JP3661984B2

JP3661984B2 - Cylindrical secondary battery

Info

Publication number: JP3661984B2
Application number: JP22649299A
Authority: JP
Inventors: 一成大北; 義人近野; 俊之能間; 育郎米津
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 1999-08-10
Filing date: 1999-08-10
Publication date: 2005-06-22
Anticipated expiration: 2019-08-10
Also published as: JP2001052674A

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筒型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７に示す様に、筒体(11)の各端部に蓋体(12)を溶接固定して、円筒状の電池缶(１)を形成し、該電池缶(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。蓋体(12)には電極端子機構(９)が取り付けられ、巻き取り電極体(２)と電極端子機構(９)とが複数本の集電タブ(３)により互いに接続されている。尚、筒体(11)の他方の端部に固定された蓋体(図示省略)にも同様の電極端子機構(図示省略)が取り付けられており、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)にはバネ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７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８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破れて開放する圧力開放式のガス排出弁(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)。
図示の如く、圧力開放式のガス排出弁(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弁膜(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７に示すバネ復帰式のガス排出弁(13)を具えた円筒型二次電池においては、電池缶(１)内部の圧力が上昇したとき、ガス排出弁(13)はバネ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７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８に示す圧力開放式のガス排出弁(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、弁膜(42)が瞬時に破れて圧力が開放されるので、圧力の上昇が効果的に抑制される。
又、圧力開放式ガス排出弁(４)はバネ復帰式ガス排出弁(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、圧力開放式ガス排出弁(４)を具えた従来の円筒型二次電池においては、特に電池が大型化した場合、電池缶(１)の蓋体(12)にガス排出弁(４)を溶接することが困難である問題があった。即ち、電池の大型化に伴って蓋体(12)の厚さが大きくなり、例えば数ｍｍ以上の厚さを有する蓋体(12)にガス排出弁(４)のリング体(41)をレーザ溶接する際、リング体(41)の厚さに比べて蓋体(12)の厚さが非常に大きいために、溶接時の熱放散が著しく、レーザを照射されて溶融した金属が急激に冷えることとなって、溶接部にピンホールやクラックなどの欠陥が発生する虞れがあった。
【０００９】
又、圧力開放式ガス排出弁(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)にはガス排出弁(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。
【００１０】
そこで本発明の目的は、ガス排出弁の構造がコンパクトで、その取り付けが容易であり、然も、電池の組立工数の減少を図ることが可能な筒型二次電池を提供することである。
【００１１】
【課題を解決する為の手段】
本発明に係る筒型二次電池においては、電池缶(１)の蓋体(12)に段付き孔(16)が開設され、該段付き孔(16)は、蓋体(12)の外側に開口すると共に内周面に内ねじが形成された大径孔(17)と、蓋体(12)の内側に開口する小径孔(18)と、大径孔(17)と小径孔(18)の間に介在する段部(19)とを具え、該段付き孔(16)の大径孔(17)の内部には、ガス排出弁(５)が設置されて、蓋体 (12) の内面と外面に挟まれた厚さ領域内に全体が収容されている。
該ガス排出弁(５)は、段付き孔(16)の段部(19)上に設置されて電池缶(１)の内圧が所定値を越えたときに開放する円板状の弁膜(７)と、該弁膜(７)を挟んで両側に配置された一対の挟圧リング ( ６ )( ８ ) と、少なくとも何れか一方の挟圧リング ( ８ ) と弁膜 ( ７ ) の間に介在するＯリング (58) とから構成され、弁膜 ( ７ ) の外側に配置された挟圧リング ( ８ ) の外周面には、段付き孔 (16) の大径孔 (17) の内ねじに螺合する外ねじ (83) が形成され、両挟圧リング ( ６ )( ８ ) にはそれぞれ、弁膜 ( ７ ) の外周部へ向けて円筒部 (62)(82) が突設され、一方の挟圧リング ( ６ ) の円筒部 (62) 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、弁膜 ( ７ ) には、両挟圧リング ( ６ )( ８ ) の円筒部 (62)(82) による挟圧によって薄肉部 (71) が形成されている。
【００１２】
上記本発明の筒型二次電池においては、電池缶(１)の蓋体(12)の段部(19)上に弁膜(７)を設置し、固定装置の外ねじを段付き孔(16)の内ねじにねじ込むことによって、弁膜(７)を段部(19)上に固定することが出来る。従って、ガス排出弁(５)を蓋体(12)に溶接固定する必要はない。
又、上記本発明の筒型電池の組立工程においては、電池缶(１)の蓋体(12)の段付き孔(16)から電解液を注入した後、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、蓋体(12)の段付き孔(16)の内ねじには、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、段付き孔(16)の内ねじにガス排出弁(５)をねじ込んで固定することが出来る。従って、電池缶(１)の蓋体(12)に別途、電解液注入孔を開設する必要はない。
【００１３】
更に又、圧力開放式のガス排出弁(５)は、復帰式ガス排出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るので、蓋体(12)の内面と外面に挟まれた厚さ領域内に全体を収容して配備することが出来る。
従って、本発明に係る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。
【００１５】
更に、上記本発明に係る筒型二次電池においては、外側挟圧リング(８)の外ねじ(83)を蓋体(12)の内ねじ(15)に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、弁膜(７)の外周部が両挟圧リング(６)(８)によって挟持されると共に、Ｏリング(58)が弁膜(７)の表面と外側挟圧リング(８)の裏面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(62)(82)は、一方の円筒部(62)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(62)(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(62)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、弁膜(７)の外周部は、両円筒部(62)(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。
【００１６】
この様に弁膜(７)に所定厚さの薄肉部(71)が形成された圧力開放式のガス排出弁(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、瞬時に弁膜(７)が開放することになる。
従って、ガス排出弁(５)の作動圧力は、弁膜(７)の薄肉部(71)の厚さ、即ち両挟圧リング(６)(８)の円筒部(62)(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。
【００１９】
【発明の効果】
本発明に係る筒型二次電池によれば、圧力開放式のガス排出弁の採用によってガス排出弁のコンパクト化が実現されると共に、ガス排出弁を蓋体の段付き孔にねじ込んで固定する構造の採用によって、ガス排出弁の取付けが容易となり、然も、段付き孔を電解液注入のために利用することが可能となって、電池の組立工数が減少する。
【００２０】
【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に示す如く、筒体(11)の各端部に蓋体(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。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)と両電極端子機構(９)とが、複数本の集電タブ(３)により互いに接続されている。尚、筒体(11)の他方の端部に溶接固定された蓋体(図示省略)にも同様の電極端子機構(図示省略)が取り付けられて、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)に開設した段付き孔(16)には、圧力開放式のガス排出弁(５)がねじ込み固定されている。
【００２１】
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。
【００２２】
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。
【００２３】
電池缶(１)の蓋体(12)に開設された段付き孔(16)は、図３に示す如く、蓋体(12)の外側に開口すると共に内周面に内ねじ(15)が形成された大径孔(17)と、蓋体(12)の内側に開口する小径孔(18)と、大径孔(17)と小径孔(18)の間に介在する段部(19)とから構成されている。
【００２４】
ガス排出弁(５)は図２〜図４に示す如く、所定厚さ(例えば２０μｍ)のアルミニウム箔からなる円板状の弁膜(７)と、弁膜(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、弁膜(７)と外側挟圧リング(８)の間に介在するシリコーン系樹脂製のＯリング(58)とから構成されている。
尚、ガス排出弁(５)の弁膜(７)は、アルミニウムに限らず、ニッケルやステンレス鋼によって形成することが可能である。
【００２５】
内側挟圧リング(６)は、中央孔(63)を有する円板部(61)の表面に円筒部(62)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、中央孔(80)を有する円板部(81)の裏面に円筒部(82)を下向きに突設して構成され、円板部(81)の外周面には外ねじ(83)が形成されている。
ここで、内側挟圧リング(６)の円筒部(62)と外側挟圧リング(８)の円筒部(82)とは同軸上に位置している。又、内側挟圧リング(６)の円筒部(62)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(62)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。
【００２６】
上記ガス排出弁(５)の組立においては、図３に示す如く蓋体(12)の段付き孔(16)の段部(19)上に、内側挟圧リング(６)、弁膜(７)及びＯリング(58)を順に設置した後、蓋体(12)の段付き孔(16)の内ねじ(15)に対して外側挟圧リング(８)の外ねじ(83)をねじ込む。
これによって、図４に示す如く、内側挟圧リング(６)と外側挟圧リング(８)によって弁膜(７)の外周部が挟圧され、内側挟圧リング(６)の円筒部(62)と外側挟圧リング(８)の円筒部(82)が金型となって、弁膜(７)の外周部を図示の如く内側挟圧リング(６)の円筒部(62)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、弁膜(７)には、両円筒部(62)(82)に挟まれた領域に、両円筒部(62)(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。
【００２７】
又、外側挟圧リング(８)のねじ込みによって、外側挟圧リング(８)と弁膜(７)の表面との間にＯリング(58)が挟圧されて、外側挟圧リング(８)と弁膜(７)の間にシールが施されることになる。
【００２８】
上記ガス排出弁(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)の段付き孔(16)から電池缶(１)の内部へ電解液を注入した後、段付き孔(16)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、段付き孔(16)にはガス排出弁(５)をねじ込んで固定する。
【００２９】
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、先ず弁膜(７)の薄肉部(71)に破れが生じて、弁膜(７)が瞬時に開放し、内圧を一気に外部へ逃がす。ここで、弁膜(７)の開放圧力は、弁膜(７)の薄肉部(71)の厚さ、即ち内側挟圧リング(６)の円筒部(62)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。
【００３０】
図５及び図６は、ガス排出弁(５)の他の構成例を表わしている。
該ガス排出弁(５)は、蓋体(12)の段付き孔(16)の段部(19)上に設置された前記同様の弁膜(７)と、該弁膜(７)の外周部を段部(19)に向けて下圧すべき下圧リング(50)と、下圧リング(50)に重なるリング状本体の外周部に外ねじ(52)を具えると共に内周部に内ねじ(53)を具えた外周側締付けリング(51)と、外周側締付けリング(51)の内ねじ(53)に螺合する外ねじ(56)を具えた内周側締付けリング(54)と、内周側締付けリング(54)と弁膜(７)の間に介在するＯリング(59)とから構成されており、内周側締付けリング(54)の裏面には円筒部(55)が下向きに突設され、内周側締付けリング(54)の中央部には、段付き孔(16)と同軸の中央孔(57)が形成されている。
【００３１】
上記ガス排出弁(５)の組立においては、蓋体(12)の段付き孔(16)の段部(19)上に、弁膜(７)及び下圧リング(50)を順に設置した後、蓋体(12)の段付き孔(16)の内ねじ(15)に対して外周側締付けリング(51)の外ねじ(52)をねじ込む。又、弁膜(７)上にＯリング(59)を設置した後、外周側締付けリング(51)の内ねじ(53)に対して内周側締付けリング(54)の外ねじ(56)をねじ込む。
これによって、図５の如く、段付き孔(16)の段部(19)と下圧リング(50)の間に弁膜(７)の外周部が挟圧されて、弁膜(７)が蓋体(12)に固定される。又、内周側締付けリング(54)と弁膜(７)の表面との間にＯリング(58)が挟圧されて、内周側締付けリング(54)と弁膜(７)の間にシールが施されることになる。
【００３２】
上記ガス排出弁(５)を具えた円筒型二次電池においては、外周側締付けリング(51)を用いて弁膜(７)に充分な締め付け力を与えると共に、内周側締付けリング(54)を用いてＯリング(59)に適度な締め付け力を与えることが出来る。
又、外周側締付けリング(51)と内周側締付けリング(54)とは同一平面上に配置されているので、図２〜図４に示すガス排出弁(５)よりも更に薄型化が可能である。
【００３３】
【実施例】
図１〜図４に示す本発明に係る円筒型二次電池(実施例１〜４)と、図７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、各電池に共通の工程について説明した後、電池毎に異なるガス排出弁の構造及びその取付けについて説明する。
【００３４】
正極の作製
正極活物質としてのＬｉＣｏＯ_２(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。
【００３５】
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。
【００３６】
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の割合で溶解して、電解液を調製した。
【００３７】
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複数本のアルミニウム製集電タブを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複数本のニッケル製集電タブを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、電池缶は、外径が４５ｍｍ、長さが２００ｍｍに形成され、筒体の肉厚は１.２５ｍｍ、蓋体の直径は４５ｍｍ、厚さは５ｍｍに形成されている。又、正負一対の電極端子機構を含む電池の全長は２２０ｍｍである。
【００３８】
実施例１
蓋体に内径５ｍｍの段付き孔を開設すると共に、該段付き孔に対して、厚さ３０μｍのアルミニウム箔からなる弁膜を具えた図１〜図３のガス排出弁(５)を取り付けて、実施例１の円筒型二次電池を作製した。
【００３９】
実施例２
厚さ２０μｍのニッケル箔からなる弁膜を用いること以外は実施例１と同様にして、実施例２の円筒型二次電池を作成した。
【００４０】
実施例３
厚さ１０μｍのステンレス鋼箔からなる弁膜を用いること以外は実施例１と同様にして、実施例３の円筒型二次電池を作成した。
【００４１】
比較例１
図８に示す圧力開放式のガス排出弁(４)を蓋体(12)にレーザ溶接して、比較例１の円筒型二次電池を作製した。
【００４２】
比較例２
図７に示す如くバネ復帰式のガス排出弁(13)を蓋体(12)にねじ込み固定して、比較例２の円筒型二次電池を作製した。尚、一対のガス排出弁(13)(13)を含む電池の全長は２２５ｍｍである。
【００４３】
体積エネルギー密度の算出
上記実施例１〜３及び比較例１及び２の各電池の容量を測定し、体積エネルギー密度を算出した。その結果を表１に示す。尚、電池の体積は、電極端子機構及びガス排出弁を含む電池全体を内包する円筒体の体積とした。
【００４４】
【表１】

【００４５】
表１から明らかな様に、何れの電池においても同一の電池エネルギーが得られたが、電池体積の差によって、実施例１〜３及び比較例１の電池は比較例２の電池よりも体積エネルギー密度が増大している。
【００４６】
又、石鹸液を用いたリークチェック試験を行なったところ、ガス排出弁をねじ込み式として溶接を行なわなかった実施例１〜３においても、ガス排出弁を溶接固定した比較例１と同じく、ガス漏れは発見されなかった。
【００４７】
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８に示す従来の電池(比較例１)では、別途、電解液注入用の孔を開設する必要があるが、本発明の電池では、筒体に開設された段付き孔を利用することが出来るので、構成が簡易となる。
又、ガス排出弁(５)は蓋体(12)に埋め込まれて固定されているので、電極端子機構(９)と干渉する問題がなく、ガス排出弁を蓋体(12)に突設した構成に比べて、弁の開口面積を大きくすることが可能である。
【００４８】
更に、複数本の二次電池を用いて組電池を組み立てる場合、本発明の電池によれば、圧力開放式のガス排出弁(５)は蓋体(12)の厚さ範囲内に収容して配置することが出来るので、各電池を導線で互いに結線する作業がガス排出弁によって阻害されることはなく、組立作業が容易となる。
更に又、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断面図である。
【図２】該円筒型二次電池に装備されているガス排出弁の分解斜視図である。
【図３】該ガス排出弁の締め付け前の状態を表わす拡大断面図である。
【図４】該ガス排出弁の締め付け後の状態を表わす拡大断面図である。
【図５】ガス排出弁の他の構成を表わす断面図である。
【図６】該ガス排出弁の分解斜視図である。
【図７】従来のバネ復帰式のガス排出弁を具えた円筒型二次電池の断面図である。
【図８】従来の圧力開放式のガス排出弁を具えた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) ガス排出弁
(58) Ｏリング
(６) 内側挟圧リング
(62) 円筒部
(７) 弁膜
(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 is a cylindrical secondary battery in which an electrode body that is a secondary battery element is accommodated inside a battery can and the generated power of the secondary battery element can be taken out 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. 7, a cylindrical lithium secondary battery having a relatively large capacity used for an electric vehicle has a cylindrical body (11) with a lid (12) welded and fixed to each end. A battery can (1) is formed, and the winding electrode body (2) is accommodated in the battery can (1). An electrode terminal mechanism (9) is attached to the lid (12), and the take-up electrode body (2) and the electrode terminal mechanism (9) are connected to each other by a plurality of current collecting tabs (3). A similar electrode terminal mechanism (not shown) is also attached to the lid (not shown) fixed to the other end of the cylinder (11), and the electric power generated by the winding electrode body (2) Can be taken out from the pair of electrode terminal mechanisms.
Each lid (12) is provided with a spring return type gas discharge valve (13).
[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. 7, for the sake of convenience, only the state where the tip ends 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. 8, a pressure release type gas discharge valve (opened in the through hole (14) opened in the lid (12) is opened when the internal pressure of the battery can (1) exceeds a predetermined value. Cylindrical secondary batteries to which 4) is attached are known (JP-A-6-68861, JP-A-9-139196, etc.).
As shown in the figure, the pressure release type gas discharge valve (4) is formed by fixing a disc-shaped valve membrane (42) made of aluminum foil having a thickness of about 20 μm on the back surface of the ring body (41). The outer peripheral portion of (41) 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 spring return type gas discharge valve (13) shown in FIG. 7, when the pressure inside the battery can (1) rises, the gas discharge valve (13) has a spring return force. However, when a sudden pressure increase occurs, there is a problem that the pressure cannot be released sufficiently in the initial stage where the opening area 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. 7, 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 release type gas discharge valve (4) shown in FIG. 8, when an abnormal pressure is generated inside the battery can (1), the valve membrane (42) is instantaneously formed. Since it is broken and the pressure is released, an increase in pressure is effectively suppressed.
In addition, the pressure release type gas discharge valve (4) has fewer components than the spring return type gas discharge valve (13) and can be downsized. Is possible.
[0008]
However, in the conventional cylindrical secondary battery provided with the pressure release type gas discharge valve (4), especially when the battery is enlarged, the gas discharge valve (4) is attached to the lid (12) of the battery can (1). There was a problem that it was difficult to weld. That is, as the battery size increases, the thickness of the lid (12) increases. For example, the ring body (41) of the gas discharge valve (4) is lasered to the lid (12) having a thickness of several millimeters or more. When welding, the thickness of the lid (12) is very large compared to the thickness of the ring body (41), so the heat dissipation during welding is remarkable, and the metal melted by laser irradiation cools down rapidly. As a result, defects such as pinholes and cracks may occur in the weld.
[0009]
Also, in the conventional cylindrical secondary battery having the pressure release type gas discharge valve (4), when the electrolyte is injected into the battery can (1) in the assembly process, the lid (12) Since the gas discharge valve (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.
[0010]
SUMMARY OF THE INVENTION An object of the present invention is to provide a cylindrical secondary battery in which the structure of a gas discharge valve is compact and easy to install, and the number of battery assembly steps can be reduced.
[0011]
[Means for solving the problems]
In the cylindrical secondary battery according to the present invention, a stepped hole (16) is formed in the lid (12) of the battery can (1), and the stepped hole (16) is formed outside the lid (12). A large-diameter hole (17) with an internal thread formed on the inner peripheral surface, a small-diameter hole (18) that opens inside the lid (12), a large-diameter hole (17), and a small-diameter hole (18 stepped portion interposed between (19) comprises between), inside the large-diameter hole (17) of the step with holes (16), the gas discharge valve (5) is installed, the lid (12) The whole is accommodated in the thickness area | region pinched | interposed into the inner surface and outer surface.
The gas discharge valve (5) is installed on the step portion (19) of the stepped hole (16) and is opened when the internal pressure of the battery can (1) exceeds a predetermined value (7 and), and a pair of clamping rings arranged on both sides of the valve membrane (7) (6) (8), interposed between at least one of the clamping ring (8) and valvular (7) On the outer peripheral surface of the pinching ring ( 8 ) , which is composed of an O-ring (58) and arranged outside the valve membrane ( 7 ) , the inner screw of the large-diameter hole (17) of the stepped hole (16) is screwed. An outer thread (83) is formed, and both pinching rings ( 6 ) ( 8 ) are respectively provided with cylindrical portions (62) (82) projecting toward the outer periphery of the valve membrane ( 7 ) . The outer diameter of the cylindrical portion (62) of the pinching ring ( 6 ) is smaller than the inner diameter of the cylindrical portion (82) of the other pinching ring ( 8 ) by a predetermined dimension, and is formed on the valve membrane ( 7 ) . the cylindrical portion of the Ryokyo圧ring (6) (8) (62) thin portions by pinching by (82) (71) It has been made.
[0012]
In the cylindrical secondary battery of the present invention, the valve membrane (7) is installed on the step (19) of the lid (12) of the battery can (1), and the external screw of the fixing device is connected to the stepped hole (16 ), The valve membrane (7) can be fixed on the step (19). Therefore, it is not necessary to weld and fix the gas discharge valve (5) to the lid (12).
Further, in the assembly process of the cylindrical battery of the present invention, after the electrolyte is injected from the stepped hole (16) of the lid (12) of the battery can (1), the pressure inside the battery can (1) is increased. When the separator is impregnated with electrolyte, the sealing plug is screwed into the inner screw of the stepped hole (16) of the lid (12), and after the pressurizing process, the sealing plug is removed and the stepped The gas discharge valve (5) can be screwed into the inner screw of the hole (16) and fixed. Therefore, it is not necessary to separately provide an electrolyte injection hole in the lid (12) of the battery can (1).
[0013]
Further, the pressure release type gas discharge valve (5) has a smaller number of parts than the reset type gas discharge valve, and can be configured compactly. The whole can be accommodated and deployed in the thickness region.
Therefore, when the assembled battery is configured using the cylindrical secondary battery according to the present invention, it is possible to reduce the size of the entire apparatus.
[0015]
Furthermore, in the above-described cylindrical secondary battery according to the present invention, both the clamping rings (8) are screwed into the inner thread (15) of the lid (12) by screwing the outer screw (83) of the outer clamping ring (8). 6) A pinching pressure is generated in (8), and the outer peripheral portion of the valve membrane (7) is sandwiched between the two pinching rings (6) and (8), and the O-ring (58) It is clamped by the back surface of the clamping ring (8). Here, in the cylindrical portions (62) and (82) projecting from both the clamping rings (6) and (8), the outer diameter of one cylindrical portion (62) is larger than the inner diameter of the other cylindrical portion (82). Also, since the cylindrical portions (62) and (82) can be fitted to each other because they are formed by a predetermined size, the outer peripheral surface of one cylindrical portion (62) 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 valve membrane (7) is pressed between the cylindrical portions (62) and (82), thereby pressing the ring-shaped space as a mold space. A thin portion (71) having a predetermined thickness defined by the dimensions is formed.
[0016]
In the pressure release type gas discharge valve (5) in which the thin part (71) having a predetermined thickness is formed on the valve membrane (7) as described above, a pressure exceeding a predetermined value is generated inside the battery can (1). At first, the thin portion (71) is torn and the valve membrane (7) is instantly opened.
Therefore, the operating pressure of the gas discharge valve (5) depends on the thickness of the thin wall portion (71) of the valve membrane (7), that is, the dimensions of the cylindrical portions (62) and (82) of the both clamping rings (6) and (8). It can be defined with high accuracy.
[0019]
【The invention's effect】
According to the cylindrical secondary battery of the present invention, the gas discharge valve can be made compact by adopting the pressure release type gas discharge valve, and the gas discharge valve is screwed into the stepped hole of the lid and fixed. By adopting the structure, it becomes easy to mount the gas discharge valve. However, the stepped hole can be used for injecting the electrolyte, and the number of battery assembly steps is reduced.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
As shown in FIG. 1, a cylindrical secondary battery according to the present invention has a cylindrical battery can (1) formed by welding and fixing a lid (12) to each end of a cylindrical body (11). The take-up electrode body (2) is accommodated. An electrode terminal mechanism (9) is attached to the lid (12), and the take-up electrode body (2) and both electrode terminal mechanisms (9) are connected to each other by a plurality of current collecting tabs (3). Has been. A similar electrode terminal mechanism (not shown) is also attached to the lid (not shown) welded and fixed to the other end of the cylindrical body (11) to generate electric power generated by the winding electrode body (2). Can be taken out from the pair of electrode terminal mechanisms.
In addition, a pressure release type gas discharge valve (5) is screwed and fixed in a stepped hole (16) opened in each lid (12).
[0021]
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.
[0022]
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.
[0023]
As shown in FIG. 3, the stepped hole (16) opened in the lid (12) of the battery can (1) opens to the outside of the lid (12) and has an inner screw (15) on the inner peripheral surface. The formed large-diameter hole (17), the small-diameter hole (18) opened inside the lid (12), and the stepped portion (19) interposed between the large-diameter hole (17) and the small-diameter hole (18) It consists of and.
[0024]
As shown in FIGS. 2 to 4, the gas discharge valve (5) clamps the disc-shaped valve membrane (7) made of aluminum foil having a predetermined thickness (for example, 20 μm) and the outer peripheral portion of the valve membrane (7) from above and below. It is composed of a pair of brass pinching rings (6) and (8) and an O-ring (58) made of silicone resin interposed between the valve membrane (7) and the outer pinching ring (8).
The valve membrane (7) of the gas discharge valve (5) is not limited to aluminum but can be formed of nickel or stainless steel.
[0025]
The inner clamping ring (6) is configured by projecting a cylindrical portion (62) upward on the surface of a disc portion (61) having a central hole (63). The outer pinching ring (8) is formed by projecting a cylindrical portion (82) downward on the back surface of the disc portion (81) having the central hole (80), and the outer periphery of the disc portion (81). An external screw (83) is formed on the surface.
Here, the cylindrical portion (62) 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 (62) of the inner clamping ring (6) is smaller than the inner diameter of the cylindrical portion (82) of the outer clamping ring (8) by a predetermined dimension (for example, 36 μm). The cylindrical portion (62) of the inner pinching ring (6) and the cylindrical portion (82) of the outer pinching ring (8) can be fitted to each other.
[0026]
In assembling the gas discharge valve (5), as shown in FIG. 3, the inner pressure ring (6) and the valve membrane (7) are formed on the step (19) of the stepped hole (16) of the lid (12). Then, after the O-ring (58) is installed in order, the outer screw (83) of the outer pinching ring (8) is screwed into the inner screw (15) of the stepped hole (16) of the lid (12).
As a result, as shown in FIG. 4, the outer peripheral portion of the valve membrane (7) is clamped by the inner clamping ring (6) and the outer clamping ring (8), and the cylindrical portion (62) of the inner clamping ring (6). And the cylindrical portion (82) of the outer clamping ring (8) serves as a mold, and the outer peripheral portion of the valve membrane (7) is connected to the cylindrical portion (62) and the disc portion (of the inner clamping ring (6) as shown in the figure. 61) Plastically deform along the surface. Accordingly, the valve membrane (7) has a predetermined thickness (for example, 18 μm) defined by the gap S between the cylindrical portions (62) and (82) in the region sandwiched between the cylindrical portions (62) and (82). The thin portion (71) is formed in a ring shape.
[0027]
Further, the screwing of the outer clamping ring (8) causes the O-ring (58) to be clamped between the outer clamping ring (8) and the surface of the valve membrane (7). A seal is applied between the valve membranes (7).
[0028]
In the assembly of the cylindrical secondary battery having the gas discharge valve (5), the electrolyte is supplied from the stepped hole (16) of the lid (12) of the battery can (1) into the battery can (1). After the injection, a sealing plug (not shown) is screwed into the stepped hole (16) and sealed, and in this state, a predetermined pressure is applied to the inside of the battery can (1) to take up the electrolytic solution ( 2) The separator (22) is impregnated. Thereafter, the sealing plug is removed, and the gas discharge valve (5) is screwed into the stepped hole (16) and fixed.
[0029]
In the cylindrical secondary battery assembled in this way, when the internal pressure of the battery can (1) increases, first, the thin part (71) of the valve membrane (7) is torn and the valve membrane (7) Opens instantly and releases the internal pressure to the outside at once. Here, the opening pressure of the valve membrane (7) depends on the thickness of the thin portion (71) of the valve membrane (7), that is, the outer diameter of the cylindrical portion (62) of the inner pressure ring (6) and the outer pressure ring (8). ) Can be accurately defined by the inner diameter of the cylindrical portion (82).
[0030]
5 and 6 show another configuration example of the gas discharge valve (5).
The gas discharge valve (5) has the same valve membrane (7) installed on the step portion (19) of the stepped hole (16) of the lid (12) and the outer peripheral portion of the valve membrane (7). A lower pressure ring (50) to be pressure-reduced toward the stepped portion (19), an outer thread (52) is provided on the outer peripheral portion of the ring-shaped main body overlapping the lower pressure ring (50), and an inner screw ( 53) an outer peripheral side tightening ring (51), an outer peripheral side tightening ring (54) having an outer screw (56) screwed into an inner screw (53) of the outer peripheral side tightening ring (51), Consists of an O-ring (59) interposed between the peripheral clamping ring (54) and the valve membrane (7). The cylindrical part (55) projects downward on the back surface of the inner circumferential clamping ring (54). A central hole (57) that is coaxial with the stepped hole (16) is formed at the center of the inner peripheral side tightening ring (54).
[0031]
In assembling the gas discharge valve (5), after the valve membrane (7) and the lower pressure ring (50) are sequentially installed on the step portion (19) of the stepped hole (16) of the lid (12), The outer screw (52) of the outer peripheral side tightening ring (51) is screwed into the inner screw (15) of the stepped hole (16) of the lid (12). In addition, after installing the O-ring (59) on the valve membrane (7), the outer screw (56) of the inner peripheral side tightening ring (54) is screwed into the inner screw (53) of the outer peripheral side tightening ring (51). .
As a result, as shown in FIG. 5, the outer peripheral portion of the valve membrane (7) is sandwiched between the step portion (19) of the stepped hole (16) and the lower pressure ring (50), and the valve membrane (7) becomes the lid. Fixed to (12). Further, an O-ring (58) is sandwiched between the inner peripheral side clamping ring (54) and the surface of the valve membrane (7), and a seal is formed between the inner peripheral side clamping ring (54) and the valve membrane (7). Will be given.
[0032]
In the cylindrical secondary battery having the gas discharge valve (5), the outer peripheral side clamping ring (51) is used to give a sufficient clamping force to the valve membrane (7), and the inner peripheral side clamping ring (54) is provided. It can be used to give an appropriate tightening force to the O-ring (59).
Further, since the outer peripheral side tightening ring (51) and the inner peripheral side tightening ring (54) are arranged on the same plane, it is possible to further reduce the thickness of the gas exhaust valve (5) shown in FIGS. It is.
[0033]
【Example】
The cylindrical secondary battery (Examples 1 to 4) according to the present invention shown in FIGS. 1 to 4 and the conventional cylindrical secondary battery (Comparative Example) shown in FIG. confirmed.
First, the steps common to each battery will be described, and then the structure and attachment of gas discharge valves that differ for each battery will be described.
[0034]
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.
[0035]
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.
[0036]
Volume ratio Preparation <br/> ethylene carbonate and diethyl carbonate electrolyte 1: mixed solvent 1, by dissolving LiPF ₆ at a rate of 1 mol / l, to prepare an electrolytic solution.
[0037]
Assembling the battery A plurality of aluminum current collecting tabs are welded to the surface of the aluminum foil constituting the positive electrode at regular intervals, and a plurality of pieces are welded on the surface of the copper foil constituting the negative electrode. Nickel current collecting tabs 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.
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.
The battery can has an outer diameter of 45 mm and a length of 200 mm, a cylindrical body having a thickness of 1.25 mm, a lid having a diameter of 45 mm and a thickness of 5 mm. The total length of the battery including the pair of positive and negative electrode terminal mechanisms is 220 mm.
[0038]
Example 1
Opening a stepped hole with an inner diameter of 5 mm in the lid, and attaching the gas discharge valve (5) of FIGS. 1 to 3 provided with a valve membrane made of aluminum foil with a thickness of 30 μm to the stepped hole, A cylindrical secondary battery of Example 1 was produced.
[0039]
Example 2
A cylindrical secondary battery of Example 2 was produced in the same manner as Example 1 except that a valve membrane made of a nickel foil having a thickness of 20 μm was used.
[0040]
Example 3
A cylindrical secondary battery of Example 3 was produced in the same manner as in Example 1 except that a valve membrane made of a stainless steel foil having a thickness of 10 μm was used.
[0041]
Comparative Example 1
A cylindrical secondary battery of Comparative Example 1 was fabricated by laser welding the pressure release type gas discharge valve (4) shown in FIG. 8 to the lid (12).
[0042]
Comparative Example 2
As shown in FIG. 7, a spring return type gas discharge valve (13) was screwed and fixed to the lid (12) to produce a cylindrical secondary battery of Comparative Example 2. The total length of the battery including the pair of gas discharge valves (13) and (13) is 225 mm.
[0043]
Calculation of volume energy density The capacities of the batteries of Examples 1 to 3 and Comparative Examples 1 and 2 were measured, and the volume energy density was calculated. The results are shown in Table 1. The volume of the battery was the volume of the cylindrical body containing the entire battery including the electrode terminal mechanism and the gas discharge valve.
[0044]
[Table 1]

[0045]
As is clear from Table 1, the same battery energy was obtained in any of the batteries, but the batteries of Examples 1 to 3 and Comparative Example 1 had a volume energy higher than that of the battery of Comparative Example 2 due to the difference in battery volume. The density is increasing.
[0046]
In addition, when a leak check test using a soap solution was performed, in Examples 1 to 3 in which the gas discharge valve was screwed in and not welded, as in Comparative Example 1 in which the gas discharge valve was welded and fixed, the gas leak Was not found.
[0047]
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 battery (Comparative Example 1) shown in FIG. However, in the battery of the present invention, since the stepped hole provided in the cylindrical body can be used, the configuration is simplified.
In addition, since the gas discharge valve (5) is embedded and fixed in the lid (12), there is no problem of interfering with the electrode terminal mechanism (9), and the gas discharge valve is protruded from the lid (12). Compared to the configuration, the opening area of the valve can be increased.
[0048]
Furthermore, when assembling an assembled battery using a plurality of secondary batteries, according to the battery of the present invention, the pressure release type gas discharge valve (5) is accommodated within the thickness range of the lid (12). Since it can arrange | position, the operation | work which connects each battery with a conducting wire mutually is not inhibited by a gas exhaust valve, and an assembly operation becomes easy.
Furthermore, when the assembled battery is configured by connecting a plurality of secondary batteries in series, according to the 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 of a cylindrical secondary battery according to the present invention.
FIG. 2 is an exploded perspective view of a gas discharge valve provided in the cylindrical secondary battery.
FIG. 3 is an enlarged sectional view showing a state before the gas discharge valve is tightened.
FIG. 4 is an enlarged cross-sectional view showing a state after the gas discharge valve is tightened.
FIG. 5 is a cross-sectional view showing another configuration of the gas discharge valve.
FIG. 6 is an exploded perspective view of the gas discharge valve.
FIG. 7 is a cross-sectional view of a cylindrical secondary battery provided with a conventional spring return type gas discharge valve.
FIG. 8 is a cross-sectional view of a cylindrical secondary battery provided with a conventional pressure release type gas discharge valve.
[Explanation of symbols]
(1) Battery can
(11) Tube
(12) Lid
(2) Winding electrode body
(3) Current collection tab
(5) Gas discharge valve
(58) O-ring
(6) Inner pinching ring
(62) Cylindrical part
(7) Valve membrane
(8) Outer pinching ring
(82) Cylindrical part
(9) Electrode terminal mechanism

Claims

A cylinder configured by accommodating an electrode body (2) serving as a secondary battery element in a battery can (1) having a lid (12) fixed to an opening of the cylinder (11) and having airtightness. In the type secondary battery, a stepped hole (16) is formed in the lid (12) of the battery can (1), and the stepped hole (16) opens to the outside of the lid (12). A large-diameter hole (17) with an inner thread formed on the peripheral surface, a small-diameter hole (18) opening inside the lid (12), and interposed between the large-diameter hole (17) and the small-diameter hole (18) And a gas discharge valve (5) is provided inside the large-diameter hole (17) of the stepped hole (16), and is provided on the inner surface and the outer surface of the lid (12). The whole is accommodated in the sandwiched thickness region, and the gas discharge valve (5) is installed on the step portion (19) of the stepped hole (16) so that the internal pressure of the battery can (1) is predetermined. and valvular (7) disc-shaped to open when it exceeds the value, a pair of clamping rings arranged on both sides of the valve membrane (7) (6) (8) less the Configured from any one of the clamping rings (8) and valvular (7) O-ring (58) interposed between the outer peripheral surface of the clamping ring disposed on the outside of the valve membrane (7) (8) Is formed with an external screw (83) that is screwed into the internal screw of the large-diameter hole (17) of the stepped hole (16) , and the pinching rings ( 6 ) and ( 8 ) are respectively provided with valve membranes ( 7 ) . Cylindrical portions (62) and (82) project toward the outer peripheral portion, and the outer diameter of the cylindrical portion (62) of one clamping ring ( 6 ) is equal to the cylindrical portion (82 ) of the other clamping ring ( 8 ). than the inner diameter of), it is formed smaller by a predetermined distance, the valvular (7), Ryokyo圧 cylindrical portion of the ring (6) (8) (62) (thin portion by pinching by 82) (71) A cylindrical secondary battery characterized in that is formed .

The outer peripheral portion of the valve membrane (7) is reduced in pressure by the cylindrical portion (82) of the other pinching ring (8), and along the outer peripheral surface of the cylindrical portion (62) of the one pinching ring (6). 2. The cylindrical secondary battery according to claim 1 , wherein the cylindrical secondary battery is plastically deformed and the thin portion (71) is formed by the plastic deformation.