JP3769377B2 - Cylindrical lithium secondary battery - Google Patents

Cylindrical lithium secondary battery Download PDF

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JP3769377B2
JP3769377B2 JP04485398A JP4485398A JP3769377B2 JP 3769377 B2 JP3769377 B2 JP 3769377B2 JP 04485398 A JP04485398 A JP 04485398A JP 4485398 A JP4485398 A JP 4485398A JP 3769377 B2 JP3769377 B2 JP 3769377B2
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negative electrode
positive electrode
current collecting
lithium secondary
collecting tab
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JPH11250934A (en
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一成 大北
丈志 前田
義人 近野
育郎 米津
俊之 能間
晃治 西尾
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Sanyo Electric Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Description

【０００１】
【発明の属する技術分野】
この発明は円筒型リチウム二次電池に係り、特に、正極と負極との間に非水電解液が含浸されたセパレータを介在させて渦巻き状に巻回した電極体を電池缶内に収容させ、正極より延出された正極集電タブを正極端子に取り付けると共に、負極より延出された負極集電タブを負極端子に取り付けるようにした円筒型リチウム二次電池において、正極集電タブと正極端子との間における接触抵抗や、負極集電タブと負極端子との間における接触抵抗を低減させて、高電圧で高容量の円筒型リチウム二次電池が得られるようにした点に特徴を有するものである。
【０００２】
【従来の技術】
近年、クリーンなエネルギを有効に利用する等の要求から二次電池が様々な分野で利用されるようになり、特に、高出力，高エネルギー密度の新型電池としてリチウム二次電池が注目されている。
【０００３】
さらに、近年においては、このようなリチウム二次電池を電気自動車の電源や家庭用のロードレベリング等に利用するために、このリチウム二次電池を大型化させて、その容量を増加させたものが開発された。
【０００４】
ここで、このようなリチウム二次電池としては、一般に、正極と負極との間に非水電解液が含浸されたセパレータを介在させて渦巻き状に巻回された電極体を円筒型の電池缶内に収容させた円筒型リチウム二次電池が利用されていた。
【０００５】
また、このような円筒型リチウム二次電池においては、正極や負極における電気エネルギーを正極端子と負極端子とから取り出すために、正極に正極集電タブを設けて、この正極集電タブを正極端子に取り付けると共に、負極に負極集電タブを設け、この負極集電タブを負極端子に取り付けるようにしていた。
【０００６】
ここで、上記のようにリチウム二次電池を大型化させて、その容量を向上させるようにした場合、正極に設ける正極集電タブや、負極に設ける負極集電タブの数が少ないと、このリチウム二次電池における電池抵抗が増大して、電池性能が低下するという問題があった。
【０００７】
このため、従来においては、上記のような円筒型リチウム二次電池において、正極や負極に設ける正極集電タブや負極集電タブの数を多くしており、またこのような正極集電タブや負極集電タブをそれぞれ正極端子や負極端子に取り付けるにあたっては、一般に正極端子や負極端子に設けられた取付部分にネジによる締め付け等で固定させるようにしていた。
【０００８】
しかし、このように正極集電タブや負極集電タブを正極端子や負極端子に設けられた取付部分に固定させる場合、これらの取付部分と正極集電タブや負極集電タブの密着性が十分ではなく、これらの取付部分における接触抵抗が高くなり、このリチウム二次電池における電池電圧や電池容量が低下するという問題があった。
【０００９】
【発明が解決しようとする課題】
この発明は、正極と負極との間に非水電解液が含浸されたセパレータを介在させて渦巻き状に巻回させた電極体を電池缶内に収容させ、正極より延出された正極集電タブを正極端子に取り付けると共に、負極より延出された負極集電タブを負極端子に取り付けるようにした円筒型リチウム二次電池における上記のような問題を解決することを課題とするものである。
【００１０】
すなわち、この発明は、上記のような円筒型リチウム二次電池において、正極より延出された正極集電タブや、負極より延出された負極集電タブを、正極端子や負極端子に取り付けるにあたり、正極集電タブと正極端子との間の密着性や、負極集電タブと負極端子との間の密着性を向上させて、正極集電タブと正極端子との間における接触抵抗や、負極集電タブと負極端子との間における接触抵抗を低減させて、電池電圧や電池容量が低下するのを抑制し、高電圧で高容量の円筒型リチウム二次電池が得られるようにすることを課題とするものである。
【００１１】
【課題を解決するための手段】
この発明における円筒型リチウム二次電池においては、上記のような課題を解決するため、リチウム複合酸化物を含む正極と、炭素材料を含む負極との間に非水電解液が含浸されたセパレータを介在させて渦巻き状に巻回した電極体を電池缶内に収容させ、上記の正極より延出された正極集電タブを正極端子に取り付けると共に、負極より延出された負極集電タブを負極端子に取り付けた円筒型リチウム二次電池において、上記の正極集電タブと負極集電タブの少なくとも一方の表面に金の薄膜を形成すると共に、上記の正極集電タブをアルミニウム材料で構成し、或いは上記の負極集電タブをニッケル材料で構成するようにしたのである。
【００１２】
ここで、この発明における円筒型リチウム二次電池のように、正極端子に取り付ける正極集電タブの表面や、負極端子に取り付ける負極集電タブの表面に金の薄膜を形成すると、この金の薄膜によって正極集電タブと正極端子との間における密着性や、負極集電タブと負極端子との間における密着性が高くなり、正極集電タブと正極端子との間における接触抵抗や、負極集電タブと負極端子との間における接触抵抗が減少して、この円筒型リチウム二次電池の内部抵抗が低くなって電池電圧や電池容量が低下するのが抑制され、高電圧で高容量の円筒型リチウム二次電池が得られるようになる。
【００１３】
ここで、正極に使用するリチウム複合酸化物としては、リチウム二次電池において一般に使用されている公知のものを用いることができ、例えば、マンガン，コバルト，ニッケル，鉄，バナジウム，ニオブの少なくとも一種を含むリチウム遷移金属複合酸化物等を使用することができる。
【００１４】
また、負極に使用する炭素材料としても、リチウム二次電池に一般に使用されている公知の炭素材料を用いることができ、例えば、リチウムイオンを吸蔵，放出することができる天然黒鉛，人造黒鉛，コークス，有機物焼成体等を用いることができる。
【００１５】
さらに、非水電解液としても、リチウム二次電池に一般に使用されている公知のものを用いることができ、その溶媒としては、例えば、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネート、ビニレンカーボネート、シクロペンタノン、スルホラン、ジメチルスルホラン、３−メチル−１，３−オキサゾリジン−２−オン、γ−ブチロラクトン、ジメチルカーボネート、ジエチルカーボネート、エチルメチルカーボネート、メチルプロピルカーボネート、ブチルメチルカーボネート、エチルプロピルカーボネート、ブチルエチルカーボネート、ジプロピルカーボネート、１，２−ジメトキシエタン、テトラヒドロフラン、２−メチルテトラヒドロフラン、１，３−ジオキソラン、酢酸メチル、酢酸エチル等の有機溶媒を１種又は２種以上組み合わせて使用することができる。
【００１６】
また、非水電解液に添加させる溶質としても、公知のものを使用することができ、例えば、トリフルオロメタンスルホン酸リチウムＬｉＣＦ3 ＳＯ3 ，ヘキサフルオロリン酸リチウムＬｉＰＦ6 ，過塩素酸リチウムＬｉＣｌＯ4 ，テトラフルオロホウ酸リチウムＬｉＢＦ4 ，トリフルオロメタンスルホン酸イミドリチウムＬｉＮ（ＣＦ3 ＳＯ2 ）2 等のリチウム化合物を用いることができる。
【００１８】
そして、上記のような正極集電タブや負極集電タブの表面に金の薄膜を形成するにあたっては、一般にメッキ法が用いられるが、蒸着法等のその他の公知の方法を使用することもできる。
【００１９】
また、上記のように正極集電タブや負極集電タブに金の薄膜を形成するにあたり、その膜厚が薄いと、正極集電タブと正極端子との間や、負極集電タブと負極端子との間における密着性が悪くなって、正極集電タブと正極端子との間における接触抵抗や、負極集電タブと負極端子との間における接触抵抗が高くなる一方、その膜厚が厚くなりすぎると、コストが高く付く等の問題があるため、この金の薄膜における膜厚を１〜１０μｍの範囲にすることが好ましい。
【００２０】
【実施例】
以下、この発明に係る円筒型リチウム二次電池について実施例を挙げて具体的に説明すると共に、この実施例における円筒型リチウム二次電池においては、正極集電タブと正極端子との間や、負極集電タブと負極端子との間における接触抵抗が低減されて、電池電圧の高い電池が得られるようになることを比較例を挙げて明らかにする。なお、この発明における円筒型リチウム二次電池は、下記の実施例に示したものに限定されものではなく、その要旨を変更しない範囲において適宜変更して実施できるものである。
【００２１】
（実施例１〜３及び比較例１）
これらの実施例１〜３及び比較例１においては、下記のようにして作製した正極と負極とを用いると共に、下記のようにして調製した非水電解液を用い、直径が６４ｍｍ、長さが２９４ｍｍの円筒状で、電池容量が７０Ａｈになった図１に示すような円筒型リチウム二次電池１０を得るようにした。
【００２２】
［正極の作製］
正極を作製するにあたっては、正極材料としてＬｉＣｏＯ2 を用い、この正極材料ＬｉＣｏＯ2 と導電剤である炭素とが９０：５の重量比になるように混合して正極合剤を調製した。そして、この正極合剤に、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（以下、ＮＭＰと略す。）に溶解させた溶液を加え、上記の正極合剤とポリフッ化ビニリデンとが９５：５の重量比になるようにし、これらを混練してスラリーを調製し、このスラリーをアルミニウム箔からなる正極集電体の両面にドクターブレード法により塗布し、これを１５０℃で２時間真空乾燥させて、シート状になった正極を作製した。
【００２３】
［負極の作製］
負極を作製するにあたっては、負極材料に平均粒径が１０μｍの黒鉛粉末を用い、この黒鉛粉末に、結着剤であるポリフッ化ビニリデンを上記のＮＭＰに溶解させた溶液を加え、黒鉛粉末とポリフッ化ビニリデンとが８５：１５の重量比になるようにし、これらを混練してスラリーを調製し、このスラリーを負極集電体である銅箔の両面にドクターブレード法により塗布し、これを１５０℃で２時間真空乾燥させてシート状になった負極を作製した。
【００２４】
［非水電解液の調製］
非水電解液を調製するにあたっては、エチレンカーボネートとジエチルカーボネートとを１：１の体積比で混合させた混合溶媒に、溶質としてヘキサフルオロリン酸リチウムＬｉＰＦ6 を１ｍｏｌ／ｌの割合で溶解させた。
【００２５】
［電池の作製］
電池を作製するにあたっては、図２及び図３に示すように、に示すように、上記のようにして作製した正極１１に複数の正極集電タブ１１ａを正極１１から延出するようにして取り付けると共に、負極１２に複数の負極集電タブ１２ａを負極１２から延出するようにして取り付け、この正極１１と負極１２との間に、ポリエチレン製のイオン透過性微多孔膜からなるセパレータ１３を介在させてスパイラル状に巻き取り、このように巻き取った電極体１４を円筒状の電池缶１５内に収容させるようにした。
【００２６】
そして、図３及び図４に示すように、上記の電池缶１５の一端を閉塞させる正極蓋１６に設けられた正極端子１６ａに一対の挟持板１６ｂ，１６ｃを設け、この一対の挟持板１６ｂ，１６ｃ間に、正極１１に設けた上記の各正極集電タブ１１ａを挟み込むようにして取り付けると共に、電池缶１５の他端を閉塞させる負極蓋１７に設けられた負極端子１７ａにも一対の挟持板１７ｂ，１７ｃを設け、この一対の挟持板１７ｂ，１７ｃ間に、負極１２に設けられた上記の各負極集電タブ１２ａを挟み込むようにして取り付けた後、図１に示すように、この電池缶１５の両端に上記の正極蓋１６と負極蓋１７とを取り付けて、この正極蓋１６と負極蓋１７とにより電池缶１５の両端を閉塞させ、その後、安全弁１８を取り付ける孔からこの電池缶１５内に上記の非水電解液を注液させて、上記の円筒型のリチウム二次電池１０を得た。また、上記の正極蓋１６と負極蓋１７にはそれぞれ安全弁１８を設けるようにした。
【００２７】
ここで、上記の正極集電タブ１１ａや負極集電タブ１２ａとして、実施例１の円筒型リチウム二次電池１０においては、幅が１５ｍｍ，厚みが１００μｍになったアルミニウム製の正極集電タブ１１ａを用いる一方、幅が１５ｍｍ，厚みが１００μｍになったニッケル製の負極集電タブ１２ａの表面に膜厚が５μｍになった金の薄膜が形成されたものを用いるようにした。
【００２８】
また、実施例２の円筒型リチウム二次電池１０においては、幅が１５ｍｍ，厚みが１００μｍになったアルミニウム製の正極集電タブ１１ａの表面に膜厚が５μｍになった金の薄膜が形成されたものを用いる一方、幅が１５ｍｍ，厚みが１００μｍになったニッケル製の負極集電タブ１２ａを用いるようにした。
【００２９】
また、実施例３の円筒型リチウム二次電池１０においては、幅が１５ｍｍ，厚みが１００μｍになったアルミニウム製の正極集電タブ１１ａの表面に膜厚が５μｍになった金の薄膜が形成されたものを用いると共に、幅が１５ｍｍ，厚みが１００μｍになったニッケル製の負極集電タブ１２ａの表面に膜厚が５μｍになった金の薄膜が形成されたものを用いるようにした。
【００３０】
一方、比較例１の円筒型リチウム二次電池１０においては、幅が１５ｍｍ，厚みが１００μｍになったアルミニウム製の正極集電タブ１１ａを用いると共に、幅が１５ｍｍ，厚みが１００μｍになったニッケル製の負極集電タブ１２ａを用いるようにし、正極集電タブ１１ａと負極集電タブ１２ａのいずれの表面にも金の薄膜を設けないようにした。
【００３１】
そして、上記の実施例１，２及び比較例１の各円筒型リチウム二次電池１０において、それぞれ１本の正極集電タブ１１ａと正極端子１１との間の抵抗値及び１本の負極集電タブ１２ａと負極端子１２との間の抵抗値を測定し、その結果を下記の表１に示した。
【００３２】
【表１】

Figure 0003769377
【００３３】
この結果、金の薄膜を形成した負極集電タブ１２ａを使用した実施例１のものにおいては、金の薄膜を形成しない負極集電タブ１２ａを使用した実施例２及び比較例１のものに比べて、１本の負極集電タブ１２ａと負極端子１２との間の抵抗値が０．０５ｍΩ低くなっており、また金の薄膜を形成した正極集電タブ１１ａを使用した実施例２のものは、金の薄膜を形成しない正極集電タブ１２ａを使用した実施例１及び比較例１のものに比べて、１本の正極集電タブ１１ａと正極端子１１との間の抵抗値が０．０３ｍΩ低くなっていた。
【００３４】
次に、正極集電タブ１１ａ及び負極集電タブ１２ａの表面にそれぞれ金の薄膜を形成したものを用いた実施例３の円筒型リチウム二次電池１０と、正極集電タブ１１ａ及び負極集電タブ１２ａのいずれの表面にも金の薄膜を形成しなかったものを用いた比較例１の円筒型リチウム二次電池１０とを用い、これらの各円筒型リチウム二次電池１０における内部抵抗を測定し、その結果を下記の表２に示した。
【００３５】
また、この実施例３及び比較例１の各円筒型リチウム二次電池１０について、それぞれ８．７５Ａ（１／８Ｃ）の定電流で充放電を行なって、その平均放電電圧を測定し、その結果を下記の表２に合わせて示した。
【００３６】
【表２】
Figure 0003769377
【００３７】
この結果、上記のように正極集電タブ１１ａ及び負極集電タブ１２ａの表面にそれぞれ金の薄膜を形成したものを用いた実施例３の円筒型リチウム二次電池１０は、正極集電タブ１１ａ及び負極集電タブ１２ａのいずれの表面にも金の薄膜を形成しなかったものを用いた比較例１の円筒型リチウム二次電池１０に比べ、電池の内部抵抗が低くなると共に、平均放電電圧が高くなっていた。
【００３８】
【発明の効果】
以上詳述したように、この発明における円筒型リチウム二次電池においては、正極端子に取り付ける正極集電タブの表面や、負極端子に取り付ける負極集電タブの表面に金の薄膜を形成すると共に、上記の正極集電タブをアルミニウム材料で構成し、或いは上記の負極集電タブをニッケル材料で構成したため、この金の薄膜により正極集電タブと正極端子との間や、負極集電タブと負極端子との間の密着性が高くなり、正極集電タブと正極端子との間における接触抵抗や、負極集電タブと負極端子との間における接触抵抗が減少した。
【００３９】
この結果、この発明における円筒型リチウム二次電池においては、その内部抵抗が低くなって電池電圧や電池容量が低下するのが抑制され、高電圧で高容量の円筒型リチウム二次電池が得られるようになった。
【図面の簡単な説明】
【図１】この発明の実施例１〜３及び比較例１における円筒型リチウム二次電池の概略図である。
【図２】図１に示した円筒型リチウム二次電池を製造するにあたり、正極と負極との間にセパレータを介在させてスパイラル状に巻き取る状態を示した概略説明図である。
【図３】図１に示した円筒型リチウム二次電池を組み立てる状態を示した概略説明図である。
【図４】図１に示した円筒型リチウム二次電池を組み立てるにあたり、正極に設けた各正極集電タブを、正極蓋に設けられた正極端子における一対の挟持板間に挟み込むようにして取り付ける状態を示した概略説明図である。
【符号の説明】
１０ 円筒型リチウム二次電池
１１ 正極
１１ａ 正極集電タブ
１２ 負極
１２ａ 負極集電タブ
１３ セパレータ
１４ 電極体
１５ 電池缶
１６ａ 正極端子
１７ａ 負極端子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cylindrical lithium secondary battery, and in particular, an electrode body wound in a spiral shape with a separator impregnated with a non-aqueous electrolyte interposed between a positive electrode and a negative electrode is accommodated in a battery can, In a cylindrical lithium secondary battery in which a positive electrode current collecting tab extended from the positive electrode is attached to the positive electrode terminal and a negative electrode current collecting tab extended from the negative electrode is attached to the negative electrode terminal, the positive electrode current collecting tab and the positive electrode terminal It has a feature in that a high-voltage and high-capacity cylindrical lithium secondary battery can be obtained by reducing the contact resistance between the negative electrode current collector tab and the negative electrode current collector tab and the negative electrode terminal. It is.
[0002]
[Prior art]
In recent years, secondary batteries have been used in various fields due to demands such as effective use of clean energy. In particular, lithium secondary batteries have attracted attention as new batteries with high output and high energy density. .
[0003]
Furthermore, in recent years, in order to use such lithium secondary batteries for power sources of electric vehicles, household load leveling, etc., the capacity of the lithium secondary batteries has been increased to increase their capacity. It has been developed.
[0004]
Here, as such a lithium secondary battery, in general, an electrode body wound in a spiral shape with a separator impregnated with a non-aqueous electrolyte interposed between a positive electrode and a negative electrode is a cylindrical battery can. Cylindrical lithium secondary batteries housed inside were used.
[0005]
Further, in such a cylindrical lithium secondary battery, in order to extract electric energy in the positive electrode and the negative electrode from the positive electrode terminal and the negative electrode terminal, a positive electrode current collecting tab is provided on the positive electrode, and the positive electrode current collecting tab is used as the positive electrode terminal. The negative electrode current collection tab was provided in the negative electrode, and this negative electrode current collection tab was attached to the negative electrode terminal.
[0006]
Here, when the capacity of the lithium secondary battery is increased by increasing the size of the lithium secondary battery as described above, if the number of positive current collecting tabs provided on the positive electrode and the number of negative current collecting tabs provided on the negative electrode is small, There has been a problem that the battery resistance in the lithium secondary battery is increased and the battery performance is lowered.
[0007]
For this reason, conventionally, in the cylindrical lithium secondary battery as described above, the number of positive electrode current collecting tabs and negative electrode current collecting tabs provided on the positive electrode and the negative electrode is increased. When attaching the negative electrode current collecting tab to the positive electrode terminal and the negative electrode terminal, respectively, generally, the fixing portions provided on the positive electrode terminal and the negative electrode terminal are fixed by tightening with screws or the like.
[0008]
However, when fixing the positive electrode current collector tab or the negative electrode current collector tab to the attachment portion provided on the positive electrode terminal or the negative electrode terminal in this way, the adhesion between these attachment portions and the positive electrode current collector tab or the negative electrode current collector tab is sufficient. However, there is a problem that the contact resistance at these attachment portions is increased, and the battery voltage and battery capacity of the lithium secondary battery are reduced.
[0009]
[Problems to be solved by the invention]
In the present invention, an electrode body wound in a spiral shape with a separator impregnated with a non-aqueous electrolyte interposed between a positive electrode and a negative electrode is accommodated in a battery can, and a positive electrode current collector extended from the positive electrode An object of the present invention is to solve the above-mentioned problems in a cylindrical lithium secondary battery in which a tab is attached to a positive electrode terminal and a negative electrode current collecting tab extended from the negative electrode is attached to the negative electrode terminal.
[0010]
That is, in the cylindrical lithium secondary battery as described above, the positive electrode current collecting tab extended from the positive electrode and the negative electrode current collecting tab extended from the negative electrode are attached to the positive electrode terminal and the negative electrode terminal. The contact resistance between the positive electrode current collector tab and the positive electrode terminal is improved by improving the adhesion between the positive electrode current collector tab and the positive electrode terminal and the adhesion between the negative electrode current collector tab and the negative electrode terminal. By reducing the contact resistance between the current collector tab and the negative electrode terminal, it is possible to suppress the battery voltage and the battery capacity from being lowered and to obtain a cylindrical lithium secondary battery having a high voltage and a high capacity. It is to be an issue.
[0011]
[Means for Solving the Problems]
In the cylindrical lithium secondary battery according to the present invention, in order to solve the above problems, a separator impregnated with a non-aqueous electrolyte is provided between a positive electrode including a lithium composite oxide and a negative electrode including a carbon material. The electrode body wound in an intervening manner is accommodated in a battery can, and the positive electrode current collecting tab extended from the positive electrode is attached to the positive electrode terminal, and the negative electrode current collecting tab extended from the negative electrode is attached to the negative electrode In the cylindrical lithium secondary battery attached to the terminal, a gold thin film is formed on at least one surface of the positive electrode current collecting tab and the negative electrode current collecting tab, and the positive electrode current collecting tab is made of an aluminum material. Alternatively, the negative electrode current collecting tab is made of a nickel material .
[0012]
Here, when the gold thin film is formed on the surface of the positive electrode current collecting tab attached to the positive electrode terminal or the surface of the negative electrode current collecting tab attached to the negative electrode terminal as in the cylindrical lithium secondary battery in the present invention, this gold thin film Improves the adhesion between the positive electrode current collector tab and the positive electrode terminal and the adhesion between the negative electrode current collector tab and the negative electrode terminal, and improves the contact resistance between the positive electrode current collector tab and the positive electrode terminal. The contact resistance between the electric tab and the negative electrode terminal is reduced, the internal resistance of the cylindrical lithium secondary battery is reduced, and the battery voltage and battery capacity are suppressed from being reduced, and the high voltage and high capacity cylinder Type lithium secondary battery can be obtained.
[0013]
Here, as the lithium composite oxide used for the positive electrode, known ones generally used in lithium secondary batteries can be used, for example, at least one of manganese, cobalt, nickel, iron, vanadium, and niobium. The lithium transition metal complex oxide etc. which contain can be used.
[0014]
As the carbon material used for the negative electrode, a known carbon material generally used for lithium secondary batteries can be used. For example, natural graphite, artificial graphite, coke that can occlude and release lithium ions can be used. An organic fired body or the like can be used.
[0015]
Furthermore, as the non-aqueous electrolyte, a known one generally used for lithium secondary batteries can be used. Examples of the solvent include ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, and cyclopentanone. , Sulfolane, dimethyl sulfolane, 3-methyl-1,3-oxazolidine-2-one, γ-butyrolactone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, butyl methyl carbonate, ethyl propyl carbonate, butyl ethyl carbonate, 1 organic solvent such as dipropyl carbonate, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, methyl acetate, ethyl acetate Or in combination of two or more can be used.
[0016]
Moreover, as a solute added to the nonaqueous electrolytic solution, a known solute can be used. For example, lithium trifluoromethanesulfonate LiCF 3 SO 3 , lithium hexafluorophosphate LiPF 6 , lithium perchlorate LiClO 4 , Lithium compounds such as lithium tetrafluoroborate LiBF 4 and lithium trifluoromethanesulfonate imido LiN (CF 3 SO 2 ) 2 can be used.
[0018]
In forming the gold thin film on the surface of the positive electrode current collecting tab or the negative electrode current collecting tab as described above, a plating method is generally used, but other known methods such as a vapor deposition method can also be used. .
[0019]
In addition, when forming a thin gold film on the positive electrode current collector tab or the negative electrode current collector tab as described above, if the film thickness is thin, it is between the positive electrode current collector tab and the positive electrode terminal, or between the negative electrode current collector tab and the negative electrode terminal. The contact resistance between the positive electrode current collector tab and the positive electrode terminal and the contact resistance between the negative electrode current collector tab and the negative electrode terminal are increased, while the film thickness is increased. If it is too high, there is a problem such as high cost, and therefore the thickness of the gold thin film is preferably in the range of 1 to 10 μm.
[0020]
【Example】
Hereinafter, the cylindrical lithium secondary battery according to the present invention will be specifically described with examples, and in the cylindrical lithium secondary battery in this example, between the positive electrode current collecting tab and the positive electrode terminal, It will be clarified by giving a comparative example that the contact resistance between the negative electrode current collecting tab and the negative electrode terminal is reduced and a battery having a high battery voltage can be obtained. In addition, the cylindrical lithium secondary battery in this invention is not limited to what was shown in the following Example, It can implement by changing suitably in the range which does not change the summary.
[0021]
(Examples 1 to 3 and Comparative Example 1)
In Examples 1 to 3 and Comparative Example 1, a positive electrode and a negative electrode prepared as described below were used, and a non-aqueous electrolyte prepared as described below was used. A cylindrical lithium secondary battery 10 as shown in FIG. 1 having a cylindrical shape of 294 mm and a battery capacity of 70 Ah was obtained.
[0022]
[Production of positive electrode]
In producing the positive electrode, LiCoO 2 was used as a positive electrode material, and the positive electrode material LiCoO 2 and carbon as a conductive agent were mixed at a weight ratio of 90: 5 to prepare a positive electrode mixture. A solution prepared by dissolving polyvinylidene fluoride as a binder in N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) is added to this positive electrode mixture, and the above positive electrode mixture, polyvinylidene fluoride, Were mixed to prepare a slurry, and the slurry was applied to both surfaces of a positive electrode current collector made of an aluminum foil by a doctor blade method, and this was applied at 150 ° C. for 2 hours. Vacuum drying was performed to produce a sheet-like positive electrode.
[0023]
[Production of negative electrode]
In producing the negative electrode, graphite powder having an average particle diameter of 10 μm was used as the negative electrode material, and a solution obtained by dissolving polyvinylidene fluoride as a binder in the above NMP was added to the graphite powder. These were kneaded to prepare a slurry, and this slurry was applied to both sides of a copper foil as a negative electrode current collector by a doctor blade method. A vacuum-dried negative electrode was produced for 2 hours.
[0024]
[Preparation of non-aqueous electrolyte]
In preparing the non-aqueous electrolyte, lithium hexafluorophosphate LiPF 6 was dissolved as a solute at a ratio of 1 mol / l in a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1. .
[0025]
[Production of battery]
When manufacturing the battery, as shown in FIGS. 2 and 3, a plurality of positive electrode current collecting tabs 11a are attached to the positive electrode 11 manufactured as described above so as to extend from the positive electrode 11, as shown in FIG. At the same time, a plurality of negative electrode current collecting tabs 12 a are attached to the negative electrode 12 so as to extend from the negative electrode 12, and a separator 13 made of a polyethylene ion-permeable microporous film is interposed between the positive electrode 11 and the negative electrode 12. The electrode body 14 wound up in this way was accommodated in a cylindrical battery can 15.
[0026]
3 and 4, a pair of clamping plates 16b and 16c are provided on the positive terminal 16a provided on the positive electrode lid 16 for closing one end of the battery can 15, and the pair of clamping plates 16b, The positive electrode current collecting tabs 11a provided on the positive electrode 11 are interposed between the positive electrode 11 and the negative electrode terminal 17a provided on the negative electrode lid 17 for closing the other end of the battery can 15. 17b and 17c, and the negative electrode current collecting tabs 12a provided on the negative electrode 12 are sandwiched between the pair of holding plates 17b and 17c. Then, as shown in FIG. The positive electrode lid 16 and the negative electrode lid 17 are attached to both ends of the battery 15, and both ends of the battery can 15 are closed with the positive electrode cover 16 and the negative electrode cover 17, and then the battery can is inserted through the hole for attaching the safety valve 18. In the 5 by pouring the above non-aqueous electrolyte, to obtain a lithium secondary battery 10 of the cylindrical. In addition, a safety valve 18 is provided on each of the positive electrode lid 16 and the negative electrode lid 17.
[0027]
Here, as the positive electrode current collecting tab 11a and the negative electrode current collecting tab 12a, in the cylindrical lithium secondary battery 10 of Example 1, the positive electrode current collecting tab 11a made of aluminum having a width of 15 mm and a thickness of 100 μm is used. On the other hand, a nickel negative electrode current collecting tab 12a having a width of 15 mm and a thickness of 100 μm and a gold thin film having a thickness of 5 μm formed on the surface thereof was used.
[0028]
Further, in the cylindrical lithium secondary battery 10 of Example 2, a gold thin film having a thickness of 5 μm was formed on the surface of the positive electrode current collecting tab 11a made of aluminum having a width of 15 mm and a thickness of 100 μm. On the other hand, a negative electrode current collecting tab 12a made of nickel having a width of 15 mm and a thickness of 100 μm was used.
[0029]
Further, in the cylindrical lithium secondary battery 10 of Example 3, a gold thin film having a thickness of 5 μm was formed on the surface of the positive electrode current collecting tab 11a made of aluminum having a width of 15 mm and a thickness of 100 μm. In addition, a nickel thin-film current collecting tab 12a having a width of 15 mm and a thickness of 100 μm and a gold thin film having a thickness of 5 μm formed on the surface thereof were used.
[0030]
On the other hand, in the cylindrical lithium secondary battery 10 of Comparative Example 1, the positive electrode current collecting tab 11a made of aluminum having a width of 15 mm and a thickness of 100 μm was used, and made of nickel having a width of 15 mm and a thickness of 100 μm. The negative electrode current collector tab 12a was used, and no gold thin film was provided on the surface of either the positive electrode current collector tab 11a or the negative electrode current collector tab 12a.
[0031]
In each of the cylindrical lithium secondary batteries 10 of Examples 1 and 2 and Comparative Example 1, the resistance value between one positive current collecting tab 11a and the positive terminal 11 and one negative current collecting are respectively obtained. The resistance value between the tab 12a and the negative electrode terminal 12 was measured, and the result is shown in Table 1 below.
[0032]
[Table 1]
Figure 0003769377
[0033]
As a result, in Example 1 using the negative electrode current collecting tab 12a in which the gold thin film was formed, compared with those in Example 2 and Comparative Example 1 using the negative electrode current collecting tab 12a in which the gold thin film was not formed. The resistance value between the negative electrode current collecting tab 12a and the negative electrode terminal 12 is lower by 0.05 mΩ, and the second example using the positive electrode current collecting tab 11a formed with a gold thin film is as follows. The resistance value between one positive electrode current collecting tab 11a and the positive electrode terminal 11 is 0.03 mΩ compared to those in Example 1 and Comparative Example 1 using the positive electrode current collecting tab 12a that does not form a gold thin film. It was low.
[0034]
Next, the cylindrical lithium secondary battery 10 of Example 3 in which the surfaces of the positive electrode current collecting tab 11a and the negative electrode current collecting tab 12a were each formed with a gold thin film, the positive electrode current collecting tab 11a, and the negative electrode current collecting The internal resistance in each of the cylindrical lithium secondary batteries 10 was measured using the cylindrical lithium secondary battery 10 of Comparative Example 1 using the tab 12a on which no gold thin film was formed. The results are shown in Table 2 below.
[0035]
Moreover, about each cylindrical lithium secondary battery 10 of this Example 3 and the comparative example 1, it charged / discharged with the constant current of 8.75A (1 / 8C), respectively, the average discharge voltage was measured, and the result Is shown in Table 2 below.
[0036]
[Table 2]
Figure 0003769377
[0037]
As a result, as described above, the cylindrical lithium secondary battery 10 of Example 3 using the positive electrode current collecting tab 11a and the negative electrode current collecting tab 12a formed with a thin gold film on the surface thereof is the positive electrode current collecting tab 11a. As compared with the cylindrical lithium secondary battery 10 of Comparative Example 1 in which no gold thin film was formed on either surface of the negative electrode current collecting tab 12a, the internal resistance of the battery was lowered and the average discharge voltage was reduced. Was high.
[0038]
【The invention's effect】
As described in detail above, in the cylindrical lithium secondary battery according to the present invention, while forming a gold thin film on the surface of the positive electrode current collector tab attached to the positive electrode terminal and the surface of the negative electrode current collector tab attached to the negative electrode terminal , Since the above positive electrode current collecting tab is made of an aluminum material or the above negative electrode current collecting tab is made of a nickel material, the gold thin film is used between the positive electrode current collecting tab and the positive electrode terminal, or between the negative electrode current collecting tab and the negative electrode. Adhesion between the terminals was increased, and contact resistance between the positive electrode current collector tab and the positive electrode terminal and contact resistance between the negative electrode current collector tab and the negative electrode terminal were reduced.
[0039]
As a result, in the cylindrical lithium secondary battery according to the present invention, the internal resistance is reduced and the battery voltage and the battery capacity are prevented from decreasing, and a high voltage and high capacity cylindrical lithium secondary battery is obtained. It became so.
[Brief description of the drawings]
FIG. 1 is a schematic view of a cylindrical lithium secondary battery in Examples 1 to 3 and Comparative Example 1 of the present invention.
FIG. 2 is a schematic explanatory view showing a state in which a separator is interposed between a positive electrode and a negative electrode and wound in a spiral shape when the cylindrical lithium secondary battery shown in FIG. 1 is manufactured.
3 is a schematic explanatory view showing a state in which the cylindrical lithium secondary battery shown in FIG. 1 is assembled. FIG.
4A and 4B, when assembling the cylindrical lithium secondary battery shown in FIG. 1, each positive electrode current collecting tab provided on the positive electrode is attached so as to be sandwiched between a pair of holding plates in the positive electrode terminal provided on the positive electrode lid. It is the schematic explanatory drawing which showed the state.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Cylindrical lithium secondary battery 11 Positive electrode 11a Positive electrode current collection tab 12 Negative electrode 12a Negative electrode current collection tab 13 Separator 14 Electrode body 15 Battery can 16a Positive electrode terminal 17a Negative electrode terminal

Claims (3)

リチウム複合酸化物を含む正極と、炭素材料を含む負極との間に非水電解液が含浸されたセパレータを介在させて渦巻き状に巻回した電極体を電池缶内に収容させ、上記の正極より延出された正極集電タブを正極端子に取り付けると共に、負極より延出された負極集電タブを負極端子に取り付けるようにした円筒型リチウム二次電池において、上記の正極集電タブと負極集電タブの少なくとも一方の表面に金の薄膜を形成すると共に、上記の正極集電タブをアルミニウム材料で構成したことを特徴とする円筒型リチウム二次電池。An electrode body wound in a spiral shape with a separator impregnated with a non-aqueous electrolyte interposed between a positive electrode including a lithium composite oxide and a negative electrode including a carbon material is accommodated in a battery can, and the positive electrode In the cylindrical lithium secondary battery in which the positive current collecting tab extended from the negative electrode is attached to the positive electrode terminal and the negative current collecting tab extended from the negative electrode is attached to the negative electrode terminal, the positive current collecting tab and the negative electrode described above A cylindrical lithium secondary battery, wherein a thin gold film is formed on at least one surface of a current collecting tab, and the positive electrode current collecting tab is made of an aluminum material . リチウム複合酸化物を含む正極と、炭素材料を含む負極との間に非水電解液が含浸されたセパレータを介在させて渦巻き状に巻回した電極体を電池缶内に収容させ、上記の正極より延出された正極集電タブを正極端子に取り付けると共に、負極より延出された負極集電タブを負極端子に取り付けるようにした円筒型リチウム二次電池において、上記の正極集電タブと負極集電タブの少なくとも一方の表面に金の薄膜を形成すると共に、上記の負極集電タブをニッケル材料で構成したことを特徴とする円筒型リチウム二次電池。An electrode body wound in a spiral shape with a separator impregnated with a non-aqueous electrolyte interposed between a positive electrode including a lithium composite oxide and a negative electrode including a carbon material is accommodated in a battery can, and the positive electrode In the cylindrical lithium secondary battery in which the positive current collecting tab extended from the negative electrode is attached to the positive electrode terminal and the negative current collecting tab extended from the negative electrode is attached to the negative electrode terminal, the positive current collecting tab and the negative electrode described above A cylindrical lithium secondary battery in which a thin gold film is formed on at least one surface of a current collecting tab and the negative electrode current collecting tab is made of a nickel material . 請求項２に記載した円筒型リチウム二次電池において、上記の正極集電タブをアルミニウム材料で構成したことを特徴とする円筒型リチウム二次電池。The cylindrical lithium secondary battery according to claim 2, wherein the positive electrode current collecting tab is made of an aluminum material .
JP04485398A 1998-02-26 1998-02-26 Cylindrical lithium secondary battery Expired - Fee Related JP3769377B2 (en)

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