (negative electrode terminal 12) hermetically sealed with an insulating material 13 and an injection hole 11 for electrolyte.
[0052]
Next, after the electrolyte is injected into the outer can 2 through the injection hole 11 of the lid 3, the injection hole is hermetically sealed. Subsequently, the insulating paper 17 is positioned on the surface of the lid 3, and the insulating paper 19 having the slit 18 is disposed on the outer surface of the bottom of the outer can 2, and the PTC element 20 folded in half on the insulating paper 18 is provided. It arrange | positions, the whole containing the said exterior can 2 is put in the exterior tube 21, and this tube 21 is heat-shrinked. As a result, the upper insulating paper 17 is fixed to the lid 3 and the lower insulating paper 19 and the PTC element 20 are fixed to the bottom of the outer can 2, respectively. A square sealed battery such as a lithium ion secondary battery is manufactured.
[0053]
In the manufacturing of the above-described sealed battery, the lid injection hole is sealed by the following three methods.
[0054]
Sealing method (1)
After injecting the electrolyte into the outer can 2 through the injection hole 11 of the lid 3, the outer can 2 is supported and fixed, and a long aluminum system is formed on the outer surface of the lid 3 including the injection hole 11. An aluminum-based metal plate material is arranged from a hoop wound with the metal plate material. Next, a cylindrical horn having a cylindrical portion 31 in the vicinity of the lower end shown in FIGS. 4A and 4B and having a large number of protrusions (for example, pyramidal protrusions) 32 formed on the lower surface of the cylindrical portion 31. The disk-shaped sealing member 15 is joined to the lid 3 by ultrasonic welding and fusing the metal plate material using an ultrasonic welding device 33. More specifically, after the lower surface of the cylindrical portion 31 of the horn 33 is brought into contact with a predetermined position of the metal plate member, the horn 33 is ultrasonically vibrated by an ultrasonic vibration member (not shown) to thereby contact the cylindrical horn 33. An ultrasonic weld is formed at the contact location, and the plate-like sealing member 15 is joined to the lid 3 by fusing the plate material at the outer peripheral edge of the horn 33, and the injection hole 11 is Seal hermetically. That is, as shown in FIG. 2 and FIG. 3 described above, the disk-shaped sealing member 15 is joined to the lid 3 by a donut-shaped ultrasonic weld 16 formed so as to surround the injection hole 11. Is done.
[0055]
In the ultrasonic welding, by forming a large number of protrusions 32 on the lower surface of the cylindrical portion 31 of the horn 33, the horn 33 effectively bites into the metal plate material and is formed into a disc-shaped seal formed by fusing. As shown in FIG. 2 and FIG. 3 described above, a deep ultrasonic weld 16 is formed from the member 15 toward the lid 3, and the injection hole 11 of the lid 3 can be satisfactorily hermetically sealed. . The effect increases as the number of the protrusions 32 increases.
[0056]
Further, the outer peripheral edge (R) of the cylindrical portion 31 of the columnar horn 33 shown in FIG.₁) Is steep to 0.2 or less, and the radius (R) of the inner peripheral edge of the cylindrical portion 31 is increased.₂) Is preferably slowed to 0.5 or more. By using the horn 33 having such a shape, when the ultrasonic vibration is applied by bringing the cylindrical portion 31 of the horn 33 into contact with the metal plate material, the outer peripheral edge of the cylindrical portion 31 serves as a cutter, The aluminum-based metal plate material can be easily melted so that a sealing member having the same outer dimensions as the cylindrical portion 31 can be joined to the lid, and the aluminum member can be prevented from being melted at the inner periphery of the cylindrical portion 31. It becomes possible.
[0057]
Sealing method (2)
A sealing member 15 having a bowl shape with a metal protruding rod 42 fixed in the vicinity of the center of the metal disk 41 is prepared, and the protruding rod 42 of the sealing member 15 is press-fitted into the injection hole 11 after the electrolyte is injected. Then, the injection hole 11 is hermetically sealed, and the flat plate 41 is brought into contact with the surface of the lid 3, and then the flat plate 41 and the lid 3 are spot-welded, for example, by the four welds 43. The sealing member 14 is joined to the lid 3.
[0058]
Sealing method (3)
A sealing member 15 having a bowl shape in which a metal protruding rod 42 is formed in the vicinity of the center of the metal disk 41 is prepared, and the protruding rod 42 of the sealing member 15 is inserted into the injection hole 11 after electrolyte injection. After the flat plate 41 is brought into contact with the surface of the lid 3, the flat plate 41 and the lid 3 are welded so as to surround the injection hole to form, for example, an annular weld 44, and the sealing The stop member 14 is joined to the lid 3 and the injection hole 11 is hermetically sealed.
[0059]
In the sealed battery according to the present invention, the injection hole is not limited to the case where the injection hole is opened in the lid 3 of the battery case 1. For example, as shown in FIG. 10, the injection hole 11 may be opened on the side surface of the outer can 2, and the sealing lid 15 may be joined to the side surface of the outer can 2 including the injection hole 11 by ultrasonic welding. Alternatively, an injection hole may be opened on the bottom surface of the outer can of the battery case, and a sealing lid may be joined to the bottom surface of the outer can including the injection hole by ultrasonic welding.
[0060]
  Moreover, in the sealed battery according to the present invention, the electrical connection between the outer can 2 and the electrode body 5 is as follows:FIG.The structure shown in FIG. That is, the outermost periphery of the electrode body 5 is the separator 7, and instead, the positive electrode lead 22 is provided on the lid body 3 side from the electrode body 5, and the positive electrode lead 22 is attached to the surface of the lid body 3 on the electrode body 5 side. Join by welding. In this way, since the lid 3 and the outer can 2 are electrically joined by welding, it is possible to indirectly join the outer can 2 and the electrode body 5 indirectly via the lid 3. it can.
[0061]
Further, when the electrode body is stored in the outer can in the above-described sealed battery, the outer can is used as a negative electrode terminal so that the negative electrode is positioned outside, and the electrode terminal hermetically sealed on the lid is used as a positive electrode terminal. It may be structured.
[0062]
The sealed battery according to the present invention is not limited to a rectangular sealed battery, but can be similarly applied to a cylindrical sealed battery or the like whose basic configuration as a battery is different only by a different shape.
[0063]
In the sealed battery according to the present invention described above, after injecting the electrolytic solution through the injection hole, the sealing member made of aluminum metal is attached to the battery case (for example, lid) made of aluminum metal around the injection hole. And are joined by ultrasonic welding.
[0064]
According to such a configuration, since the battery case and the sealing member are made of a relatively soft aluminum-based metal, the members can be easily joined by ultrasonic welding with stable welding conditions. In particular, if the softest aluminum O material tempered by annealing is used as the material of the sealing member, even better ultrasonic welding can be realized for the battery case. Moreover, ultrasonic welding with higher reliability can be realized by setting the thickness of the welding margin of the sealing member that seals the injection hole to 0.08 to 0.30 mm.
[0065]
Even if the electrolyte is attached to the inner surface of the injection hole, the electrolyte does not exist on the outer surface of the battery case (for example, the lid) around the injection hole, which is an ultrasonic welding location. The sealing member can be satisfactorily ultrasonically welded to the lid including the injection hole without being affected by the above.
[0066]
Therefore, a lightweight sealed battery in which the electrolyte injection hole opened in the battery case is hermetically sealed with the sealing member can be obtained. In particular, the injection hole can be hermetically sealed even more by making the shape of the ultrasonic weld between the sealing member and the battery case around the injection hole a donut shape.
[0067]
According to the method of the present invention, the step of housing the power generating element having the positive electrode and the negative electrode facing each other with the separator sandwiched in the outer can made of an aluminum-based metal, and the lid made of the aluminum-based metal in the opening of the outer can Joining the bodies by welding to produce a battery case, opening an injection hole for injecting an electrolyte into the battery case, and injecting an electrolyte into the battery case through the injection hole, After the aluminum-based metal plate material is disposed on the battery case including the injection hole, the metal plate material is formed on the tip surface of the cylindrical portion in the columnar horn having a cylindrical portion on one end side with a plurality of protrusions formed on the tip surface. The cylindrical part is contacted so as to surround the injection hole, and ultrasonic welding is applied to the metal plate through the horn and welding is performed along the outer edge of the cylindrical part. A step of joining the disk-shaped sealing member to the battery case and hermetically sealing the injection hole, whereby the electrolyte injection hole opened in the battery case is formed by the sealing member. A lightweight sealed battery that is well hermetically sealed can be easily manufactured.
[0068]
Another sealed battery according to the present invention uses a hook-shaped sealing member in which a metal protruding bar is formed near the center of a metal flat plate, and presses the protruding bar into the injection hole after the electrolyte is injected. The injection hole is hermetically sealed, the flat plate is brought into contact with the case surface, and the flat and the case are welded and joined to the case.
[0069]
According to such a configuration, the protruding rod of the sealing member is inserted into the injection hole of the battery case (for example, the lid), and the flat plate of the sealing member that is in contact with the surface of the battery case is welded. Thus, a sealed battery in which the electrolyte injection hole opened in the battery case is hermetically sealed with the sealing member can be obtained.
[0070]
In particular, the injection hole can be hermetically sealed even better by using the sealing member having a protruding rod having an outer diameter 0.02 to 0.1 mm larger than the diameter of the injection hole. become.
[0071]
According to another method of the present invention, a step of housing a power generation element having a positive electrode and a negative electrode opposed to each other with a separator sandwiched in a metal outer can, and a lid made of metal in the opening of the outer can A battery case that is hermetically fixed by welding or caulking, a step of opening an injection hole for injecting the electrolyte into the battery case, and injecting the electrolyte into the battery case through the injection hole And a sealing member having a bowl shape in which a metal protruding rod is formed in the vicinity of the center of the metal flat plate, and the protruding rod of the sealing member is inserted into the injection hole so that the injection hole is hermetically sealed. And a step of welding the flat plate and the case after the flat plate is brought into contact with the surface of the case, so that the electrolyte injection hole opened in the battery case is formed by the sealing member. Very good Capable of producing a sealed battery that is hermetically sealed.
[0072]
Still another sealed battery according to the present invention uses a sealing member having a bowl shape in which a metal protruding bar is formed near the center of a metal flat plate, and the protruding bar is used as an injection hole of a battery case (for example, a lid). The injection hole is hermetically sealed by inserting the flat plate into contact with the case surface and welding the flat plate and the case so as to surround the injection hole and joining to the case. Have.
[0073]
According to such a configuration, the sealing member can be easily positioned on the battery case including the injection hole by inserting the protruding rod of the sealing member into the injection hole of the battery case (for example, the lid). In addition, since the displacement of the sealing member can be prevented when welding the flat plate of the sealing member in contact with the surface of the battery case so as to surround the injection hole, the electrolytic solution opened in the battery case It is possible to obtain a sealed battery in which the injection hole is hermetically sealed with a sealing member very well.
[0074]
According to still another method of the present invention, a step of storing a power generating element having a positive electrode and a negative electrode opposed to each other with a separator sandwiched in a metal outer can, and a metal cap at the opening of the outer can A step of manufacturing a battery case by airtightly fixing the body by welding or caulking, a step of opening an injection hole for injecting an electrolytic solution into the battery case, and an electrolytic solution in the battery case through the injection hole Preparing a sealing member having a bowl shape in which a metal projecting rod is formed in the vicinity of the center of the metal flat plate, and inserting the projecting rod of the sealing member into the injection hole to insert the flat plate into the case And a step of welding the flat plate and the case so as to surround the injection hole and hermetically sealing the injection hole, thereby bringing the electrolyte solution opened in the battery case into contact with the surface. Seal the injection hole Can be produced very well sealed battery hermetically sealed by.
[0075]
【Example】
  The preferred embodiments of the present invention have been described above.11, FIG.This will be described in detail with reference to the square sealed battery shown in FIG.
[0076]
Example 1
First, the insulating paper 4 is disposed on the bottom surface of the bottomed rectangular tube-shaped outer can 2 made of aluminum (JIS alloy number A3003), and the positive electrode 8 and the negative electrode 6 are wound in a spiral shape with the separator 7 interposed therebetween. The electrode body 5 formed into a flat shape was accommodated. Subsequently, after arranging a spacer 9 having a lead extraction hole in the vicinity of the center on the electrode body 5 in the outer can 2, the lid body 3 made of aluminum (JIS alloy number A3003) having a thickness of 1.0 mm is used. The outer can 2 was hermetically joined to the upper end opening of the outer can 2 by laser welding. The lid 3 has a negative electrode terminal 12 hermetically sealed with an insulating material 13 and an electrolyte injection hole 11 (hole diameter: 2.0 mm).
[0077]
Next, a nonaqueous solvent electrolyte solution in which an electrolyte of lithium phosphorus hexafluoride was dissolved in ethylene carbonate and methyl ethyl carbonate was injected into the outer can 2 through the injection hole 11 of the lid 3. Subsequently, a plate material drawn out of a long plate material hoop made of aluminum (O material annealed with JIS alloy number A3003) having a width of 6 mm and a thickness of 0.05 mm is provided outside the lid 3 including the injection hole 11. Arranged on the surface.
[0078]
Next, an ultrasonic welding apparatus provided with the above-described cylindrical horn 33 shown in FIG. 3 was prepared. The cylindrical horn 33 has an outer diameter of 4.5 mm and an inner diameter of 3.0 mm in the vicinity of the lower end, and an outer peripheral edge R.₁Is 0.2, inner edge R₂Has a cylindrical portion 31 of 0.5, and a large number of pyramidal protrusions 32 having a height of 0.05 mm and a pitch of 0.2 mm are formed on the lower surface of the cylindrical portion 31. After a large number of protrusions 32 on the lower surface of the cylindrical portion 31 of the columnar horn 33 are brought into contact with a predetermined position of the aluminum plate of the lid 3, the horn 33 is ultrasonically vibrated by an ultrasonic vibration member (not shown). As shown in FIG. 2, the doughnut-shaped ultrasonic weld 16 having an outer diameter of 4.5 mm and an inner diameter of 3.0 mm is formed at the contact point of the cylindrical horn 33, and the outer peripheral edge of the horn 33 is By cutting the plate material by a cutter action, a disc-shaped sealing member 15 having an outer diameter of 4.5 mm was joined to the lid 3 to close the injection hole 11. The ultrasonic welding conditions at this time were an amplitude of 18 μm, a pressure of 2.5 kgf / cm 2, and an energy of 0.70 J.
[0079]
  Next, the insulating paper 17 is disposed on the surface of the lid 3, and the insulating paper 19 having the slit 18 is disposed on the outer surface of the bottom of the outer can 2, and the PTC element 20 folded in half is disposed on the insulating paper 19. did. The entirety including the outer can 2 is placed in an outer tube 21, and the tube 21 is thermally shrunk so that the upper insulating paper 17 is placed on the lid 3, and the lower insulating paper 19 and the PTC element 20 are placed on the outer can. Figure mentioned above by fixing to the bottom of 211A square sealed lithium ion secondary battery having the structure shown in FIG.
[0080]
  (Examples 2 to 6)
  An ultrasonic welding condition by an ultrasonic welding apparatus having a width of 6 mm and made of an aluminum O material having the thickness shown in Table 1 below and having a horn having the same shape as that of Example 1 was set to an amplitude of 18 μm and a pressure of 1 The sealing member was ultrasonically welded to the lid including the injection hole of the battery case by the same method as in Example 1 except that the pressure was 0.0 to 3.0 kgf / cm 2 and the energy was 0.4 to 0.75 J. Figure11Five types of prismatic sealed lithium ion secondary batteries having the structure shown in FIG.
[0081]
About 100 obtained each secondary battery of Examples 1-6, the ratio of the good article which does not raise | generate the leakage of electrolyte solution etc. was investigated. The results are shown in Table 1 below.
[0082]
[Table 1]

[0083]
As can be seen from Table 1, the secondary battery having a sealing member having a thickness of 0.08 to 0.30 mm has a very high yield rate.
[0084]
  (Reference example 1)
  In the same manner as in Example 1, the electrode body was accommodated in the outer can, and the lid body in which the injection hole was opened was hermetically joined by laser welding, and then the electrolytic solution was injected through the injection hole. Subsequently, a rod-shaped sealing member having a protruding rod having an outer diameter of less than 2.08 mm and a disc thickness of 0.15 mm is used, and the protruding rod of this sealing member is injected into the lid of the battery case. While being inserted into a hole (hole diameter; 2.0 mm), the disk was brought into contact with the surface of the lid. After this, it was described above by spot welding the disk and the lid.FIG., FIG. 5 and FIG. 6 were used to manufacture a prismatic sealed lithium ion secondary battery.
[0085]
  (Reference examples 2 and 3)
  First, using a bowl-shaped sealing member in which a protruding rod having an outer diameter of less than 2.0 mm is formed near the center of a disk having a thickness of 0.15 mm, the electrode body is stored and the electrolytic solution is injected in the same manner as in Example 1. The protruding rod of the sealing member was inserted into the injection hole (hole diameter: 2.0 mm) of the lid of the battery case. Thereafter, an ultrasonic welding apparatus including a horn having a cylindrical portion in the vicinity of the lower part as in Example 1, an outer diameter of 4.5 mm, an outer peripheral edge of 0.2, and a circular lower surface having a height of 0.05 mm Ultrasonic welding conditions with an amplitude of 18 μm, a pressure of 2.0 kgf / cm 2 and an energy of 0.6 J using an ultrasonic welding apparatus provided with a horn having a cylindrical shape as a whole on which a large number of pyramid-shaped protrusions with a pitch of 0.2 mm are formed As described above by ultrasonic weldingFIG.Two types of prismatic sealed lithium ion secondary batteries having the structures shown in FIGS. 8 and 9 were manufactured.
[0086]
  ObtainedReference examples 1 to 3For each of the secondary batteries, the ratio of non-defective products that did not cause electrolyte leakage or the like was examined. The results are shown in Table 2 below.
[0087]
[Table 2]

[0088]
As is apparent from Table 2, it was welded to the lid including the injection hole of the battery case using the hook-shaped sealing member.Reference examples 1 to 3It can be seen that all of the secondary batteries have a very high yield rate.
[0089]
【The invention's effect】
As described in detail above, according to the present invention, the battery case has a battery case in which the lid is airtightly joined or crimped to the opening of the outer can, and the injection hole of the battery case is airtight with the metal sealing member. A sealed battery with high reliability and a manufacturing method thereof can be provided.
[Brief description of the drawings]
[Figure 1]The partial notch perspective view which shows another form of the square-shaped sealed lithium ion secondary battery concerning this invention.
FIG. 2 is a view showing a lid of the secondary battery of FIG.
3 is a cross-sectional view taken along line III-III in FIG.
FIG. 4 is a view showing a horn incorporated in an ultrasonic welding apparatus.
FIG. 5 is a view showing a lid in another sealed battery according to the present invention.
6 is a cross-sectional view of the main part of FIG.
7 is a perspective view of a main part of FIG.
FIG. 8 is a view showing a lid in yet another sealed battery according to the present invention.
9 is a cross-sectional view of the main part of FIG.
FIG. 10 is a side view showing another embodiment of a square sealed lithium ion secondary battery according to the present invention.
FIG. 111 is a partially cutaway perspective view showing a square sealed lithium ion secondary battery that is an example of a sealed battery according to the present invention. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Battery case, 2 ... Exterior can, 3 ... Cover body, 5 ... Electrode body, 11 ... Injection hole, 15 ... Sealing member, 16 ... Ultrasonic welding part, 20 ... PTC element, 21 ... Exterior tube, 31 ... Cylindrical part, 32 ... projection, 33 ... horn, 41 ... disc, 42 ... projecting rod, 43, 44 ... welded part.

Claims

Storing a power generation element having a positive electrode and a negative electrode facing each other with a separator sandwiched in an outer can made of an aluminum-based metal;
A step of producing a battery case by joining a lid made of an aluminum-based metal to the opening of the outer can by welding;
Injecting an electrolyte into the battery case through an injection hole opened in the case;
Disposing an aluminum-based metal plate in the battery case including the injection hole;
Providing a columnar horn having a cylindrical portion on one end side and having a plurality of protrusions formed on a tip surface of the cylindrical portion; and
The end face of the cylindrical portion of the columnar horn is brought into contact with the metal plate material so that the cylindrical portion surrounds the injection hole, and ultrasonic waves are applied to the metal plate material through the horn. Welding the metal plate material along the outer edge of the cylindrical portion and joining the disk-shaped sealing member to the battery case to hermetically seal the injection hole ;
The manufacturing method of the sealed battery characterized by comprising.

The method for manufacturing a sealed battery according to claim 1, wherein the injection hole is opened in the lid of the battery case.

The method for manufacturing a sealed battery according to claim 1, wherein the plurality of protrusions formed on the front end surface of the cylindrical portion of the columnar horn have a pyramid shape.

4. The hermetic seal according to claim 1, wherein the cylindrical horn has a rounded outer periphery of the cylindrical portion of 0.2 or less and an inner peripheral edge of the cylindrical portion of 0.5 or more. Battery manufacturing method.

The method for manufacturing a sealed battery according to any one of claims 1 to 4, wherein the aluminum-based metal plate is made of an aluminum O material.

6. The method for manufacturing a sealed battery according to claim 1, wherein a thickness of a welding margin portion of the sealing member made of the metal plate material is 0.08 to 0.30 mm.