JP4020555B2

JP4020555B2 - Cylindrical battery

Info

Publication number: JP4020555B2
Application number: JP37033199A
Authority: JP
Inventors: 昇中野; 直哉中西; 俊之能間; 育郎米津
Original assignee: Sanyo Electric Co Ltd
Current assignee: Sanyo Electric Co Ltd
Priority date: 1999-12-27
Filing date: 1999-12-27
Publication date: 2007-12-12
Anticipated expiration: 2019-12-27
Also published as: JP2001185222A

Description

【０００１】
【発明の属する技術分野】
本発明は、円筒状の電池缶の内部に収容された巻き取り電極体の発生電力を一対の電極端子部から外部へ取り出すことが出来る円筒型電池に関し、特に、外部から加わる振動や衝撃に対して高い耐久性を有する円筒型電池に関するものである。
【０００２】
【従来の技術】
近年、クリーンなエネルギーとして二次電池が様々な分野で利用されるようになっており、高出力、高エネルギー密度で且つ長期に亘って安定した性能を発揮し得る二次電池に期待が寄せられている。
又、自動車の排ガスによる大気汚染が世界的な問題となっている中で、電気を動力源とする電気自動車が注目を集めており、電気自動車に搭載して好適な二次電池の開発が要請されている。
【０００３】
図４は、従来の円筒型リチウムイオン二次電池を表わしており、筒体(11)の両開口部に蓋体(12)(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(４)が収容されており、該巻き取り電極体(４)の各電極と各蓋体(12)に取り付けられた電極端子機構(９)とをリード部材(33)によって互いに接続している。これによって、巻き取り電極体(４)が発生する電力を正負一対の電極端子機構(９)(９)から外部へ取り出すことが出来るのである。
尚、蓋体(12)には、圧力開放型のガス排出弁(13)が取り付けられている。
【０００４】
図示する二次電池においては、巻き取り電極体(４)の発生電力を取り出すために、所謂タブレス構造が採用されている。即ち、巻き取り電極体(４)の両端部にはそれぞれ円板状の集電板(32)がレーザ溶接され、該集電板(32)が帯板状のリード(33)を介して電極端子機構(９)に接続される。
【０００５】
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電極端子(91)を具え、該電極端子(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)と電極端子(91)の間の電気的絶縁性とシール性が保たれている。電極端子(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、第１ナット(95)及び第２ナット(96)が螺合している。そして、第１ナット(95)を締め付けて、電極端子(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。
前記リード(33)の先端部は、電極端子(91)の鍔部(92)に、抵抗溶接或いは超音波溶接によって固定されている。
【０００６】
【発明が解決しようとする課題】
ところで、図４に示す如き構造のリチウムイオン二次電池を電気自動車に電源として搭載した場合、電気自動車の走行に伴って、リチウムイオン二次電池には、大きな振動や衝撃力が繰り返し加えられることになる。
【０００７】
巻き取り電極体(４)は、最外周部に絶縁性のセパレータを複数回巻き付け、その外周面を電池缶(１)の内周面に対向させて、電気的絶縁を図ると共に、巻き取り電極体(４)の半径方向の移動を拘束しているが、巻き取り電極体(４)の軸方向の移動に対しては、保持力が充分でなく、上述の如く大きな振動や衝撃力が繰り返し加わった場合、巻き取り電極体(４)が電池缶(１)内で軸方向に振動することになる。
これによって、集電板(32)が筒体(11)の内周面や蓋体(12)の内面に衝突すると、巻き取り電極体(４)と電池缶(１)とが電気的に短絡する問題が発生する。
又、巻き取り電極体(４)自体が振動を受けて巻崩れを生じる虞れがあり、特にタブレス構造の二次電池では、巻き取り電極体(４)の巻崩れによって、電極端縁と集電板の間の接触状態が悪化し、集電性能の低下ひいては出力密度の低下を来たす問題がある。
【０００８】
尚、電池缶(１)を構成する蓋体(12)の内面に円板状の絶縁部材を設置して、集電板(32)と蓋体(12)の間の電気的絶縁を図ることは可能であるが、巻き取り電極体(４)が電池缶(１)内で大きく振動して、絶縁部材に衝突した場合、電気的絶縁が破壊される虞れがある。
【０００９】
そこで本発明の目的は、外部から加わる振動や衝撃力に起因する電池缶と巻き取り電極体の間の絶縁性の低下や、巻き取り電極体の巻崩れを効果的に防止することが出来る円筒型電池を提供することである。
【００１０】
【課題を解決する為の手段】
本発明に係る円筒型電池において、電池缶(１)の内部には、少なくとも一方の端部に、電池缶 ( １ )の内周面に嵌合する円筒状絶縁体(２)が設置され、該円筒状絶縁体(２)の内周面には、巻き取り電極体(４)の端面に被さる鍔部(22)が突設されている。
【００１１】
上記本発明の円筒型電池において、電池缶(１)内の巻き取り電極体(４)は、円筒状絶縁体(２)の鍔部(22)によって軸方向の移動が拘束されており、然も、巻き取り電極体(４)の端部を包囲する電池缶(１)の内周面は、円筒状絶縁体(２)によって覆われているので、外部から振動や衝撃力が加わったとしても、巻き取り電極体(４)の端部が電池缶(１)の内周面に直接に接触することはない。
又、巻き取り電極体(４)が電池缶(１)内で振動することがないので、巻崩れの虞れもない。
【００１２】
具体的には、円筒状絶縁体(２)の鍔部(22)は、リング状に形成されている。
これによって、鍔部(22)を薄く形成した場合にも、鍔部(22)は充分な強度を発揮し、巻き取り電極体(４)の拘持が強固なものとなる。
【００１３】
更に具体的には、電池缶(１)の内周面(15)に、円筒状絶縁体(２)が嵌合する凹部(14)が形成され、該凹部(14)に円筒状絶縁体(２)が拘持されている。
該構造によれば、大きな振動や衝撃力が加わった場合にも、円筒状絶縁体(２)は電池缶(１)によって拘持されているので、該円筒状絶縁体(２)による巻き取り電極体(４)の拘持がより強固なものとなる。
【００１４】
又、所謂タブレス構造の円筒型電池においては、巻き取り電極体(４)は、それぞれ帯状の正極(41)と負極(43)の間にセパレータ(42)を介在させてこれらを積層したものであって、正極(41)及び負極(43)はそれぞれ、帯状芯体の表面に活物質を塗布して構成され、電極体(４)の両端部には、正極(41)及び負極(43)の帯状芯体の端縁(48)(48)が突出し、各端縁(48)に集電板(32)が接合されている。この場合、集電板(32)の表面に、円筒状絶縁体(２)の鍔部(22)が被さる。
従って、巻き取り電極体(４)の集電板(32)が電池缶(１)の内面に接触することはない。
【００１５】
【発明の効果】
本発明に係る円筒型電池によれば、外部から振動や衝撃力が繰り返し加わった場合にも、巻き取り電極体(４)が円筒状絶縁体(２)によって電池缶(１)内に確実に拘持されており、電池缶(１)内で大きく移動することはないので、長期に亘って、電気的絶縁と高い出力密度が維持される。
【００１６】
【発明の実施の形態】
以下、本発明を円筒型リチウムイオン二次電池に実施した形態につき、図面に沿って具体的に説明する。尚、本発明は下記実施の形態により何ら限定されるものではなく、その要旨を変更しない範囲において適宜変更して実施することが可能である。
【００１７】
本発明に係る円筒型リチウムイオン二次電池は、図１に示す如く、筒体(11)の両開口部に蓋体(12)(12)を溶接固定して電池缶(１)を形成し、該電池缶(１)の内部に巻き取り電極体(４)を設置して構成されており、該巻き取り電極体(４)が発生する電力を、両蓋体(12)(12)に取り付けた正負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。
尚、蓋体(12)には、圧力開閉式のガス排出弁(13)が取り付けられている。
【００１８】
巻き取り電極体(４)は、図３に示す如く、アルミニウム箔からなる芯体(45)の表面にリチウム複合酸化物からなる正極活物質(44)を塗布してなる正極(41)と、銅箔からなる芯体(47)の表面に炭素材料を含む負極活物質(46)を塗布してなる負極(43)と、非水電解液が含浸されたセパレータ(42)とから構成され、正極(41)及び負極(43)はそれぞれセパレータ(42)上に幅方向へずらして重ね合わされ、渦巻き状に巻き取られている。これによって、巻き取り電極体(４)の巻き軸方向の両端部の内、一方の端部では、セパレータ(42)の端縁よりも外方へ正極(41)の芯体(45)の端縁(48)が突出すると共に、他方の端部では、セパレータ(42)の端縁よりも外方へ負極(43)の芯体(47)の端縁(48)が突出している。
そして、巻き取り電極体(４)の両端部にはそれぞれ円板状の集電板(32)がレーザ溶接され、該集電板(32)がリード部材(33)を介して前記電極端子機構(９)に接続される。
図１に示す如く、電極端子機構(９)には従来と同じ構造が採用されている。
【００１９】
筒体(11)の内周面(15)の両端部にはそれぞれ円筒状の凹部(14)が形成されており、各凹部(14)にポリプロピレン製の円筒状絶縁体(２)が嵌合している。円筒状絶縁体(２)は、筒体(11)の凹部(14)に嵌まる円筒状の筒部(21)と、該筒部(21)の内周面の中間位置に突設されたリング状の鍔部(22)とから構成され、鍔部(22)は、巻き取り電極体(４)の集電板(32)の表面に被さっている。
【００２０】
例えば図２において、筒体(11)は、外径Ｄ１が５７ｍｍ、凹部(14)が形成された領域の肉厚Ｔ１が０.５ｍｍ、凹部(14)の深さＴ２が１ｍｍに形成され、円筒状絶縁体(２)は、筒部(21)の外径Ｄ２が５５.５ｍｍ、内径Ｄ３が５３.５ｍｍ、鍔部(22)の板厚Ｔ３が１ｍｍに形成されている。
【００２１】
図１に示す円筒型リチウムイオン二次電池においては、筒体(11)の凹部(14)に円筒状絶縁体(２)が拘持され、該円筒状絶縁体(２)の鍔部(22)によって、巻き取り電極体(４)の軸方向の移動が拘束されているので、外部から振動や衝撃力が加わったとしても、巻き取り電極体(４)が軸方向に移動することはない。従って、集電板(32)が筒体(11)の内面に接触することはなく、又、巻き取り電極体(４)に巻崩れが発生する虞れもない。
然も、巻き取り電極体(４)の端部を包囲する筒体(11)の内周面は、円筒状絶縁体(２)の筒部(21)によって覆われているので、集電板(32)が筒体(11)の内周面に直接に接触することはない。
この結果、上記リチウムイオン二次電池を電気自動車などに搭載して使用した場合にも、長期に亘って、高い出力密度と電気的絶縁が維持される。
【００２２】
次に、上記本発明の円筒型リチウムイオン二次電池の具体的な作製方法と、作製した各種電池を対象とする性能評価試験の結果について説明する。
【００２３】
【実施例１】
正極の作製
正極活物質としての平均粒径５μｍのリチウム複合酸化物(ＬｉＣｏＯ_２)粉末と、導電剤としての人造黒鉛とを重量比９：１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(ＰＶｄＦ)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、スラリーを調製した。その後、このスラリーを厚さ２０μｍ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(41)を得た。尚、正極(41)には、正極端子機構側の端部に、一定幅の非塗工部を形成した。
【００２４】
負極の作製
炭素塊(ｄ００２＝３.３５６Å；Ｌｃ＞１０００)に空気流を噴射して粉砕し、炭素粉末を作製した。また、結着剤であるＰＶｄＦをＮＭＰに溶解させてＮＭＰ溶液を調製し、前記炭素粉末とＰＶｄＦの重量比が８５：１５となる様に両者を混練してスラリーを調製した。その後、このスラリーを厚さ２０μｍ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(43)を得た。尚、負極(43)には、負極端子機構側の端部に、一定幅の非塗工部を形成した。
【００２５】
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の割合で溶かして、電解液を調製した。
【００２６】
電池の組立
セパレータ(42)となるイオン透過性のポリプロピレン製微多孔膜を数回巻いた後、セパレータ(42)が正極(41)と負極(43)の間に介在する様に、セパレータ(42)、正極(41)、セパレータ(42)及び負極(43)の４枚を重ね合わせ、これらを渦巻きに巻き取って、巻き取り電極体(４)を得た。尚、正極(41)、セパレータ(42)及び負極(43)は、各電極の非塗工部がセパレータ(42)の両端縁から外側へ突出するように重ね合わせた。
【００２７】
その後、巻き取り電極体(４)の正極側の端縁には、厚さ１ｍｍのアルミニウム製集電板(32)をレーザ溶接し、負極側の端縁には、厚さ１ｍｍのニッケル製集電板(32)をレーザ溶接した。
更に、アルミニウム製の正極用リード部材(33)と、ニッケル製の負極用リード部材(33)とを作製し、各リード部材(33)の基端部を各集電板(32)の表面にレーザ溶接した。
【００２８】
その後、巻き取り電極体(４)を筒体(11)の内部に装填し、更に該巻き取り電極体(４)の各集電板(32)を覆うように、筒体(11)の両端部に円筒状絶縁体(２)(２)を設置した。一方、各蓋体(12)には電極端子機構(９)を取り付けた。
尚、円筒状絶縁体(２)の鍔部(22)は、その平面形状の面積が集電板(32)の平面形状の面積の１２％の大きさとなる様に形成した。
【００２９】
次に、巻き取り電極体(４)の各端部に突出するリード部材(33)の先端部を各蓋体(12)の電極端子機構(９)の基端部にレーザ溶接した後、各蓋体(12)を筒体(11)の各端部にレーザ溶接した。
そして、ガス排出弁のネジ孔から電解液を注入した後、ガス排出弁をねじ込んで、外径５７、長さ２２０ｍｍの本発明電池Ａを組み立てた。
【００３０】
【実施例２】
電池缶(１)の筒体(11)に凹部(14)が形成されておらず、筒体(11)の内周面(15)に円筒状絶縁体(２)が嵌まっていること以外は上記本発明電池Ａと同様にして、本発明電池Ｂを組み立てた。
【００３１】
電池の評価
本発明電池Ａ及び本発明電池Ｂに対し、振幅１ｍｍ、周波数１０〜５５Ｈｚ、掃引速度１Ｈｚ/ｍｉｎの条件で、互いに直角に交わるＸＹＺ方向へ１００分間の振動を加え、振動試験の前後で、出力特性(ＤＯＤ５０％、１５秒間放電時の出力密度)の変化(振動試験後の出力密度−振動試験前の出力密度)を調べ、性能を評価した。
その結果を表１に示す。
【００３２】
【表１】

【００３３】
表１に示す様に、本発明電池Ａでは、本発明電池Ｂよりも出力密度の低下が少なくなっている。これは、本発明電池Ａでは、円筒状絶縁体(２)が電池缶(１)の凹部(14)に拘持されているために、高い耐振性を発揮して、巻き取り電極体(４)の位置ずれ及び巻崩れが確実に防止されたためであると考えられる。
【００３４】
【実施例３】
本発明電池Ａにおいて、集電板(32)の面積に対する円筒状絶縁体(２)の鍔部(22)の面積の割合を１〜５０％の範囲で変化させた本発明電池２−１〜本発明電池２−９を作製し、同様の振動試験によって性能を評価した。
その結果を表２に示す。
【００３５】
【表２】

【００３６】
表２に示す様に、円筒状絶縁体(２)の鍔部(22)の集電板(32)に対する面積割合が３％以上の電池では、出力密度の低下が３０Ｗ/ｋｇ以下に抑えられている。これに対し、鍔部(22)の面積割合が２％以下の電池では、出力密度の低下が３０Ｗ/ｋｇを越えている。
これは、鍔部(22)の面積割合が２％以下では、鍔部(22)の強度が低く、巻き取り電極体(４)に対する拘持力が不十分なため、大きな振動が加わることによって、鍔部(22)が変形し、この結果、巻き取り電極体(４)が振動を受けて巻崩れを起こしたためと考えられる。
【００３７】
又、鍔部(22)の面積割合が３０％以下の電池では、振動試験前の出力密度が５００Ｗ/ｋｇ以上であるのに対し、鍔部(22)の面積割合が４０％以上の電池では、振動試験前の出力密度が５００Ｗ/ｋｇ以下となっている。
これは、鍔部(22)の面積割合が４０％以上では、電池組立時の電解液注入の際、円筒状絶縁体(２)の鍔部(22)が注液の妨げとなって、巻き取り電極体(４)の全体に電解液を均一且つ十分に含浸させることが出来ず、この結果、電池の内部抵抗が増大したためと考えられる。
【００３８】
以上の結果から、本発明に係るリチウムイオン二次電池においては、電池缶(１)を構成する筒体(11)の内周面(15)には凹部(14)を形成して、該凹部(14)に円筒状絶縁体(２)を嵌合せしめると共に、円筒状絶縁体(２)の鍔部(22)は、集電板(32)に対する面積割合を３％〜３０％の範囲に設定することが望ましいと言える。
【図面の簡単な説明】
【図１】本発明に係る円筒型リチウムイオン二次電池の一部破断正面図である。
【図２】該二次電池の各部寸法を説明する為の図である。
【図３】該二次電池に装備される巻き取り電極体の一部展開斜視図である。
【図４】従来の円筒型リチウムイオン二次電池の一部破断正面図である。
【符号の説明】
(１) 電池缶
(11) 筒体
(12) 蓋体
(14) 凹部
(15) 内周面
(２) 円筒状絶縁体
(21) 筒部
(22) 鍔部
(４) 巻き取り電極体
(32) 集電板
(33) リード部材
(９) 電極端子機構[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cylindrical battery capable of taking out the generated power of a winding electrode body housed inside a cylindrical battery can from the pair of electrode terminal portions, and particularly against vibration and impact applied from the outside. The present invention relates to a cylindrical battery having high durability.
[0002]
[Prior art]
In recent years, secondary batteries have come to be used in various fields as clean energy, and there are expectations for secondary batteries that can exhibit high output, high energy density, and stable performance over a long period of time. ing.
In addition, air pollution caused by exhaust gas from automobiles has become a global problem, and electric vehicles using electricity as a power source are attracting attention, and the development of secondary batteries suitable for use in electric vehicles is required. Has been.
[0003]
FIG. 4 shows a conventional cylindrical lithium ion secondary battery. In a battery can (1) in which lids (12) and (12) are fixed to both openings of a cylinder (11), A winding electrode body (4) serving as a secondary battery element is accommodated, and leads each electrode of the winding electrode body (4) and an electrode terminal mechanism (9) attached to each lid body (12). The members (33) are connected to each other. Thereby, the electric power generated by the winding electrode body (4) can be taken out from the pair of positive and negative electrode terminal mechanisms (9), (9).
The lid (12) is provided with a pressure release type gas discharge valve (13).
[0004]
In the illustrated secondary battery, a so-called tabless structure is adopted in order to take out the electric power generated by the winding electrode body (4). That is, a disc-shaped current collector plate (32) is laser-welded to both ends of the winding electrode body (4), and the current collector plate (32) is connected to the electrode via a strip-shaped lead (33). Connected to the terminal mechanism (9).
[0005]
The electrode terminal mechanism (9) includes an electrode terminal (91) attached through the lid (12) of the battery can (1), and the base end of the electrode terminal (91) has a flange (92). ) 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 electrode terminal (91) are maintained. A washer (94) is fitted to the electrode terminal (91) from the outside of the lid (12), and a first nut (95) and a second nut (96) are screwed together. The first nut (95) is tightened, and the insulating packing (93) is clamped by the flange (92) and the washer (94) of the electrode terminal (91), thereby improving the sealing performance.
The tip of the lead (33) is fixed to the flange (92) of the electrode terminal (91) by resistance welding or ultrasonic welding.
[0006]
[Problems to be solved by the invention]
By the way, when a lithium ion secondary battery having a structure as shown in FIG. 4 is mounted as a power source in an electric vehicle, a large vibration or impact force is repeatedly applied to the lithium ion secondary battery as the electric vehicle travels. become.
[0007]
The take-up electrode body (4) has an insulative separator wound around the outermost periphery a plurality of times, and its outer peripheral surface is opposed to the inner peripheral surface of the battery can (1) to achieve electrical insulation, and the take-up electrode Although the movement of the body (4) in the radial direction is constrained, the holding force is not sufficient for the movement of the winding electrode body (4) in the axial direction, and the large vibration and impact force are repeated as described above. When added, the winding electrode body (4) vibrates in the axial direction in the battery can (1).
As a result, when the current collector plate (32) collides with the inner peripheral surface of the cylindrical body (11) or the inner surface of the lid (12), the winding electrode body (4) and the battery can (1) are electrically short-circuited. Problems occur.
In addition, there is a possibility that the winding electrode body (4) itself is subject to vibrations and collapses. In particular, in a secondary battery having a tabless structure, the winding edge of the winding electrode body (4) collapses and collects the electrode edge. There is a problem in that the contact state between the electric plates deteriorates, resulting in a decrease in current collecting performance and a decrease in output density.
[0008]
In addition, a disk-shaped insulating member is installed on the inner surface of the lid (12) constituting the battery can (1) to achieve electrical insulation between the current collector plate (32) and the lid (12). However, if the winding electrode body (4) vibrates greatly in the battery can (1) and collides with the insulating member, the electrical insulation may be destroyed.
[0009]
Accordingly, an object of the present invention is to provide a cylinder that can effectively prevent deterioration of insulation between the battery can and the winding electrode body due to externally applied vibration or impact force, and the winding electrode body can be prevented from collapsing. Type battery.
[0010]
[Means for solving the problems]
In the cylindrical battery according to the present invention, a cylindrical insulator (2) fitted to the inner peripheral surface of the battery can ( 1 ) is installed at least at one end inside the battery can ( 1 ) . On the inner peripheral surface of the cylindrical insulator (2), a flange portion (22) is provided so as to cover the end surface of the winding electrode body (4).
[0011]
In the cylindrical battery of the present invention, the winding electrode body (4) in the battery can (1) is restrained from moving in the axial direction by the flange (22) of the cylindrical insulator (2). However, since the inner peripheral surface of the battery can (1) surrounding the end of the winding electrode body (4) is covered with the cylindrical insulator (2), it is assumed that vibration or impact force is applied from the outside. However, the end of the winding electrode body (4) does not directly contact the inner peripheral surface of the battery can (1).
Further, since the take-up electrode body (4) does not vibrate in the battery can (1), there is no possibility of collapse.
[0012]
Specifically, the flange portion (22) of the cylindrical insulator (2) is formed in a ring shape.
Thus, even when the collar part (22) is formed thin, the collar part (22) exhibits sufficient strength, and the take-up electrode body (4) is firmly held.
[0013]
More specifically, a recess (14) into which the cylindrical insulator (2) is fitted is formed on the inner peripheral surface (15) of the battery can (1), and a cylindrical insulator (14) is formed in the recess (14). 2) is in custody.
According to this structure, even when a large vibration or impact force is applied, the cylindrical insulator (2) is held by the battery can (1), so that it is wound by the cylindrical insulator (2). The holding of the electrode body (4) becomes stronger.
[0014]
In a so-called tabless cylindrical battery, the take-up electrode body (4) is formed by laminating a separator (42) between a strip-like positive electrode (41) and a negative electrode (43). The positive electrode (41) and the negative electrode (43) are each formed by applying an active material to the surface of the belt-like core, and the positive electrode (41) and the negative electrode (43) are formed at both ends of the electrode body (4). Edges (48) and (48) of the belt-shaped core body project, and a current collector plate (32) is joined to each edge (48). In this case, the collar part (22) of the cylindrical insulator (2) covers the surface of the current collector plate (32).
Therefore, the current collector plate (32) of the winding electrode body (4) does not contact the inner surface of the battery can (1).
[0015]
【The invention's effect】
According to the cylindrical battery according to the present invention, the winding electrode body (4) is reliably placed in the battery can (1) by the cylindrical insulator (2) even when vibration or impact force is repeatedly applied from the outside. Since it is held and does not move greatly in the battery can (1), electrical insulation and high power density are maintained over a long period of time.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention applied to a cylindrical lithium ion secondary battery will be described in detail with reference to the drawings. In addition, this invention is not limited at all by the following embodiment, In the range which does not change the summary, it can change suitably and can implement.
[0017]
As shown in FIG. 1, a cylindrical lithium ion secondary battery according to the present invention forms a battery can (1) by welding and fixing lids (12) and (12) to both openings of a cylindrical body (11). The winding electrode body (4) is installed inside the battery can (1), and the electric power generated by the winding electrode body (4) is supplied to both lid bodies (12) (12). The attached positive and negative electrode terminal mechanisms (9) and (9) can be taken out to the outside.
The lid (12) is provided with a pressure open / close gas discharge valve (13).
[0018]
As shown in FIG. 3, the wound electrode body (4) includes a positive electrode (41) obtained by applying a positive electrode active material (44) made of a lithium composite oxide to the surface of a core body (45) made of an aluminum foil, A negative electrode (43) formed by applying a negative electrode active material (46) containing a carbon material on the surface of a core (47) made of copper foil, and a separator (42) impregnated with a non-aqueous electrolyte, The positive electrode (41) and the negative electrode (43) are superimposed on the separator (42) while being shifted in the width direction, and wound in a spiral shape. As a result, the end of the core body (45) of the positive electrode (41) is more outward than the edge of the separator (42) at one end of both ends in the winding axis direction of the winding electrode body (4). The edge (48) protrudes, and at the other end, the end edge (48) of the core (47) of the negative electrode (43) protrudes outward from the end edge of the separator (42).
A disc-shaped current collector plate (32) is laser welded to both ends of the winding electrode body (4), and the current collector plate (32) is connected to the electrode terminal mechanism via a lead member (33). Connected to (9).
As shown in FIG. 1, the electrode terminal mechanism (9) has the same structure as the conventional one.
[0019]
Cylindrical recesses (14) are formed at both ends of the inner peripheral surface (15) of the cylinder (11), and a polypropylene cylindrical insulator (2) is fitted into each recess (14). is doing. The cylindrical insulator (2) is provided so as to protrude at an intermediate position between the cylindrical cylindrical portion (21) that fits into the concave portion (14) of the cylindrical body (11) and the inner peripheral surface of the cylindrical portion (21). It is comprised from a ring-shaped collar part (22), and the collar part (22) covers the surface of the current collecting plate (32) of the winding electrode body (4).
[0020]
For example, in FIG. 2, the cylinder (11) has an outer diameter D1 of 57 mm, a thickness T1 of the region where the recess (14) is formed, 0.5 mm, and a depth T2 of the recess (14) of 1 mm. The cylindrical insulator (2) is formed such that the outer diameter D2 of the cylindrical portion (21) is 55.5 mm, the inner diameter D3 is 53.5 mm, and the plate thickness T3 of the flange portion (22) is 1 mm.
[0021]
In the cylindrical lithium ion secondary battery shown in FIG. 1, the cylindrical insulator (2) is held in the recess (14) of the cylindrical body (11), and the flange (22) of the cylindrical insulator (2) is held. ) Restricts the axial movement of the take-up electrode body (4), so that the take-up electrode body (4) does not move in the axial direction even if vibration or impact force is applied from the outside. . Therefore, the current collector plate (32) does not come into contact with the inner surface of the cylindrical body (11), and there is no possibility that the winding electrode body (4) will collapse.
However, since the inner peripheral surface of the cylinder (11) surrounding the end of the winding electrode body (4) is covered with the cylinder (21) of the cylindrical insulator (2), the current collector plate (32) does not directly contact the inner peripheral surface of the cylinder (11).
As a result, even when the lithium ion secondary battery is used in an electric vehicle or the like, high output density and electrical insulation are maintained for a long time.
[0022]
Next, a specific method for producing the cylindrical lithium ion secondary battery of the present invention and results of a performance evaluation test for various produced batteries will be described.
[0023]
[Example 1]
Production of positive electrode Lithium composite oxide (LiCoO ₂ ) powder having an average particle diameter of 5 µm as a positive electrode active material and artificial graphite as a conductive agent are mixed at a weight ratio of 9: 1 to produce a positive electrode mixture. did. Next, polyvinylidene fluoride (PVdF) 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 were mixed so that the weight ratio of the positive electrode mixture and polyvinylidene fluoride was 95: 5 to prepare a slurry. Thereafter, this slurry was applied to both surfaces of an aluminum foil having a thickness of 20 μm by a doctor blade method, followed by vacuum drying at 150 ° C. for 2 hours to obtain a positive electrode (41). The positive electrode (41) was formed with a non-coated portion having a certain width at the end on the positive electrode terminal mechanism side.
[0024]
Production of negative electrode A carbon powder (d002 = 3.356Å; Lc> 1000) was jetted and pulverized to produce a carbon powder. Further, an NMP solution was prepared by dissolving PVdF as a binder in NMP, and both were kneaded so that the weight ratio of the carbon powder to PVdF was 85:15 to prepare a slurry. Then, this slurry was apply | coated to both surfaces of 20-micrometer-thick copper foil by the doctor blade method, and it vacuum-dried at 150 degreeC for 2 hours, and obtained the negative electrode (43). In the negative electrode (43), a non-coated portion having a constant width was formed at the end on the negative electrode terminal mechanism side.
[0025]
Volume ratio Preparation <br/> ethylene carbonate and diethyl carbonate electrolyte 1: mixed solvent at 1, the LiPF ₆ dissolved at a rate of 1 mol / L, to prepare an electrolytic solution.
[0026]
Battery assembly After winding the ion-permeable polypropylene microporous membrane to be the separator (42) several times, the separator (42) is interposed between the positive electrode (41) and the negative electrode (43). The separator (42), the positive electrode (41), the separator (42) and the negative electrode (43) were superposed and wound into a spiral to obtain a wound electrode body (4). The positive electrode (41), the separator (42), and the negative electrode (43) were overlapped so that the non-coated portions of the electrodes protruded outward from both end edges of the separator (42).
[0027]
Thereafter, an aluminum current collector plate (32) having a thickness of 1 mm is laser-welded to the edge on the positive electrode side of the winding electrode body (4), and a nickel current collector having a thickness of 1 mm is applied to the edge on the negative electrode side. The electroplate (32) was laser welded.
Further, a positive electrode lead member (33) made of aluminum and a negative electrode lead member (33) made of nickel were prepared, and the base end portion of each lead member (33) was placed on the surface of each current collector plate (32). Laser welded.
[0028]
Thereafter, the take-up electrode body (4) is loaded inside the cylinder body (11), and further, both ends of the cylinder body (11) are covered so as to cover the current collector plates (32) of the take-up electrode body (4). Cylindrical insulators (2) and (2) were installed in the part. On the other hand, an electrode terminal mechanism (9) was attached to each lid (12).
The flange portion (22) of the cylindrical insulator (2) was formed so that its planar area was 12% of the planar area of the current collector plate (32).
[0029]
Next, the front end of the lead member (33) protruding from each end of the take-up electrode body (4) is laser welded to the base end of the electrode terminal mechanism (9) of each lid (12). The lid (12) was laser welded to each end of the cylinder (11).
And after inject | pouring electrolyte solution from the screw hole of a gas exhaust valve, the gas exhaust valve was screwed in and this invention battery A of outer diameter 57 and length 220mm was assembled.
[0030]
[Example 2]
The cylindrical body (11) of the battery can (1) is not formed with the recess (14), and the cylindrical insulator (2) is fitted on the inner peripheral surface (15) of the cylindrical body (11). Was assembled in the same manner as the battery A of the present invention.
[0031]
Evaluation of the battery The present invention battery A and the present invention battery B were subjected to vibration for 100 minutes in the XYZ directions intersecting at right angles to each other under conditions of an amplitude of 1 mm, a frequency of 10 to 55 Hz, and a sweep speed of 1 Hz / min. Before and after the vibration test, the change in output characteristics (DOD 50%, power density during discharge for 15 seconds) (power density after vibration test-power density before vibration test) was examined to evaluate performance.
The results are shown in Table 1.
[0032]
[Table 1]

[0033]
As shown in Table 1, in the battery A of the present invention, the decrease in output density is less than that of the battery B of the present invention. In the battery A of the present invention, since the cylindrical insulator (2) is held by the recess (14) of the battery can (1), it exhibits high vibration resistance and the winding electrode body (4 This is considered to be because the displacement and collapse of the) were reliably prevented.
[0034]
[Example 3]
In the present invention battery A, the present invention battery 2-1 in which the ratio of the area of the collar portion (22) of the cylindrical insulator (2) to the area of the current collector plate (32) is changed in the range of 1 to 50%. Invention battery 2-9 was prepared and performance was evaluated by the same vibration test.
The results are shown in Table 2.
[0035]
[Table 2]

[0036]
As shown in Table 2, in the case of a battery in which the area ratio of the collar portion (22) of the cylindrical insulator (2) to the current collector plate (32) is 3% or more, the decrease in output density is suppressed to 30 W / kg or less. ing. On the other hand, in the battery in which the area ratio of the buttocks (22) is 2% or less, the decrease in the output density exceeds 30 W / kg.
This is because when the area ratio of the buttocks (22) is 2% or less, the strength of the buttocks (22) is low and the gripping force on the winding electrode body (4) is insufficient, so that a large vibration is applied. This is probably because the collar portion (22) was deformed, and as a result, the winding electrode body (4) was subjected to vibration and collapsed.
[0037]
In addition, the battery with an area ratio of the buttock (22) of 30% or less has a power density of 500 W / kg or more before the vibration test, whereas the battery with an area ratio of the buttock (22) of 40% or more. The power density before the vibration test is 500 W / kg or less.
This is because, when the area ratio of the collar portion (22) is 40% or more, the collar portion (22) of the cylindrical insulator (2) hinders the injection when the electrolyte is injected during battery assembly. This is probably because the entire electrode assembly (4) could not be uniformly and sufficiently impregnated with the electrolyte, resulting in an increase in the internal resistance of the battery.
[0038]
From the above results, in the lithium ion secondary battery according to the present invention, the recess (14) is formed on the inner peripheral surface (15) of the cylindrical body (11) constituting the battery can (1). The cylindrical insulator (2) is fitted to (14), and the flange portion (22) of the cylindrical insulator (2) has an area ratio with respect to the current collector plate (32) in the range of 3% to 30%. It can be said that setting is desirable.
[Brief description of the drawings]
FIG. 1 is a partially broken front view of a cylindrical lithium ion secondary battery according to the present invention.
FIG. 2 is a diagram for explaining dimensions of each part of the secondary battery.
FIG. 3 is a partially developed perspective view of a take-up electrode body provided in the secondary battery.
FIG. 4 is a partially cutaway front view of a conventional cylindrical lithium ion secondary battery.
[Explanation of symbols]
(1) Battery can
(11) Tube
(12) Lid
(14) Concave
(15) Inner peripheral surface
(2) Cylindrical insulator
(21) Tube section
(22) Buttocks
(4) Winding electrode body
(32) Current collector
(33) Lead member
(9) Electrode terminal mechanism

Claims

In the cylindrical battery in which the electric power generated by the take-up electrode body (4) accommodated in the cylindrical battery can (1) can be taken out from the pair of electrode terminal portions, the battery can (1) is provided inside the battery can (1). Is provided with a cylindrical insulator (2) fitted to the inner peripheral surface of the battery can ( 1 ) at at least one end, and the inner peripheral surface of the cylindrical insulator (2) is wound up. A cylindrical battery characterized in that a flange (22) covering the end face of the electrode body (4) is provided in a protruding manner.

The cylindrical battery according to claim 1, wherein the flange (22) of the cylindrical insulator (2) is formed in a ring shape.

A concave portion (14) into which the cylindrical insulator (2) is fitted is formed on the inner peripheral surface (15) of the battery can (1), and the cylindrical insulator (2) is held in the concave portion (14). The cylindrical battery according to claim 1 or claim 2, wherein

The take-up electrode body (4) is formed by laminating a separator (42) between a belt-like positive electrode (41) and a negative electrode (43), respectively. The positive electrode (41) and the negative electrode (43) Is formed by applying an active material to the surface of the belt-shaped core, and the edges (48) (48) of the belt-shaped core of the positive electrode (41) and the negative electrode (43) are formed at both ends of the electrode body (4). ) Projecting, the current collecting plate (32) is joined to each end edge (48), and the collar portion (22) of the cylindrical insulator (2) covers the surface of the current collecting plate (32). The cylindrical battery according to any one of claims 1 to 3.