【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が収容されて、電極缶に設けた一対の電極端子部から巻き取り電極体の発生電力を取り出すことが出来る非水電解液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イオン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イオン二次電池は、図４及び図５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)の両極と両電極端子機構(９)(９)とが、それぞれ複数本の電極タブ(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)には圧力開閉式のガス排出弁(13)が取り付けられている。
【０００３】
巻き取り電極体(２)は、図６に示す様に、それぞれ帯状の正極(21)と負極(23)の間に帯状のセパレータ(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。正極(21)は、アルミニウム箔からなる帯状芯体の両面にリチウム複合酸化物からなる正極活物質(24)を塗布して構成され、負極(23)は、銅箔からなる帯状芯体の両面に炭素材料を含む負極活物質(25)を塗布して構成されている。セパレータ(22)には、非水電解液が含浸されている。
正極(21)及び負極(23)には夫々、複数本の電極タブ(３)の基端部がスポット溶接等によって接合され、先端部は巻き取り電極体(２)から突出している。尚、正極(21)に接合された電極タブ(３)はアルミニウム箔から形成され、負極(23)に接合された電極タブ(３)は銅箔から形成されている。
【０００４】
そして、図５に示す如く、極性が同じ複数本の電極タブ(３)の先端部(31)が１つの電極端子機構(９)に接続されている。尚、図５においては、便宜上、一部の電極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、他の電極タブについては、先端部が電極端子機構(９)に接続されている状態の図示を省略している。
【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。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。
前記複数本の電極タブ(３)の先端部(31)は、電極端子(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。
【０００６】
ところで、リチウムイオン二次電池においては、電池の大型化に伴って、正極及び負極の長さが大きくなるため、上述の如き電極タブによる集電構造では集電性が低く、内部抵抗にばらつきが発生したり、放電容量が低下するなどの問題が生じる。
【０００７】
そこで、正極及び負極の全長に亘って均一な集電性を得るべく、図７に示す如き集電構造が提案されている。該集電構造において、巻き取り電極体(４)は同様に、芯体(45)の表面に正極活物質(44)を塗布してなる正極(41)と、芯体(47)の表面に負極活物質(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)とから構成されるが、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)が抵抗溶接され、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。
【０００８】
しかしながら、図７に示す集電構造を有する非水電解液二次電池においては、巻き取り電極体(４)の正極(41)及び負極(43)を構成する芯体(45)(47)の端縁(48)(48)の面積が小さいため、芯体端縁と集電板(32)の間の接触面積が小さく、これによって電池の内部抵抗が大きくなる問題があった。
又、高出力を得るためには、出来るだけ内部抵抗を低減させることが必要であり、更に、製造コスト削減のためには、生産性に優れた集電構造が必要となる。
【０００９】
そこで、図８に示す様に、平板状本体(63)に複数の折曲部(64)を形成した集電板(62)を用い、該集電板(62)を巻き取り電極体(４)の芯体端縁(48)に押し付けた状態で、該折曲部(64)を芯体端縁(48)に抵抗溶接する集電構造が提案されている(例えば特開平１１−３１４９７号参照)。
【００１０】
又、円板状の集電板に代えて、図９に示す如く複数のスリット(66)が凹設された集電部材(65)を巻き取り電極体(４)の端部に設置し、該集電部材(65)のスリット(66)へ芯体端縁(48)を嵌入せしめた状態で、集電部材(65)の表面にレーザビームを照射して、レーザ溶接を施す集電構造が提案されている(例えば特開平１０−２６１４４１号参照)。
【００１１】
【発明が解決しようとする課題】
ところが、図８の如く折曲部を形成した集電板を抵抗溶接する集電構造においては、リチウムイオン二次電池の如く芯体の厚さが極めて小さい場合、溶接が困難であるばかりでなく、溶接部における電気抵抗が大きく、依然として集電性能が低い問題があった。
【００１２】
又、図９の如く複数のスリットが凹設された集電部材を芯体端縁にレーザ溶接する集電構造では、複雑な形状を有する集電部材が必要となるばかりでなく、集電部材に対する溶接作業が必要であるために生産性に劣る問題があった。
【００１３】
本発明の目的は、従来よりも内部抵抗が低く、然も生産性に優れた集電構造を有する非水電解液二次電池を提供することである。
【００１４】
【課題を解決する為の手段】
本発明に係る非水電解液二次電池は、電池缶(１)の内部に巻き取り電極体(４)を収納して構成される。巻き取り電極体(４)は、それぞれ帯状の正極(41)と負極(43)の間に非水電解液を含むセパレータ(42)を介在させてこれらを渦巻き状に巻き取ったものであり、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る。巻き取り電極体(４)が発生する電力は、一対の電極端子部から外部へ取り出すことが出来る。
ここで、前記一対の電極端子部はそれぞれ、電池缶(１)と同軸上に電池缶(１)を貫通して取り付けられた金属製の電極端子(91)によって構成されている。
又、巻き取り電極体(４)の軸方向の少なくとも一方の端部には、正極(41)或いは負極(43)を構成する芯体に活物質の塗布されていない非塗工部が突出し、該突出部には集電機構が連結され、これによって該突出部が巻き取り電極体(４)の中心軸と同軸上に並ぶ複数のリング状領域(4a)(4b)(4c)に分けられている。
前記集電機構は、最内周のリング状領域の内周面に嵌入する金属製の丸軸部材(97)と、丸軸部材(97)の１本の半径線上に配設されて、隣接するリング状領域の間にそれぞれ介在する１或いは複数枚の金属製のスペーサ片(５)と、前記１本の半径線上に設置されて、最外周のリング状領域の外周面に接合された金属製の押圧片(51)と、押圧片(51)を丸軸部(97)に向かって押圧するための金属製のねじ機構とを具え、前記丸軸部材(97)及びねじ機構がそれぞれ、電池缶(１)内に突出する電極端子(91)の端部に連結されている。
【００１５】
上記本発明のリチウムイオン二次電池においては、ねじ機構を締め付けることによって、押圧片(51)が丸軸部材(97)に向かって駆動される。この結果、最内周のリング状領域は、丸軸部材(97)とスペーサ片(５)によって強く挟圧されて、芯体非塗工面どうしが密着した非塗工芯体束(49)に束ねられる。又、最外周のリング状領域は、押圧片(51)とスペーサ片(５)によって強く挟圧されて、芯体非塗工面どうしが密着した非塗工芯体束(49)に束ねられる。更に、中間のリング状領域は２枚のスペーサ片(５)(５)によって強く挟圧されて、芯体非塗工面どうしが密着した非塗工芯体束(49)に束ねられる。
この様にして、巻き取り電極体(４)の各非塗工芯体束(49)と、集電機構の各構成部材、即ち丸軸部材(97)、スペーサ片(５)及び押圧片(51)とが、互いに広い接触面積で圧着するので、接触面における電気抵抗は極めて小さくなる。
【００１６】
尚、スペーサ片(５)は、丸軸部材(97)及び押圧片(51)から独立しており、丸軸部材(97)と押圧片(51)の間で自由に移動可能であるため、各非塗工芯体束(49)に均等な挟圧力を与えることが出来る。又、巻き取り電極体(４)の芯体非塗工部は、スペーサ片(５)の介在によって、局所的に大きな変形を生じることはなく、この結果、活物質塗布層の剥離を防止することが出来る。
【００１７】
巻き取り電極体(４)が発生する電流は、前記集電機構によって集電された後、丸軸部材(97)から電極端子(91)へ流れるルートと、押圧片(51)及びねじ機構から電極端子(91)へ流れるルートを経て、外部へ取り出される。ここで、巻き取り電極体(４)と集電機構の間の電気抵抗は小さいので、高い出力密度が得られる。又、上述の２つの電流取り出しルートが形成されるので、大電流での出力が可能である。
【００１８】
具体的には、前記巻き取り電極体(４)の各リング状領域(4a)(4b)(4c)は、それらの領域を展開したときの長さが略同一となる様に分割されている。
該具体的構成によれば、集電機構によって、巻き取り電極体(４)から均一に集電が行なわれるので、高い集電性能が得られる。
【００１９】
更に具体的な構成において、スペーサ片(５)及び押圧片(51)はそれぞれ、丸軸部材(97)と同心の円弧線に沿う形状に形成されている。これによって、スペーサ片(５)及びスペーサ片(５)と非塗工芯体束(49)との間の密着面積が大きくなり、更に電気抵抗が小さくなる。
【００２０】
尚、正極側の集電機構の各構成部材(丸軸部材(97)、スペーサ片(５)、押圧片(51)、ねじ機構)は、アルミニウム、ステンレス鋼、ニッケル等を用いて作製することが出来る。又、負極側の集電機構の各構成部材は、銅、ステンレス鋼、ニッケル等を用いて作製することが出来る。
巻き取り電極体(４)を構成する正極活物質としては、金属酸化物であるＬｉＣｏＯ２、ＬｉＮｉＯ２、ＬｉＣｏ１−ＸＮｉＸＯ２、ＬｉＭｎ２Ｏ４及びこれらの複合化合物からなる群から選択される、少なくとも一種の材料を用いることが出来る。負極活物質としては、黒鉛、コークス等の炭素材料、リチウム金属、リチウム合金、ＬｉＸＦｅ２Ｏ３、ＬｉＸＷＯ２等の金属酸化物材料や、ポリアセチレン等の導電性高分子材料を用いることが出来る。
電解質としては、リチウムイオンなどの金属イオンを含むＬｉＰＦ６、ＬｉＣｌＯ４、ＬｉＣＦ３ＳＯ３等が挙げられる。また、電解質の有機溶媒には、エチレンカーボネート、ジエチルカーボネート、ジメトキシメタン、スルホラン等を単独或いは混合して用いることが出来る。電解液としては、これら溶媒に前記電解質を０.７〜１.５Ｍ(ｍｏｌ／ｌ)程度の割合で溶解した溶液が挙げられる。
【００２１】
【発明の効果】
本発明に係る非水電解液二次電池において、集電機構を構成するスペーサ片(５)及び押圧片(51)は、例えば金属板をプレス加工することによって、容易に作製することが出来、ねじ機構は、ねじ軸を用いて容易に作製することが出来る。又、集電機構の取付けは、ねじ込み作業だけで行なうことが出来、溶接等は不要であるため、取付け工程は簡易であり、これによって、従来よりも高い生産性が実現される。然も、巻き取り電極体と集電機構の間の電気抵抗を小さく抑えることが出来るので、集電効率が改善されて、従来よりも高い出力密度が得られる。
【００２２】
【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。
本発明に係る円筒型リチウムイオン二次電池は、図４及び図１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(４)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(４)の両極と両電極端子機構(９)(９)とが、それぞれ後述する集電構造により互いに接続されて、巻き取り電極体(４)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)には圧力開閉式のガス排出弁(13)が取り付けられている。
【００２３】
巻き取り電極体(４)は、図２に示す様に、それぞれ帯状の正極(41)と負極(43)の間に帯状のセパレータ(42)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。正極(41)は、アルミニウム箔からなる帯状芯体(45)の両面にリチウム複合酸化物からなる正極活物質(44)を塗布して構成され、負極(43)は、銅箔からなる帯状芯体(47)の両面に炭素材料を含む負極活物質(46)を塗布して構成されている。セパレータ(42)には、非水電解液が含浸されている。
又、正極(41)の一方の端部には、正極活物質(44)の塗布されていない芯体非塗工部が形成され、負極(43)の他方の端部には、負極活物質(46)の塗布されていない芯体非塗工部が形成されている。
【００２４】
巻き取り電極体(４)の作製において、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)の芯体非塗工部の端縁(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)の芯体非塗工部の端縁(48)が突出している。
【００２５】
巻き取り電極体(４)の正極側及び負極側の端部にはそれぞれ、図３に示す集電機構が取り付けられ、該集電機構が図１に示す電極端子機構(９)に連結されている。
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(90)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。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。
【００２６】
電極端子(91)の下端部には、図３に示す如く鍔部(90)に、円筒状の丸軸部材(97)が突設されている。又、鍔部(90)の外周面には、左右一対のアーム(６)(６)が突設され、各アーム(６)の先端部には、垂直板部(61)が下向きに突設されている。そして、各垂直板部(61)にねじ軸(52)が螺合し、該ねじ軸(52)の先端部には、丸軸部材(97)の外周面に対向して、押圧片(51)が取り付けられている。更に、両押圧片(51)と丸軸部材(97)の間にはそれぞれ、２枚のスペーサ片(５)(５)が配置されている。ここで、スペーサ片(５)及び押圧片(51)は、丸軸部材(97)と同心の円弧線に沿う円弧状に形成されている。
【００２７】
尚、正極側の丸軸部材(97)、アーム(６)、ねじ軸(52)、押圧片(51)及びスペーサ片(５)はそれぞれアルミニウム製であり、負極側の丸軸部材(97)、アーム(６)、ねじ軸(52)、押圧片(51)及びスペーサ片(５)はそれぞれ銅製である。
【００２８】
図１に示す如く、巻き取り電極体(４)の各端部に突出する芯体非塗工部は、巻き取り電極体(４)の半径方向に並ぶ３つのリング状領域(4a)(4b)(4c)に分けられて、最内周のリング状領域(4c)の内周面には丸軸部材(97)が嵌入し、最外周のリング状領域(4a)の外周面には、１８０度の角度差で一対の押圧片(51)(51)が接合されている。又、最内周のリング状領域(4c)と中間のリング状領域(4b)の間、並びに最外周のリング状領域(4a)と中間のリング状領域(4b)の間にはそれぞれ、１８０度の角度差で２枚のスペーサ片(５)(５)が介在している。これによって、巻き取り電極体(４)の直径線上に並ぶ６つの非塗工芯体束(49)〜(49)が形成されている。
尚、巻き取り電極体(４)の３つのリング状領域(4a)(4b)(4c)は、これらの領域を展開したときの長さ、即ち活物質塗布層の面積が略同一となる様に分けられている。
【００２９】
図３に示す集電機構の取付けにおいては、先ず、巻き取り電極体(４)の端部に４枚のスペーサ片(５)〜(５)を挿入すると共に、巻き取り電極体(４)の中央孔へ丸軸部材(97)を嵌入せしめた後、両ねじ軸(52)(52)を締め付ける。これによって、各押圧片(51)が丸軸部材(97)に向かって駆動される。
この結果、図１に示す最内周のリング状領域(4c)は、丸軸部材(97)とスペーサ片(５)によって強く挟圧されて、芯体非塗工面どうしが密着した非塗工芯体束(49)に束ねられる。又、最外周のリング状領域(4a)は、押圧片(51)とスペーサ片(５)によって強く挟圧されて、芯体非塗工面どうしが密着した非塗工芯体束(49)に束ねられる。更に、中間のリング状領域(4b)は２枚のスペーサ片(５)(５)によって強く挟圧されて、芯体非塗工面どうしが密着した非塗工芯体束(49)に束ねられる。
【００３０】
この様にして、巻き取り電極体(４)の各非塗工芯体束(49)の両面に、集電機構の各構成部材、即ち丸軸部材(97)、スペーサ片(５)及び押圧片(51)が圧着されて、集電機構の固定が行なわれる。
該集電構造においては、巻き取り電極体(４)と集電機構とが広い接触面積で互いに圧着するので、接触面での電気抵抗は極めて小さなものとなる。
【００３１】
上記円筒型リチウムイオン二次電池において、巻き取り電極体(４)が発生する電流は、丸軸部材(97)を経て電極端子(91)へ至るルートと、押圧片(51)、ねじ軸(52)及びアーム(６)を経て電極端子(91)へ至るルートを流れて、外部へ取り出される。ここで、巻き取り電極体(４)と集電機構の間の電気抵抗は小さいので、高い出力密度が得られる。又、上述の２つの電流取り出しルートが形成されるので、大電流での出力が可能である。
更に、集電機構を構成するスペーサ片(５)、押圧片(51)及びアーム(６)は、例えば金属板をプレス加工することによって、容易に作製することが出来、集電機構の取付けは、ねじ軸(52)をねじ込みだけで行なうことが出来るので、従来よりも高い生産性が実現される。
【００３２】
【実施例】
次の様にして、図１に示す実施例電池Ａと図５に示す比較例電池Ｂとを作製し、性能を比較した。
【００３３】
実施例電池Ａの作製
(正極の作製)
正極活物質としてのＬｉＮｉ０ . ７Ｃｏ０ . ３Ｏ２は、リチウムの水酸化物とニッケルの水酸化物とコバルトの水酸化物とを混合し、８００℃の空気中で２４時間の焼成を施すことにより得た。この正極活物質と導電剤としての炭素を重量比９０：５の割合で混合し、正極合剤を得た。次に、結着剤であるポリフッ化ビニリデンをＮ−メチル−２−ピロリドン(ＮＭＰ)に溶解させて、ＮＭＰ溶液を調製した。そして、正極合剤とポリフッ化ビニリデンの重量比が９５：５になるように正極合剤とＮＭＰ溶液を混練して、スラリーを調製した。このスラリーを、正極芯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、正極を得た。尚、正極芯体には、芯体端縁からの幅が２０ｍｍの非塗工部を形成した。
【００３４】
(負極の作製)
炭素塊(ｄ００２＝３.３５６Å；Ｌｃ＞１０００Å)に空気流を噴射して粉砕し、これをふるいにかけて、平均粒子径１８μｍの黒鉛粉末を得た。次に、コークス塊に空気流を噴射して粉砕し、これをふるいにかけて、平均粒子径１８μｍのコークス粉末を得た。又、結着剤であるポリフッ化ビニリデンをＮＭＰに溶解させて、ＮＭＰ溶液を調製した。そして、黒鉛粉末とコークス粉末とポリフッ化ビニリデンの重量比が７２：１８：１０になる様に黒鉛粉末とコークス粉末とＮＭＰ溶液とを混練して、スラリーを調製した。このスラリーを、負極芯体としての銅箔の両面にドクターブレード法により塗布し、１５０℃で２時間の真空乾燥を施して、負極を得た。尚、負極芯体には、芯体端縁からの幅が２０ｍｍの非塗工部を形成した。
【００３５】
(電池の組立)
以上の工程によって得られた正極及び負極と、イオン透過性のポリエチレン製微多孔膜からなるセパレータとを用いて、図２に示す巻き取り電極体(４)を作製した。そして、巻き取り電極体(４)の両端部にそれぞれ、図１に示す本発明の集電機構と、電極端子機構(９)を構成する電極端子(91)とを取り付けた後、ねじ軸(52)(52)を締め付けた。次に、該巻き取り電極体(４)を筒体(11)の内部に収容し、該筒体(11)の各開口部に蓋体(12)を溶接固定した。最後に電極端子(91)にナット(95)(96)を螺合せしめて、実施例電池Ａを組み立てた。
【００３６】
比較例電池Ｂの作製
正極及び負極の作製工程で、非塗工部を設けることなく、芯体にスラリーを全面塗布したこと以外は実施例電池Ａと同様にして、正極及び負極を作製した。
(電池の組立)
図６に示す様に、正極を構成しているアルミニウム箔の表面に１５本のアルミニウム製電極タブを２０ｃｍ間隔で溶接すると共に、負極を構成している銅箔の表面に１５本の銅製電極タブを２０ｃｍ間隔で溶接した。そして、正極と負極の間にイオン透過性のポリエチレン製微多孔膜からなるセパレータを挟んで、これらを渦巻き状に巻回し、巻き取り電極体(２)を作製した。尚、正極及び負極の電極タブの厚さは０.１ｍｍとした。
そして、図５に示す如く、各電極の電極タブ(３)を電極端子機構(９)の鍔部(92)に溶接して、比較例電池Ｂを組み立てた。
尚、実施例電池Ａと比較例電池Ｂの各電極の活物質塗布量は同量とした。
【００３７】
(性能比較実験)
実施例電池Ａ及び比較例電池Ｂについて、巻き取り電極体を筒体に収容する前に、１ｋＨｚにおける交流インピーダンスを測定したところ、下記表１に示す結果が得られた。尚、交流インピーダンスの測定は、正極側、負極側ともに、巻き取り電極体の最外周部に位置する芯体非塗工部と電極端子との間で行なった。
【００３８】
【表１】
【００３９】
表１から明らかな様に、正極側、負極側の何れにおいても、実施例電池Ａのインピーダンスは、比較例電池Ｂのインピーダンスよりも小さくなっており、このことから、本発明の円筒型リチウムイオン二次電池によれば、従来の電池よりも高い出力密度を得ることが出来ると言える。
【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に採用されている集電機構の断面構成及び平面構成を示す図である。
【図２】該二次電池に装備されている巻き取り電極体の一部展開斜視図である。
【図３】本発明の集電機構の分解斜視図である。
【図４】円筒型リチウムイオン二次電池の外観を示す斜視図である。
【図５】従来の円筒型リチウムイオン二次電池に採用されている集電構造を表わす断面図である。
【図６】該二次電池に装備されている巻き取り電極体の一部展開斜視図である。
【図７】従来の他の集電構造を具えた巻き取り電極体の一部展開斜視図である。
【図８】従来の更に他の集電構造を表わす斜視図である。
【図９】従来の更に他の集電構造を表わす斜視図である。
【符号の説明】
(１) 電池缶
(11) 筒体
(12) 蓋体
(４) 巻き取り電極体
(49) 非塗工芯体束
(９) 電極端子機構
(97) 丸軸部材
(５) スペーサ片
(51) 押圧片
(52) ねじ軸
(６) アーム[0001]
BACKGROUND OF THE INVENTION
The present invention is a non-aqueous electrolysis in which a wound electrode body serving as a secondary battery element is accommodated inside a battery can, and power generated by the wound electrode body can be taken out from a pair of electrode terminal portions provided on the electrode can. The present invention relates to a liquid secondary battery.
[0002]
[Prior art]
In recent years, lithium ion secondary batteries with high energy density have attracted attention as power sources for portable electronic devices and electric vehicles. For example, in a relatively large capacity cylindrical lithium ion secondary battery used in an electric vehicle, as shown in FIGS. 4 and 5, lids (12) and (12) are fixed by welding to both ends of the cylinder (11). A winding electrode body (2) is accommodated in a cylindrical battery can (1). A pair of positive and negative electrode terminal mechanisms (9), (9) is attached to the lids (12), (12), and both electrodes of the winding electrode body (2) and the electrode terminal mechanisms (9), (9) Are connected to each other by a plurality of electrode tabs (3), and the electric power generated by the take-up electrode body (2) can be taken out from the pair of electrode terminal mechanisms (9) and (9). ing. Each lid (12) is provided with a pressure open / close gas discharge valve (13).
[0003]
As shown in FIG. 6, the take-up electrode body (2) is formed by interposing a strip-shaped separator (22) between a strip-shaped positive electrode (21) and a negative electrode (23), and winding them in a spiral shape. It is configured. The positive electrode (21) is configured by applying a positive electrode active material (24) made of a lithium composite oxide on both surfaces of a strip-shaped core made of aluminum foil, and the negative electrode (23) is formed on both surfaces of the strip-shaped core made of copper foil. A negative electrode active material (25) containing a carbon material is applied to the substrate. The separator (22) is impregnated with a non-aqueous electrolyte.
Each of the positive electrode (21) and the negative electrode (23) has a base end portion of a plurality of electrode tabs (3) joined by spot welding or the like, and a distal end portion protruding from the take-up electrode body (2). The electrode tab (3) joined to the positive electrode (21) is made of aluminum foil, and the electrode tab (3) joined to the negative electrode (23) is made of copper foil.
[0004]
And as shown in FIG. 5, the front-end | tip part (31) of the several electrode tab (3) with the same polarity is connected to one electrode terminal mechanism (9). In FIG. 5, for the sake of convenience, only the state where the tip portions of some of the electrode tabs are connected to the electrode terminal mechanism (9) is shown, and the tip portions of the other electrode tabs are connected to the electrode terminal mechanism (9). Illustration of the state of being connected to is omitted.
[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 fastening member (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 portions (31) of the plurality of electrode tabs (3) are fixed to the flange portion (92) of the electrode terminal (91) by spot welding or ultrasonic welding.
[0006]
By the way, in a lithium ion secondary battery, since the length of a positive electrode and a negative electrode becomes large with the enlargement of a battery, in the current collection structure by an electrode tab as mentioned above, current collection property is low and internal resistance varies. This causes problems such as generation and discharge capacity reduction.
[0007]
Therefore, a current collecting structure as shown in FIG. 7 has been proposed in order to obtain a uniform current collecting property over the entire length of the positive electrode and the negative electrode. In the current collecting structure, the winding electrode body (4) is similarly formed on the surface of the core body (45) and the positive electrode (41) obtained by applying the positive electrode active material (44) to the surface of the core body (45). A negative electrode (43) formed by applying a negative electrode active material (46) and a separator (42) impregnated with a non-aqueous electrolyte, the positive electrode (41) and the negative electrode (43) are each a separator (42 ) Are overlapped and shifted in the width direction, and wound up 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 resistance-welded to both ends of the wound electrode body (4), and the current collector plate (32) is connected to the electrode terminal mechanism via a lead member (33). Connected to (9).
[0008]
However, in the non-aqueous electrolyte secondary battery having the current collecting structure shown in FIG. 7, the cores (45) and (47) constituting the positive electrode (41) and the negative electrode (43) of the winding electrode body (4). Since the areas of the edges (48) and (48) are small, there is a problem that the contact area between the edge of the core body and the current collector plate (32) is small, thereby increasing the internal resistance of the battery.
Further, in order to obtain a high output, it is necessary to reduce the internal resistance as much as possible. Further, in order to reduce the manufacturing cost, a current collecting structure with excellent productivity is required.
[0009]
Therefore, as shown in FIG. 8, a current collector plate (62) in which a plurality of bent portions (64) are formed on a flat plate-like body (63) is used, and the current collector plate (62) is taken up as a winding electrode body (4 A current collecting structure has been proposed in which the bent portion (64) is resistance-welded to the core end edge (48) in a state of being pressed against the core end edge (48) (see, for example, JP-A-11-31497). reference).
[0010]
Further, in place of the disk-shaped current collector plate, a current collecting member (65) having a plurality of slits (66) recessed as shown in FIG. 9 is installed at the end of the winding electrode body (4). A current collecting structure for performing laser welding by irradiating the surface of the current collecting member (65) with a laser beam in a state where the core end edge (48) is fitted into the slit (66) of the current collecting member (65). Has been proposed (see, for example, JP-A-10-261441).
[0011]
[Problems to be solved by the invention]
However, in the current collecting structure in which the current collector plate having the bent portion as shown in FIG. 8 is resistance-welded, when the thickness of the core is extremely small as in the lithium ion secondary battery, welding is not only difficult. There is a problem that the electric resistance in the welded portion is large and the current collecting performance is still low.
[0012]
In the current collecting structure in which a current collecting member having a plurality of slits recessed as shown in FIG. 9 is laser-welded to the edge of the core body, not only a current collecting member having a complicated shape is required but also the current collecting member. There is a problem that productivity is inferior because welding work is required.
[0013]
An object of the present invention is to provide a non-aqueous electrolyte secondary battery having a current collecting structure having lower internal resistance than that of the prior art and excellent in productivity.
[0014]
[Means for solving the problems]
The non-aqueous electrolyte secondary battery according to the present invention is configured by accommodating a wound electrode body (4) inside a battery can (1). The take-up electrode body (4) is formed by winding a separator (42) containing a non-aqueous electrolyte between a strip-like positive electrode (41) and a negative electrode (43), respectively, Each of the positive electrode (41) and the negative electrode (43) is configured by applying an active material to the surface of the belt-like core. The electric power generated by the winding electrode body (4) can be taken out from the pair of electrode terminal portions.
Here, each of the pair of electrode terminal portions is constituted by a metal electrode terminal (91) attached through the battery can (1) coaxially with the battery can (1).
Further, at least one end of the winding electrode body (4) in the axial direction protrudes from the core body constituting the positive electrode (41) or the negative electrode (43) where no active material is applied, A current collecting mechanism is connected to the projecting portion, whereby the projecting portion is divided into a plurality of ring-shaped regions (4a) (4b) (4c) arranged coaxially with the central axis of the winding electrode body (4). ing.
The current collecting mechanism is disposed on one radial line of a metal round shaft member (97) and a round shaft member (97) fitted into the inner peripheral surface of the innermost ring-shaped region, and is adjacent to the metal round shaft member (97). One or a plurality of metal spacer pieces (5) respectively interposed between the ring-shaped regions and the metal that is installed on the one radial line and joined to the outer peripheral surface of the outermost ring-shaped region A pressing piece (51) made of metal and a metal screw mechanism for pressing the pressing piece (51) toward the round shaft portion (97), each of the round shaft member (97) and the screw mechanism, It is connected to the end of the electrode terminal (91) protruding into the battery can (1).
[0015]
In the lithium ion secondary battery of the present invention, the pressing piece (51) is driven toward the round shaft member (97) by tightening the screw mechanism. As a result, the innermost ring-shaped region is strongly pinched by the round shaft member (97) and the spacer piece (5), and the non-coated core bundle (49) in which the core non-coated surfaces are in close contact with each other. Bundled. Further, the outermost ring-shaped region is strongly pinched by the pressing piece (51) and the spacer piece (5), and is bundled into the non-coated core bundle (49) in which the core non-coated surfaces are in close contact with each other. Further, the intermediate ring-shaped region is strongly pinched by the two spacer pieces (5) and (5), and is bundled into the non-coated core bundle (49) in which the core non-coated surfaces are in close contact with each other.
In this way, each non-coated core bundle (49) of the winding electrode body (4) and each component of the current collecting mechanism, that is, the round shaft member (97), the spacer piece (5) and the pressing piece ( 51) are bonded to each other with a wide contact area, so that the electrical resistance at the contact surface becomes extremely small.
[0016]
The spacer piece (5) is independent of the round shaft member (97) and the pressing piece (51) and can freely move between the round shaft member (97) and the pressing piece (51). An equal clamping pressure can be applied to each non-coated core bundle (49). Further, the core body non-coating portion of the winding electrode body (4) is not greatly deformed locally by the interposition of the spacer piece (5), and as a result, peeling of the active material coating layer is prevented. I can do it.
[0017]
The current generated by the take-up electrode body (4) is collected from the current collecting mechanism and then flows from the round shaft member (97) to the electrode terminal (91), the pressing piece (51), and the screw mechanism. It is taken out through a route flowing to the electrode terminal (91). Here, since the electrical resistance between the winding electrode body (4) and the current collecting mechanism is small, a high output density can be obtained. Further, since the above-described two current extraction routes are formed, output with a large current is possible.
[0018]
Specifically, the ring-shaped regions (4a), (4b), and (4c) of the winding electrode body (4) are divided so that the lengths when the regions are expanded are substantially the same. .
According to this specific configuration, the current collecting mechanism uniformly collects current from the winding electrode body (4), so that high current collecting performance can be obtained.
[0019]
In a more specific configuration, each of the spacer piece (5) and the pressing piece (51) is formed in a shape along an arc line concentric with the round shaft member (97). Thereby, the contact area between the spacer piece (5) and the spacer piece (5) and the non-coated core bundle (49) is increased, and the electrical resistance is further reduced.
[0020]
Each component (round shaft member (97), spacer piece (5), pressing piece (51), screw mechanism) of the current collecting mechanism on the positive electrode side should be made of aluminum, stainless steel, nickel or the like. I can do it. Further, each component of the current collecting mechanism on the negative electrode side can be manufactured using copper, stainless steel, nickel or the like.
As the positive electrode active material constituting the take-up electrode (4), selected from the group consisting of LiCoO 2, LiNiO 2, LiCo 1 -X Ni X O 2, LiMn 2 O 4 , and their complex compounds are metal oxides At least one material can be used. As the negative electrode active material, carbon materials such as graphite and coke, metal oxide materials such as lithium metal, lithium alloy, Li X Fe 2 O 3 and Li X WO 2 , and conductive polymer materials such as polyacetylene should be used. I can do it.
Examples of the electrolyte include LiPF 6 , LiClO 4 , and LiCF 3 SO 3 containing metal ions such as lithium ions. Moreover, ethylene carbonate, diethyl carbonate, dimethoxymethane, sulfolane, etc. can be used individually or in mixture for the organic solvent of electrolyte. Examples of the electrolytic solution include a solution in which the electrolyte is dissolved in these solvents at a ratio of about 0.7 to 1.5 M (mol / l).
[0021]
【The invention's effect】
In the nonaqueous electrolyte secondary battery according to the present invention, the spacer piece (5) and the pressing piece (51) constituting the current collecting mechanism can be easily manufactured by, for example, pressing a metal plate, The screw mechanism can be easily manufactured using a screw shaft. In addition, the current collecting mechanism can be attached only by screwing work, and welding or the like is not required. Therefore, the attachment process is simple, and thereby higher productivity than the conventional one is realized. However, since the electrical resistance between the winding electrode body and the current collecting mechanism can be kept small, the current collecting efficiency is improved, and a higher power density than the conventional one can be obtained.
[0022]
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.
As shown in FIGS. 4 and 1, a cylindrical lithium ion secondary battery according to the present invention is a cylindrical battery can formed by welding and fixing lids (12) and (12) to both ends of a cylindrical body (11). The winding electrode body (4) is accommodated inside (1). A pair of positive and negative electrode terminal mechanisms (9), (9) is attached to both the lids (12), (12), and both poles of the winding electrode body (4) and both electrode terminal mechanisms (9), (9) Are connected to each other by a current collecting structure to be described later, and the electric power generated by the winding electrode body (4) can be taken out from the pair of electrode terminal mechanisms (9) and (9). Each lid (12) is provided with a pressure open / close gas discharge valve (13).
[0023]
As shown in FIG. 2, the take-up electrode body (4) is formed by interposing a strip-shaped separator (42) between the strip-shaped positive electrode (41) and the negative electrode (43), and winding them in a spiral shape. It is configured. The positive electrode (41) is configured by applying a positive electrode active material (44) made of a lithium composite oxide on both surfaces of a band-shaped core (45) made of an aluminum foil, and the negative electrode (43) is made of a band-shaped core made of a copper foil. The negative electrode active material (46) containing a carbon material is applied to both surfaces of the body (47). The separator (42) is impregnated with a non-aqueous electrolyte.
In addition, a core body non-coated portion not coated with the positive electrode active material (44) is formed at one end of the positive electrode (41), and a negative electrode active material is formed at the other end of the negative electrode (43). An uncoated portion of the core body (46) is formed.
[0024]
In the production of the take-up electrode body (4), the positive electrode (41) and the negative electrode (43) are respectively superimposed on the separator (42) while being shifted in the width direction and wound in a spiral shape. As a result, at one end of both ends in the winding axis direction of the winding electrode body (4), the core uncoated portion of the positive electrode (41) is more outward than the edge of the separator (42). The edge (48) protrudes, and at the other end, the edge (48) of the core-uncoated portion of the negative electrode (43) protrudes outward from the edge of the separator (42).
[0025]
A current collecting mechanism shown in FIG. 3 is attached to each of the positive electrode side and negative electrode side ends of the winding electrode body (4), and the current collecting mechanism is connected to the electrode terminal mechanism (9) shown in FIG. Yes.
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 (90). ) 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 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.
[0026]
At the lower end of the electrode terminal (91), a cylindrical round shaft member (97) projects from the collar (90) as shown in FIG. A pair of left and right arms (6) and (6) project from the outer peripheral surface of the collar (90), and a vertical plate (61) projects downward from the tip of each arm (6). Has been. Then, the screw shaft (52) is screwed into each vertical plate portion (61), and the tip of the screw shaft (52) is opposed to the outer peripheral surface of the round shaft member (97), and the pressing piece (51 ) Is attached. Further, two spacer pieces (5) and (5) are arranged between the pressing pieces (51) and the round shaft member (97), respectively. Here, the spacer piece (5) and the pressing piece (51) are formed in an arc shape along an arc line concentric with the round shaft member (97).
[0027]
In addition, the round shaft member (97), the arm (6), the screw shaft (52), the pressing piece (51), and the spacer piece (5) on the positive electrode side are each made of aluminum, and the round shaft member (97) on the negative electrode side. The arm (6), the screw shaft (52), the pressing piece (51) and the spacer piece (5) are each made of copper.
[0028]
As shown in FIG. 1, the core non-coated portion protruding from each end of the winding electrode body (4) has three ring-shaped regions (4a) (4b) arranged in the radial direction of the winding electrode body (4). ) (4c), the round shaft member (97) is fitted on the inner peripheral surface of the innermost ring-shaped region (4c), and the outer peripheral surface of the outermost ring-shaped region (4a) A pair of pressing pieces (51) and (51) are joined with an angle difference of 180 degrees. In addition, between the innermost ring-shaped region (4c) and the middle ring-shaped region (4b) and between the outermost ring-shaped region (4a) and the middle ring-shaped region (4b), 180 respectively. Two spacer pieces (5) and (5) are interposed with an angle difference of degrees. As a result, six uncoated core bundles (49) to (49) arranged on the diameter line of the winding electrode body (4) are formed.
The three ring-shaped regions (4a), (4b), and (4c) of the wound electrode body (4) are such that the length when these regions are expanded, that is, the area of the active material coating layer is substantially the same. It is divided into.
[0029]
In attaching the current collecting mechanism shown in FIG. 3, first, four spacer pieces (5) to (5) are inserted into the end portion of the winding electrode body (4), and the winding electrode body (4) is mounted. After fitting the round shaft member (97) into the central hole, the screw shafts (52) (52) are tightened. Thereby, each pressing piece (51) is driven toward the round shaft member (97).
As a result, the innermost ring-shaped region (4c) shown in FIG. 1 is strongly pinched by the round shaft member (97) and the spacer piece (5), and the non-coated surface in which the core non-coated surfaces are in close contact with each other. It is bundled in the core bundle (49). In addition, the outermost ring-shaped region (4a) is strongly pinched by the pressing piece (51) and the spacer piece (5), and the non-coated core bundle (49) in which the core non-coated surfaces are in close contact with each other. Bundled. Further, the intermediate ring-shaped region (4b) is strongly pinched by the two spacer pieces (5) and (5), and is bundled into a non-coated core bundle (49) in which the core non-coated surfaces are in close contact with each other. .
[0030]
In this manner, each component of the current collecting mechanism, that is, the round shaft member (97), the spacer piece (5), and the pressing member are formed on both surfaces of each non-coated core bundle (49) of the winding electrode body (4). The piece (51) is crimped to fix the current collecting mechanism.
In the current collecting structure, the winding electrode body (4) and the current collecting mechanism are pressure-bonded to each other with a wide contact area, so that the electrical resistance at the contact surface is extremely small.
[0031]
In the cylindrical lithium ion secondary battery, the current generated by the take-up electrode body (4) includes the route from the round shaft member (97) to the electrode terminal (91), the pressing piece (51), the screw shaft ( 52) and the arm (6) through the route to the electrode terminal (91) to be taken out. Here, since the electrical resistance between the winding electrode body (4) and the current collecting mechanism is small, a high output density can be obtained. Further, since the above-described two current extraction routes are formed, output with a large current is possible.
Furthermore, the spacer piece (5), the pressing piece (51) and the arm (6) constituting the current collecting mechanism can be easily manufactured by, for example, pressing a metal plate. Since the screw shaft (52) can be carried out only by screwing, higher productivity than the conventional one can be realized.
[0032]
【Example】
Example battery A shown in FIG. 1 and comparative example battery B shown in FIG. 5 were produced as follows, and the performances were compared.
[0033]
Example Preparation of Battery A
(Preparation of positive electrode)
LiNi 0. 7 Co 0 as the positive electrode active material. 3 O 2 are mixed and hydroxides and cobalt of lithium hydroxide and nickel, the calcined for 24 hours in a 800 ° C. in air It was obtained by applying. This positive electrode active material and carbon as a conductive agent were mixed at a weight ratio of 90: 5 to obtain 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 were kneaded so that the weight ratio of the positive electrode mixture and polyvinylidene fluoride was 95: 5 to prepare a slurry. This slurry was applied to both surfaces of an aluminum foil as a positive electrode core by a doctor blade method and vacuum dried at 150 ° C. for 2 hours to obtain a positive electrode. In addition, the non-coating part whose width from a core body edge is 20 mm was formed in the positive electrode core.
[0034]
(Preparation of negative electrode)
The carbon mass (d002 = 3.356Å; Lc> 1000Å) was sprayed and pulverized, and sieved to obtain a graphite powder having an average particle size of 18 μm. Next, the coke mass was sprayed and pulverized and sieved to obtain a coke powder having an average particle size of 18 μm. Also, an NMP solution was prepared by dissolving polyvinylidene fluoride as a binder in NMP. And graphite powder, coke powder, and NMP solution were knead | mixed so that the weight ratio of graphite powder, coke powder, and polyvinylidene fluoride might be 72:18:10, and the slurry was prepared. This slurry was applied to both surfaces of a copper foil as a negative electrode core by a doctor blade method, followed by vacuum drying at 150 ° C. for 2 hours to obtain a negative electrode. In addition, the non-coating part whose width from a core body edge is 20 mm was formed in the negative electrode core.
[0035]
(Battery assembly)
A take-up electrode body (4) shown in FIG. 2 was produced using the positive electrode and negative electrode obtained by the above steps and a separator made of an ion-permeable polyethylene microporous membrane. And after attaching the current collection mechanism of this invention shown in FIG. 1 and the electrode terminal (91) which comprises an electrode terminal mechanism (9) to the both ends of a winding electrode body (4), respectively, after attaching a screw shaft ( 52) (52) was tightened. Next, the winding electrode body (4) was accommodated inside the cylinder body (11), and the lid body (12) was welded and fixed to each opening of the cylinder body (11). Finally, nuts (95) and (96) were screwed onto the electrode terminal (91) to assemble Example Battery A.
[0036]
Production of comparative battery B In the production process of the positive electrode and the negative electrode, the positive electrode and the negative electrode were prepared in the same manner as in the battery A, except that the slurry was applied to the entire core without providing an uncoated portion. Was made.
(Battery assembly)
As shown in FIG. 6, 15 aluminum electrode tabs are welded to the surface of the aluminum foil constituting the positive electrode at intervals of 20 cm, and 15 copper electrode tabs are attached to the surface of the copper foil constituting the negative electrode. Were welded at 20 cm intervals. And the separator which consists of an ion-permeable polyethylene microporous film was pinched | interposed between the positive electrode and the negative electrode, these were wound in the shape of a spiral, and the winding electrode body (2) was produced. In addition, the thickness of the electrode tab of a positive electrode and a negative electrode was 0.1 mm.
And as shown in FIG. 5, the electrode tab (3) of each electrode was welded to the collar part (92) of the electrode terminal mechanism (9), and the comparative battery B was assembled.
In addition, the active material application amount of each electrode of Example battery A and Comparative example battery B was the same amount.
[0037]
(Performance comparison experiment)
About Example battery A and comparative example battery B, before accommodating a winding electrode body in a cylinder, when the alternating current impedance in 1 kHz was measured, the result shown in following Table 1 was obtained. In addition, the measurement of alternating current impedance was performed between the core body non-coating part and electrode terminal which are located in the outermost periphery part of a winding electrode body in the positive electrode side and the negative electrode side.
[0038]
[Table 1]
[0039]
As is clear from Table 1, the impedance of Example Battery A is smaller than that of Comparative Battery B on both the positive electrode side and the negative electrode side. From this, the cylindrical lithium ion of the present invention According to the secondary battery, it can be said that a higher output density than that of the conventional battery can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing a cross-sectional configuration and a planar configuration of a current collecting mechanism employed in a cylindrical lithium ion secondary battery according to the present invention.
FIG. 2 is a partially developed perspective view of a take-up electrode body provided in the secondary battery.
FIG. 3 is an exploded perspective view of the current collecting mechanism of the present invention.
FIG. 4 is a perspective view showing an appearance of a cylindrical lithium ion secondary battery.
FIG. 5 is a cross-sectional view showing a current collecting structure employed in a conventional cylindrical lithium ion secondary battery.
FIG. 6 is a partially developed perspective view of a take-up electrode body provided in the secondary battery.
FIG. 7 is a partially developed perspective view of a take-up electrode body having another conventional current collecting structure.
FIG. 8 is a perspective view showing still another conventional current collecting structure.
FIG. 9 is a perspective view showing still another conventional current collecting structure.
[Explanation of symbols]
(1) Battery can
(11) Tube
(12) Lid
(4) Winding electrode body
(49) Uncoated core bundle
(9) Electrode terminal mechanism
(97) Round shaft member
(5) Spacer piece
(51) Pressing piece
(52) Screw shaft
(6) Arm
