JP3661974B2

JP3661974B2 - Cylindrical secondary battery

Info

Publication number: JP3661974B2
Application number: JP31146798A
Authority: JP
Inventors: 一成大北; 義人近野; 俊之能間; 育郎米津; 晃治西尾
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 1998-10-30
Filing date: 1998-10-30
Publication date: 2005-06-22
Anticipated expiration: 2018-10-30
Also published as: JP2000138047A

Description

【０００１】
【発明の属する技術分野】
本発明は、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、電池缶に取り付けられた一対の電極端子から二次電池要素の発生電力を取り出すことが可能な二次電池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４に示す様に、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)と両電極端子機構(９)(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、蓋体(12)には復帰式の安全弁(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４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５に示す如く、蓋体(12)に開設した貫通孔(14)に、電池缶(１)の内圧が所定値を越えたときに作動する圧力開放型の安全弁(４)を取り付けた円筒型二次電池が知られている(特開平6-68861号、特開平9-139196号等)。
図５に示す安全弁(４)は、リング体(41)の裏面に、厚さ２０μｍ程度のアルミニウム箔からなる円板状の圧力開放板(42)を固定してなり、リング体(41)の外周部が蓋体(12)の貫通孔(14)の開口縁にレーザ溶接されて、蓋体(12)に固定されている。
【０００６】
【発明が解決しようとする課題】
しかしながら、図４に示す復帰式安全弁(13)を具えた円筒型二次電池では、電池缶(１)内部の圧力が上昇したとき、安全弁(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、復帰式安全弁(13)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４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５に示す圧力開放型安全弁(４)を具えた円筒型二次電池では、電池缶(１)の内部に異常圧力が発生したとき、圧力開放板(42)が作動して、圧力が瞬時に開放されるので、圧力の上昇は十分に抑制される。
又、圧力開放型安全弁(４)は復帰式安全弁(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。
ところが、圧力開放型安全弁(４)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)には安全弁(４)が溶接固定されているため、別途、電解液注入用のねじ孔を開設しておき、電解液注入後、このねじ孔を塞ぐ必要がある。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。
【０００８】
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する円筒型二次電池を提供することである。
【０００９】
【課題を解決する為の手段】
本発明に係る円筒型二次電池においては、電池缶(１)を構成する蓋体(12)に、電池缶(１)の内圧が所定値を越えたときに作動する円板状の圧力開放板(７)を具えた安全弁(５)が、蓋体(12)に開設したねじ孔(15)にねじ込み固定されている。
前記安全弁 ( ５ ) は、前記蓋体 (12) のねじ孔 (15) に螺合する外ねじ (52) を具えた円筒部材 (51) の内部に、円板状の圧力開放板 ( ７ ) と、該圧力開放板 ( ７ ) の外周部を挟圧すべき一対の挟圧リング ( ６ )( ８ ) とを収容すると共に、両挟圧リング ( ６ )( ８ ) の外側には、円筒部材 (51) の内周面に形成した内ねじ (53) に螺合する固定リング (55) を配置して構成され、両挟圧リング ( ６ )( ８ ) には、圧力開放板 ( ７ ) に向けてそれぞれ円筒部 (63)(82) が突設されている。
一方の挟圧リング ( ６ ) の円筒部 (63) の外径は、他方の挟圧リング ( ８ ) の円筒部 (82) の内径よりも、所定寸法だけ小さく形成されており、圧力開放板 ( ７ ) には、両挟圧リング ( ６ )( ８ ) の円筒部 (63)(82) による挟圧によって薄肉部 (71) が形成されている。
【００１０】
上記本発明に係る円筒型二次電池においては、圧力開放型の安全弁(５)が蓋体(12)にねじ込み固定されているので、組立工程にて電池缶(１)の内部に圧力をかけて電解液をセパレータに含浸させる際は、蓋体 (12) のねじ孔 (15)には、封口栓をねじ込んでおき、加圧工程の後に、封口栓を取り外し、電池缶(１)のねじ孔(15)に安全弁(５)をねじ込んで固定することが出来る。
【００１１】
又、圧力開放型の安全弁(５)は、復帰式安全弁に比べて部品点数が少なく、コンパクトに構成することが出来、例えば、蓋体(12)に突設された電流取り出し用の電極端子機構(９)の高さよりも低く形成することが出来る。
従って、本発明に係る円筒型二次電池を用いて組電池を構成する場合、装置全体を小形化することが可能である。
【００１３】
更に上記本発明に係る円筒型二次電池においては、固定リング(55)を円筒部材(51)の内部へ向けてねじ込むことによって、両挟圧リング(６)(８)に挟圧力が発生し、圧力開放板(７)の外周部が両挟圧リング(６)(８)によって挟圧される。ここで、両挟圧リング(６)(８)に突設された円筒部(63)(82)は、一方の円筒部(63)の外径が、他方の円筒部(82)の内径よりも、所定寸法だけ小さく形成されているので、両円筒部(63)(82)は互いに嵌合可能であり、該嵌合によって、一方の円筒部(63)の外周面と他方の円筒部(82)の内周面の間に、所定寸法のリング状空間が形成されることになる。
従って、圧力開放板(７)の外周部は、両円筒部(63)(82)により挟圧されることによって、前記リング状空間を金型空間とするプレス加工が施され、この結果、リング状空間の寸法によって規定される所定厚さの薄肉部(71)が形成される。
この様に圧力開放板(７)に所定厚さの薄肉部(71)が形成された圧力開放型安全弁(５)においては、電池缶(１)の内部に所定値を越える圧力が発生したとき、先ず薄肉部(71)に破れが発生して、瞬時に圧力開放板(７)が作動することになる。従って、安全弁(５)の作動圧力は、圧力開放板(７)の薄肉部(71)の厚さ、即ち両挟圧リング(６)(８)の円筒部(63)(82)の寸法によって精度良く規定することが出来るのである。
【００１４】
更に具体的には、電池缶(１)の内側寄りに設置された内側挟圧リング(６)と円筒部材(51)との対向面間、並びに電池缶(１)の外側寄りに配置された外側挟圧リング(８)と圧力開放板(７)との対向面間に、それぞれＯリング(57)(58)が介在している。
これによって、電池缶(１)の内部を高い気密性でシールすることが出来る。
【００１５】
【発明の効果】
本発明に係る円筒型二次電池においては、ねじ込み式圧力開放型安全弁の装備によってコンパクト化が実現されると共に、安全弁ねじ込み用の孔を電解液注入のために利用することが出来るので、構成が簡易となり、組立工数も少なくて済む。
【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)と両電極端子機構(９)(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、圧力開放型の安全弁(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】
安全弁(５)は、図３(ａ)(ｂ)に示す如く段部(54)を有する円筒部材(51)を具え、該円筒部材(51)には、下端部に外ねじ(52)、上端部に内ねじ(53)が形成され、外ねじ(52)は蓋体(12)のねじ孔(15)に螺合し、内ねじ(53)には、固定リング(55)が外ねじ(56)を螺合させて固定されている。
円筒部材(51)の内部には、所定厚さ(例えば２０μｍ)を有するアルミニウム製の円板状の圧力開放板(７)と、圧力開放板(７)の外周部を上下から挟圧する真鍮製の一対の挟圧リング(６)(８)とが、円筒部材(51)と同軸上に配備され、電池缶(１)の内側寄りの内側挟圧リング(６)と円筒部材(51)の段部(54)との間、並びに電池缶(１)の外側寄りの外側挟圧リング(８)と圧力開放板(７)との間には、それぞれシリコーン製のＯリング(57)(58)が介在している。
【００２０】
内側挟圧リング(６)は、円板部(61)の裏面にスリーブ(62)を下向きに突設すると共に、円板部(61)の表面に円筒部(63)を上向きに突設して構成されている。又、外側挟圧リング(８)は、円板部(81)の裏面に円筒部(82)を下向きに突設して構成されている。ここで、内側挟圧リング(６)の円筒部(63)と外側挟圧リング(８)の円筒部(82)とは同軸上に位置する。
内側挟圧リング(６)の円筒部(63)の外径は、外側挟圧リング(８)の円筒部(82)の内径よりも、所定寸法(例えば３６μｍ)だけ小さく形成されており、内側挟圧リング(６)の円筒部(63)と外側挟圧リング(８)の円筒部(82)とは互いに嵌合可能である。
【００２１】
安全弁(５)の組立においては、図３(ａ)に示す如く円筒部材(51)の内部に、Ｏリング(57)、内側挟圧リング(６)、圧力開放板(７)、外側挟圧リング(８)及び固定リング(55)を順に取り付けた後、同図(ｂ)の如く固定リング(55)を円筒部材(51)の内部へ向けてねじ込む。
これによって、内側挟圧リング(６)と外側挟圧リング(８)の間に圧力開放板(７)の外周部が挟圧され、内側挟圧リング(６)の円筒部(63)と外側挟圧リング(８)の円筒部(82)が金型となって、圧力開放板(７)の外周部を図示の如く内側挟圧リング(６)の円筒部(63)及び円板部(61)の表面に沿って塑性変形させる。これによって、圧力開放板(７)には、両円筒部(63)(82)に挟まれた領域に、両円筒部(63)(82)の隙間Ｓによって規定される所定厚さ(例えば１８μｍ)の薄肉部(71)が、リング状に形成されることになる。
【００２２】
又、固定リング(55)のねじ込みによって、内側挟圧リング(６)と円筒部材(51)の段部(54)との間にＯリング(57)が挟圧されると共に、外側挟圧リング(８)と圧力開放板(７)の間にＯリング(58)が挟圧されて、円筒部材(51)の内外間のシールが施されることになる。
【００２３】
上記安全弁(５)を具えた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、ねじ孔(15)に封口栓(図示省略)をねじ込んで封止し、この状態で電池缶(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)のセパレータ(22)に含浸させる。その後、封口栓を取り外し、ねじ孔(15)には安全弁(５)をねじ込んで固定する。
【００２４】
この様にして組み立てられた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、先ず圧力開放板(７)の薄肉部(71)に破れが生じて、圧力開放板(７)が瞬時に作動し、内圧を一気に外部へ逃がすことが出来る。ここで、圧力開放板(７)の作動圧力は、圧力開放板(７)の薄肉部(71)の厚さ、即ち内側挟圧リング(６)の円筒部(63)の外径と外側挟圧リング(８)の円筒部(82)の内径とによって、精度良く規定することが出来る。
【００２５】
【実施例】
図１〜図３に示す本発明に係る円筒型二次電池(本発明例１〜４)と、図４及び図５に示す従来の円筒型二次電池(比較例１、２)を作製して、本発明の効果を確認した。
先ず、各電池に共通の工程について説明した後、電池毎に異なる安全弁の構造及びその取付けについて説明する。
【００２６】
正極の作製
正極活物質としてのＬiＣoＯ₂(リチウム複合酸化物)と導電剤としての炭素を重量比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となる様に正極合剤とＮＭＰ溶液を混合して、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。
【００２７】
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、粒子径１０μｍの黒鉛粉末とポリフッ化ビニリデンの重量比が８５：１５となる様に混練してスラリーと調製した。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って塗布し、１５０℃で２時間の真空乾燥を施して負極を作製した。
【００２８】
電解液の調製
エチレンカーボネートとジエルチルカーボネートを体積比１：１で混合した溶媒に、ＬiＰＦ₆を１mol／lの割合で溶解し、電解液を調製した。
【００２９】
電池の組立
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。
この巻き取り電極体を電池缶となる筒体の内部に装填し、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た後、該蓋体を筒体に溶接固定して、円筒型二次電池を組み立てた。
尚、電池缶の筒体は、外径６０ｍｍ、高さ３００ｍｍ、厚さ２ｍｍのものを採用し、蓋体は、直径６０ｍｍ、厚さ５ｍｍのものを採用した。電極端子機構の高さは、蓋体表面から２０ｍｍである。
又、電池の平均放電電圧は３.６Ｖ、電池容量は７０Ａｈ(放電電流８.７５Ａ)である。
【００３０】
本発明例１
蓋体に、厚さ５０μｍのアルミニウム箔からなる圧力開放板を具えたねじ込み式の安全弁(高さ１０ｍｍ)を２つ取り付けて、本発明に係る円筒型電池(本発明例１)を作製した。
【００３１】
本発明例２
蓋体に、厚さ５μｍのニッケル箔からなる圧力開放板を具えたねじ込み式の安全弁(高さ１０ｍｍ)を４つ取り付けて、本発明に係る円筒型電池(本発明例２)を作製した。
【００３２】
本発明例３
蓋体に、厚さ３０μｍの銅箔からなる圧力開放板を具えたねじ込み式の安全弁(高さ１０ｍｍ)を４つ取り付けて、本発明に係る円筒型電池(本発明例３)を作製した。
【００３３】
本発明例４
蓋体に、厚さ５μｍのステンレス鋼箔からなる圧力開放板を具えたねじ込み式の安全弁(高さ５ｍｍ)を２つ取り付けて、本発明に係る円筒型電池(本発明例４)を作製した。
【００３４】
比較例１
蓋体に、設定圧力１０ｋｇ／ｃｍ²の復帰式安全弁を２つ取り付けて、従来の円筒型二次電池(比較例１)を作製した。
【００３５】
比較例２
蓋体に、厚さ５０μｍのアルミニウム箔からなる圧力開放板を具えた溶接固定式の安全弁を１つ取り付けて、従来の円筒型二次電池(比較例２)を作製した。
【００３６】
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５に示す従来の二次電池(比較例２)では、別途、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、筒体に開設された安全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。
又、複数本の二次電池を用いて組電池を組み立てる場合、上記本発明例１〜３の如く圧力開放型の安全弁は、電極端子機構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安全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。
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、安全弁を電池缶にねじ込む様子を表わす斜視図である。
【図３】本発明に係る安全弁において、固定リングを締め付ける前の状態(ａ)と締め付けた後の状態(ｂ)を表わす拡大断面図である。
【図４】復帰式安全弁を具えた従来の円筒型二次電池の断面図である。
【図５】圧力開放型安全弁を溶接固定した従来の円筒型二次電池の断面図である。
【符号の説明】
(１) 電池缶
(11) 筒体
(12) 蓋体
(２) 巻き取り電極体
(３) 集電タブ
(５) 安全弁
(51) 円筒部材
(52) 外ねじ
(55) 固定リング
(６) 内側挟圧リング
(63) 円筒部
(７) 圧力開放板
(71) 薄肉部
(８) 外側挟圧リング
(82) 円筒部
(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 battery can, and a secondary battery capable of taking out the generated power of the secondary battery element from a pair of electrode terminals attached to the battery can. It relates to batteries.
[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. 4, a cylindrical lithium secondary battery having a relatively large capacity used in an electric vehicle is a cylinder formed by welding and fixing lids (12) and (12) to both ends of a cylinder (11). The take-up electrode body (2) is accommodated in a battery-like battery can (1). A pair of positive and negative electrode terminal mechanisms (9), (9) is attached to the lid bodies (12), (12), and the winding electrode body (2) and the both electrode terminal mechanisms (9), (9) are provided. The electric power generated by the winding electrode body (2) connected to each other by a plurality of current collecting tabs (3) can be taken out from the pair of electrode terminal mechanisms (9), (9). . In addition, a resettable safety 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. 4, 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]
In addition, as shown in FIG. 5, a pressure relief type safety valve (4) that operates when the internal pressure of the battery can (1) exceeds a predetermined value is attached to the through hole (14) opened in the lid (12). Cylindrical secondary batteries are also known (JP-A-6-68861, JP-A-9-139196, etc.).
The safety valve (4) shown in FIG. 5 is formed by fixing a disc-shaped pressure release plate (42) made of aluminum foil having a thickness of about 20 μm to the back surface of the ring body (41). The outer peripheral portion is laser welded to the opening edge of the through hole (14) of the lid (12) and is fixed to the lid (12).
[0006]
[Problems to be solved by the invention]
However, in the cylindrical secondary battery having the reset safety valve (13) shown in FIG. 4, when the pressure inside the battery can (1) rises, the safety valve (13) is opened against the reset force. However, when a sudden pressure increase occurs, there is a problem that the pressure cannot be sufficiently released at the initial stage where the opening area of the resettable safety 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. 4, 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 the cylindrical secondary battery having the pressure relief type safety valve (4) shown in FIG. 5, when an abnormal pressure is generated inside the battery can (1), the pressure relief plate (42) is activated. Since the pressure is released instantaneously, the pressure rise is sufficiently suppressed.
Further, the pressure relief type safety valve (4) has a smaller number of components and can be reduced in size as compared with the resettable safety valve (13), so that it can be made compact even when an assembled battery is constituted.
However, in the conventional cylindrical secondary battery having the pressure relief type safety valve (4), when injecting the electrolyte into the battery can (1) in the assembly process, the lid (12) has a safety valve ( Since 4) is fixed by welding, it is necessary to open a screw hole for injecting the electrolyte separately and close the screw hole after injecting the electrolyte. As a result, there is a problem that not only the configuration becomes complicated but also the number of assembly steps increases.
[0008]
Accordingly, an object of the present invention is to provide a cylindrical secondary battery that is compact and has a simple configuration that does not increase the number of assembly steps.
[0009]
[Means for solving the problems]
In the cylindrical secondary battery according to the present invention, a disc-shaped pressure release that operates when the internal pressure of the battery can (1) exceeds a predetermined value is applied to the lid (12) constituting the battery can (1). A safety valve (5) having a plate (7) is screwed and fixed into a screw hole (15) opened in the lid (12).
The safety valve ( 5 ) has a disk-shaped pressure release plate ( 7 ) inside a cylindrical member (51) having an external screw (52) screwed into the screw hole (15 ) of the lid (12 ). If, pressure releasing plate outer peripheral portion (7) accommodates a pinching push to a pair of clamping rings (6) (8), on the outside of Ryokyo圧ring (6) (8), the cylindrical member (51) is constructed by arranging the fixing ring to be screwed to the internal thread formed in the inner peripheral surface (53) (55) of the Ryokyo圧ring (6) (8), pressure release plate (7) Cylindrical portions (63) and (82) are provided so as to project toward the rear.
The outer diameter of the cylindrical part (63) of one clamping ring ( 6 ) is smaller than the inner diameter of the cylindrical part (82) of the other clamping ring ( 8 ) by a predetermined dimension. In ( 7 ) , a thin-walled portion (71) is formed by clamping pressure by the cylindrical portions (63) and (82) of the both clamping pressure rings ( 6 ) and ( 8 ) .
[0010]
In the cylindrical secondary battery according to the present invention, the pressure open type safety valve (5) is screwed into the lid (12), apply pressure to the battery can (1) at the assembly process When the electrolyte is impregnated into the separator, the sealing plug is screwed into the screw hole (15) of the lid (12) , and after the pressurizing step, the sealing plug is removed and the screw of the battery can (1) is removed. The safety valve (5) can be screwed into the hole (15) and fixed.
[0011]
In addition, the pressure relief type safety valve (5) has a smaller number of parts than the return type safety valve and can be configured compactly. For example, an electrode terminal mechanism for taking out a current projecting from the lid (12). It can be formed lower than the height of (9).
Therefore, when the assembled battery is configured using the cylindrical secondary battery according to the present invention, the entire apparatus can be reduced in size.
[0013]
Furthermore, in the cylindrical secondary battery according to the present invention , the fixing ring (55) is screwed toward the inside of the cylindrical member (51), so that a clamping pressure is generated in the both clamping rings (6) and (8). The outer peripheral portion of the pressure release plate (7) is pinched by both the pinching rings (6) and (8). Here, in the cylindrical portions (63) and (82) projecting from both the clamping rings (6) and (8), the outer diameter of one cylindrical portion (63) is larger than the inner diameter of the other cylindrical portion (82). Also, since it is formed smaller by a predetermined dimension, both the cylindrical portions (63) (82) can be fitted to each other, and by the fitting, the outer peripheral surface of one cylindrical portion (63) and the other cylindrical portion ( 82), a ring-shaped space having a predetermined size is formed between the inner peripheral surfaces.
Accordingly, the outer peripheral portion of the pressure release plate (7) is pressed between the cylindrical portions (63) and (82), thereby pressing the ring-shaped space as a mold space. A thin portion (71) having a predetermined thickness defined by the size of the shaped space is formed.
In the pressure relief type safety valve (5) in which the thin part (71) having a predetermined thickness is formed on the pressure release plate (7) in this way, when a pressure exceeding a predetermined value is generated inside the battery can (1). First, a tear occurs in the thin wall portion (71), and the pressure release plate (7) is instantaneously operated. Accordingly, the operating pressure of the safety valve (5) depends on the thickness of the thin wall portion (71) of the pressure release plate (7), that is, the dimensions of the cylindrical portions (63) and (82) of the both clamping rings (6) and (8). It can be defined with high accuracy.
[0014]
More specifically, it is arranged between the opposed surfaces of the inner clamping ring (6) and the cylindrical member (51) installed on the inner side of the battery can (1) and on the outer side of the battery can (1). O-rings (57) and (58) are interposed between the opposing surfaces of the outer pinching ring (8) and the pressure release plate (7), respectively.
Thus, the inside of the battery can (1) can be sealed with high airtightness.
[0015]
【The invention's effect】
In the cylindrical secondary battery according to the present invention, a compact structure is realized by the provision of a screw-in type pressure relief safety valve, and a hole for screwing the safety valve can be used for electrolyte injection, so the configuration is This simplifies and requires fewer assembly steps.
[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 lid bodies (12), (12), and the winding electrode body (2) and the both electrode terminal mechanisms (9), (9) are provided. The electric power generated by the winding electrode body (2) connected to each other by a plurality of current collecting tabs (3) can be taken out from the pair of electrode terminal mechanisms (9), (9). .
In addition, a pressure relief type safety valve (5) is screwed into 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]
The safety valve (5) includes a cylindrical member (51) having a stepped portion (54) as shown in FIGS. 3 (a) and 3 (b). The cylindrical member (51) has an external screw (52) at its lower end, An inner screw (53) is formed at the upper end, the outer screw (52) is screwed into the screw hole (15) of the lid (12), and the fixing ring (55) is connected to the inner screw (53). (56) is fixed by screwing.
Inside the cylindrical member (51), an aluminum disc-shaped pressure release plate (7) having a predetermined thickness (for example, 20 μm) and a brass made to clamp the outer periphery of the pressure release plate (7) from above and below. The pair of pinching rings (6) and (8) are arranged coaxially with the cylindrical member (51), and the inner pinching ring (6) near the inner side of the battery can (1) and the cylindrical member (51) Between the step portion (54) and between the outer pinching ring (8) near the outer side of the battery can (1) and the pressure release plate (7), an O-ring made of silicone (57) (58 ) Intervenes.
[0020]
The inner clamping ring (6) has a sleeve (62) protruding downward on the back surface of the disk portion (61) and a cylindrical portion (63) protruding upward on the surface of the disk portion (61). Configured. The outer pinching ring (8) is formed by projecting a cylindrical portion (82) downward on the back surface of the disc portion (81). Here, the cylindrical portion (63) of the inner pinching ring (6) and the cylindrical portion (82) of the outer pinching ring (8) are positioned coaxially.
The outer diameter of the cylindrical portion (63) of the inner pinching ring (6) is smaller than the inner diameter of the cylindrical portion (82) of the outer pinching ring (8) by a predetermined dimension (for example, 36 μm). The cylindrical portion (63) of the pinching ring (6) and the cylindrical portion (82) of the outer pinching ring (8) can be fitted to each other.
[0021]
When assembling the safety valve (5), as shown in FIG. 3 (a), inside the cylindrical member (51), an O-ring (57), an inner clamping ring (6), a pressure release plate (7), an outer clamping pressure are provided. After attaching the ring (8) and the fixing ring (55) in this order, the fixing ring (55) is screwed toward the inside of the cylindrical member (51) as shown in FIG.
As a result, the outer peripheral portion of the pressure release plate (7) is pinched between the inner pinching ring (6) and the outer pinching ring (8), and the cylindrical portion (63) of the inner pinching ring (6) and the outer side The cylindrical portion (82) of the pinching ring (8) becomes a mold, and the outer peripheral portion of the pressure release plate (7) is connected to the cylindrical portion (63) and the disc portion (see FIG. 61) Plastically deform along the surface. Thus, the pressure release plate (7) has a predetermined thickness (for example, 18 μm) defined by the gap S between the cylindrical portions (63) and (82) in a region sandwiched between the cylindrical portions (63) and (82). ) Is formed in a ring shape.
[0022]
Further, by screwing the fixing ring (55), the O-ring (57) is clamped between the inner clamping ring (6) and the step (54) of the cylindrical member (51), and the outer clamping ring. The O-ring (58) is sandwiched between (8) and the pressure release plate (7), and the inside and outside of the cylindrical member (51) is sealed.
[0023]
In the assembly of the cylindrical secondary battery having the safety valve (5), after the electrolyte is injected into the battery can (1) from the screw hole (15) of the lid (12) of the battery can (1). Then, a sealing plug (not shown) is screwed into the screw hole (15) and sealed. In this state, a predetermined pressure is applied to the inside of the battery can (1) to take up the electrolyte and to separate the separator of the electrode body (2). Impregnate (22). Thereafter, the sealing plug is removed, and the safety valve (5) is screwed into the screw hole (15) and fixed.
[0024]
In the cylindrical secondary battery assembled in this way, when the internal pressure of the battery can (1) increases, the thin part (71) of the pressure release plate (7) is first torn and the pressure release The plate (7) operates instantly, and the internal pressure can be released to the outside at once. Here, the operating pressure of the pressure release plate (7) depends on the thickness of the thin portion (71) of the pressure release plate (7), that is, the outer diameter of the cylindrical portion (63) of the inner clamping ring (6). It can be accurately defined by the inner diameter of the cylindrical portion (82) of the pressure ring (8).
[0025]
【Example】
A cylindrical secondary battery according to the present invention shown in FIGS. 1 to 3 (Inventive Examples 1 to 4) and a conventional cylindrical secondary battery (Comparative Examples 1 and 2) shown in FIGS. Thus, the effect of the present invention was confirmed.
First, the steps common to each battery will be described, and then the structure of the safety valve that is different for each battery and its mounting will be described.
[0026]
Preparation <br/> LiCoO ₂ (lithium composite oxides) as the positive electrode active material and the weight ratio of carbon as a conductive agent of the positive electrode 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. Then, the positive electrode mixture and the NMP solution are mixed so that the weight ratio of the positive electrode mixture and polyvinylidene fluoride is 95: 5 to prepare a slurry, and this slurry is formed on both surfaces of the aluminum foil as the positive electrode current collector. The positive electrode was produced by applying by a doctor blade method and vacuum drying at 150 ° C. for 2 hours.
[0027]
Production of negative electrode Polyvinylidene fluoride as a binder was dissolved in NMP to prepare an NMP solution, and kneaded so that the weight ratio of graphite powder having a particle diameter of 10 μm and polyvinylidene fluoride was 85:15. A slurry was prepared. This slurry was applied to both surfaces of a copper foil as a negative electrode current collector by a doctor blade method, and vacuum dried at 150 ° C. for 2 hours to produce a negative electrode.
[0028]
Volume ratio Preparation <br/> ethylene carbonate and diethyl rutile carbonate electrolyte 1: mixed solvent at 1, the LiPF ₆ was dissolved at a ratio of 1 mol / l, to prepare an electrolytic solution.
[0029]
Battery assembly Ten aluminum current collecting tabs with a thickness of 0.1 mm are welded at regular intervals to the surface of the aluminum foil constituting the positive electrode, and the copper constituting the negative electrode is formed. Ten nickel current collecting tabs with a thickness of 0.1 mm were welded to the surface of the foil 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.
After loading this take-up electrode body into a cylindrical body serving as a battery can, and connecting the positive and negative current collecting tabs extending from the take-up electrode body to an electrode terminal mechanism attached to the lid, respectively. The lid was welded and fixed to the cylinder, and a cylindrical secondary battery was assembled.
In addition, the cylindrical body of the battery can employs an outer diameter of 60 mm, a height of 300 mm, and a thickness of 2 mm, and the lid body has a diameter of 60 mm and a thickness of 5 mm. The height of the electrode terminal mechanism is 20 mm from the lid surface.
The average discharge voltage of the battery is 3.6 V, and the battery capacity is 70 Ah (discharge current 8.75 A).
[0030]
Invention Example 1
Two screw-in type safety valves (height 10 mm) each having a pressure release plate made of an aluminum foil having a thickness of 50 μm were attached to the lid, to produce a cylindrical battery according to the present invention (Invention Example 1).
[0031]
Invention Example 2
Four screw-type safety valves (height 10 mm) each having a pressure release plate made of nickel foil having a thickness of 5 μm were attached to the lid, thereby producing a cylindrical battery according to the present invention (Invention Example 2).
[0032]
Invention Example 3
Four screw-type safety valves (height 10 mm) each having a pressure release plate made of a copper foil having a thickness of 30 μm were attached to the lid to produce a cylindrical battery according to the present invention (Invention Example 3).
[0033]
Invention Example 4
Two screw-type safety valves (height 5 mm) having a pressure release plate made of a stainless steel foil having a thickness of 5 μm were attached to the lid to produce a cylindrical battery according to the present invention (Invention Example 4). .
[0034]
Comparative Example 1
^Two return-type safety valves with a set pressure of 10 kg / cm ² were attached to the lid to produce a conventional cylindrical secondary battery (Comparative Example 1).
[0035]
Comparative Example 2
A conventional cylindrical secondary battery (Comparative Example 2) was manufactured by attaching one weld-fixed safety valve having a pressure release plate made of an aluminum foil having a thickness of 50 μm to the lid.
[0036]
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 (Comparative Example 2) shown in FIG. Although it is necessary to open a hole for injecting liquid, the secondary battery of the present invention can use the screw hole for screwing the safety valve opened in the cylindrical body, so that the configuration becomes simple.
Further, when assembling an assembled battery using a plurality of secondary batteries, the pressure relief type safety valve can be formed lower than the height of the electrode terminal mechanism as in the first to third invention examples. The work of connecting the secondary batteries to each other with the lead wires is not hindered by the safety valve, and the assembly work becomes easier as compared with the case of assembling the same assembled battery using the secondary battery of the conventional example.
Furthermore, when the assembled battery is configured by connecting a plurality of secondary batteries in series, according to the present invention, compared to the case where a similar assembled battery is configured using a conventional secondary battery, Miniaturization is possible.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a cylindrical secondary battery according to the present invention.
FIG. 2 is a perspective view showing a state in which a safety valve is screwed into a battery can in the cylindrical secondary battery according to the present invention.
FIG. 3 is an enlarged sectional view showing a state (a) before tightening a fixing ring and a state (b) after tightening in a safety valve according to the present invention.
FIG. 4 is a cross-sectional view of a conventional cylindrical secondary battery provided with a resettable safety valve.
FIG. 5 is a cross-sectional view of a conventional cylindrical secondary battery in which a pressure relief type safety valve is fixed by welding.
[Explanation of symbols]
(1) Battery can
(11) Tube
(12) Lid
(2) Winding electrode body
(3) Current collection tab
(5) Safety valve
(51) Cylindrical member
(52) External thread
(55) Retaining ring
(6) Inner pinching ring
(63) Cylindrical part
(7) Pressure release plate
(71) Thin part
(8) Outer pinching ring
(82) Cylindrical part
(9) Electrode terminal mechanism

Claims

The lid (12) is fixed to the opening of the cylindrical body (11), and the wound battery electrode (2) serving as the secondary battery element is housed in the airtight battery can (1). In the cylindrical secondary battery, a safety valve (5) having a disk-shaped pressure release plate (7) that operates when the internal pressure of the battery can (1) exceeds a predetermined value is provided on the lid (12). The safety valve ( 5 ) is fixed inside the cylindrical member (51) having an external screw (52) screwed into the screw hole (15) of the lid (12). to the pressure release plate (7), the outer peripheral portion of the pressure releasing plate (7) accommodates a pair of clamping ring to push nip (6) (8), Ryokyo圧ring (6) ( 8 ) is provided with a fixing ring (55) that is screwed into an inner screw (53) formed on the inner peripheral surface of the cylindrical member (51) , and both clamping rings ( 6 ) ( 8 ) the respective cylindrical portion toward the pressure release plate (7) (63) (82) is projected, The outer diameter of the cylindrical portion of the square clamping ring (6) (63), than the inner diameter of the cylindrical portion of the other clamping ring (8) (82) are formed smaller by a predetermined distance, pressure release plate ( 7 ) A cylindrical secondary battery , wherein the thin-walled portion (71) is formed by clamping between the cylindrical portions (63) and (82) of the both clamping rings ( 6 ) and ( 8 ) .

Inside the cylindrical member (51), a stepped portion (54) is formed for receiving both the clamping rings (6) and (8), and the cylindrical portion (63) (82) is inserted by screwing the fixing ring (55). The cylindrical secondary battery according to claim 1 , wherein the pressure release plate sandwiches the outer peripheral portion of the pressure release plate.

The inner pinching ring (6) installed near the inner side of the battery can (1) is configured by projecting a cylindrical portion (63) on the inner peripheral portion of the disc portion (61), while the battery can ( The outer pinching ring (8) arranged on the outer side of 1) is formed by projecting a cylindrical portion (82) on the inner peripheral portion of the disc portion (81), and the inner pinching ring (6) The outer diameter of the cylindrical portion (63) is smaller than the inner diameter of the cylindrical portion (82) of the outer pinching ring (8), and the outer peripheral portion of the pressure release plate (7) is the cylindrical portion of the outer pinching ring (8) ( 82) is subjected to pressure reduction and plastically deforms along the surfaces of the disc part (61) and the cylindrical part (63) of the inner clamping ring (6), and the thin part (71) is formed by the plastic deformation. The cylindrical secondary battery according to claim 1 or 2 .

Pressure relief between the disk part (61) of the inner clamping ring (6) and the step part (54) of the cylindrical member (51) and the disk part (81) of the outer clamping ring (8). The cylindrical secondary battery according to claim 3 , wherein O-rings (57) and (58) are respectively interposed between surfaces facing the outer peripheral portion of the plate (7).