JP3661989B2

JP3661989B2 - Manufacturing method of cylindrical secondary battery

Info

Publication number: JP3661989B2
Application number: JP2000067773A
Authority: JP
Inventors: 一成大北; 淳浩船橋; 俊之能間; 育郎米津
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 2000-03-10
Filing date: 2000-03-10
Publication date: 2005-06-22
Anticipated expiration: 2020-03-10
Also published as: JP2001256946A

Description

【０００１】
【発明の属する技術分野】
本発明は、円筒状電池缶の内部に二次電池要素となる巻き取り電極体を収容して、電池缶に設けられた一対の電極端子部から巻き取り電極体の発生電力を取り出すことが可能な円筒型二次電池の製造方法に関するものである。
【０００２】
【従来の技術】
近年、携帯型電子機器、電気自動車等の電源として、エネルギー密度の高いリチウム二次電池が注目されている。
例えば電気自動車に用いられる比較的大きな容量の円筒型リチウム二次電池は、図５に示す様に、筒体(11)の両端部のそれぞれに蓋体(12)を溶接固定してなる円筒状の電池缶(１)の内部に、巻き取り電極体(２)を収容して構成されている。各蓋体(12)には、電極端子機構(９)が取り付けられており、巻き取り電極体(２)と各電極端子機構(９)とが、複数本の集電タブ(３)により互いに接続されて、巻き取り電極体(２)が発生する電力を両電極端子機構(９)(９)から外部に取り出すことが可能となっている。又、蓋体(12)には、ばね復帰式のガス排出弁(13)が取り付けられている。
【０００３】
巻き取り電極体(２)は、リチウム複合酸化物を含む正極(21)と炭素材料を含む負極(23)の間に、非水電解液が含浸されたセパレータ(22)を介在させて、これらを渦巻き状に巻回して構成されている。
巻き取り電極体(２)の正極(21)及び負極(23)からは夫々複数本の集電タブ(３)が引き出され、極性が同じ複数本の集電タブ(３)の先端部(31)が１つの電極端子機構(９)に接続されている。尚、図５においては、便宜上、一部の集電タブの先端部が電極端子機構(９)に接続されている状態のみを示し、他の集電タブについては、電極端子機構(９)に接続された先端部分の図示を省略している。
【０００４】
電極端子機構(９)は、電池缶(１)の蓋体(12)を貫通して取り付けられたネジ部材(91)を具え、該ネジ部材(91)の基端部には鍔部(92)が形成されている。蓋体(12)の貫通孔には絶縁パッキング(93)が装着され、蓋体(12)と締結部材(91)の間の電気的絶縁性とシール性が保たれている。ネジ部材(91)には、筒体(11)の外側からワッシャ(94)が嵌められると共に、ナット(95)が螺合している。このナット(95)を締め付けて、ネジ部材(91)の鍔部(92)とワッシャ(94)によって絶縁パッキング(93)を挟圧することにより、シール性を高めている。
前記複数本の集電タブ(３)の先端部(31)は、ネジ部材(91)の鍔部(92)に、スポット溶接或いは超音波溶接によって固定されている。
【０００５】
又、図６に示す如く、蓋体(12)に開設した貫通孔(14)を塞いで、クラッド板(４)からなる圧力開放型のガス排出弁を設置した円筒型二次電池が提案されている(特開平１１−８６８２０号)。クラッド板(４)は、リング部材(41)の片面に、厚さ１０〜１００μｍ程度のアルミニウム箔からなる金属薄膜(42)をクラッドして作製されており、リング部材(41)が筒体(11)の貫通孔(14)の開口縁にレーザ溶接されている。
【０００６】
【発明が解決しようとする課題】
しかしながら、図５に示すばね復帰式のガス排出弁(13)を具えた円筒型二次電池おいては、電池缶(１)の内圧が上昇したとき、ガス排出弁(13)は復帰力に抗して開かれることになるが、急激な圧力上昇が発生した場合、ガス排出弁(13)の弁孔の開口面積が小さい初期の段階で、圧力を十分に逃がすことが出来ない問題がある。
又、バネや弁機構などの構成部品が多く、図５の如く電極端子機構(９)を越える高さとなるため、例えば複数の二次電池を配列して組電池を構成する場合、組電池の筐体が大形化する問題がある。
【０００７】
これに対し、図６に示す如くクラッド板(４)からなるガス排出弁を具えた円筒型二次電池においては、電池缶(１)の内部に所定値を越える高い圧力が発生したとき、クラッド板(４)の金属薄膜(42)が破れて、圧力が一気に開放されるので、圧力の上昇は瞬時に抑制される。
又、クラッド板(４)からなるガス排出弁は、ばね復帰式のガス排出弁(13)に比べて構成部品の数が少なく、小型化が可能であるため、組電池を構成する場合にもコンパクト化が可能である。
【０００８】
ところが、クラッド板(４)からなるガス排出弁を具えた従来の円筒型二次電池では、その組立工程において、電池缶(１)の内部に電解液を注入する際、蓋体(12)にはクラッド板(４)が溶接固定されているため、蓋体(12)の別の位置に、電解液注入孔(12a)を開設して、該電解液注入孔(12a)から電解液を注入しているが、最後にこの孔(12a)を塞ぐ必要がある。この結果、構成が複雑となるばかりでなく、組立工数が増加する問題がある。
又、電解液の注入後、電解液注入孔(12a)を塞いだ状態で、電池缶の内部を加圧して、巻き取り電極体に電解液を含浸させる工程において、加圧力が高くなると、クラッド板(４)の金属薄膜(42)が破れる虞れがあるため、十分な圧力で加圧を行なうことが出来ず、この結果、電解液の含浸に長い時間を要する問題があった。
【０００９】
そこで本発明の目的は、コンパクトで且つ、組立工数の増大することのない簡易な構成を有し、然も電解液の含浸を短時間で行なうことが出来る円筒型二次電池の製造方法を提供することである。
【００１０】
【課題を解決する為の手段】
本発明の製造方法によって製造すべき円筒型二次電池は、筒体 (11) の両開口部にそれぞれ蓋体 (12) を固定してなる電池缶 ( １ ) の内部に、二次電池要素となる巻き取り電極体 ( ２ ) が収納され、該巻き取り電極体 ( ２ ) が発生する電力を一対の電極端子部から外部に取り出すことが可能であって、少なくとも何れか一方の蓋体(12)には、電池缶(１)の内圧が所定値を越えたときに作動するガス排出弁(５)が、蓋体(12)に開設されたねじ孔(15)にねじ込み固定されている。
該ガス排出弁(５)は、蓋体(12)のねじ孔(15)に螺合する外ねじ(52)を具えた円筒状の弁座(51)と、該弁座(51)の中央孔(53)を塞いで弁座(51)の端部に固定されたクラッド板(４)とから構成され、該クラッド板(４)は、前記弁座(51)と同軸に設置されて弁座(51)の開口縁に溶接されたリング部材(41)と、該リング部材(41)の片面にクラッドされた金属薄膜(42)とから構成されている。
本発明に係る円筒型二次電池の製造方法は、前記筒体 (11) 内に巻き取り電極体 ( ２ ) を装填すると共に該筒体 (11) の両開口部に蓋体 (12)(12) を固定して、電池缶 ( １ ) を作製する工程と、
蓋体 (12) のねじ孔 (15) からガス排出弁 ( ５ ) を取り外した状態で、電池缶 ( １ ) の内部に電解液を注入した後、該ねじ孔 (15) を通じて電池缶 ( １ ) の内部を所定の圧力に加圧することにより、巻き取り電極体 ( ２ ) に電解液を含浸させる工程と、
該含浸工程の後に、前記ガス排出弁 ( ５ ) を蓋体 (12) のねじ孔 (15) にねじ込み固定する工程
とを有している。
【００１１】
上記本発明の円筒型二次電池においては、電池缶(１)の内圧が所定値を越えて上昇すると、ガス排出弁(５)を構成するクラッド板(４)の金属薄膜(42)が破れて、電池缶(１)内部のガスが一気に外部へ放出される。
【００１２】
上記本発明の円筒型二次電池の組立において、巻き取り電極体(２)に電解液を含浸させる工程では、筒体(11)内に巻き取り電極体(２)を装填し、該筒体(11)の両開口部に蓋体(12)(12)を溶接固定した後、蓋体(12)のねじ孔(15)から電解液を注入し、電池缶(１)の内部を所定の圧力に加圧する。これによって、巻き取り電極体(２)に電解液が含浸される。この際、蓋体(12)にはガス排出弁(５)が取り付けられていないので、電池缶(１)の内部には充分に大きな圧力をかけることが出来る。その後、蓋体(12)のねじ孔(15)にガス排出弁(５)をねじ込み固定して、電池の組立を完了する。
従って、従来の如く蓋体(12)に電解液注入用のねじ孔を別に開設する必要がなく、この結果、組立工程の工数が減少する。
【００１３】
具体的構成において、ガス排出弁(５)の弁座(51)には、中央孔(53)の出口側の端部に、クラッド板(４)の厚さと同等の深さを有する段部(54)が凹設され、該段部(54)にクラッド板(４)が収容され、該クラッド板(４)は、金属薄膜(42)が段部(54)の底面に密着する向きに設置されている。
【００１４】
該具体的構成においては、クラッド板(４)の金属薄膜(42)が、弁座(51)の段部(54)の底面に設置され、ガス排出弁(５)の表面よりも低い位置に取り付けられているので、異物がガス排出弁(５)の表面に衝突した場合にも、この異物が金属薄膜(42)に直接に当たる虞れは低く、安全である。
【００１５】
【発明の効果】
本発明に係る円筒型二次電池の製造方法によって作製された円筒型二次電池は、クラッド板(４)を具えた圧力開放型のガス排出弁(５)を蓋体(12)にねじ込み固定した構成を有しているので、ばね復帰式のガス排出弁を具えた従来の電池よりも、構造の簡易化、小型化が図られる。
又、本発明に係る円筒型二次電池の製造方法によれば、ガス排出弁(５)をねじ込むためのねじ孔(15)を電解液注入のために利用することが出来、これによって組立工数の減少が図られる。然も、電解液の含浸を充分な圧力で行なうことが出来るので、短時間で含浸が終了する。
【００１６】
【発明の実施の形態】
以下、本発明の実施の形態につき、図面に沿って具体的に説明する。
本発明に係る円筒型二次電池は、図１及び図２に示す如く、筒体(11)の両端部に蓋体(12)(12)を溶接固定してなる円筒状の電池缶(１)の内部に、巻き取り電極体(２)を収容して構成されている。両蓋体(12)(12)には、正負一対の電極端子機構(９)(９)が取り付けられており、巻き取り電極体(２)の両極と両電極端子機構(９)(９)とがそれぞれ、複数本の集電タブ(３)により互いに接続されて、巻き取り電極体(２)が発生する電力を一対の電極端子機構(９)(９)から外部に取り出すことが可能となっている。
又、各蓋体(12)に開設したねじ孔(15)には、圧力開放型のガス排出弁(５)がねじ込み固定されている。
【００１７】
巻き取り電極体(２)は、リチウム複合酸化物を含む正極(21)と炭素材料を含む負極(23)の間に、非水電解液が含浸されたセパレータ(22)を介在させて、これらを渦巻き状に巻回して構成されている。
巻き取り電極体(２)の正極(21)及び負極(23)からは夫々複数本の集電タブ(３)が引き出され、極性が同じ複数本の集電タブ(３)の先端部(31)が１つの電極端子機構(９)に接続されている。尚、図１においては、便宜上、一部の集電タブの先端部が電極端子機構(９)に接続されている状態のみを示し、他の集電タブについては、電極端子機構(９)に接続された先端部分の図示を省略している。
【００１８】
電極端子機構(９)は、電池缶(１)の蓋体(12)を貫通して取り付けられたネジ部材(91)を具え、該ネジ部材(91)の基端部には鍔部(92)が形成されている。蓋体(12)の貫通孔には絶縁パッキング(93)が装着され、蓋体(12)と締結部材(91)の間の電気的絶縁性とシール性が保たれている。ネジ部材(91)には、蓋体(12)の外側からワッシャ(94)が嵌められると共に、ナット(95)が螺合している。このナット(95)を締め付けて、ネジ部材(91)の鍔部(92)とワッシャ(94)によって絶縁パッキング(93)を挟圧することにより、シール性を高めている。
前記複数本の集電タブ(３)の先端部(31)は、ネジ部材(91)の鍔部(92)に、スポット溶接或いは超音波溶接によって固定されている。
【００１９】
ガス排出弁(５)は、図３及び図４に示す如く、円筒状の弁座(51)と円板状のクラッド板(４)とから構成される。弁座(51)は、蓋体(12)に開設されたねじ孔(15)に螺合する外ねじ(52)を具えると共に、中央孔(53)の出口側に段部(54)を有し、該段部(54)にクラッド板(４)が設置されている。
クラッド板(４)は、リング部材(41)の片面に、厚さ３０μｍのアルミニウム箔からなる金属薄膜(42)をクラッドして作製され、金属薄膜(42)を弁座(51)の段部(54)に密着させた向きで設置されて、リング部材(41)の外周縁が弁座(51)にレーザ溶接(６)されている。
【００２０】
尚、クラッド板(４)の外径Ｄは９ｍｍ、厚さＳは０.６ｍｍである。一方、弁座(51)の高さＨは７ｍｍ、外ねじ(52)の長さＬは４ｍｍ、中央孔(53)の内径Ｅは５ｍｍ、外ねじ(52)のねじ径Ｆは１／４インチ、段部(54)の深さＴは０.６ｍｍである。又、段部(54)の内径は９ｍｍであって、クラッド板(４)の外径Ｄに対して＋０.２ｍｍ、−０ｍｍの公差を有している。
【００２１】
図１に示す円筒型二次電池の組立においては、電池缶(１)の蓋体(12)のねじ孔(15)から電池缶(１)の内部へ電解液を注入した後、電池缶(１)の内部に所定の圧力をかけて、電解液を巻き取り電極体(２)の正極(21)、セパレータ(22)及び負極(23)に含浸させる。その後、ねじ孔(15)にガス排出弁(５)をねじ込んで固定する。
【００２２】
上記円筒型二次電池においては、電池缶(１)の内部の圧力が増大したとき、ガス排出弁(５)を構成するクラッド板(４)の金属薄膜(42)に破れが生じて、内圧を一気に外部へ逃がすことが出来る。
【００２３】
【実施例】
図１に示す本発明に係る円筒型二次電池(実施例１及び２)と、図６に示す従来の円筒型二次電池(比較例)を作製して、本発明の効果を確認した。
先ず、各電池に共通の製造工程について説明した後、電池毎に異なる組立工程について説明する。
【００２４】
（正極の作製）
正極活物質としてのリチウム複合酸化物（ＬｉＮｉ_０ _. _７Ｃｏ_０ _. _３Ｏ_２）と導電剤としての炭素とを重量比９０：５で混合し、正極合剤を作製した。次に、結着剤であるポリフッ化ビニリデンをＮ−メチル−２−ピロリドン（ＮＭＰ）に溶解させて、ＮＭＰ溶液を調製した。そして、正極合剤とポリフッ化ビニリデンの重量比が９５：５になるように正極合剤とＮＭＰ溶液を混練してスラリーを調製し、このスラリーを正極集電体としてのアルミニウム箔の両面にドクターブレード法により塗布し、１５０℃で２時間の真空乾燥を施して、正極を作製した。
【００２５】
（負極の作製）
結着剤であるポリフッ化ビニリデンをＮＭＰに溶解させて、ＮＭＰ溶液を調製した。そして、黒鉛粉末とコークス粉末をポリフッ化ビニリデンの重量比が９５：５になるように混練してスラリーを調製し、このスラリーを負極集電体としての銅箔の両面にドクターブレード法により塗布し、１５０℃で２時間の真空乾燥を施して、負極を作製した。
【００２６】
（電解液の調製）
エチレンカーボネートとジエチルカーボネートを体積比１：１で混合した溶媒に、ＬｉＰＦ_６を１ｍｏｌ／ｌの割合で溶解せしめ、電解液を調製した。
【００２７】
（巻き取り電極体の作製）
正極を構成しているアルミニウム箔の表面に、厚さ０.１ｍｍのアルミニウム製集電タブを１０本、一定間隔をおいて溶接すると共に、負極を構成している銅箔の表面に、厚さ０.１ｍｍのニッケル製集電タブを１０本、一定間隔をおいて溶接した。そして、正極と負極の間にセパレータを挟んで渦巻き状に巻回し、巻き取り電極体を構成した。尚、セパレータとしては、イオン透過性のポリエチレン製の微多孔性膜を用いた。
【００２８】
（電池の組立）
電池缶を構成すべき筒体の内部に巻き取り電極体を装填し、該巻き取り電極体から伸びる正側及び負側の集電タブを夫々、蓋体に取り付けられた電極端子機構に接続し、該蓋体を筒体の開口部に溶接固定した後、電解液を注入して、円筒型二次電池を組み立てた。
尚、電池缶は、筒体の外径が６４ｍｍ、高さが３４０ｍｍ、厚さが１ｍｍであり、蓋体の外径が６４ｍｍ、厚さが５ｍｍである。
【００２９】
実施例１
開口径５ｍｍのリング部材に厚さ３０μｍのアルミニウム薄膜をクラッドしてクラッド板を作製し、レーザビームによって該クラッド板を弁座に溶接し、作動圧８ｋｇｆ／ｃｍ^２(７８.４×１０^４Ｐａ)のガス排出弁を作製した。そして、電池缶に巻き取り電極体を収容して、電解液の注入、加圧を行なった後、蓋体に上記ガス排出弁をねじ込み固定し、図１に示す二次電池(実施例１)を組み立てた。
【００３０】
実施例２
開口径９ｍｍのリング部材を用いてクラッド板を作製し、電子ビームによって該クラッド板を弁座に溶接し、作動圧５ｋｇｆ／ｃｍ^２(４９.０×１０^４Ｐａ)のガス排出弁を作製したこと以外は実施例１と同様にして、図１に示す二次電池(実施例２)を組み立てた。
【００３１】
比較例
開口径５ｍｍのリング部材に厚さ３０μｍのアルミニウム薄膜をクラッドしてクラッド板を作製し、レーザビームによって該クラッド板を蓋体に直接に溶接して、作動圧８ｋｇｆ／ｃｍ^２(７８.４×１０^４Ｐａ)のガス排出弁を構成した(図６参照)。そして、電池缶に巻き取り電極体を収容して、蓋体に別に開設した電解液注入孔から電解液を注入し、加圧を行なった後、電解液注入孔を栓で塞いで、従来の二次電池(比較例)を組み立てた。
【００３２】
充放電試験
比較例については、ガス排出弁の作動圧が８ｋｇｆ／ｃｍ^２であることから、電解液注入後に、作動圧よりも低い圧力７ｋｇｆ／ｃｍ^２(６８.６Ｐａ×１０^４)により、５時間、１０時間、及び１５時間の加圧後、充放電試験を行なって、放電容量を測定した。
一方、実施例１及び実施例２については、蓋体のねじ孔に開閉バルブを取り付け、電解液注入後、バルブを閉じた状態で、１０ｋｇｆ／ｃｍ^２(９８.１×１０^４Ｐａ)の圧力により、５時間、１０時間、及び１５時間の加圧後、それぞれガス排出弁をねじ込み固定した状態で充放電試験を行なって、放電容量を測定した。
充放電試験の結果を表１に示す。
【００３３】
【表１】

【００３４】
表１に示す様に、実施例１及び実施例２では、加圧時間が１０時間で電解液が電極及びセパレータに浸透したため、設計容量７０Ａｈが得られたが、比較例では、加圧力が実施例１及び２よりも低いため、設計容量を得るために１５時間が必要であった。
この様に、実施例１及び２では、比較例よりも大きな圧力を加えることが出来るので、電解液の含浸時間が短くなり、電池の組立に必要な時間を短縮することが出来る。
【００３５】
上述の如く、本発明に係る円筒型二次電池によれば、電池の組立工程において、電池缶の内部に電解液を注入する際、図６に示す従来の二次電池では、別に電解液注入用の孔を開設する必要があるが、本発明の二次電池では、蓋体に開設されたガス排出弁ねじ込み用のねじ孔を利用することが出来るので、構成が簡易となる。
【００３６】
又、複数本の二次電池を用いて組電池を組み立てる場合、本発明の二次電池においては、図１に示す圧力開放型のガス排出弁(５)は、電極端子機構(９)の高さよりも低く形成することが出来るので、各二次電池を導線で互いに結線する作業が圧力開放弁によって阻害されることはなく、従来例の二次電池を用いて同様の組電池を組み立てる場合に比べて、組立作業が容易となる。
【００３７】
更に、複数本の二次電池を直列に接続して組電池を構成する場合、本発明の二次電池によれば、従来の二次電池を用いて同様の組電池を構成する場合に比べて、筐体の小形化が可能である。
【図面の簡単な説明】
【図１】本発明に係る円筒型二次電池の要部を示す断面図である。
【図２】本発明に係る円筒型二次電池において、電池缶にガス排出弁をねじ込む様子を表わす斜視図である。
【図３】本発明に係るガス排出弁の拡大断面図である。
【図４】本発明に係るガス排出弁からクラッド板を分解した状態の拡大断面図である。
【図５】ばね復帰式のガス排出弁を具えた従来の円筒型二次電池の断面図である。
【図６】圧力開放型のガス排出弁を具えた従来の円筒型二次電池の要部を示す断面図である。
【符号の説明】
(１) 電池缶
(11) 筒体
(12) 蓋体
(15) ねじ孔
(２) 巻き取り電極体
(３) 集電タブ
(４) クラッド板
(41) リング部材
(42) 金属薄膜
(５) ガス排出弁
(51) 弁座
(52) 外ねじ
(９) 電極端子機構[0001]
BACKGROUND OF THE INVENTION
The present invention accommodates a wound electrode body serving as a secondary battery element inside a cylindrical battery can, and can take out electric power generated by the wound electrode body from a pair of electrode terminal portions provided on the battery can. The present invention relates to a method for manufacturing a cylindrical secondary battery.
[0002]
[Prior art]
In recent years, lithium secondary batteries with high energy density have attracted attention as power sources for portable electronic devices and electric vehicles.
For example, as shown in FIG. 5, a cylindrical lithium secondary battery having a relatively large capacity used in an electric vehicle has a cylindrical shape in which a lid (12) is welded and fixed to both ends of the cylindrical body (11). The winding electrode body (2) is accommodated in the battery can (1). An electrode terminal mechanism (9) is attached to each lid (12), and the take-up electrode body (2) and each electrode terminal mechanism (9) are mutually connected by a plurality of current collecting tabs (3). It is possible to take out the electric power generated by the winding electrode body (2) connected to the outside from both electrode terminal mechanisms (9) and (9). A spring return type gas discharge valve (13) is attached to the lid (12).
[0003]
The take-up electrode body (2) includes a separator (22) impregnated with a non-aqueous electrolyte between a positive electrode (21) containing a lithium composite oxide and a negative electrode (23) containing a carbon material. Is wound in a spiral shape.
A plurality of current collecting tabs (3) are drawn out from the positive electrode (21) and the negative electrode (23) of the winding electrode body (2), respectively, and the tips (31) of the plurality of current collecting tabs (3) having the same polarity are drawn out. ) Is connected to one electrode terminal mechanism (9). In FIG. 5, for the sake of convenience, only the state where the tip portions of some of the current collecting tabs are connected to the electrode terminal mechanism (9) is shown, and the other current collecting tabs are shown in the electrode terminal mechanism (9). Illustration of the connected tip portion is omitted.
[0004]
The electrode terminal mechanism (9) includes a screw member (91) attached through the lid (12) of the battery can (1), and a hook (92) is provided at the base end of the screw member (91). ) Is formed. An insulating packing (93) is attached to the through hole of the lid (12), and electrical insulation and sealing between the lid (12) and the fastening member (91) are maintained. A washer (94) is fitted to the screw member (91) from the outside of the cylindrical body (11), and a nut (95) is screwed. The nut (95) is tightened, and the insulating packing (93) is clamped between the flange (92) and the washer (94) of the screw member (91), thereby improving the sealing performance.
The tip portions (31) of the plurality of current collecting tabs (3) are fixed to the flange portion (92) of the screw member (91) by spot welding or ultrasonic welding.
[0005]
Further, as shown in FIG. 6, a cylindrical secondary battery is proposed in which a through-hole (14) opened in the lid (12) is closed and a pressure relief type gas discharge valve made of a clad plate (4) is installed. (Japanese Patent Laid-Open No. 11-86820). The clad plate (4) is produced by clad a metal thin film (42) made of an aluminum foil having a thickness of about 10 to 100 μm on one surface of a ring member (41), and the ring member (41) is a cylinder ( It is laser welded to the opening edge of the through hole (14) of 11).
[0006]
[Problems to be solved by the invention]
However, in the cylindrical secondary battery having the spring return type gas discharge valve (13) shown in FIG. 5, when the internal pressure of the battery can (1) rises, the gas discharge valve (13) has a return force. However, when a sudden pressure rise occurs, there is a problem that the pressure cannot be released sufficiently in the initial stage where the opening area of the valve hole of the gas discharge valve (13) is small. .
In addition, since there are many components such as a spring and a valve mechanism, and the height exceeds the electrode terminal mechanism (9) as shown in FIG. 5, for example, when an assembled battery is configured by arranging a plurality of secondary batteries, There is a problem that the case becomes larger.
[0007]
On the other hand, in a cylindrical secondary battery having a gas discharge valve comprising a clad plate (4) as shown in FIG. 6, when a high pressure exceeding a predetermined value is generated inside the battery can (1), the clad Since the metal thin film (42) of the plate (4) is torn and the pressure is released at once, the pressure rise is suppressed instantaneously.
Also, the gas discharge valve consisting of the clad plate (4) has fewer components than the spring return type gas discharge valve (13) and can be downsized. Compact size is possible.
[0008]
However, in the conventional cylindrical secondary battery having a gas discharge valve made of the clad plate (4), when the electrolyte is injected into the battery can (1) in the assembly process, the lid (12) Since the clad plate (4) is fixed by welding, an electrolyte injection hole (12a) is opened at another position of the lid (12) and the electrolyte is injected from the electrolyte injection hole (12a). However, it is necessary to close this hole (12a) at the end. As a result, there is a problem that not only the configuration becomes complicated but also the number of assembly steps increases.
In addition, after the injection of the electrolytic solution, in the state where the electrolytic solution injection hole (12a) is closed, the inside of the battery can is pressurized and the winding electrode body is impregnated with the electrolytic solution. Since there is a possibility that the metal thin film (42) of the plate (4) may be torn, pressurization with sufficient pressure cannot be performed, and as a result, there is a problem that it takes a long time to impregnate the electrolytic solution.
[0009]
SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a cylindrical secondary battery that is compact and has a simple configuration that does not increase the number of assembly steps, and that can be impregnated with an electrolytic solution in a short time. It is to be.
[0010]
[Means for solving the problems]
The cylindrical secondary battery to be manufactured by the manufacturing method of the present invention includes a secondary battery element in a battery can ( 1 ) formed by fixing lids (12) to both openings of the cylinder (11). The winding electrode body ( 2 ) is stored, and the electric power generated by the winding electrode body ( 2 ) can be taken out from the pair of electrode terminal portions, and at least one of the lid bodies ( In 12), a gas discharge valve (5) that operates when the internal pressure of the battery can (1) exceeds a predetermined value is screwed and fixed into a screw hole (15) opened in the lid (12). .
The gas discharge valve (5) includes a cylindrical valve seat (51) having an external screw (52) screwed into the screw hole (15) of the lid (12), and a center of the valve seat (51). A clad plate (4) which closes the hole (53) and is fixed to the end of the valve seat (51), and the clad plate (4) is installed coaxially with the valve seat (51) to A ring member (41) welded to the opening edge of the seat (51) and a metal thin film (42) clad on one surface of the ring member (41) .
Method of manufacturing a cylindrical secondary battery according to the present invention, the lid (12) both openings of the tubular member (11) with loading the cylindrical body (11) wound electrode body in (2) ( 12) fixing the battery can ( 1 ) ,
In a state that the threaded hole (15) removed gas discharge valve (5) of the lid (12), after injection of the interior electrolyte of the battery can (1), the battery can (1 through the screw hole (15) ) By impregnating the winding electrode body ( 2 ) with an electrolytic solution by pressurizing the interior of
After the impregnation step, the gas discharge valve ( 5 ) is screwed and fixed into the screw hole (15) of the lid (12).
And have.
[0011]
In the cylindrical secondary battery of the present invention, when the internal pressure of the battery can (1) rises above a predetermined value, the metal thin film (42) of the clad plate (4) constituting the gas discharge valve (5) is broken. Thus, the gas inside the battery can (1) is released to the outside at once.
[0012]
In the assembly of the cylindrical secondary battery of the present invention, in the step of impregnating the winding electrode body (2) with the electrolytic solution, the winding electrode body (2) is loaded into the cylinder body (11), and the cylinder body After the lids (12) and (12) are welded and fixed to both openings of (11), the electrolytic solution is injected from the screw holes (15) of the lid (12), and the inside of the battery can (1) is predetermined. Pressurize to pressure. Thus, the winding electrode body (2) is impregnated with the electrolytic solution. At this time, since the gas discharge valve (5) is not attached to the lid (12), a sufficiently large pressure can be applied to the inside of the battery can (1). Thereafter, the gas discharge valve (5) is screwed and fixed into the screw hole (15) of the lid (12) to complete the assembly of the battery.
Therefore, it is not necessary to separately provide a screw hole for injecting the electrolyte in the lid (12) as in the prior art, and as a result, the number of steps in the assembly process is reduced.
[0013]
In a specific configuration, the valve seat (51) of the gas discharge valve (5) has a stepped portion having a depth equivalent to the thickness of the clad plate (4) at the end on the outlet side of the central hole (53). 54) is recessed, and the clad plate (4) is accommodated in the step portion (54), and the clad plate (4) is installed in such a direction that the metal thin film (42) is in close contact with the bottom surface of the step portion (54). Has been.
[0014]
In the specific configuration, the metal thin film (42) of the clad plate (4) is installed on the bottom surface of the step portion (54) of the valve seat (51) and is positioned lower than the surface of the gas discharge valve (5). Since it is attached, even when a foreign object collides with the surface of the gas discharge valve (5), the possibility that the foreign object directly hits the metal thin film (42) is low and safe.
[0015]
【The invention's effect】
A cylindrical secondary battery manufactured by the method for manufacturing a cylindrical secondary battery according to the present invention is fixed by screwing a pressure release type gas discharge valve (5) having a clad plate (4) into a lid (12). Therefore, the structure can be simplified and miniaturized as compared with a conventional battery having a spring return type gas discharge valve.
Further, according to the method for manufacturing a cylindrical secondary battery according to the present invention, the screw hole (15) for screwing the gas discharge valve (5) can be used for injecting the electrolyte solution, thereby assembling man-hours. Is reduced. However, since the impregnation of the electrolytic solution can be performed at a sufficient pressure, the impregnation is completed in a short time.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
As shown in FIGS. 1 and 2, the cylindrical secondary battery according to the present invention has a cylindrical battery can (1) formed by welding and fixing lids (12) and (12) to both ends of a cylindrical body (11). ) Is housed in a winding electrode body (2). A pair of positive and negative electrode terminal mechanisms (9), (9) is attached to the lids (12), (12), and both electrodes of the winding electrode body (2) and the electrode terminal mechanisms (9), (9) Are connected to each other by a plurality of current collecting tabs (3), and the electric power generated by the winding electrode body (2) can be taken out from the pair of electrode terminal mechanisms (9), (9). It has become.
In addition, a pressure release type gas discharge valve (5) is screwed and fixed to the screw hole (15) opened in each lid (12).
[0017]
The take-up electrode body (2) includes a separator (22) impregnated with a non-aqueous electrolyte between a positive electrode (21) containing a lithium composite oxide and a negative electrode (23) containing a carbon material. Is wound in a spiral shape.
A plurality of current collecting tabs (3) are drawn out from the positive electrode (21) and the negative electrode (23) of the winding electrode body (2), respectively, and the tips (31) of the plurality of current collecting tabs (3) having the same polarity are drawn out. ) Is connected to one electrode terminal mechanism (9). In FIG. 1, for the sake of convenience, only the state in which the tip portions of some of the current collecting tabs are connected to the electrode terminal mechanism (9) is shown, and the other current collecting tabs are shown in the electrode terminal mechanism (9). Illustration of the connected tip portion is omitted.
[0018]
The electrode terminal mechanism (9) includes a screw member (91) attached through the lid (12) of the battery can (1), and a hook (92) is provided at the base end of the screw member (91). ) Is formed. An insulating packing (93) is attached to the through hole of the lid (12), and electrical insulation and sealing between the lid (12) and the fastening member (91) are maintained. A washer (94) is fitted to the screw member (91) from the outside of the lid (12), and a nut (95) is screwed. The nut (95) is tightened, and the insulating packing (93) is clamped between the flange (92) and the washer (94) of the screw member (91), thereby improving the sealing performance.
The tip portions (31) of the plurality of current collecting tabs (3) are fixed to the flange portion (92) of the screw member (91) by spot welding or ultrasonic welding.
[0019]
As shown in FIGS. 3 and 4, the gas discharge valve (5) is composed of a cylindrical valve seat (51) and a disc-shaped clad plate (4). The valve seat (51) includes an external screw (52) that is screwed into a screw hole (15) provided in the lid (12), and a step (54) on the outlet side of the central hole (53). And a clad plate (4) is installed on the step (54).
The clad plate (4) is produced by clad a metal thin film (42) made of aluminum foil having a thickness of 30 μm on one side of the ring member (41), and the metal thin film (42) is formed on the stepped portion of the valve seat (51). The outer peripheral edge of the ring member (41) is laser welded (6) to the valve seat (51).
[0020]
The clad plate (4) has an outer diameter D of 9 mm and a thickness S of 0.6 mm. On the other hand, the height H of the valve seat (51) is 7 mm, the length L of the outer screw (52) is 4 mm, the inner diameter E of the central hole (53) is 5 mm, and the screw diameter F of the outer screw (52) is 1/4. The depth T of the inch and step (54) is 0.6 mm. Further, the inner diameter of the step portion (54) is 9 mm, and has tolerances of +0.2 mm and −0 mm with respect to the outer diameter D of the clad plate (4).
[0021]
In the assembly of the cylindrical secondary battery shown in FIG. 1, an electrolyte is injected into the inside of the battery can (1) from the screw hole (15) of the lid (12) of the battery can (1), and then the battery can ( A predetermined pressure is applied to the inside of 1), and the positive electrode (21), separator (22) and negative electrode (23) of the wound electrode body (2) are impregnated with the electrolyte. Thereafter, the gas discharge valve (5) is screwed into the screw hole (15) and fixed.
[0022]
In the cylindrical secondary battery, when the internal pressure of the battery can (1) increases, the metal thin film (42) of the clad plate (4) constituting the gas discharge valve (5) is torn, and the internal pressure Can escape to the outside at once.
[0023]
【Example】
A cylindrical secondary battery (Examples 1 and 2) according to the present invention shown in FIG. 1 and a conventional cylindrical secondary battery (comparative example) shown in FIG. 6 were produced, and the effects of the present invention were confirmed.
First, a manufacturing process common to each battery will be described, and then an assembly process different for each battery will be described.
[0024]
(Preparation of positive electrode)
Lithium composite oxide as a positive electrode active material _{_{_{_{_{(.. LiNi 0 7 Co 0}}}}} 3 O 2) the weight ratio of the carbon as a conductive agent 90 were mixed with 5 to prepare a positive electrode mixture. Next, polyvinylidene fluoride as a binder was dissolved in N-methyl-2-pyrrolidone (NMP) to prepare an NMP solution. The positive electrode mixture and the NMP solution were kneaded so that the weight ratio of the positive electrode mixture and polyvinylidene fluoride was 95: 5, and a slurry was prepared. The slurry was applied to both surfaces of the aluminum foil as the positive electrode current collector. The positive electrode was produced by coating by a blade method and vacuum drying at 150 ° C. for 2 hours.
[0025]
(Preparation of negative electrode)
Polyvinylidene fluoride as a binder was dissolved in NMP to prepare an NMP solution. Then, a graphite powder and a coke powder are kneaded so that the weight ratio of polyvinylidene fluoride is 95: 5 to prepare a slurry, and this slurry is applied to both surfaces of a copper foil as a negative electrode current collector by a doctor blade method. Then, vacuum drying was performed at 150 ° C. for 2 hours to produce a negative electrode.
[0026]
(Preparation of electrolyte)
LiPF ₆ was dissolved at a ratio of 1 mol / l in a solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1 to prepare an electrolytic solution.
[0027]
(Preparation of wound electrode body)
Ten aluminum current collecting tabs with a thickness of 0.1 mm are welded to the surface of the aluminum foil constituting the positive electrode at regular intervals, and the surface of the copper foil constituting the negative electrode is thickened. Ten nickel current collecting tabs of 0.1 mm were welded at regular intervals. Then, the separator was sandwiched between the positive electrode and the negative electrode and wound in a spiral shape to form a wound electrode body. As the separator, an ion-permeable polyethylene microporous membrane was used.
[0028]
(Battery assembly)
A take-up electrode body is loaded inside a cylindrical body to constitute a battery can, and positive and negative current collecting tabs extending from the take-up electrode body are connected to an electrode terminal mechanism attached to the lid body, respectively. The lid was welded and fixed to the opening of the cylindrical body, and then the electrolyte was injected to assemble a cylindrical secondary battery.
The battery can has an outer diameter of 64 mm, a height of 340 mm, and a thickness of 1 mm, and an outer diameter of the lid of 64 mm and a thickness of 5 mm.
[0029]
Example 1
A clad plate is prepared by clad an aluminum thin film with a thickness of 30 μm on a ring member having an opening diameter of 5 mm, and the clad plate is welded to a valve seat by a laser beam, and an operating pressure of 8 kgf / cm ² (78.4 × 10 ⁴ Pa). ) Gas discharge valve. Then, after the wound electrode body is accommodated in the battery can, the electrolyte is injected and pressurized, the gas discharge valve is screwed and fixed to the lid body, and the secondary battery shown in FIG. 1 (Example 1) Assembled.
[0030]
Example 2
A clad plate was produced using a ring member having an opening diameter of 9 mm, and the clad plate was welded to the valve seat by an electron beam to produce a gas discharge valve with an operating pressure of 5 kgf / cm ² (49.0 × 10 ⁴ Pa). A secondary battery (Example 2) shown in FIG. 1 was assembled in the same manner as Example 1 except for the above.
[0031]
Comparative example A clad plate is prepared by clad an aluminum thin film with a thickness of 30 μm on a ring member having an opening diameter of 5 mm, and the clad plate is directly welded to the lid by a laser beam, and an operating pressure of 8 kgf / cm is obtained. ² (78.4 × 10 ⁴ Pa) gas discharge valve was constructed (see FIG. 6). Then, the wound electrode body is accommodated in the battery can, the electrolyte is injected from the electrolyte injection hole separately provided in the lid, and after pressurization, the electrolyte injection hole is closed with a stopper, A secondary battery (comparative example) was assembled.
[0032]
Charge / discharge test In the comparative example, since the operating pressure of the gas discharge valve is 8 kgf / cm ² , the pressure 7 kgf / cm ² (68.6 Pa × 10 ⁴⁾ lower than the operating pressure after the electrolyte injection. ), After 5 hours, 10 hours, and 15 hours of pressurization, a charge / discharge test was performed to measure the discharge capacity.
On the other hand, for Example 1 and Example 2, a pressure of 10 kgf / cm ² (98.1 × 10 ⁴ Pa) was attached with an open / close valve attached to the screw hole of the lid, and after the electrolyte was injected, the valve was closed. Then, after pressurizing for 5 hours, 10 hours, and 15 hours, a charge / discharge test was performed with the gas discharge valve screwed and fixed, and the discharge capacity was measured.
The results of the charge / discharge test are shown in Table 1.
[0033]
[Table 1]

[0034]
As shown in Table 1, in Example 1 and Example 2, the electrolyte capacity permeated into the electrode and the separator in a pressurization time of 10 hours, so that a design capacity of 70 Ah was obtained. Since it was lower than Examples 1 and 2, 15 hours were required to obtain the design capacity.
Thus, in Examples 1 and 2, a larger pressure can be applied than in the comparative example, so that the time for impregnation with the electrolyte is shortened, and the time required for battery assembly can be shortened.
[0035]
As described above, according to the cylindrical secondary battery of the present invention, when the electrolyte is injected into the battery can in the battery assembly process, the conventional secondary battery shown in FIG. However, in the secondary battery of the present invention, since the screw hole for screwing the gas discharge valve opened in the lid can be used, the configuration is simplified.
[0036]
Further, when assembling an assembled battery using a plurality of secondary batteries, in the secondary battery of the present invention, the pressure release type gas discharge valve (5) shown in FIG. Since the pressure release valve does not hinder the work of connecting the secondary batteries to each other with conductive wires, when assembling the same assembled battery using the secondary battery of the conventional example In comparison, the assembly work is facilitated.
[0037]
Furthermore, when the assembled battery is configured by connecting a plurality of secondary batteries in series, according to the secondary battery of the present invention, compared to the case where a similar assembled battery is configured using a conventional secondary battery. The housing can be downsized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a main part of a cylindrical secondary battery according to the present invention.
FIG. 2 is a perspective view showing a state in which a gas discharge valve is screwed into a battery can in the cylindrical secondary battery according to the present invention.
FIG. 3 is an enlarged cross-sectional view of a gas discharge valve according to the present invention.
FIG. 4 is an enlarged cross-sectional view of a state in which a clad plate is disassembled from a gas discharge valve according to the present invention.
FIG. 5 is a cross-sectional view of a conventional cylindrical secondary battery including a spring return type gas discharge valve.
FIG. 6 is a cross-sectional view showing a main part of a conventional cylindrical secondary battery including a pressure release type gas discharge valve.
[Explanation of symbols]
(1) Battery can
(11) Tube
(12) Lid
(15) Screw hole
(2) Winding electrode body
(3) Current collection tab
(4) Clad plate
(41) Ring member
(42) Metal thin film
(5) Gas discharge valve
(51) Valve seat
(52) External thread
(9) Electrode terminal mechanism

Claims

A take-up electrode body (2) serving as a secondary battery element is housed in a battery can (1) having a lid (12) fixed to both openings of the cylinder (11). The electric power generated by the electrode body (2) can be taken out from the pair of electrode terminal portions, and the internal pressure of the battery can (1) has a predetermined value in at least one of the lid bodies (12). gas exhaust valve that operates when exceeded (5) is, in the method of manufacturing the cylindrical secondary battery are screwed into screw holes opened in the lid (12) (15),
The gas discharge valve (5) includes a cylindrical valve seat (51) having an external screw (52) screwed into the screw hole (15) of the lid (12), and a center of the valve seat (51). A clad plate (4) which closes the hole (53) and is fixed to the end of the valve seat (51), and the clad plate (4) is installed coaxially with the valve seat (51) to The ring member (41) welded to the opening edge of the seat (51), and a metal thin film (42) clad on one side of the ring member (41) ,
Prepared by fixing the lid (12) (12) to both the openings of the tubular member (11), a battery can (1) with loading the cylindrical body wound electrode body into the (11) (2) And a process of
In a state that the threaded hole (15) removed gas discharge valve (5) of the lid (12), after injection of the interior electrolyte of the battery can (1), the battery can (1 through the screw hole (15) ) By impregnating the winding electrode body ( 2 ) with an electrolytic solution by pressurizing the interior of
After the impregnation step, the gas discharge valve ( 5 ) is screwed and fixed into the screw hole (15) of the lid (12).
The manufacturing method of the cylindrical secondary battery characterized by having.

The valve seat (51) of the gas discharge valve (5) has a stepped portion (54) having a depth equivalent to the thickness of the clad plate (4) at the end on the outlet side of the central hole (53). The clad plate (4) is accommodated in the step portion (54), and the clad plate (4) is disposed in a direction in which the metal thin film (42) is in close contact with the bottom surface of the step portion (54). A method for producing the cylindrical secondary battery according to claim 1.