JP2014086293A - Lithium ion secondary battery and method for manufacturing lithium ion secondary battery - Google Patents

Lithium ion secondary battery and method for manufacturing lithium ion secondary battery Download PDF

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JP2014086293A
JP2014086293A JP2012234742A JP2012234742A JP2014086293A JP 2014086293 A JP2014086293 A JP 2014086293A JP 2012234742 A JP2012234742 A JP 2012234742A JP 2012234742 A JP2012234742 A JP 2012234742A JP 2014086293 A JP2014086293 A JP 2014086293A
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negative electrode
separator
active material
positive electrode
material layer
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JP5849927B2 (en
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Toshihiko Mihashi
利彦 三橋
Hideaki Fujita
秀明 藤田
Kaoru Inoue
薫 井上
Yukihiro Okada
行広 岡田
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Toyota Motor Corp
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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
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    • 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

Abstract

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery capable of restraining a short circuit between cathode and anode from occurring due to deposition of metal on an anode active material layer under high temperature, and a method for manufacturing the same.SOLUTION: A battery 1 comprises an electrode body 10 formed by winding a cathode plate 30 and an anode plate 40 via separators 20X, 20Y, and an electrolyte 50. The anode plate has an outer circumferential anode part 40S and an inner circumferential anode part 40T, while an anode foil 48 and two anode active material layers 41's form a common other-side end face 40P at an edge on an other side DX2 in the axial direction. The separators have interposing portions 22XT, 22XU, 22YS, 22YU interposed between a cathode active material layer 31 and opposed portions 42, 42SH, 42TH of the anode active material layers opposed thereto, and liquid retention reducing portions 26XS, 26XT, 26YS, 26YT whose electrolyte retention capability is reduced than that of the interposing portions. At least either an outer circumferential end face 40SP or an inner circumferential end face 40TP out of the other-side end face of the anode plate is covered with the liquid retention reducing portions.

Description

本発明は、正極活物質層を有する正極板と負極活物質層を有する負極板とを、セパレータを介して捲回した電極体を備えるリチウムイオン二次電池、及び、このようなリチウムイオン二次電池の製造方法に関する。   The present invention relates to a lithium ion secondary battery including an electrode body obtained by winding a positive electrode plate having a positive electrode active material layer and a negative electrode plate having a negative electrode active material layer through a separator, and such a lithium ion secondary The present invention relates to a battery manufacturing method.

近年、ハイブリッド自動車、電気自動車などの車両や、ノート型パソコン、ビデオカムコーダなどのポータブル電子機器の駆動用電源に、充放電可能なリチウムイオン二次電池（以下、単に電池ともいう）が利用されている。
このような電池に関して、例えば、特許文献１には、捲回型の電極体を有する電池の初期充電工程及びエージング工程を備える電池の製造方法が開示されている。また、特許文献２には、セパレータに、互いに対向しあう正極合材層と負極合材層との間でリチウムイオンの移動を許容するイオン通過部と、このイオン通過部の外側に位置し、正極合材層から負極合材層の端面へのリチウムイオンの移動を制限するイオン制限部とを形成した蓄電デバイスが開示されている。 In recent years, lithium-ion secondary batteries (hereinafter also simply referred to as “batteries”) that can be charged and discharged have been used as driving power sources for vehicles such as hybrid vehicles and electric vehicles, and portable electronic devices such as notebook computers and video camcorders. Yes.
Regarding such a battery, for example, Patent Document 1 discloses a battery manufacturing method including an initial charging process and an aging process of a battery having a wound electrode body. Further, in Patent Document 2, the separator is positioned outside the ion passage portion, an ion passage portion that allows lithium ions to move between the positive electrode mixture layer and the negative electrode mixture layer facing each other, An electricity storage device in which an ion restricting portion that restricts the movement of lithium ions from the positive electrode mixture layer to the end face of the negative electrode mixture layer is disclosed.

特開２０１２−８４３４６号公報JP 2012-84346 A 特開２００９−１８８０３７号公報JP 2009-188037 A

ところで、上述の特許文献１に記載の、捲回型の電極体を備える電池を充電（初期充電）した後に、例えば８０℃以上の高温下で放置すると、正極板のうち電極体の径方向の最外周に位置する正極最外周部の正極活物質層の一部が、リチウムイオンを放出し過ぎて、局所的に正極電位が高い状態となる場合があることが判ってきた。この理由は、以下であると考えられる。
図１には、捲回型の電極体２１０を備える従来の電池２０１のうち、電極体２１０の部分拡大断面図を示す。この電極体２１０では、正極板２３０のうち、電極体２１０の径方向ＤＲ（図１中、上下方向）の最外周（図中、上方）に正極最外周部３３０を、負極板２４０のうち負極外周部３４０で、セパレータ２２０を介して径方向外側ＤＲ１（図中、上方）から覆っている。なお、この負極外周部３４０は、セパレータ２２０を挟んで正極最外周部３３０に対向しており、セパレータ２２０のうちセパレータ外周部３２０が、正極最外周部３３０と負極外周部３４０との間に介在している。 By the way, after charging (initial charging) a battery having a wound electrode body described in Patent Document 1 described above, if the battery is left at a high temperature of, for example, 80 ° C. or higher, the radial direction of the electrode body in the positive electrode plate It has been found that a part of the positive electrode active material layer at the outermost peripheral portion of the positive electrode located at the outermost periphery may release lithium ions too much to locally have a high positive electrode potential. The reason for this is considered as follows.
FIG. 1 shows a partially enlarged cross-sectional view of an electrode body 210 in a conventional battery 201 including a wound electrode body 210. In the electrode body 210, the positive electrode outermost peripheral portion 330 is disposed on the outermost periphery (upward in the drawing) of the electrode body 210 in the radial direction DR (upward and downward direction in FIG. 1). The outer peripheral portion 340 covers the separator 220 from the radially outer side DR1 (upward in the figure). The negative electrode outer peripheral portion 340 faces the positive electrode outermost peripheral portion 330 with the separator 220 interposed therebetween, and the separator outer peripheral portion 320 of the separator 220 is interposed between the positive electrode outermost peripheral portion 330 and the negative electrode outer peripheral portion 340. doing.

なお、この電池２０１では、軸線方向ＤＸ（図中、左右方向）に見て、負極活物質層２４１が正極活物質層２３１よりも幅広に形成されている。従って、負極外周部３４０において負極活物質層３４１は、セパレータ外周部３２０を介して、正極最外周部３３０の正極活物質層３３１に対向する対向部３４２と、この対向部３４２よりも軸線方向ＤＸの一方側ＤＸ１（図中、右側）に配置され、正極活物質層３３１と対向しない一方側非対向部３４３と、対向部３４２よりも軸線方向ＤＸの他方側ＤＸ２（図中、左側）に配置され、正極活物質層３３１と対向しない他方側非対向部３４４とを有している。
また、負極板２４０の負極箔４８及び２つの負極活物質層２４１，２４１は、軸線方向ＤＸの他方側ＤＸ２の端縁において共通の他方側端面２４０Ｐをなしている。この他方側端面２４０Ｐのうち、負極外周部３４０に属するものを外周部端面３４０Ｐとする（図１参照）。 In the battery 201, the negative electrode active material layer 241 is formed wider than the positive electrode active material layer 231 when viewed in the axial direction DX (left-right direction in the figure). Accordingly, the negative electrode active material layer 341 in the negative electrode outer peripheral portion 340 is opposed to the positive electrode active material layer 331 of the positive electrode outermost peripheral portion 330 via the separator outer peripheral portion 320, and the axial direction DX more than the opposite portion 342. 1 is disposed on one side DX1 (right side in the figure) and is disposed on the other side DX2 (left side in the figure) in the axial direction DX with respect to the one side non-opposing part 343 that does not face the positive electrode active material layer 331. And the other side non-facing portion 344 that does not face the positive electrode active material layer 331.
Further, the negative electrode foil 48 and the two negative electrode active material layers 241 and 241 of the negative electrode plate 240 form a common other side end surface 240P at the end edge of the other side DX2 in the axial direction DX. Of the other side end surface 240P, one belonging to the negative electrode outer peripheral portion 340 is defined as an outer peripheral end surface 340P (see FIG. 1).

この電池２０１を充電すると、正極活物質層２３１からリチウムイオンが放出され、セパレータ２２０を介して負極活物質層２４１に挿入される。従って、正極最外周部３３０の正極活物質層３３１からもリチウムイオンが放出され、セパレータ外周部３２０を通じて、負極外周部３４０の第１外周活物質層３４１Ｈ（負極外周部３４０の表裏の負極活物質層３４１，３４１のうち、正極活物質層３３１に対向するもの）の第１対向部３４２Ｈにもリチウムイオンが挿入される（図１参照）。すると、この第１外周活物質層３４１Ｈの第１対向部３４２Ｈに挿入されたリチウムイオンの一部は、拡散によって、隣在する第１一方側非対向部３４３Ｈ（上述の一方側非対向部３４３のうち第１外周活物質層３４１Ｈに含まれるもの）、及び、第１他方側非対向部３４４Ｈ（上述の他方側非対向部３４４のうち第１外周活物質層３４１Ｈに含まれるもの）にまでそれぞれ拡がる（図２参照）。   When the battery 201 is charged, lithium ions are released from the positive electrode active material layer 231 and inserted into the negative electrode active material layer 241 through the separator 220. Accordingly, lithium ions are also released from the positive electrode active material layer 331 of the positive electrode outermost peripheral portion 330, and the first outer peripheral active material layer 341H of the negative electrode outer peripheral portion 340 (the negative electrode active materials on the front and back of the negative electrode outer peripheral portion 340) through the separator outer peripheral portion 320. Lithium ions are also inserted into the first facing portion 342H of the layers 341 and 341 facing the positive electrode active material layer 331 (see FIG. 1). Then, a part of the lithium ions inserted into the first facing portion 342H of the first outer peripheral active material layer 341H is diffused to be adjacent to the first one-side non-facing portion 343H (the one-side non-facing portion 343 described above). Of the first outer peripheral active material layer 341H) and the first other-side non-facing portion 344H (of the other-side non-facing portion 344 described above, included in the first outer peripheral active material layer 341H). Each expands (see FIG. 2).

ところで、負極外周部３４０の外周部端面３４０Ｐに電解液が付着すると、負極箔４８を挟んで２つの負極活物質層３４１，３４１の間（具体的には、第１外周活物質層３４１Ｈと、負極外周部３４０の負極活物質層３４１，３４１のうち、第１外周活物質層３４１Ｈよりも径方向外側に位置し、セパレータ２２０を介して正極活物質層３３１と対向していない第２外周活物質層３４１Ｊとの間）で、電解液を通じた液絡が生じる（図２参照）。すると、第１外周活物質層３４１Ｈの第１他方側非対向部３４４Ｈに移動したリチウムイオンがさらに電解液を介して第２外周活物質層３４１Ｊに拡散移動する。
従って、第１対向部３４２Ｈのうち第１他方側非対向部３４４Ｈに隣在する部位３４２ＨＰでは、さらに多くのリチウムイオンが第１他方側非対向部３４４Ｈに向けて拡散することとなり、結果として、この部位３４２ＨＰに挿入されたリチウムイオンの濃度が低くなり、局所的に負極電位が高くなる（図３参照）。 By the way, when the electrolytic solution adheres to the outer peripheral end surface 340P of the negative electrode outer peripheral portion 340, between the two negative electrode active material layers 341 and 341 (specifically, the first outer peripheral active material layer 341H, Of the negative electrode active material layers 341 and 341 of the negative electrode outer peripheral portion 340, the second outer peripheral active material that is located radially outside the first outer peripheral active material layer 341H and does not face the positive electrode active material layer 331 with the separator 220 interposed therebetween. Between the material layer 341J), a liquid junction through the electrolytic solution is generated (see FIG. 2). Then, the lithium ions that have moved to the first other-side non-opposing portion 344H of the first outer circumferential active material layer 341H are further diffused and moved to the second outer circumferential active material layer 341J through the electrolytic solution.
Accordingly, in the portion 342HP adjacent to the first other-side non-facing portion 344H in the first facing portion 342H, more lithium ions diffuse toward the first other-side non-facing portion 344H. The concentration of lithium ions inserted into this portion 342HP decreases, and the negative electrode potential locally increases (see FIG. 3).

すると、正極活物質層３３１の他方側ＤＸ２の端部（正極活物質層３３１のうち、上述の部位３４２ＨＰに対向する正極リード部３９）に沿う部位３３１Ｐからは、セパレータ外周部３２０を介してさらにリチウムイオンが放出される。
かくして、電池２０１を充電すると、正極最外周部３３０のうち、正極活物質層３３１の他方側ＤＸ２の端部３３１Ｐで、正極活物質からリチウムイオンを放出し過ぎて、局所的に正極電位が高い状態となる（図３参照）。 Then, from the portion 331P along the end portion of the other side DX2 of the positive electrode active material layer 331 (the positive electrode lead portion 39 facing the above-described portion 342HP in the positive electrode active material layer 331), further through the separator outer peripheral portion 320, Lithium ions are released.
Thus, when the battery 201 is charged, lithium ions are excessively released from the positive electrode active material at the end portion 331P of the other side DX2 of the positive electrode active material layer 331 in the positive electrode outermost peripheral portion 330, and the positive electrode potential is locally high. A state is reached (see FIG. 3).

ところで、リチウムイオンを過剰に放出した正極活物質粒子では、正極活物質粒子を構成している遷移金属がイオンとなって電解液中に溶出しやすい。溶出した金属イオンは、高温エージングなど電池が高温（８０℃以上）に保持された場合に、第１外周活物質層３４１Ｈ（対向部３４２Ｈのうち他方側非対向部３４４Ｈに隣在する部位３４２ＨＰ）上で金属化し針状に析出する。これにより、この針状結晶が多孔質状のセパレータを貫通すると正負極間で微小短絡が生じる虞がある。   By the way, in the positive electrode active material particles from which lithium ions are excessively released, the transition metal constituting the positive electrode active material particles is easily ionized and eluted into the electrolytic solution. When the battery is kept at a high temperature (80 ° C. or higher) such as high-temperature aging, the eluted metal ions are the first outer peripheral active material layer 341H (site 342HP adjacent to the other non-opposing portion 344H of the opposing portion 342H). It is metallized above and precipitates in a needle shape. Thereby, when this acicular crystal penetrates a porous separator, there is a possibility that a micro short circuit may occur between the positive and negative electrodes.

なお、図２に示すように、負極外周部３４０のうち、軸線方向ＤＸの一方側ＤＸ１には、負極箔４８の露出した負極リード部４９が存在しているため、この負極外周部３４０の一方側ＤＸ１では、第１外周活物質層３４１Ｈと第２外周活物質層３４１Ｊとの間で電解液による液絡は生じない。このため、正極活物質層３３１の一方側ＤＸ１では、上述の現象は生じない。
また、上述した正極最外周部３３０の正極活物質層３３１の一部のほか、正極板３０のうち径方向の最内周に位置する正極最内周部の正極活物質層の一部でも、同様に局所的に正極電位が高い状態となりうる。 As shown in FIG. 2, the negative electrode lead portion 49 where the negative electrode foil 48 is exposed is present on one side DX1 in the axial direction DX of the negative electrode outer peripheral portion 340. On the side DX1, a liquid junction due to the electrolytic solution does not occur between the first outer peripheral active material layer 341H and the second outer peripheral active material layer 341J. Therefore, the above phenomenon does not occur on one side DX1 of the positive electrode active material layer 331.
Further, in addition to a part of the positive electrode active material layer 331 of the positive electrode outermost peripheral part 330 described above, even a part of the positive electrode active material layer of the positive electrode innermost peripheral part located in the radially innermost periphery of the positive electrode plate 30, Similarly, the positive electrode potential can be locally high.

一方、前述した特許文献２に記載のセパレータを備えるリチウムイオン二次電池には、セパレータにイオン制限部があるため、充電の際、正極活物質層から放出されたリチウムイオンが、セパレータを通じて、負極活物質層のうち正極活物質層と対向しない部位や負極活物質層の端面に直接移動できない。
しかしながら、このリチウムイオン二次電池でも、前述した外周部端面３４０Ｐを有する場合には、この外周部端面に液絡が生じてしまう。このため、このリチウムイオン二次電池を初充電した後に高温エージングを行うと、このリチウムイオン二次電池においても、正極板の正極電位が局所的に高い状態になり、正負極間で微小短絡が生じる虞がある。 On the other hand, in the lithium ion secondary battery provided with the separator described in Patent Document 2 described above, since the separator has an ion limiting portion, lithium ions released from the positive electrode active material layer during charging pass through the separator through the negative electrode. It cannot move directly to the portion of the active material layer that does not face the positive electrode active material layer or to the end face of the negative electrode active material layer.
However, even in this lithium ion secondary battery, when it has the above-described outer peripheral end face 340P, a liquid junction occurs on the outer peripheral end face. For this reason, when high-temperature aging is performed after the lithium ion secondary battery is initially charged, the positive electrode potential of the positive electrode plate is also locally high in this lithium ion secondary battery, and there is a minute short circuit between the positive and negative electrodes. May occur.

本発明は、かかる知見に鑑みてなされたものであって、高温下での負極活物質層上への金属の析出による正負極間の短絡の発生を抑制できるリチウムイオン二次電池を提供することを目的とする。また、このようなリチウムイオン二次電池の製造方法を提供することを目的とする。   The present invention has been made in view of such knowledge, and provides a lithium ion secondary battery capable of suppressing the occurrence of a short circuit between positive and negative electrodes due to metal deposition on a negative electrode active material layer at a high temperature. With the goal. Moreover, it aims at providing the manufacturing method of such a lithium ion secondary battery.

本発明の一態様は、帯状の正極板と帯状の負極板とを帯状のセパレータを介して捲回してなる電極体、及び、上記セパレータに含浸された電解液を備え、上記負極板は、捲回された上記正極板のうち最外周に位置する正極最外周部に、上記セパレータを介して径方向外側から対向する負極外周部、及び、上記正極板のうち最内周に位置する正極最内周部に、上記セパレータを介して上記径方向内側から対向する負極内周部、を有するリチウムイオン二次電池であって、上記正極板は、帯状の正極箔及びこの正極箔の両主面上で、捲回軸に沿う軸線方向の一方側に位置する正極活物質層を有し、上記負極板は、帯状の負極箔及びこの負極箔の両主面上で上記軸線方向の他方側に位置する負極活物質層を有し、上記負極箔及び２つの上記負極活物質層は、上記他方側の端縁で共通の他方側端面をなし、上記負極活物質層は、上記セパレータを介して上記正極活物質層に対向する対向部と、この対向部の上記他方側に隣在し上記正極活物質層に対向しない他方側非対向部とを含み、上記セパレータは、上記正極活物質層とこれに対向する上記負極活物質層の上記対向部との間に介在する介在部及び上記介在部よりも上記電解液の保持性を低下させた液保持性低下部を有し、上記負極板の上記他方側端面のうち、上記負極外周部に属する外周部端面及び上記負極内周部に属する内周部端面の少なくともいずれかは、上記セパレータの上記液保持性低下部で覆われてなるリチウムイオン二次電池である。   One embodiment of the present invention includes an electrode body obtained by winding a strip-shaped positive electrode plate and a strip-shaped negative electrode plate through a strip-shaped separator, and an electrolytic solution impregnated in the separator. The positive electrode outermost part located on the outermost periphery of the rotated positive electrode plate, the negative electrode outer peripheral part facing from the radially outer side through the separator, and the innermost positive electrode located on the innermost periphery of the positive electrode plate A lithium ion secondary battery having a negative electrode inner peripheral part facing from the radially inner side through the separator in the peripheral part, the positive electrode plate comprising a strip-shaped positive foil and both main surfaces of the positive foil A positive electrode active material layer positioned on one side in the axial direction along the winding axis, and the negative electrode plate is positioned on the other side in the axial direction on both main surfaces of the strip-shaped negative electrode foil and the negative electrode foil A negative electrode active material layer, and the negative electrode foil and the two negative electrode active materials The layer forms a common other side end face at the other side edge, and the negative electrode active material layer has a facing portion facing the positive electrode active material layer via the separator and the other side of the facing portion. And the other side non-facing portion that is adjacent and does not face the positive electrode active material layer, and the separator is interposed between the positive electrode active material layer and the facing portion of the negative electrode active material layer facing the separator. And a liquid retainability lowering portion in which the electrolytic solution retainability is lower than that of the intermediate portion and the interposition portion, and of the other side end surface of the negative electrode plate, the outer peripheral end surface belonging to the negative electrode outer peripheral portion and the negative electrode At least one of the end surfaces of the inner peripheral portion belonging to the peripheral portion is a lithium ion secondary battery that is covered with the liquid retention lowering portion of the separator.

上述のリチウムイオン二次電池では、負極板の他方側端面のうち、少なくとも外周部端面及び内周部端面のいずれかが、セパレータの液保持性低下部で覆われている。液保持性低下部では電解液の保持性が低いので、これに覆われない従来の他方側端面に比して、液保持性低下部に覆われた外周部端面や内周部端面において、２つの負極活物質層同士の液絡に寄与する電解液の量を少なくできる。これにより、液絡によって正極活物質層と対向していない側の負極活物質層にまでリチウムイオンが拡散移動するのを抑えることができる。
かくして、少なくとも正極最外周部及び正極最内周部のいずれかにおいて、正極活物質層の正極活物質粒子から金属イオンが溶出するのを抑制することができ、高温下での負極活物質層上への金属の析出による短絡の発生を抑制した電池とすることができる。 In the above-described lithium ion secondary battery, at least one of the outer peripheral end surface and the inner peripheral end surface of the other end surface of the negative electrode plate is covered with the liquid retention lowering portion of the separator. Since the electrolyte retainability is low in the liquid retainability lowered portion, the outer peripheral end face and the inner peripheral end face covered with the liquid retainable degraded portion are 2 in comparison with the other end face on the other side that is not covered with this. The amount of the electrolyte solution that contributes to the liquid junction between the two negative electrode active material layers can be reduced. Thereby, it is possible to prevent lithium ions from diffusing and moving to the negative electrode active material layer on the side not facing the positive electrode active material layer due to liquid junction.
Thus, it is possible to suppress the elution of metal ions from the positive electrode active material particles of the positive electrode active material layer at least in any one of the positive electrode outermost peripheral part and the positive electrode innermost peripheral part, and on the negative electrode active material layer at a high temperature. Thus, a battery in which occurrence of a short circuit due to metal deposition on the battery is suppressed can be obtained.

なお、液保持性低下部の形態としては、例えば、負極板の他方側端面のうち、負極外周部の外周部端面のみを覆う形態、内周部端面のみを覆う形態、外周部端面及び内周部端面を覆う形態、及び、負極板全体の他方側端面を覆う形態が挙げられる。また、セパレータの液保持性低下部としては、多孔性樹脂からなるセパレータの該当部位を加熱により熱収縮させたり、該当部位に樹脂等を塗布して介在部よりも空孔率を低下させたものや、該当部位に電解液に濡れずにこれをはじく特性を付与したものが挙げられる。
また、正極最外周部は、捲回された正極板のうち最外周に位置する部位、即ち、正極板のうち最外側の一周分の捲回をなす部位である。一方、正極最内周部は、捲回された正極板のうち最内周に位置する部位、即ち、正極版のうち最内側の一周分の捲回をなす部位である。
また、負極外周部は、捲回された負極板のうち正極最外周部にセパレータを介して径方向外側から対向する部位である。つまり、この負極外周部は、負極板が上述した正極最外周部の正極活物質層に対向する負極活物質層と、この負極活物質層よりも外側に位置し、セパレータを介して正極活物質層とは対向していない負極活物質層とを有する形態である。一方、負極内周部は、捲回された負極板のうち正極最内周部にセパレータを介して径方向内側から対向する部位である。つまり、この負極内周部は、上述した正極最内周部の正極活物質層に対向する負極活物質層と、この負極活物質層よりも内側に位置し、セパレータを介して正極活物質層とは対向していない負極活物質層とを有する形態である。 In addition, as a form of a liquid retainability fall part, the form which covers only the outer peripheral part end surface of a negative electrode outer peripheral part among the other side end surfaces of a negative electrode plate, the form which covers only an inner peripheral part end surface, an outer peripheral part end surface, and an inner periphery The form which covers a part end surface and the form which covers the other side end surface of the whole negative electrode plate are mentioned. In addition, as the liquid retention lowering portion of the separator, the corresponding portion of the separator made of porous resin is thermally contracted by heating, or the porosity is lower than the intervening portion by applying resin or the like to the corresponding portion. Or what gave the characteristic which repels this, without getting wet to electrolyte solution to an applicable site | part is mentioned.
The positive electrode outermost peripheral portion is a portion located on the outermost periphery of the wound positive electrode plate, that is, a portion forming the outermost one turn of the positive electrode plate. On the other hand, the innermost peripheral portion of the positive electrode is a portion located on the innermost periphery of the wound positive electrode plate, that is, a portion forming the innermost turn of the positive electrode plate.
The negative electrode outer peripheral portion is a portion of the wound negative electrode plate that faces the outermost positive electrode outer peripheral portion from the radially outer side via a separator. That is, the negative electrode outer peripheral portion is located on the outer side of the negative electrode active material layer with the negative electrode plate facing the positive electrode active material layer of the positive electrode outermost peripheral portion described above, and the positive electrode active material via the separator. The layer has a negative electrode active material layer that is not opposed to the layer. On the other hand, the inner periphery of the negative electrode is a portion of the wound negative electrode plate that faces the innermost peripheral portion of the positive electrode from the inner side in the radial direction via a separator. That is, the negative electrode inner peripheral part is located on the inner side of the negative electrode active material layer facing the positive electrode active material layer of the positive electrode innermost peripheral part, and the positive electrode active material layer via the separator. Is a form having a negative electrode active material layer not facing each other.

さらに、上述のリチウムイオン二次電池であって、前記他方側端面のうち、少なくとも前記外周部端面及び前記内周部端面は、前記セパレータの前記液保持性低下部で覆われてなるリチウムイオン二次電池とすると良い。   Furthermore, in the above-described lithium ion secondary battery, at least the outer peripheral end surface and the inner peripheral end surface of the other side end surface are covered with the liquid retention lowering portion of the separator. A secondary battery is recommended.

上述の電池では、負極外周部及び負極内周部にそれぞれ属する外周部端面及び内周部端面が、液保持性低下部で覆われている。このため、負極外周部及び負極内周部のいずれにおいても液絡によって、２つの負極活物質層のうちセパレータを介して正極活物質層と対向していない側の負極活物質層にまで、リチウムイオンが拡散移動するのを確実に抑えることができる。従って、正極最外周部及び正極最内周部において、正極活物質層の正極活物質粒子から金属イオンが溶出するのを確実に抑制することができる。   In the battery described above, the outer peripheral end face and the inner peripheral end face belonging to the negative electrode outer peripheral part and the negative electrode inner peripheral part, respectively, are covered with the liquid retainability lowering part. For this reason, in both of the negative electrode outer peripheral portion and the negative electrode inner peripheral portion, the lithium negative electrode active material layer on the side that does not face the positive electrode active material layer through the separator of the two negative electrode active material layers It is possible to reliably prevent ions from diffusing and moving. Therefore, in the positive electrode outermost peripheral part and the positive electrode innermost peripheral part, it can suppress reliably that a metal ion elutes from the positive electrode active material particle of a positive electrode active material layer.

なお、液保持性低下部の形態としては、例えば、負極板の他方側端面のうち、外周部端面及び内周部端面を覆う形態、及び、負極板全体の他方側端面を覆う形態が挙げられる。   In addition, as a form of a liquid retainability fall part, the form which covers the outer peripheral part end surface and an inner peripheral part end surface among the other side end surfaces of a negative electrode plate, and the form which covers the other side end surface of the whole negative electrode plate are mentioned, for example. .

さらに、上述のリチウムイオン二次電池であって、前記負極板は、前記負極外周部と前記負極内周部との間に位置する負極中間部を有し、前記他方側端面のうち、前記外周部端面及び前記内周部端面は、前記セパレータの前記液保持性低下部で覆われてなり、上記他方側端面のうち、上記負極中間部に属する中間部端面は、前記電極体の前記他方側に露出してなるリチウムイオン二次電池とすると良い。   Furthermore, in the above-described lithium ion secondary battery, the negative electrode plate has a negative electrode intermediate part located between the negative electrode outer peripheral part and the negative electrode inner peripheral part, and the outer periphery of the other side end face The end face of the part and the end face of the inner peripheral part are covered with the liquid retention lowering part of the separator, and the end face of the intermediate part belonging to the negative electrode intermediate part is the other side of the electrode body. Lithium ion secondary battery exposed to

セパレータの液保持性低下部で負極板の他方側端面を覆うと、電極体の他方側から負極活物質層に電解液を含浸させ難くなる。特に、負極板全体にわたり液保持性低下部で他方側端面を覆う場合には、他方側端面を通じて負極活物質層に電解液を含浸できないため、負極活物質層において、軸線方向について電解液の含浸状態にムラが生じ易い。
これに対し、上述の電池では、他方側端面のうち、外周部端面及び内周部端面が液保持性低下部で覆われているものの、負極中間部に属する中間部端面が電極体の他方側に露出している。このため、正極最外周部及び正極最内周部で金属イオンの溶出を確実に抑制できる一方で、負極板のうちの負極中間部において、他方側からも電極体に電解液を含浸させることできる。従って、負極活物質層における、軸線方向についての電解液の含浸状態のムラを抑制することができる。 If the other side end surface of the negative electrode plate is covered with the liquid retention lowering portion of the separator, it is difficult to impregnate the negative electrode active material layer with the electrolytic solution from the other side of the electrode body. In particular, when the other side end face is covered with the liquid retention lowering portion over the entire negative electrode plate, the negative electrode active material layer cannot be impregnated with the electrolyte solution through the other side end face. Unevenness is likely to occur in the state.
On the other hand, in the battery described above, of the other side end surface, the outer peripheral end surface and the inner peripheral end surface are covered with the liquid retention lowering portion, but the intermediate end surface belonging to the negative electrode intermediate portion is the other side of the electrode body. Is exposed. For this reason, while elution of metal ions can be reliably suppressed in the positive electrode outermost peripheral part and the positive electrode innermost peripheral part, the electrode body can be impregnated with the electrolyte from the other side in the negative electrode intermediate part of the negative electrode plate. . Therefore, unevenness in the impregnated state of the electrolytic solution in the axial direction in the negative electrode active material layer can be suppressed.

さらに、上述のいずれかのリチウムイオン二次電池であって、前記セパレータは、多孔質の樹脂からなるセパレータ本体と、上記セパレータ本体の片方の主面上に形成され、無機粒子を含む耐熱層と、を有し、前記電極体において、上記セパレータ本体が前記負極活物質層側となる形態に配置されてなり、前記液保持性低下部は、加熱により上記セパレータ本体を熱収縮させてなるリチウムイオン二次電池とすると良い。   Furthermore, in any of the above lithium ion secondary batteries, the separator is formed of a separator body made of a porous resin, and a heat-resistant layer including inorganic particles formed on one main surface of the separator body. In the electrode body, the separator body is arranged in a form on the negative electrode active material layer side, and the liquid retention reduced portion is a lithium ion formed by heat shrinking the separator body by heating. A secondary battery is recommended.

上述の電池では、セパレータが上述のセパレータ本体と耐熱層とを有するため、電池内の温度が上昇してセパレータ本体が溶融しても、耐熱層により正極板と負極板との接触を防ぐことができる。
また、セパレータは、電極体において、セパレータ本体が負極活物質層側となる形態に配置されてなるため、加熱によりセパレータ本体を熱収縮させると、セパレータ全体がセパレータ本体側に曲がるので、負極板の他方側端面を覆う液保持性低下部を容易かつ確実に形成できる。かくして、介在部よりもセパレータ全体の空孔率を低下させた液保持性低下部で負極板の他方側端面を確実に覆った電池とすることができる。 In the battery described above, since the separator has the separator main body and the heat-resistant layer, even if the temperature in the battery rises and the separator main body melts, the heat-resistant layer prevents contact between the positive electrode plate and the negative electrode plate. it can.
Further, since the separator is arranged in the electrode body such that the separator main body is on the negative electrode active material layer side, when the separator main body is thermally contracted by heating, the entire separator is bent to the separator main body side. It is possible to easily and reliably form the liquid retainability lowering portion that covers the other end face. Thus, a battery can be obtained in which the other end face of the negative electrode plate is reliably covered with the liquid retention lowering portion in which the porosity of the entire separator is lower than that of the interposition portion.

なお、耐熱層に含まれる無機粒子としては、例えば、アルミナ、マグネシア、ジルコニア、シリカ等が挙げられる。また、耐熱層としては、上述の無機粒子に加え、ポリフッ化ビニリデン（ＰＶＤＦ）、ポリテトラフルオロエチレン（ＰＴＦＥ）等の結着材を含むものも挙げられる。   In addition, as an inorganic particle contained in a heat-resistant layer, an alumina, a magnesia, a zirconia, a silica etc. are mentioned, for example. Examples of the heat-resistant layer include those containing a binder such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) in addition to the inorganic particles described above.

さらに、本発明の他の一態様は、帯状の正極板と帯状の負極板とを帯状のセパレータを介して捲回してなる電極体、及び、上記セパレータに含浸された電解液を備え、上記負極板は、捲回された上記正極板のうち最外周に位置する正極最外周部に、上記セパレータを介して径方向外側から対向する負極外周部、及び、上記正極板のうち最内周に位置する正極最内周部に、上記セパレータを介して上記径方向内側から対向する負極内周部、を有し、上記正極板は、帯状の正極箔及びこの正極箔の両主面上で、捲回軸に沿う軸線方向の一方側に位置する正極活物質層を有し、上記負極板は、帯状の負極箔及びこの負極箔の両主面上で上記軸線方向の他方側に位置する負極活物質層を有し、上記負極箔及び２つの上記負極活物質層は、上記他方側の端縁で共通の他方側端面をなし、上記負極活物質層は、上記セパレータを介して上記正極活物質層に対向する対向部と、この対向部の上記他方側に隣在し上記正極活物質層に対向しない他方側非対向部とを含み、上記セパレータは、上記正極活物質層とこれに対向する上記負極活物質層の上記対向部との間に介在する介在部及び上記介在部よりも上記電解液の保持性を低下させた液保持性低下部を有し、上記負極板の上記他方側端面のうち、上記負極外周部に属する外周部端面及び上記負極内周部に属する内周部端面の少なくともいずれかは、上記セパレータの上記液保持性低下部で覆われてなるリチウムイオン二次電池の製造方法であって、帯状の上記正極板と帯状の上記負極板とを帯状で上記液保持性低下部を有さないセパレータを介して捲回して、電極体を作製する電極体作製工程と、上記電極体をなして捲回された上記セパレータに、上記液保持性低下部を形成する低下部形成工程と、を備えるリチウムイオン二次電池の製造方法である。   Furthermore, another aspect of the present invention includes an electrode body obtained by winding a strip-shaped positive electrode plate and a strip-shaped negative electrode plate through a strip-shaped separator, and an electrolyte solution impregnated in the separator, The plate is positioned on the innermost periphery of the positive electrode plate, on the outermost periphery of the positive electrode located on the outermost periphery of the wound positive electrode, on the outer periphery of the negative electrode facing the outer side in the radial direction via the separator A negative electrode inner peripheral portion facing from the inner side in the radial direction through the separator on the innermost peripheral portion of the positive electrode, and the positive electrode plate has a strip-shaped positive foil and both main surfaces of the positive foil. A positive electrode active material layer positioned on one side in the axial direction along the rotation axis, and the negative electrode plate comprises a strip-shaped negative electrode foil and a negative electrode active material positioned on the other side in the axial direction on both main surfaces of the negative electrode foil. The negative electrode foil and the two negative electrode active material layers are provided on the other side. The negative electrode active material layer has a common end face at the edge, and the negative electrode active material layer is opposed to the positive electrode active material layer with the separator interposed therebetween, and is adjacent to the other side of the opposed portion and the positive electrode active material layer. And the separator is interposed between the positive electrode active material layer and the opposed portion of the negative electrode active material layer opposed to the positive electrode active material layer, and more than the interposed portion. A liquid retainability lowering portion in which the retainability of the electrolytic solution is lowered, and of the other side end surface of the negative electrode plate, an outer peripheral end surface belonging to the negative electrode outer peripheral portion and an inner peripheral end surface belonging to the negative electrode inner peripheral portion Is a method for manufacturing a lithium ion secondary battery covered with the liquid retention lowering portion of the separator, wherein the belt-like positive electrode plate and the belt-like negative electrode plate are in a belt shape and the liquid is retained. Through a separator that does not have an A lithium ion secondary comprising: an electrode body manufacturing step of winding to produce an electrode body; and a lowering portion forming step of forming the liquid retention lowering portion on the separator wound to form the electrode body It is a manufacturing method of a battery.

上述のリチウムイオン二次電池の製造方法は、上述の電極体作製工程と低下部形成工程とを備える。このため、負極板の他方側端面のうち、少なくとも外周部端面及び内周部端面のいずれかがセパレータの液保持性低下部で覆われた電池を製造することができる。従って、少なくとも正極最外周部及び正極最内周部のいずれかにおいて、正極活物質層の正極活物質粒子から金属イオンが溶出するのを抑制することができ、高温下での負極活物質層上への金属の析出による短絡の発生を抑制した電池を製造することができる。   The above-described method for manufacturing a lithium ion secondary battery includes the above-described electrode body manufacturing step and the lowered portion forming step. For this reason, a battery in which at least one of the outer peripheral end face and the inner peripheral end face of the other side end face of the negative electrode plate is covered with the liquid retention lowering portion of the separator can be manufactured. Therefore, it is possible to suppress the elution of metal ions from the positive electrode active material particles of the positive electrode active material layer at least in either the positive electrode outermost peripheral part or the positive electrode innermost peripheral part, and on the negative electrode active material layer at a high temperature. A battery that suppresses the occurrence of a short circuit due to metal deposition on the substrate can be produced.

さらに、上述のリチウムイオン二次電池の製造方法であって、前記セパレータは、多孔質の樹脂からなるセパレータ本体と、上記セパレータ本体の片方の主面上に形成され、無機粒子を含む耐熱層と、を有し、前記電極体において、上記セパレータ本体が前記負極活物質層側となる形態に配置されてなり、前記液保持性低下部は、加熱により上記セパレータ本体を熱収縮させてなり、前記低下部形成工程は、前記電極体をなして捲回された前記液保持性低下部を有さないセパレータのうち、前記他方側端面よりも、他方側に突出する突出部を加熱し、上記セパレータ本体を熱収縮させて上記液保持性低下部を形成するリチウムイオン二次電池の製造方法とすると良い。   Furthermore, in the above-described method for manufacturing a lithium ion secondary battery, the separator includes a separator body made of a porous resin, a heat-resistant layer including inorganic particles formed on one main surface of the separator body. In the electrode body, the separator body is arranged in a form that is on the negative electrode active material layer side, and the liquid retention lowering portion is formed by thermally shrinking the separator body by heating, The lowering portion forming step heats a protruding portion that protrudes to the other side of the other end surface of the separator that does not have the liquid retention decreasing portion wound around the electrode body, A method of manufacturing a lithium ion secondary battery in which the main body is thermally shrunk to form the liquid retention lowering portion is preferable.

上述の電池の製造方法のうち低下部形成工程では、電極体をなして捲回されたセパレータの突出部を加熱して、セパレータ本体を熱収縮させて液保持性低下部を形成する。なお、セパレータ本体と耐熱層とを有するセパレータを加熱すると、セパレータ本体が大きく熱収縮するため、セパレータ本体側に曲がり、他方側端面を覆う形態の液保持性低下部を容易に形成することができる。   In the lowered part forming step of the battery manufacturing method described above, the protrusion of the separator wound as an electrode body is heated, and the separator main body is thermally contracted to form the liquid retention reduced part. In addition, when a separator having a separator body and a heat-resistant layer is heated, the separator body largely heat shrinks, so that it is possible to easily form a liquid retainability lowering portion that is bent toward the separator body and covers the other end face. .

なお、セパレータ本体を熱収縮させて液保持性低下部を形成する手法としては、例えば、加熱した２枚の金属板を用いて、セパレータの突出部を加熱し熱収縮させて形成する手法や、ヒータ等の加熱装置を、電極体の他方側から正極板（正極箔）の端部に接触させて正極箔を加熱し、他方側から徐々に加熱された正極箔によって、正極板同士間に位置するセパレータの突出部を間接的に加熱し熱収縮させて形成する手法も挙げられる。また、ヒータ等の加熱装置で、正極箔を挟んでこれを加熱して、間接的に突出部を加熱し熱収縮させて形成する手法も挙げられる。さらに、負極外周部の外周部端面を覆う熱収縮部を形成する場合には、電極体の径方向外側から加熱装置をセパレータの突出部に当接させて、これを加熱し熱収縮させる手法が挙げられる。   In addition, as a method of forming the liquid retention reduced portion by thermally shrinking the separator body, for example, using a heated two metal plate, a method of forming the separator protrusion by heating and shrinking, A heating device such as a heater is brought into contact with the end of the positive electrode plate (positive electrode foil) from the other side of the electrode body to heat the positive electrode foil, and the positive electrode foil gradually heated from the other side is positioned between the positive electrode plates. There is also a method in which the protruding portion of the separator to be formed is indirectly heated and thermally contracted. In addition, there is also a method in which a positive electrode foil is sandwiched and heated by a heating device such as a heater, and the protrusion is indirectly heated and thermally contracted. Furthermore, in the case of forming a heat-shrinkable portion covering the outer peripheral end face of the negative electrode outer peripheral portion, there is a method in which a heating device is brought into contact with the protruding portion of the separator from the radially outer side of the electrode body, and this is heated and thermally contracted. Can be mentioned.

従来の電池にかかり、捲回型の電極体における、充電時の正極板から負極板へのリチウムイオンの移動を示す説明図である。It is explanatory drawing which shows the movement of the lithium ion from the positive electrode plate at the time of charge in the winding type electrode body concerning a conventional battery at the time of charge. 従来の電池にかかり、充電時の負極活物質層内及び負極活物質層間におけるリチウムイオンの拡散移動を示す説明図である。It is explanatory drawing which shows the diffusion movement of the lithium ion in the negative electrode active material layer at the time of charge concerning the conventional battery, and between negative electrode active material layers. 従来の電池にかかり、負極活物質層における、電位の分布を示す説明図である。It is explanatory drawing which shows the distribution of the electric potential in the negative electrode active material layer concerning the conventional battery. 実施形態にかかる電池の斜視図である。It is a perspective view of the battery concerning an embodiment. 実施形態にかかる電池に用いる正極板の斜視図である。It is a perspective view of the positive electrode plate used for the battery concerning an embodiment. 実施形態にかかる電池に用いる負極板の斜視図である。It is a perspective view of the negative electrode plate used for the battery concerning an embodiment. 実施形態にかかる電池の断面図（図４のＣ−Ｃ矢視断面図）である。It is sectional drawing (CC sectional view taken on the line of FIG. 4) of the battery concerning embodiment. 実施形態にかかる電池における電極体のうち外側部分の部分拡大断面図（図７のＤ−Ｄ断面）である。It is a partial expanded sectional view (DD section of Drawing 7) of an outside portion among electrode bodies in a battery concerning an embodiment. 実施形態にかかる電池における電極体のうち内側部分の部分拡大断面図（図７のＤ−Ｄ断面）である。It is the elements on larger scale of the inner part among the electrode bodies in the battery concerning embodiment (DD section of Drawing 7). 実施形態にかかる電池の製造方法の説明図（電極体作製工程に用いる形成前セパレータの斜視図）である。It is explanatory drawing (the perspective view of the separator before formation used for an electrode body production process) of the manufacturing method of the battery concerning embodiment. 実施形態にかかる電池の製造方法のうち、電極体作製工程の説明図である。It is explanatory drawing of an electrode body preparation process among the manufacturing methods of the battery concerning embodiment. 実施形態にかかる電池の製造方法のうち、低下部形成工程の説明図である。It is explanatory drawing of a fall part formation process among the manufacturing methods of the battery concerning embodiment. 実施形態にかかる電池の製造方法のうち、低下部形成工程の説明図である。It is explanatory drawing of a fall part formation process among the manufacturing methods of the battery concerning embodiment.

次に、本発明の実施形態について、図面を参照しつつ説明する。
まず、本実施形態にかかる電池１について、図４を参照して説明する。
この電池１は、いずれも長手方向ＤＡに延びる帯状の正極板３０と負極板４０とを帯状の２枚のセパレータ２０Ｘ，２０Ｙを介して捲回した捲回型の電極体１０、及び、セパレータ２０に含浸された電解液５０を備えるリチウムイオン二次電池である（図４参照）。この電池１は、さらにこれら電極体１０，電解液５０のほか、電極体１０及び電解液５０を内部に収容する電池ケース８０と、正極集電部材９１と負極集電部材９２とを備える（図４参照）。このうち、アルミニウム製でクランク状に屈曲した板状の正極集電部材９１は、電極体１０をなす正極板３０の正極リード部３９（後述）と接合している。また、銅製でクランク状に屈曲した板状の負極集電部材９２は、電極体１０をなす負極板４０の負極リード部４９（後述）と接合している。 Next, embodiments of the present invention will be described with reference to the drawings.
First, the battery 1 according to the present embodiment will be described with reference to FIG.
The battery 1 includes a wound electrode body 10 in which a belt-like positive electrode plate 30 and a negative electrode plate 40 both extending in the longitudinal direction DA are wound through two belt-like separators 20X and 20Y, and the separator 20 It is a lithium ion secondary battery provided with the electrolyte solution 50 impregnated in (see FIG. 4). In addition to the electrode body 10 and the electrolytic solution 50, the battery 1 further includes a battery case 80 that accommodates the electrode body 10 and the electrolytic solution 50 therein, and a positive current collecting member 91 and a negative current collecting member 92 (see FIG. 4). Among these, a plate-like positive electrode current collector 91 made of aluminum and bent in a crank shape is joined to a positive electrode lead portion 39 (described later) of the positive electrode plate 30 constituting the electrode body 10. A plate-shaped negative electrode current collector 92 made of copper and bent in a crank shape is joined to a negative electrode lead portion 49 (described later) of the negative electrode plate 40 constituting the electrode body 10.

また、電池ケース８０は、いずれもアルミニウム製の電池ケース本体８１及び封口蓋８２を有する。このうち電池ケース本体８１は有底矩形箱形であり、この電池ケース８０と電極体１０との間には、樹脂からなり、箱状に折り曲げた絶縁フィルム（図示しない）が介在させてある。また、封口蓋８２は矩形板状であり、電池ケース本体８１の開口を閉塞して、この電池ケース本体８１に溶接されている。この封口蓋８２には、正極集電部材９１及び負極集電部材９２のうち、それぞれ先端に位置する正極端子部９１Ａ及び負極端子部９２Ａが貫通しており、図４中、上方に向く蓋表面８２ａから突出している。これら正極端子部９１Ａ及び負極端子部９２Ａと封口蓋８２との間には、それぞれ絶縁性の樹脂からなる絶縁部材９５が介在し、互いを絶縁している。さらに、この封口蓋８２には矩形板状の安全弁９７も封着されている。   The battery case 80 includes an aluminum battery case body 81 and a sealing lid 82. Among these, the battery case main body 81 has a bottomed rectangular box shape, and an insulating film (not shown) made of a resin and bent into a box shape is interposed between the battery case 80 and the electrode body 10. The sealing lid 82 has a rectangular plate shape, closes the opening of the battery case body 81, and is welded to the battery case body 81. Of the positive electrode current collecting member 91 and the negative electrode current collecting member 92, the positive electrode terminal portion 91A and the negative electrode terminal portion 92A, which are located at the tips, pass through the sealing lid 82, and the lid surface facing upward in FIG. Projecting from 82a. Insulating members 95 made of insulating resin are interposed between the positive electrode terminal portion 91A and the negative electrode terminal portion 92A and the sealing lid 82 to insulate each other. Further, a rectangular plate-shaped safety valve 97 is also sealed on the sealing lid 82.

また、電解液５０は、エチレンカーボネート（ＥＣ）とジエチルカーボネート（ＤＥＣ）とエチルメチルカーボネート（ＥＭＣ）を、体積比でＥＣ：ＤＥＣ：ＥＭＣ＝３：３：４に調整した混合有機溶媒に、溶質としてＬｉＰＦ6を添加し、リチウムイオンを１ｍｏｌ／ｌの濃度とした非水電解液である。 The electrolytic solution 50 is a solute in a mixed organic solvent in which ethylene carbonate (EC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) are adjusted to a volume ratio of EC: DEC: EMC = 3: 3: 4. LiPF 6 is added as a nonaqueous electrolyte solution with a lithium ion concentration of 1 mol / l.

また、電極体１０は、正極板３０及び負極板４０が、２枚のセパレータ２０Ｘ，２０Ｙを介して、捲回軸ＡＸの周りを扁平形状に捲回された形態である（図４，７参照）。
電極体１０をなす正極板３０は、図５の斜視図に示すように、長手方向ＤＡに延びる帯状で、アルミニウム製の正極箔３８と、この正極箔３８の両主面３８Ｆ、３８Ｆ上にそれぞれ形成された２つの正極活物質層３１，３１とを有している。なお、正極板３０を捲回した電極体１０において、正極板３０の幅方向は、電極体１０の捲回軸ＡＸに沿う軸線方向ＤＸと一致する。そこで、以下では、正極板３０について、その幅方向に代えて軸線方向ＤＸを用いて説明する。 The electrode body 10 has a configuration in which the positive electrode plate 30 and the negative electrode plate 40 are wound in a flat shape around the winding axis AX via two separators 20X and 20Y (see FIGS. 4 and 7). ).
As shown in the perspective view of FIG. 5, the positive electrode plate 30 constituting the electrode body 10 has a strip shape extending in the longitudinal direction DA, and is formed on an aluminum positive electrode foil 38 and both main surfaces 38F and 38F of the positive electrode foil 38. The two positive electrode active material layers 31 and 31 are formed. In the electrode body 10 wound with the positive electrode plate 30, the width direction of the positive electrode plate 30 coincides with the axial direction DX along the winding axis AX of the electrode body 10. Therefore, in the following, the positive electrode plate 30 will be described using the axial direction DX instead of the width direction.

この正極板３０は、正極箔３８の軸線方向ＤＸの他方側ＤＸ２（図５中、左上側）に位置し、この正極箔３８の両主面３８Ｆ，３８Ｆが露出した正極リード部３９を有している（図５参照）。
逆に、正極板３０の正極活物質層３１は、正極箔３８（両主面３８Ｆ，３８Ｆ）上の軸線方向ＤＸの一方側ＤＸ１（図５中、右下側）に配置されている。この正極活物質層３１は、ＬｉＮｉ1/3Ｃｏ1/3Ｍｎ1/3Ｏ2からなる正極活物質粒子（図示しない）と、アセチレンブラックからなる導電材（図示しない）と、ポリフッ化ビニリデン（ＰＶＤＦ）からなる結着材（図示しない）とを含む。 The positive electrode plate 30 is located on the other side DX2 (upper left side in FIG. 5) of the positive electrode foil 38 in the axial direction DX, and has a positive electrode lead portion 39 in which both main surfaces 38F and 38F of the positive electrode foil 38 are exposed. (See FIG. 5).
Conversely, the positive electrode active material layer 31 of the positive electrode plate 30 is arranged on one side DX1 (lower right side in FIG. 5) in the axial direction DX on the positive electrode foil 38 (both main surfaces 38F, 38F). The positive electrode active material layer 31 includes positive electrode active material particles (not shown) made of LiNi 1/3 Co 1/3 Mn 1/3 O 2, a conductive material (not shown) made of acetylene black, polyvinylidene fluoride ( And a binder (not shown) made of PVDF.

なお、電極体１０において、正極板３０は、このうち、径方向ＤＲの外側ＤＲ１（図８中、上方）の最外周に位置する正極最外周部３０Ｓと、径方向ＤＲの内側ＤＲ２（図９中、下方）の最内周に位置する正極最内周部３０Ｔと、これら正極最外周部３０Ｓと正極最内周部３０Ｔとの間に位置する正極中間部３０Ｕとに分けられる（図８，９参照）。このうち、正極最外周部３０Ｓは、第２セパレータ２０Ｙ（このうち後述する第２セパレータ外周部２０ＹＳ）を介して径方向ＤＲの外側ＤＲ１から負極板４０（このうち後述する負極外周部４０Ｓ）に覆われている。また、正極最内周部３０Ｔは、第１セパレータ２０Ｘ（このうち後述する第１セパレータ内周部２０ＸＴ）を介して径方向ＤＲの内側から負極板４０（このうち後述する負極内周部４０Ｔ）に覆われている。   In addition, in the electrode body 10, the positive electrode plate 30 includes a positive electrode outermost peripheral portion 30S located on the outermost periphery of the outer side DR1 in the radial direction DR (upward in FIG. 8) and an inner side DR2 in the radial direction DR (FIG. 9). The innermost positive electrode innermost portion 30T located in the innermost and lowermost inner periphery, and the positive electrode intermediate portion 30U located between the outermost positive electrode outer peripheral portion 30S and the innermost positive electrode inner peripheral portion 30T (FIG. 8, 9). Among these, the positive electrode outermost peripheral portion 30S passes from the outer side DR1 in the radial direction DR to the negative electrode plate 40 (of which the negative electrode outer peripheral portion 40S described later) via the second separator 20Y (the second separator outer peripheral portion 20YS described later). Covered. The positive innermost peripheral portion 30T is connected to the negative electrode plate 40 (the negative inner peripheral portion 40T described later) from the inside in the radial direction DR through the first separator 20X (the first separator inner peripheral portion 20XT described below). Covered with

また、負極板４０は、図６の斜視図に示すように、長手方向ＤＡに延びる帯状で、銅製の負極箔４８と、この負極箔４８の両主面４８Ｆ、４８Ｆ上にそれぞれ形成された２つの負極活物質層４１，４１とを有している。なお、負極板４０を捲回した電極体１０において、負極板の幅方向もまた、前述した正極板３０と同様、電極体１０の軸線方向ＤＸと一致する。そこで、以下では、負極板４０についても、その幅方向に代えて軸線方向ＤＸを用いて説明する。   Further, as shown in the perspective view of FIG. 6, the negative electrode plate 40 has a strip shape extending in the longitudinal direction DA, and is formed on the copper negative electrode foil 48 and the two main surfaces 48F and 48F of the negative electrode foil 48, respectively. Two negative electrode active material layers 41, 41. In the electrode body 10 in which the negative electrode plate 40 is wound, the width direction of the negative electrode plate also coincides with the axial direction DX of the electrode body 10 as in the positive electrode plate 30 described above. Therefore, hereinafter, the negative electrode plate 40 will also be described using the axial direction DX instead of the width direction.

この負極板４０は、負極箔４８の軸線方向ＤＸの一方側ＤＸ１に位置し、この負極箔４８の両主面４８Ｆ，４８Ｆが露出した負極リード部４９を有している（図６参照）。
逆に、負極板４０の負極活物質層４１は、負極箔４８（両主面４８Ｆ，４８Ｆ）上の軸線方向ＤＸの他方側ＤＸ２に配置されている。この負極活物質層４１は、黒鉛からなる負極活物質粒子（図示しない）、及び、スチレンブタジエンゴム（ＳＢＲ）からなる結着材（図示しない）を含む。 The negative electrode plate 40 is located on one side DX1 of the negative electrode foil 48 in the axial direction DX, and has a negative electrode lead portion 49 in which both main surfaces 48F and 48F of the negative electrode foil 48 are exposed (see FIG. 6).
Conversely, the negative electrode active material layer 41 of the negative electrode plate 40 is disposed on the other side DX2 in the axial direction DX on the negative electrode foil 48 (both main surfaces 48F, 48F). The negative electrode active material layer 41 includes negative electrode active material particles (not shown) made of graphite and a binder (not shown) made of styrene butadiene rubber (SBR).

なお、本実施例１では、負極活物質層４１は、長手方向ＤＡ及び軸線方向ＤＸの寸法が、正極活物質層３１に比してそれぞれ大きくされている。このため、図６，８に示すように、負極活物質層４１は、セパレータ２０Ｘ（２０Ｙ）を介して正極活物質層３１に対向する対向部４２と、この対向部４２の軸線方向一方側ＤＸ１に隣在し、正極活物質層３１に対向しない一方側非対向部４３と、対向部４２の軸線方向他方側ＤＸ２に隣在し、正極活物質層３１に対向しない他方側非対向部４４とを含む。さらに、この負極活物質層４１は、上述の対向部４２、一方側非対向部４３及び他方側非対向部４４よりも長手方向ＤＡの外側で、電極体１０において径方向内側に位置する内側部４５と、電極体１０において径方向外側に位置する外側部４６とを含む（図６参照）。
つまり、負極活物質層４１では、対向部４２が、負極活物質層４１の、長手方向ＤＡ及び軸線方向ＤＸのそれぞれ中央に位置し、一方側非対向部４３、他方側非対向部４４、内側部４５及び外側部４６が、対向部４２の周囲に枠状に位置している（図６参照）。但し、負極活物質層４１における対向部４２、一方側非対向部４３、他方側非対向部４４、内側部４５及び外側部４６の境界は、負極板４０、２枚のセパレータ２０Ｘ，２０Ｙ及び正極板３０を捲回して電極体１０を作製したときに定まる。 In Example 1, the negative electrode active material layer 41 has the dimensions in the longitudinal direction DA and the axial direction DX larger than those of the positive electrode active material layer 31. Therefore, as shown in FIGS. 6 and 8, the negative electrode active material layer 41 includes a facing portion 42 that faces the positive electrode active material layer 31 through the separator 20X (20Y), and one axial direction DX1 of the facing portion 42. Adjacent to the positive electrode active material layer 31 and the other non-facing portion 44 adjacent to the other side DX2 in the axial direction of the opposing portion 42 and not facing the positive electrode active material layer 31. including. Further, the negative electrode active material layer 41 is an inner portion located on the radially inner side in the electrode body 10 on the outer side in the longitudinal direction DA than the above-described facing portion 42, one side non-facing portion 43, and the other side non-facing portion 44. 45 and an outer portion 46 positioned radially outward in the electrode body 10 (see FIG. 6).
That is, in the negative electrode active material layer 41, the facing portion 42 is located in the center of each of the longitudinal direction DA and the axial direction DX of the negative electrode active material layer 41, and the one side non-facing portion 43, the other side non-facing portion 44, and the inside The part 45 and the outer part 46 are located in a frame shape around the facing part 42 (see FIG. 6). However, the boundaries of the facing portion 42, the one-side non-facing portion 43, the other-side non-facing portion 44, the inner portion 45 and the outer portion 46 in the negative electrode active material layer 41 are the negative electrode plate 40, the two separators 20X and 20Y, and the positive electrode. It is determined when the electrode body 10 is produced by winding the plate 30.

また、図６に示すように、負極箔４８及び２つの負極活物質層４１，４１は、他方側ＤＸ２の端縁が切断によって形成されており、共通の他方側端面４０Ｐをなしている。この他方側端面４０Ｐに電解液５０が付着すると、負極箔４８を挟んで２つの負極活物質層４１，４１の間で、電解液５０を通じた液絡が生じる。   Further, as shown in FIG. 6, the negative electrode foil 48 and the two negative electrode active material layers 41, 41 are formed by cutting the edge of the other side DX2 to form a common other side end face 40P. When the electrolytic solution 50 adheres to the other end face 40P, a liquid junction through the electrolytic solution 50 is generated between the two negative electrode active material layers 41 and 41 with the negative electrode foil 48 interposed therebetween.

なお、電極体１０において、負極板４０は、このうち、第２セパレータ２０Ｙを介して径方向ＤＲの外側ＤＲ１から前述の正極最外周部３０Ｓに対向する負極外周部４０Ｓと、第１セパレータ２０Ｘを介して径方向ＤＲの内側ＤＲ２から前述の正極最内周部３０Ｔに対向する負極内周部４０Ｔと、これら負極外周部４０Ｓと負極内周部４０Ｔとの間に位置する負極中間部４０Ｕとを有する（図８，９参照）。
このうち、負極外周部４０Ｓは、２層の負極活物質層４１，４１のうち、正極最外周部３０Ｓの正極活物質層３１に対向する第１外周活物質層４１ＳＨと、この第１外周活物質層４１ＳＨよりも径方向外側ＤＲ１に位置し、第１セパレータ２０Ｘ（後述する第１セパレータ外周部２０ＸＳ）を介して正極活物質層とは対向していない第２外周活物質層４１ＳＪとを有する（図８参照）。このうち、第１外周活物質層４１ＳＨは、正極活物質層３１に対向する対向部４２ＳＨと、この対向部４２ＳＨの一方側ＤＸ１に隣在し、正極活物質層３１に対向しない一方側非対向部４３ＳＨと、対向部４２ＳＨの他方側ＤＸ２に隣在し、正極活物質層３１に対向しない他方側非対向部４４ＳＨとを含む。 In the electrode body 10, the negative electrode plate 40 includes a negative electrode outer peripheral portion 40S facing the positive outermost peripheral portion 30S from the outer side DR1 in the radial direction DR via the second separator 20Y, and the first separator 20X. A negative electrode inner peripheral portion 40T opposed to the positive electrode innermost peripheral portion 30T from the inner side DR2 in the radial direction DR, and a negative electrode intermediate portion 40U positioned between the negative electrode outer peripheral portion 40S and the negative electrode inner peripheral portion 40T. (See FIGS. 8 and 9).
Among these, the negative electrode outer peripheral portion 40S includes a first outer peripheral active material layer 41SH facing the positive electrode active material layer 31 of the positive electrode outermost peripheral portion 30S among the two negative electrode active material layers 41 and 41, and the first outer peripheral active material layer 41SH. It has a second outer peripheral active material layer 41SJ that is located on the radially outer side DR1 from the material layer 41SH and is not opposed to the positive electrode active material layer via the first separator 20X (first separator outer peripheral portion 20XS described later). (See FIG. 8). Among these, the first outer peripheral active material layer 41SH is adjacent to the facing portion 42SH facing the positive electrode active material layer 31 and one side DX1 of the facing portion 42SH, and does not face the positive electrode active material layer 31. Part 43SH and the other side non-facing part 44SH that is adjacent to the other side DX2 of the facing part 42SH and does not face the positive electrode active material layer 31.

一方、負極内周部４０Ｔは、２層の負極活物質層４１，４１のうち、正極最内周部３０Ｔの正極活物質層３１に対向する第１内周活物質層４１ＴＨと、この第１内周活物質層４１ＴＨよりも径方向内側ＤＲ２に位置し、第２セパレータ２０Ｙ（後述する第２セパレータ内周部２０ＹＴ）を介して正極活物質層とは対向していない第２内周活物質層４１ＴＪとを有する（図９参照）。このうち、第１内周活物質層４１ＴＨは、正極活物質層３１に対向する対向部４２ＴＨと、この対向部４２ＴＨの一方側ＤＸ１に隣在し、正極活物質層３１に対向しない一方側非対向部４３ＴＨと、対向部４２ＴＨの他方側ＤＸ２に隣在し、正極活物質層３１に対向しない他方側非対向部４４ＴＨとを含む。   On the other hand, the negative electrode inner peripheral portion 40T includes a first inner peripheral active material layer 41TH facing the positive electrode active material layer 31 of the positive innermost peripheral portion 30T of the two negative electrode active material layers 41 and 41, and the first inner peripheral active material layer 41TH. The second inner peripheral active material that is located on the radially inner side DR2 from the inner peripheral active material layer 41TH and is not opposed to the positive electrode active material layer via the second separator 20Y (second separator inner peripheral portion 20YT described later). Layer 41TJ (see FIG. 9). Among these, the first inner peripheral active material layer 41TH is adjacent to the facing portion 42TH facing the positive electrode active material layer 31 and one side DX1 of the facing portion 42TH, and is not on one side not facing the positive electrode active material layer 31. It includes a facing portion 43TH and a second non-facing portion 44TH that is adjacent to the other side DX2 of the facing portion 42TH and does not face the positive electrode active material layer 31.

なお、電極体１０において、負極板４０の他方側端面４０Ｐのうち、負極外周部４０Ｓに属する外周部端面４０ＳＰは、後述する第１熱収縮部２６ＸＳ，第２熱収縮部２６ＹＳで覆われている。また、負極内周部４０Ｔに属する内周部端面４０ＴＰは、後述する第１熱収縮部２６ＸＴ，第２熱収縮部２６ＹＴで覆われている（図８，９参照）。これに対し、負極中間部４０Ｕに属する中間部端面４０ＵＰは、電極体１０の他方側ＤＸ２に露出している（図８参照）。   In the electrode body 10, the outer peripheral end surface 40SP belonging to the negative electrode outer peripheral portion 40S among the other end surface 40P of the negative electrode plate 40 is covered with a first heat contraction portion 26XS and a second heat contraction portion 26YS described later. . Further, the inner peripheral end face 40TP belonging to the negative electrode inner peripheral portion 40T is covered with a first heat shrinkable portion 26XT and a second heat shrinkable portion 26YT described later (see FIGS. 8 and 9). On the other hand, the intermediate portion end face 40UP belonging to the negative electrode intermediate portion 40U is exposed on the other side DX2 of the electrode body 10 (see FIG. 8).

一方、２枚のセパレータ２０Ｘ，２０Ｙは、多孔質の樹脂からなるセパレータ本体２０Ａと、このセパレータ本体２０Ａの片方の主面２０ＡＦ上に形成された耐熱層２０Ｂとを有する。このうち、セパレータ本体２０Ａは、ポリプロピレン（ＰＰ）製の２枚の多孔質状フィルムの間にポリエチレン（ＰＥ）製の１枚の多孔質状フィルムを重ね合わせた３層構造である。一方、耐熱層２０Ｂは、アルミナからなる無機粒子（図示しない）と結着材（図示しない）とを含む。   On the other hand, the two separators 20X and 20Y have a separator body 20A made of porous resin and a heat-resistant layer 20B formed on one main surface 20AF of the separator body 20A. Among these, the separator main body 20A has a three-layer structure in which one porous film made of polyethylene (PE) is overlapped between two porous films made of polypropylene (PP). On the other hand, the heat-resistant layer 20B includes inorganic particles (not shown) made of alumina and a binder (not shown).

なお、２枚のセパレータ２０Ｘ，２０Ｙのうち、電極体１０において負極板４０の径方向外側ＤＲ１に位置する第１セパレータ２０Ｘは、負極外周部４０Ｓの径方向外側ＤＲ１に位置する第１セパレータ外周部２０ＸＳと、負極内周部４０Ｔの径方向外側ＤＲ１に位置する第１セパレータ内周部２０ＸＴと、これら第１セパレータ外周部２０ＸＳと第１セパレータ内周部２０ＸＴとの間に位置する第１セパレータ中間部２０ＸＵとに分けられる。なお、この第１セパレータ２０Ｘは、負極板４０側、即ち径方向内側ＤＲ２に、セパレータ本体２０Ａが位置し、耐熱層２０Ｂが一方側ＤＸ１に位置する形態に配置されている。
また、２枚のセパレータ２０Ｘ，２０Ｙのうち、電極体１０において負極板４０の径方向内側ＤＲ２に位置する第２セパレータ２０Ｙは、負極外周部４０Ｓの径方向内側ＤＲ２に位置する第２セパレータ外周部２０ＹＳと、負極内周部４０Ｔの径方向内側ＤＲ２に位置する第２セパレータ内周部２０ＹＴと、これら第２セパレータ外周部２０ＹＳと第２セパレータ内周部２０ＹＴとの間に位置する第２セパレータ中間部２０ＹＵとに分けられる。なお、この第２セパレータ２０Ｙは、負極板４０側、即ち径方向外側ＤＲ１に、セパレータ本体２０Ａが位置し、耐熱層２０Ｂが他方側ＤＸ２に位置する形態に配置されている。 Of the two separators 20X and 20Y, the first separator 20X located on the radial outer side DR1 of the negative electrode plate 40 in the electrode body 10 is the first separator outer peripheral part located on the radial outer side DR1 of the negative electrode outer peripheral part 40S. 20XS, the 1st separator inner peripheral part 20XT located in radial direction outer side DR1 of the negative electrode inner peripheral part 40T, and the 1st separator intermediate | middle located between these 1st separator outer peripheral part 20XS and 1st separator inner peripheral part 20XT It is divided into 20XU. The first separator 20X is arranged in such a manner that the separator body 20A is located on the negative electrode plate 40 side, that is, on the radially inner side DR2, and the heat-resistant layer 20B is located on the one side DX1.
Of the two separators 20X and 20Y, the second separator 20Y located on the radial inner side DR2 of the negative electrode plate 40 in the electrode body 10 is the second separator outer circumferential part located on the radial inner side DR2 of the negative electrode outer circumferential part 40S. 20YS, the second separator inner peripheral portion 20YT located on the radially inner side DR2 of the negative electrode inner peripheral portion 40T, and the second separator intermediate portion located between the second separator outer peripheral portion 20YS and the second separator inner peripheral portion 20YT. And 20YU. The second separator 20Y is arranged in such a manner that the separator body 20A is located on the negative electrode plate 40 side, that is, the radially outer side DR1, and the heat-resistant layer 20B is located on the other side DX2.

このうち、第１セパレータ２０Ｘの第１セパレータ中間部２０ＸＵは、正極活物質層３１とこの正極活物質層３１に対向する負極活物質層４１の対向部４２との間に介在する介在部２２ＸＵと、この介在部２２ＸＵから軸線方向ＤＸの一方側ＤＸ１に延出する一方側延出部２３ＸＵと、介在部２２ＸＵから他方側ＤＸ２に延出する他方側延出部２４ＸＵとからなる（図８参照）。なお、これら介在部２２ＸＵ、一方側延出部２３ＸＵ及び他方側延出部２４ＸＵは、前述した多孔質のセパレータ本体２０Ａ及び耐熱層２０Ｂからなり、電解液５０を十分に保持できる。
第２セパレータ２０Ｙの第２セパレータ中間部２０ＹＵもまた、第１セパレータ中間部２０ＸＵと同様、正極活物質層３１と負極活物質層４１の対向部４２との間に介在する介在部２２ＹＵと、この介在部２２ＹＵから一方側ＤＸ１に延出する一方側延出部２３ＹＵと、他方側ＤＸ２に延出する他方側延出部２４ＹＵとからなる（図８参照）。なお、これら介在部２２ＹＵ、一方側延出部２３ＹＵ及び他方側延出部２４ＹＵもまた、第１セパレータ中間部２０ＸＵと同様に、多孔質のセパレータ本体２０Ａ及び耐熱層２０Ｂからなり、電解液５０を十分に保持できる。 Among these, the first separator intermediate portion 20XU of the first separator 20X includes an intervening portion 22XU interposed between the positive electrode active material layer 31 and the facing portion 42 of the negative electrode active material layer 41 facing the positive electrode active material layer 31. The one-side extension 23XU extending from the interposition part 22XU to the one side DX1 in the axial direction DX and the other-side extension part 24XU extending from the interposition part 22XU to the other side DX2 (see FIG. 8). . In addition, these interposition part 22XU, the one side extension part 23XU, and the other side extension part 24XU consist of the porous separator main body 20A and the heat-resistant layer 20B mentioned above, and can fully hold the electrolyte solution 50.
Similarly to the first separator intermediate portion 20XU, the second separator intermediate portion 20YU of the second separator 20Y also includes an intervening portion 22YU interposed between the positive electrode active material layer 31 and the facing portion 42 of the negative electrode active material layer 41. It consists of one side extension part 23YU extending from the interposition part 22YU to one side DX1, and the other side extension part 24YU extending to the other side DX2 (see FIG. 8). The intervening portion 22YU, the one-side extending portion 23YU, and the other-side extending portion 24YU are also composed of a porous separator body 20A and a heat-resistant layer 20B in the same manner as the first separator intermediate portion 20XU. Can hold enough.

一方、第１セパレータ２０Ｘの第１セパレータ外周部２０ＸＳは、セパレータ本体２０Ａ及び耐熱層２０Ｂからなる第１本体部２５ＸＳと、この第１本体部２５ＸＳの軸線方向他方側ＤＸ２に位置し、耐熱層２０Ｂ、及び、セパレータ本体２０Ａをなす樹脂が熱収縮した収縮セパレータ本体２０Ｃからなる第１熱収縮部２６ＸＳとからなる（図８参照）。第１熱収縮部２６ＸＳをなす収縮セパレータ本体２０Ｃは、第１本体部２５ＸＳのセパレータ本体２０Ａよりも空孔率が低くなっているため、例えば、前述した第１セパレータ中間部２０ＸＵの介在部２２ＸＵなど、セパレータ本体２０Ａを有する第１セパレータ２０Ｘの部位よりも、第１熱収縮部２６ＸＳでは電解液５０の保持性が低くなっている。   On the other hand, the first separator outer peripheral portion 20XS of the first separator 20X is located on the first main body portion 25XS composed of the separator main body 20A and the heat-resistant layer 20B and the other axial side DX2 of the first main body portion 25XS, and the heat-resistant layer 20B. And a first heat shrinking portion 26XS comprising a shrinking separator body 20C in which the resin constituting the separator body 20A is heat-shrinked (see FIG. 8). Since the shrinkage separator main body 20C forming the first heat shrinkable portion 26XS has a lower porosity than the separator main body 20A of the first main body portion 25XS, for example, the interposition portion 22XU of the first separator intermediate portion 20XU described above, etc. The retention of the electrolytic solution 50 is lower in the first heat contraction portion 26XS than in the portion of the first separator 20X having the separator body 20A.

また、第２セパレータ２０Ｘの第２セパレータ外周部２０ＹＳは、セパレータ本体２０Ａ及び耐熱層２０Ｂからなる第２本体部２５ＹＳと、この第２本体部２５ＹＳの軸線方向他方側ＤＸ２に位置し、耐熱層２０Ｂ、及び、上述した収縮セパレータ本体２０Ｃからなる第２熱収縮部２６ＹＳとからなる（図８参照）。このうち、第２本体部２５ＹＳは、正極最外周部３０Ｓの正極活物質層３１と、この正極活物質層３１に対向する、負極外周部４０Ｓの第１外周活物質層４１ＳＨの対向部４２ＳＨとの間に介在する介在部２２ＹＳを含む形態である。
第２熱収縮部２６ＹＳをなす収縮セパレータ本体２０Ｃも、第２本体部２５ＹＳのセパレータ本体２０Ａよりも空孔率が低くなっているため、第２本体部２５ＹＳに含む介在部２２ＹＳよりも、第２熱収縮部２６ＹＳでは電解液５０の保持性が低くなっている。 Further, the second separator outer peripheral portion 20YS of the second separator 20X is positioned on the second main body portion 25YS composed of the separator main body 20A and the heat resistant layer 20B and the other axial side DX2 of the second main body portion 25YS, and the heat resistant layer 20B. And the second heat shrink part 26YS comprising the shrink separator body 20C described above (see FIG. 8). Among these, the second main body portion 25YS includes a positive electrode active material layer 31 of the positive electrode outermost peripheral portion 30S and a facing portion 42SH of the first outer peripheral active material layer 41SH of the negative electrode outer peripheral portion 40S facing the positive electrode active material layer 31. It is a form including the interposition part 22YS intervening between.
The shrinkage separator body 20C forming the second heat shrinkage part 26YS also has a lower porosity than the separator body 20A of the second body part 25YS, so that the second separator part 20YS is second than the interposition part 22YS included in the second body part 25YS. In the heat shrink part 26YS, the retainability of the electrolyte solution 50 is low.

なお、図８に示すように、第１セパレータ外周部２０ＸＳの第１熱収縮部２６ＸＳと、第２セパレータ外周部２０ＹＳの第２熱収縮部２６ＹＳとは、負極外周部４０Ｓの外周部端面４０ＳＰよりも他方側ＤＸ２で互いに接合している。具体的には、第１熱収縮部２６ＸＳをなす収縮セパレータ本体２０Ｃと、第２熱収縮部２６ＹＳをなす収縮セパレータ本体２０Ｃとは、熱収縮すると共に互いに溶着している。これにより、外周部端面４０ＳＰは、第１セパレータ外周部２０ＸＳの第１熱収縮部２６ＸＳ、及び、第２セパレータ外周部２０ＹＳの第２熱収縮部２６ＹＳで覆われている。   As shown in FIG. 8, the first heat contraction portion 26XS of the first separator outer peripheral portion 20XS and the second heat contraction portion 26YS of the second separator outer peripheral portion 20YS are from the outer peripheral end surface 40SP of the negative electrode outer peripheral portion 40S. Are joined to each other on the other side DX2. Specifically, the shrink separator body 20C forming the first heat shrink portion 26XS and the shrink separator body 20C forming the second heat shrink portion 26YS are thermally contracted and welded to each other. Thereby, the outer peripheral end surface 40SP is covered with the first heat shrinking part 26XS of the first separator outer peripheral part 20XS and the second heat shrinking part 26YS of the second separator outer peripheral part 20YS.

なお、本実施形態の電池１では、負極外周部４０Ｓの外周部端面４０ＳＰのみならず、負極外周部４０Ｓのうち他方側ＤＸ２の端部も、第１熱収縮部２６ＸＳ及び第２熱収縮部２６ＹＳで覆われている（図８参照）。
但し、第１熱収縮部２６ＸＳ及び第２熱収縮部２６ＹＳの形態としては、負極外周部４０Ｓの外周部端面４０ＳＰのみを覆う形態としても良い。また、外周部端面４０ＳＰのほか第１外周活物質層４１ＳＨの他方側非対向部４４ＳＨ全体を第２熱収縮部２６ＹＳで覆う形態としても良い。 In the battery 1 of the present embodiment, not only the outer peripheral end surface 40SP of the negative electrode outer peripheral portion 40S but also the end portion on the other side DX2 of the negative electrode outer peripheral portion 40S is not limited to the first heat contraction portion 26XS and the second heat contraction portion 26YS. (See FIG. 8).
However, as a form of the 1st heat contraction part 26XS and the 2nd heat contraction part 26YS, it is good also as a form which covers only the outer peripheral part end surface 40SP of the negative electrode outer peripheral part 40S. Moreover, it is good also as a form which covers the whole other side non-facing part 44SH of 1st outer periphery active material layer 41SH other than outer peripheral part end surface 40SP with the 2nd heat contraction part 26YS.

また、第１セパレータ２０Ｘの第１セパレータ内周部２０ＸＴは、セパレータ本体２０Ａ及び耐熱層２０Ｂからなる第１本体部２５ＸＴと、この第１本体部２５ＸＴの軸線方向他方側ＤＸ２に位置し、耐熱層２０Ｂ及び前述した収縮セパレータ本体２０Ｃからなる第１熱収縮部２６ＸＴとからなる（図９参照）。このうち、第１本体部２５ＸＴは、正極最内周部３０Ｔの正極活物質層３１と、この正極活物質層３１に対向する、負極内周部４０Ｔの第１内周活物質層４１ＴＨの対向部４２ＴＨとの間に介在する介在部２２ＸＴを含む形態である。
第１熱収縮部２６ＸＴをなす収縮セパレータ本体２０Ｃも、第１本体部２５ＸＴのセパレータ本体２０Ａよりも空孔率が低くなっているため、第１本体部２５ＸＴに含む介在部２２ＸＴよりも、第１熱収縮部２６ＸＴでは電解液５０の保持性が低くなっている。 The first separator inner peripheral portion 20XT of the first separator 20X is located on the first main body portion 25XT composed of the separator main body 20A and the heat-resistant layer 20B, and the other axial side DX2 of the first main body portion 25XT, and the heat-resistant layer. 20B and the first thermal contraction portion 26XT composed of the shrink separator body 20C described above (see FIG. 9). Among these, the first main body portion 25XT is opposed to the positive electrode active material layer 31 of the positive innermost periphery portion 30T and the first inner peripheral active material layer 41TH of the negative electrode inner peripheral portion 40T facing the positive electrode active material layer 31. It is a form including the interposition part 22XT interposed between the part 42TH.
The shrinkable separator body 20C that forms the first heat shrink part 26XT also has a lower porosity than the separator body 20A of the first body part 25XT. Therefore, the shrinkage separator body 20C is more first than the interposed part 22XT included in the first body part 25XT. In the heat shrink part 26XT, the retainability of the electrolyte solution 50 is low.

また、第２セパレータ２０Ｙの第２セパレータ内周部２０ＹＴは、セパレータ本体２０Ａ及び耐熱層２０Ｂからなる第２本体部２５ＹＴと、この第２本体部２５ＹＴの軸線方向他方側ＤＸ２に位置し、耐熱層２０Ｂ及び収縮セパレータ本体２０Ｃからなる第２熱収縮部２６ＹＴとからなる（図９参照）。第２熱収縮部２６ＹＴをなす収縮セパレータ本体２０Ｃも、第２本体部２５ＹＴのセパレータ本体２０Ａよりも空孔率が低くなっているため、例えば、前述した第２セパレータ中間部２０ＹＵの介在部２２ＹＵなど、セパレータ本体２０Ａを有する第２セパレータ２０Ｙの部位よりも、第２熱収縮部２６ＹＴでは電解液５０の保持性が低くなっている。   The second separator inner peripheral portion 20YT of the second separator 20Y is positioned on the second main body portion 25YT composed of the separator main body 20A and the heat-resistant layer 20B, and on the other axial side DX2 of the second main body portion 25YT. 20B and the 2nd heat contraction part 26YT which consists of shrinkable separator main body 20C (refer FIG. 9). Since the shrinkage separator body 20C forming the second heat shrink part 26YT also has a lower porosity than the separator body 20A of the second body part 25YT, for example, the interposition part 22YU of the second separator intermediate part 20YU described above, etc. In addition, the retention of the electrolytic solution 50 is lower in the second heat contraction portion 26YT than in the portion of the second separator 20Y having the separator body 20A.

なお、図９に示すように、第１セパレータ内周部２０ＸＴの第１熱収縮部２６ＸＴと、第２セパレータ内周部２０ＹＴの第２熱収縮部２６ＹＴとは、負極内周部４０Ｔの内周部端面４０ＴＰよりも他方側ＤＸ２で互いに接合している。具体的には、第１熱収縮部２６ＸＴをなす収縮セパレータ本体２０Ｃと、第２熱収縮部２６ＹＴをなす収縮セパレータ本体２０Ｃとは、熱収縮すると共に互いに溶着している。これにより、内周部端面４０ＴＰは、第１セパレータ内周部２０ＸＴの第１熱収縮部２６ＸＴ、及び、第２セパレータ内周部２０ＹＴの第２熱収縮部２６ＹＴで覆われている。   As shown in FIG. 9, the first heat contraction portion 26XT of the first separator inner peripheral portion 20XT and the second heat contraction portion 26YT of the second separator inner peripheral portion 20YT are the inner periphery of the negative electrode inner peripheral portion 40T. They are joined to each other on the other side DX2 with respect to the part end face 40TP. Specifically, the shrink separator body 20C forming the first heat shrink portion 26XT and the shrink separator body 20C forming the second heat shrink portion 26YT are thermally contracted and welded to each other. Thereby, the inner peripheral end face 40TP is covered with the first heat shrinking part 26XT of the first separator inner peripheral part 20XT and the second heat shrinking part 26YT of the second separator inner peripheral part 20YT.

なお、本実施形態の電池１では、負極内周部４０Ｔの内周部端面４０ＴＰのみならず、負極内周部４０Ｔのうち他方側ＤＸ２の端部も、第１熱収縮部２６ＸＴ及び第２熱収縮部２６ＹＴで覆われている（図９参照）。
但し、第１熱収縮部２６ＸＴ及び第２熱収縮部２６ＹＴの形態としては、負極内周部４０Ｔの内周部端面４０ＴＰのみを覆う形態としても良い。また、内周部端面４０ＴＰのほか第１内周活物質層４１ＴＨの他方側非対向部４４ＴＨ全体を第１熱収縮部２６ＸＴで覆う形態としても良い。 In the battery 1 of the present embodiment, not only the inner peripheral end face 40TP of the negative electrode inner peripheral portion 40T but also the end portion on the other side DX2 of the negative electrode inner peripheral portion 40T is not limited to the first heat contraction portion 26XT and the second heat. It is covered with the contraction portion 26YT (see FIG. 9).
However, as a form of the 1st heat contraction part 26XT and the 2nd heat contraction part 26YT, it is good also as a form which covers only the inner peripheral part end surface 40TP of the negative electrode inner peripheral part 40T. Further, in addition to the inner peripheral end face 40TP, the entire other side non-facing portion 44TH of the first inner peripheral active material layer 41TH may be covered with the first thermal contraction portion 26XT.

ところで、本実施形態（実施例１とする）にかかる電池１（ｎ＝１０）について、高温エージング下での微小短絡の発生の有無を確認するため、以下に示す試験を行った。
具体的には、製造後直ちに初期充電及び高温エージングを行った電池１を用いて、自己放電調査を行った。
まず、上述の初期充電として、２５℃の温度環境下で、電池の端子間電圧が所定の充電終止電圧の値（＝４．４Ｖ）になるまで０．２Ｃの定電流で充電を行った（定電流充電）。そして、上述の高温エージングとして、図示しない恒温槽内に電池１を投入し、８０℃の温度環境下で２日間静置した。
高温エージング後の電池１について、電池１の端子間電圧を測定して、端子間電圧が４．１Ｖ以下のものをＮＧと判定した。ｎ＝１０のうち、ＮＧの数（ＮＧ数）を表１に記す。 By the way, the battery 1 (n = 10) according to the present embodiment (referred to as Example 1) was subjected to the following tests in order to confirm the presence or absence of the occurrence of a micro short circuit under high temperature aging.
Specifically, self-discharge investigation was performed using the battery 1 which was subjected to initial charging and high-temperature aging immediately after production.
First, as the above-described initial charging, charging was performed at a constant current of 0.2 C under a temperature environment of 25 ° C. until the voltage between the terminals of the battery reached a predetermined charging end voltage value (= 4.4 V) ( Constant current charging). And as above-mentioned high temperature aging, the battery 1 was thrown into the thermostat which is not shown in figure, and left still for 2 days in a 80 degreeC temperature environment.
About the battery 1 after high temperature aging, the voltage between the terminals of the battery 1 was measured, and the battery having an inter-terminal voltage of 4.1 V or less was determined to be NG. Table 1 shows the number of NG (number of NG) out of n = 10.

Figure 2014086293
Figure 2014086293

また、実施例２〜４及び比較例１の各電池をそれぞれ用意した。このうち、実施例２の電池は、負極板の他方側端面のうち、負極外周部の外周部端面のみをセパレータの熱収縮部で覆った点で、実施例３の電池は、負極板の他方側端面のうち、負極内周部の内周部端面のみをセパレータの熱収縮部で覆った点で、実施例１の電池１と異なる。また、実施例４の電池は、負極板全体の他方側端面をセパレータの熱収縮部で覆った点で、実施例１と異なる。
一方、比較例１の電池は、負極板の他方側端面をセパレータの熱収縮部で覆わなかった点で、実施例１と異なる。
これら実施例２〜４及び比較例１の各電池についても、上述した実施例１の電池１と同様にして、高温エージング下での短絡の発生の有無を調べた（ｎ＝１０）。各電池の結果についても、表１に記す。 Moreover, each battery of Examples 2-4 and Comparative Example 1 was prepared. Of these, the battery of Example 2 is the same as the battery of Example 3 in that only the outer peripheral end surface of the negative electrode outer peripheral portion of the other end surface of the negative electrode plate is covered with the thermal contraction portion of the separator. It differs from the battery 1 of Example 1 in that, of the side end surfaces, only the inner peripheral end surface of the negative electrode inner peripheral portion is covered with the thermal contraction portion of the separator. Further, the battery of Example 4 differs from Example 1 in that the other end face of the entire negative electrode plate is covered with the heat shrinkage part of the separator.
On the other hand, the battery of Comparative Example 1 differs from Example 1 in that the other side end face of the negative electrode plate was not covered with the heat shrink portion of the separator.
For each of the batteries of Examples 2 to 4 and Comparative Example 1, whether or not a short circuit occurred under high temperature aging was examined in the same manner as the battery 1 of Example 1 described above (n = 10). The results for each battery are also shown in Table 1.

表１によれば、比較例１の電池ではＮＧ数が６個であったのに対し、実施例１〜４の各電池におけるＮＧ数は０〜３個であり、ＮＧと判定された数が少ない。このことから、負極板の他方側端面がセパレータの熱収縮部に覆われない比較例１の電池では、充電の際、正極最外周部や正極最内周部で正極活物質粒子から金属イオンが溶出しやすく、高温エージング下で負極活物質層上にその金属イオンが析出して、正負極間の短絡を引き起こしていると考えられる。一方、負極板の他方側端面のうち、少なくとも外周部端面及び内周部端面のいずれかが、セパレータの熱収縮部で覆われた実施例１〜４の電池では、比較例１の電池よりも、正極最外周部及び正極最内周部の少なくともいずれかにおいて、金属イオンの溶出を防いで、短絡の発生を抑えることができることが判る。   According to Table 1, while the number of NG in the battery of Comparative Example 1 was 6, the number of NG in each battery of Examples 1 to 4 was 0 to 3, and the number determined as NG was Few. Therefore, in the battery of Comparative Example 1 in which the other end surface of the negative electrode plate is not covered with the heat shrinkage portion of the separator, metal ions are extracted from the positive electrode active material particles at the positive electrode outermost periphery and the positive electrode innermost periphery during charging. It is considered that the metal ions are easily eluted and the metal ions are deposited on the negative electrode active material layer under high temperature aging, thereby causing a short circuit between the positive and negative electrodes. On the other hand, in the batteries of Examples 1 to 4 in which at least one of the outer peripheral end face and the inner peripheral end face is covered with the thermal contraction part of the separator among the other side end faces of the negative electrode plate, the battery of Comparative Example 1 is used. It can be seen that, in at least one of the positive electrode outermost peripheral portion and the positive electrode innermost peripheral portion, elution of metal ions can be prevented and occurrence of a short circuit can be suppressed.

さらに、実施例２，３の各電池ではＮＧ数が２個及び３個であったのに対し、実施例１，４の各電池ではＮＧ数がいずれも０個であった。他方側端面のうち、外周部端面または内周部端面の一方のみをセパレータの熱収縮部で覆った電池（実施例２，３）では、外周部端面及び内周部端面のうち、熱収縮部で覆っていない端面において、充電時に負極活物質層同士の液絡が生じる。そして、この液絡によって、正極活物質層と対向していない側の負極活物質層にまでリチウムイオンが拡散移動して、正極活物質粒子からの金属イオンの溶出が生じてしまったと考えられる。
これに対し、外周部端面及び内周部端面のいずれをも熱収縮部で覆った電池（実施例１，４）では、外周部端面及び内周部端面において、負極活物質層同士の液絡に寄与する電解液の量を少なくして、正極活物質層と対向していない側の負極活物質層へのリチウムイオンの拡散移動を抑えることができ、短絡の発生を抑えることができたことが判る。 Furthermore, in each battery of Examples 2 and 3, the number of NGs was 2 and 3, whereas in each battery of Examples 1 and 4, the number of NGs was 0. In the battery (Examples 2 and 3) in which only one of the outer peripheral end face and the inner peripheral end face is covered with the thermal contraction part of the separator among the other end faces, the thermal contraction part among the outer peripheral end face and the inner peripheral end face. On the end surface not covered with, a liquid junction occurs between the negative electrode active material layers during charging. Then, it is considered that lithium ions diffused and moved to the negative electrode active material layer on the side not facing the positive electrode active material layer due to this liquid junction, and elution of metal ions from the positive electrode active material particles occurred.
On the other hand, in the batteries (Examples 1 and 4) in which both the outer peripheral end face and the inner peripheral end face are covered with the heat shrinkage part, the liquid junction between the negative electrode active material layers is formed on the outer peripheral end face and the inner peripheral end face. The amount of the electrolyte solution that contributes to the negative electrode active material layer can be reduced, lithium ion diffusion movement to the negative electrode active material layer on the side not facing the positive electrode active material layer can be suppressed, and the occurrence of short circuits has been suppressed. I understand.

なお、実施例１〜４の各電池では、セパレータの熱収縮部で負極板の他方側端面を覆うため、熱収縮部を設けない比較例１の電池に比べて、電極体の他方側ＤＸ２から負極活物質層に電解液５０を含浸させ難くなる。特に、実施例１〜４の各電池のうち、負極板全体に熱収縮部が他方側端面を覆った形態である実施例４の電池の場合には、他方側端面を通じて負極活物質層に電解液５０を含浸できない。このため、この実施例４の電池は、一部の他方側端面が熱収縮部に覆われずに、電極体の他方側ＤＸ２に露出している電池（実施例１〜３）に比べて、負極活物質層全体に電解液５０を含浸させるのに長い時間を要する。また、負極活物質層において、軸線方向ＤＸに電解液５０の含浸状態にムラが生じ易いと考えられる。   In addition, in each battery of Examples 1-4, since the other side end surface of a negative electrode plate is covered with the heat contraction part of a separator, from the other side DX2 of the electrode body compared with the battery of the comparative example 1 which does not provide a heat contraction part. It becomes difficult to impregnate the negative electrode active material layer with the electrolytic solution 50. In particular, among the batteries of Examples 1 to 4, in the case of the battery of Example 4 in which the thermal contraction portion covers the other side end face of the entire negative electrode plate, the negative electrode active material layer is electrolyzed through the other side end face. The liquid 50 cannot be impregnated. For this reason, the battery of Example 4 is not covered with the heat shrinkage part of the other side end surface, and compared with the battery exposed to the other side DX2 of the electrode body (Examples 1 to 3), It takes a long time to impregnate the entire negative electrode active material layer with the electrolytic solution 50. In addition, in the negative electrode active material layer, it is considered that unevenness easily occurs in the impregnated state of the electrolytic solution 50 in the axial direction DX.

本実施形態にかかる実施例１〜４の各電池（電池１）では、負極板４０の他方側端面４０Ｐのうち、少なくとも外周部端面４０ＳＰ及び内周部端面４０ＴＰのいずれかが、セパレータ２０Ｘ，２０Ｙの液保持性低下部である熱収縮部２６ＸＳ，２６ＸＴ，２６ＹＳ，２６ＹＴで覆われている。熱収縮部２６ＸＳ，２６ＸＴ，２６ＹＳ，２６ＹＴでは電解液５０の保持性が低いので、これに覆われない従来の他方側端面に比して、熱収縮部２６ＸＳ，２６ＸＴ，２６ＹＳ，２６ＹＴに覆われた外周部端面４０ＳＰあるいは内周部端面４０ＴＰにおいて、２つの負極活物質層同士（第１外周活物質層４１ＳＨ及び第２外周活物質層４１ＳＪ同士や、第１内周活物質層４１ＴＨ及び第２内周活物質層４１ＴＪ同士）の液絡に寄与する電解液５０の量を少なくできる。これにより、液絡によって正極活物質層３１と対向していない側の負極活物質層（第２外周活物質層４１ＳＪや第２内周活物質層４１ＴＪ）にまでリチウムイオンが拡散移動するのを抑えることができる。
かくして、少なくとも正極最外周部３０Ｓ及び正極最内周部３０Ｔのいずれかにおいて、正極活物質層３１の正極活物質粒子から金属イオンが溶出するのを抑制することができ、高温下での負極活物質層４１上への金属の析出による短絡の発生を抑制した電池１とすることができる。 In each battery (battery 1) of Examples 1 to 4 according to the present embodiment, at least one of the outer peripheral end surface 40SP and the inner peripheral end surface 40TP is the separators 20X and 20Y among the other end surface 40P of the negative electrode plate 40. Are covered with heat shrinkage portions 26XS, 26XT, 26YS, and 26YT. The heat-shrinkable portions 26XS, 26XT, 26YS, and 26YT are covered with the heat-shrinkable portions 26XS, 26XT, 26YS, and 26YT, as compared with the conventional other end face that is not covered with the electrolyte solution 50 because the electrolyte solution 50 has low retainability. In the outer peripheral end face 40SP or the inner peripheral end face 40TP, the two negative electrode active material layers (the first outer peripheral active material layer 41SH and the second outer peripheral active material layer 41SJ, the first inner peripheral active material layer 41TH, and the second inner active material layer 41TH) The amount of the electrolytic solution 50 that contributes to the liquid junction between the circumferential active material layers 41TJ) can be reduced. As a result, lithium ions diffuse and move to the negative electrode active material layer (second outer peripheral active material layer 41SJ and second inner peripheral active material layer 41TJ) on the side not facing the positive electrode active material layer 31 due to the liquid junction. Can be suppressed.
Thus, at least in any one of the positive electrode outermost peripheral portion 30S and the positive electrode innermost peripheral portion 30T, the elution of metal ions from the positive electrode active material particles of the positive electrode active material layer 31 can be suppressed, and the negative electrode active at a high temperature can be suppressed. It can be set as the battery 1 which suppressed generation | occurrence | production of the short circuit by deposition of the metal on the material layer 41. FIG.

また、本実施形態のうち実施例１，４の各電池（電池１）では、負極外周部４０Ｓ及び負極内周部４０Ｔにそれぞれ属する外周部端面４０ＳＰ及び内周部端面４０ＴＰが、熱収縮部２６ＸＳ，２６ＸＴ，２６ＹＳ，２６ＹＴで覆われている。このため、負極外周部４０Ｓ及び負極内周部４０Ｔのいずれにおいても液絡によって、２つの負極活物質層４１のうちセパレータを介して正極活物質層３１と対向していない側の負極活物質層（第２外周活物質層４１ＳＪ及び第２内周活物質層４１ＴＪ）にまで、リチウムイオンが拡散移動するのを確実に抑えることができる。従って、正極最外周部３０Ｓ及び正極最内周部３０Ｔにおいて、正極活物質層３１の正極活物質粒子から金属イオンが溶出するのを確実に抑制することができる。   Moreover, in each battery (battery 1) of Examples 1 and 4 in the present embodiment, the outer peripheral end face 40SP and the inner peripheral end face 40TP belonging to the negative electrode outer peripheral portion 40S and the negative electrode inner peripheral portion 40T, respectively, are heat-shrinkable portions 26XS. , 26XT, 26YS, and 26YT. For this reason, the negative electrode active material layer on the side of the two negative electrode active material layers 41 that is not opposed to the positive electrode active material layer 31 via the separator in both the negative electrode outer peripheral portion 40S and the negative electrode inner peripheral portion 40T due to liquid junction. Lithium ions can be reliably prevented from diffusing and moving to (second outer peripheral active material layer 41SJ and second inner peripheral active material layer 41TJ). Therefore, the elution of metal ions from the positive electrode active material particles of the positive electrode active material layer 31 can be reliably suppressed in the positive electrode outermost peripheral portion 30S and the positive electrode innermost peripheral portion 30T.

また、実施例１の電池１では、他方側端面４０Ｐのうち、外周部端面４０ＳＰ及び内周部端面４０ＴＰが熱収縮部２６ＸＳ，２６ＸＴ，２６ＹＳ，２６ＹＴで覆われているものの、負極中間部４０Ｕに属する中間部端面４０ＵＰが電極体１０の他方側ＤＸ２に露出している。このため、正極最外周部３０Ｓ及び正極最内周部３０Ｔで金属イオンの溶出を確実に抑制できる一方で、負極板４０のうちの負極中間部４０Ｕにおいて、他方側ＤＸ２からも電極体１０に電解液５０を含浸させることできる。従って、負極活物質層４１における、軸線方向ＤＸについての電解液５０の含浸状態のムラを抑制することができる。   Further, in the battery 1 of Example 1, the outer peripheral end surface 40SP and the inner peripheral end surface 40TP of the other side end surface 40P are covered with the heat shrink portions 26XS, 26XT, 26YS, and 26YT, but the negative electrode intermediate portion 40U. The intermediate end face 40UP to which it belongs is exposed on the other side DX2 of the electrode body 10. For this reason, while elution of metal ions can be reliably suppressed at the positive electrode outermost peripheral portion 30S and the positive electrode innermost peripheral portion 30T, in the negative electrode intermediate portion 40U of the negative electrode plate 40, the electrode body 10 is also electrolyzed from the other side DX2. Liquid 50 can be impregnated. Therefore, unevenness of the impregnation state of the electrolytic solution 50 in the axial direction DX in the negative electrode active material layer 41 can be suppressed.

また、本実施形態にかかる実施例１〜４の各電池（電池１）では、セパレータ２０Ｘ，２０Ｙが上述のセパレータ本体２０Ａと耐熱層２０Ｂとを有するため、電池１内の温度が上昇してセパレータ本体２０Ａが溶融しても、耐熱層２０Ｂにより正極板３０と負極板４０との接触を防ぐことができる。
また、セパレータ２０Ｘ，２０Ｙは、電極体１０において、セパレータ本体２０Ａが負極活物質層４１側となる形態に配置されてなるため、加熱によりセパレータ本体２０Ａを熱収縮させると、セパレータ２０Ｘ，２０Ｙ全体がセパレータ本体２０Ａ側に曲がるので、負極板４０の他方側端面４０Ｐを覆う熱収縮部２６ＸＳ，２６ＸＴ，２６ＹＳ，２６ＹＴを容易かつ確実に形成できる。かくして、介在部２２（２２ＸＵ，２２ＸＴ，２２ＹＳ，２２ＹＵ）よりもセパレータ本体２０Ａの空孔率を低下させた収縮セパレータ本体２０Ｃを有する熱収縮部２６ＸＳ，２６ＸＴ，２６ＹＳ，２６ＹＴで負極板４０の他方側端面４０Ｐを確実に覆った電池１とすることができる。 Moreover, in each battery (battery 1) of Examples 1 to 4 according to this embodiment, since the separators 20X and 20Y have the separator body 20A and the heat-resistant layer 20B, the temperature in the battery 1 rises and the separator Even if the main body 20A is melted, the contact between the positive electrode plate 30 and the negative electrode plate 40 can be prevented by the heat-resistant layer 20B.
The separators 20X and 20Y are arranged in the electrode body 10 so that the separator body 20A is on the negative electrode active material layer 41 side. Therefore, when the separator body 20A is thermally contracted by heating, the separators 20X and 20Y are entirely Since it bends to the separator body 20A side, the heat-shrinkable portions 26XS, 26XT, 26YS, and 26YT that cover the other end surface 40P of the negative electrode plate 40 can be easily and reliably formed. Thus, the other side of the negative electrode plate 40 at the heat-shrinkable portion 26XS, 26XT, 26YS, 26YT having the shrinkable separator body 20C in which the porosity of the separator body 20A is lower than the interposition portion 22 (22XU, 22XT, 22YS, 22YU). It can be set as the battery 1 which covered the end surface 40P reliably.

次いで、本実施形態（実施例１）の電池１の製造方法について説明する。
まず、電極体１０をなす正極板３０及び負極板４０を公知の手法でそれぞれ作製した（図５，６参照）。
一方、電極体１０をなす前述した第１セパレータ２０Ｘ及び第２セパレータ２０Ｙにおける熱収縮部２６ＸＳ，２６ＸＴ，２６ＹＳ，２６ＹＴを形成する前の第１形成前セパレータ２０ＸＢ及び第２形成前セパレータ２０ＹＢをそれぞれ作製する。具体的には、多孔質の樹脂からなる帯状シートのセパレータ本体２０Ａの片方の主面２０ＡＦ上に、既知の塗工装置を用いて、アルミナからなる無機粒子と結着材とを溶媒中に混合したペースト（図示しない）を塗布し、セパレータ本体２０Ａ上で乾燥させて、前述の耐熱層２０Ｂとした。かくして、帯状の第１形成前セパレータ２０ＸＢ及び第２形成前セパレータ２０ＹＢを作製した（図１０参照）。 Next, a method for manufacturing the battery 1 of this embodiment (Example 1) will be described.
First, the positive electrode plate 30 and the negative electrode plate 40 constituting the electrode body 10 were respectively produced by known methods (see FIGS. 5 and 6).
On the other hand, the first pre-formation separator 20XB and the second pre-formation separator 20YB before forming the heat shrink portions 26XS, 26XT, 26YS, and 26YT in the first separator 20X and the second separator 20Y that form the electrode body 10 are respectively produced. To do. Specifically, inorganic particles made of alumina and a binder are mixed in a solvent using a known coating device on one main surface 20AF of the separator main body 20A of a strip-like sheet made of porous resin. The paste (not shown) was applied and dried on the separator body 20A to obtain the heat-resistant layer 20B. Thus, strip-shaped first pre-formation separator 20XB and second pre-formation separator 20YB were produced (see FIG. 10).

次いで、電極体作製工程について説明する。正極板３０及び負極板４０を、上述のように作製した、２枚の形成前セパレータ２０ＸＢ，２０ＹＢと共に円筒状に捲回した。このとき、第２形成前セパレータ２０ＹＢ、負極板４０、第１形成前セパレータ２０ＸＢ及び正極板３０の順に重ねて捲回した。このため、正極板３０の内側には第１形成前セパレータ２０ＸＢ、第１形成前セパレータ２０ＸＢの内側には負極板４０、負極板４０の内側には第２形成前セパレータ２０ＹＢが配置される（図１１参照）。一方、正極板３０の外側には第２形成前セパレータ２０ＹＢ、第２形成前セパレータ２０ＹＢの外側には負極板４０、負極板４０の外側には第１形成前セパレータ２０ＸＢが配置される。
また、正極リード部３９が軸線ＡＸに平行な軸線方向ＤＸの一方側ＤＸ１（図１１中、下方）に位置するように、また、負極リード部４９が軸線方向ＤＸの他方側ＤＸ２（図１１中、上方）に位置するように、正極板３０及び負極板４０をそれぞれ配置した。さらに、第１形成前セパレータ２０ＸＢのセパレータ本体２０Ａ、及び、第２形成前セパレータ２０ＹＢのセパレータ本体２０Ａが、負極板４０の負極活物質層４１側となる形態に配置した。
捲回後、円筒面を両側から押し潰して、横断面が扁平な長円形状で扁平捲回型の電極体１０を作製した。 Next, the electrode body manufacturing process will be described. The positive electrode plate 30 and the negative electrode plate 40 were wound in a cylindrical shape together with the two pre-formation separators 20XB and 20YB prepared as described above. At this time, the second pre-formation separator 20YB, the negative electrode plate 40, the first pre-formation separator 20XB, and the positive electrode plate 30 were stacked in order and wound. Therefore, the first pre-formation separator 20XB is arranged inside the positive electrode plate 30, the negative electrode plate 40 is arranged inside the first pre-formation separator 20XB, and the second pre-formation separator 20YB is arranged inside the negative electrode plate 40 (FIG. 11). On the other hand, the second pre-formation separator 20YB is disposed outside the positive electrode plate 30, the negative electrode plate 40 is disposed outside the second pre-formation separator 20YB, and the first pre-formation separator 20XB is disposed outside the negative electrode plate 40.
Further, the positive electrode lead portion 39 is positioned on one side DX1 (downward in FIG. 11) in the axial direction DX parallel to the axis line AX, and the negative electrode lead portion 49 is positioned on the other side DX2 in the axial direction DX (in FIG. 11). The positive electrode plate 30 and the negative electrode plate 40 are arranged so as to be located on the upper side. Furthermore, the separator main body 20A of the first pre-formation separator 20XB and the separator main body 20A of the second pre-formation separator 20YB are arranged in a form that is on the negative electrode active material layer 41 side of the negative electrode plate 40.
After winding, the cylindrical surface was crushed from both sides, and a flat wound electrode body 10 having an oblong shape with a flat cross section was produced.

次いで、電極体１０をなして捲回された形成前セパレータ２０ＸＢ，２０ＹＢに、熱収縮部２６ＸＳ，２６ＸＴ，２６ＹＳ，２６ＹＴを形成する低下部形成工程について説明する。
この低下部形成工程では、平板状の２枚の金属板ＭＢ，ＭＢを用いる（図１２参照）。これら２枚の金属板ＭＢ，ＭＢは、いずれも加熱されて高温状態（２００℃程度）となっている。このため、これら金属板ＭＢ，ＭＢが電極体１０の形成前セパレータ２０ＸＢ，２０ＹＢに接触すると、この接触部位及びこの付近の部位のセパレータ本体２０Ａが熱収縮する。 Next, a description will be given of a lowered portion forming step for forming the heat shrinkage portions 26XS, 26XT, 26YS, and 26YT on the pre-formation separators 20XB and 20YB wound around the electrode body 10.
In this lowered portion forming step, two flat metal plates MB, MB are used (see FIG. 12). These two metal plates MB, MB are both heated and in a high temperature state (about 200 ° C.). For this reason, when these metal plates MB and MB come into contact with the separators 20XB and 20YB before the electrode body 10 is formed, the separator main body 20A at the contact portion and the vicinity thereof is thermally contracted.

低下部形成工程では、上述した金属板ＭＢを用いて、形成前セパレータ２０ＸＢ，２０ＹＢのうち、負極板４０の他方側端面４０Ｐよりも、軸線方向ＤＸの他方側ＤＸ２に突出する突出部２６ＸＢ，２６ＹＢを加熱する。
なお、本実施例１では、２枚の金属板ＭＢ，ＭＢの一方を、第１形成前セパレータ２０ＸＢのうち、前述した負極外周部４０Ｓの径方向外側ＤＲ１に位置する部位の突出部２６ＸＢに、径方向外側ＤＲ１から当接させて、突出部２６ＸＢを加熱する（図１２，１３参照）。これにより、この突出部２６ＸＢ及び付近の部位のセパレータ本体２０Ａが熱収縮する。なお、第１形成前セパレータ２０ＸＢをなすセパレータ本体２０Ａと耐熱層２０Ｂのうち、セパレータ本体２０Ａの方が大きく熱収縮するため、突出部２６ＸＢ及び付近の部位は、セパレータ本体２０Ａ側、つまり負極外周部４０Ｓ側に曲がる。
これと同時に、もう一方の金属板ＭＢを、第２形成前セパレータ２０ＹＢのうち、負極外周部４０Ｓの径方向内側ＤＲ２に位置する部位の突出部２６ＹＢに、径方向内側ＤＲ２から当接させて、この突出部２６ＹＢを加熱する（図１２，１３参照）。これにより、この突出部２６ＹＢ及び付近の部位のセパレータ本体２０Ａが熱収縮する。なお、第２形成前セパレータ２０ＸＢでもセパレータ本体２０Ａが大きく熱収縮するため、突出部２６ＹＢ及びその付近の部位も、負極外周部４０Ｓ側に曲がる。 In the lowered portion forming step, the protruding portions 26XB and 26YB protruding from the other side end face 40P of the negative electrode plate 40 to the other side DX2 of the negative electrode plate 40 among the pre-formation separators 20XB and 20YB using the metal plate MB described above. Heat.
In the first embodiment, one of the two metal plates MB, MB is placed on the protruding portion 26XB of the portion of the first pre-formation separator 20XB located on the radially outer side DR1 of the negative electrode outer peripheral portion 40S described above. The protrusion 26XB is heated from the radially outer side DR1 (see FIGS. 12 and 13). As a result, the protrusion 26XB and the separator body 20A in the vicinity are thermally contracted. Of the separator main body 20A and the heat-resistant layer 20B forming the first pre-formation separator 20XB, the separator main body 20A is more thermally contracted, and therefore the protrusion 26XB and the vicinity thereof are on the separator main body 20A side, that is, the negative electrode outer peripheral portion. Turn to the 40S side.
At the same time, the other metal plate MB is brought into contact with the protruding portion 26YB located at the radially inner side DR2 of the negative electrode outer peripheral portion 40S in the second pre-formation separator 20YB from the radially inner side DR2, The protrusion 26YB is heated (see FIGS. 12 and 13). As a result, the protrusion 26YB and the separator body 20A in the vicinity are thermally contracted. In the second pre-formation separator 20XB, the separator body 20A is largely thermally contracted, so that the protruding portion 26YB and the vicinity thereof are also bent toward the negative electrode outer peripheral portion 40S.

さらに、２枚の金属板ＭＢ，ＭＢを径方向ＤＲに互いに近づけて、第１形成前セパレータ２０ＸＢの突出部２６ＸＢと、第２形成前セパレータ２０ＹＢの突出部２６ＹＢとを挟む（図１３参照）。これにより、第１形成前セパレータ２０ＸＢの突出部２６ＸＢのセパレータ本体２０Ａと、第２形成前セパレータ２０ＹＢの突出部２６ＹＢのセパレータ本体２０Ａとが、熱収縮すると共に溶着する。かくして、第１形成前セパレータ２０ＸＢには前述した第１熱収縮部２６ＸＳが、また、第２形成前セパレータ２０ＹＢには前述した第２熱収縮部２６ＹＳが形成される（図８参照）。
また、前述した負極内周部４０Ｔにおける形成前セパレータ２０ＸＢ，２０ＹＢについても、同様にして、第１形成前セパレータ２０ＸＢに前述した第１熱収縮部２６ＸＴを、また、第２形成前セパレータ２０ＹＢに前述した第２熱収縮部２６ＹＴをそれぞれ形成する。 Further, the two metal plates MB, MB are brought close to each other in the radial direction DR, and the protrusion 26XB of the first pre-formation separator 20XB and the protrusion 26YB of the second pre-formation separator 20YB are sandwiched (see FIG. 13). Thereby, the separator main body 20A of the protrusion 26XB of the first pre-formation separator 20XB and the separator main body 20A of the protrusion 26YB of the second pre-formation separator 20YB are thermally contracted and welded. Thus, the first heat shrinkage part 26XS described above is formed in the first pre-formation separator 20XB, and the second heat shrinkage part 26YS described above is formed in the second pre-formation separator 20YB (see FIG. 8).
Similarly, for the pre-formation separators 20XB and 20YB in the negative electrode inner peripheral portion 40T described above, the first heat-shrink part 26XT described above is applied to the first pre-formation separator 20XB and the second pre-formation separator 20YB is described above. The second heat contraction part 26YT thus formed is formed.

その後、電極体１０をなす正極板３０の正極リード部３９に正極集電部材９１を、負極板４０の負極リード部４９に負極集電部材９２をそれぞれ溶接する。そして、電極体１０を電池ケース本体８１に収容し、電解液５０を注液した後、電池ケース本体８１を封口蓋８２で封口して、電池１を完成させた（図４参照）。   Thereafter, the positive electrode current collecting member 91 is welded to the positive electrode lead portion 39 of the positive electrode plate 30 constituting the electrode body 10, and the negative electrode current collecting member 92 is welded to the negative electrode lead portion 49 of the negative electrode plate 40. And after accommodating the electrode body 10 in the battery case main body 81 and injecting the electrolyte solution 50, the battery case main body 81 was sealed with the sealing lid 82, and the battery 1 was completed (refer FIG. 4).

本実施形態にかかる電池１の製造方法は、前述の電極体作製工程と低下部形成工程とを備える。このため、負極板４０の他方側端面４０Ｐのうち、少なくとも外周部端面４０ＳＰ及び内周部端面４０ＴＰのいずれかがセパレータ２０Ｘ，２０Ｙの熱収縮部２６ＸＳ，２６ＸＴ，２６ＹＳ，２６ＹＴで覆われた電池１を製造することができる。従って、少なくとも正極最外周部３０Ｓ及び正極最内周部３０Ｔのいずれかにおいて、正極活物質層３１の正極活物質粒子から金属イオンが溶出するのを抑制することができ、高温下での負極活物質層４１上への金属の析出による短絡の発生を抑制した電池１を製造することができる。   The manufacturing method of the battery 1 according to the present embodiment includes the above-described electrode body manufacturing step and the lowered portion forming step. Therefore, the battery 1 in which at least one of the outer peripheral end surface 40SP and the inner peripheral end surface 40TP among the other end surface 40P of the negative electrode plate 40 is covered with the heat shrink portions 26XS, 26XT, 26YS, and 26YT of the separators 20X and 20Y. Can be manufactured. Accordingly, it is possible to suppress the elution of metal ions from the positive electrode active material particles of the positive electrode active material layer 31 at least in any one of the positive electrode outermost peripheral portion 30S and the positive electrode innermost peripheral portion 30T. The battery 1 in which the occurrence of a short circuit due to metal deposition on the material layer 41 is suppressed can be manufactured.

また、低下部形成工程では、電極体１０をなして捲回された形成前セパレータ２０ＸＢ，２０ＹＢのうち、他方側端面４０Ｐよりも、他方側ＤＸ２に突出する突出部２６ＸＢ，２６ＹＢを加熱して、セパレータ本体２０Ａを熱収縮させて熱収縮部２６ＸＳ，２６ＸＴ，２６ＹＳ，２６ＹＴを形成する。なお、セパレータ本体２０Ａと耐熱層２０Ｂとを有する形成前セパレータ２０ＸＢ，２０ＹＢを加熱すると、セパレータ本体２０Ａが大きく熱収縮するため、セパレータ本体２０Ａ側に曲がり、他方側端面４０Ｐを覆う形態の熱収縮部２６ＸＳ，２６ＸＴ，２６ＹＳ，２６ＹＴを容易に形成することができる。   Further, in the lowered portion forming step, among the pre-formation separators 20XB and 20YB wound around the electrode body 10, the protruding portions 26XB and 26YB protruding from the other side end face 40P to the other side DX2 are heated. The separator main body 20A is thermally contracted to form the thermal contraction portions 26XS, 26XT, 26YS, and 26YT. When the pre-formation separators 20XB and 20YB having the separator main body 20A and the heat-resistant layer 20B are heated, the separator main body 20A is largely heat-shrinked. Therefore, the heat-shrinkable portion is bent toward the separator main body 20A and covers the other end face 40P. 26XS, 26XT, 26YS, and 26YT can be easily formed.

以上において、本発明を実施形態（実施例１〜４）に即して説明したが、本発明は上記実施形態に限定されるものではなく、その要旨を逸脱しない範囲で、適宜変更して適用できることは言うまでもない。
例えば、前述の実施形態では、セパレータの液保持性低下部として、多孔性樹脂からなるセパレータの該当部位を加熱により熱収縮させて介在部よりも空孔率を低下させたものを例示した。しかし、セパレータの液保持性低下部として、そのほかに、該当部位に樹脂等を塗布して介在部よりも空孔率を低下させたものや、該当部位に電解液に濡れずにこれをはじく特性を付与したものを用いることもできる。
さらに、実施形態では、多孔質の樹脂からなるセパレータ本体と耐熱層とを有するセパレータを備える電池を示したが、セパレータ本体のみからなるセパレータを備える電池でも良い。 In the above, the present invention has been described with reference to the embodiments (Examples 1 to 4). However, the present invention is not limited to the above-described embodiments, and can be appropriately modified and applied without departing from the gist thereof. Needless to say, you can.
For example, in the above-described embodiment, the liquid retention lowering portion of the separator is exemplified by a portion where the corresponding portion of the separator made of porous resin is thermally contracted by heating to lower the porosity than the interposition portion. However, as the liquid retention lowering part of the separator, in addition to this, the resin is applied to the corresponding part to lower the porosity than the intervening part, and the characteristic part repels without getting wet with the electrolyte solution Those provided with can also be used.
Furthermore, although the battery provided with the separator which has the separator main body which consists of porous resin, and a heat-resistant layer was shown in embodiment, the battery provided with the separator which consists only of a separator main body may be sufficient.

また、実施形態では、低下部形成工程として、２枚の金属板ＭＢ，ＭＢを用いて、形成前セパレータ２０ＸＢ，２０ＹＢの突出部２６ＸＢ，２６ＹＢを加熱し、熱収縮させて熱収縮部２６ＸＳ，２６ＸＴ，２６ＹＳ，２６ＹＴを形成する工程を例示した。しかし、低下部形成工程として、例えば、ヒータ等の加熱装置を、電極体の他方側ＤＸ２から正極リード部（正極箔）の端部に接触させて、この端部から正極リード部を加熱する。そして、他方側ＤＸ２から徐々に加熱された正極リード部によって、正極リード部同士間に位置するセパレータの突出部を間接的に加熱し、熱収縮させて液保持性低下部を形成する手法も挙げられる。また、ヒータ等の加熱装置で、正極リード部を挟んで正極リード部を加熱して突出部を間接的に加熱し、熱収縮させて液保持性低下部を形成する手法も挙げられる。さらに、負極外周部の外周部端面を覆う液保持性低下部を形成する場合には、電極体の径方向外側から加熱装置をセパレータの突出部に当接させて、この突出部を加熱し熱収縮させて液保持性低下部を形成する手法が挙げられる。   Further, in the embodiment, as the lowered portion forming step, the protrusions 26XB and 26YB of the pre-formation separators 20XB and 20YB are heated and thermally contracted by using the two metal plates MB and MB, and the heat contracted portions 26XS and 26XT are formed. , 26YS, 26YT are exemplified. However, as the lowered portion forming step, for example, a heating device such as a heater is brought into contact with the end portion of the positive electrode lead portion (positive electrode foil) from the other side DX2 of the electrode body, and the positive electrode lead portion is heated from this end portion. And the method of forming the liquid-retention reduced portion by indirectly heating the protrusions of the separator located between the positive electrode lead portions by the positive electrode lead portion gradually heated from the other side DX2 and causing thermal contraction. It is done. In addition, a method of heating the positive electrode lead portion with the positive electrode lead portion sandwiched therebetween by a heating device such as a heater to indirectly heat the projecting portion and causing thermal contraction to form a liquid retention lowering portion is also mentioned. Further, in the case of forming a liquid retention reduced portion that covers the outer peripheral end face of the negative electrode outer peripheral portion, a heating device is brought into contact with the protruding portion of the separator from the radially outer side of the electrode body, and the protruding portion is heated and heated. A method of forming the liquid retention lowering portion by contraction is exemplified.

１ 電池（リチウムイオン二次電池）
１０ 電極体
２０Ａ セパレータ本体
２０ＡＦ 本体主面（（セパレータ本体の）主面）
２０Ｂ 耐熱層
２０Ｘ 第１セパレータ（セパレータ）
２０ＸＢ 第１形成前セパレータ（液保持性低下部を有さないセパレータ）
２０Ｙ 第２セパレータ（セパレータ）
２０ＹＢ 第２形成前セパレータ（液保持性低下部を有さないセパレータ）
２２ＸＴ，２２ＸＵ，２２ＹＳ，２２ＹＵ 介在部
２６ＸＢ，２６ＹＢ 突出部
２６ＸＳ，２６ＸＴ 第１熱収縮部（液保持性低下部）
２６ＹＳ，２６ＹＴ 第２熱収縮部（液保持性低下部）
３０ 正極板
３０Ｓ 正極最外周部
３０Ｔ 正極最内周部
３１ 正極活物質層
３８ 正極箔
３８Ｆ （正極箔の）主面
４０ 負極板
４０Ｐ 他方側端面
４０Ｓ 負極外周部
４０ＳＰ 外周部端面
４０Ｔ 負極内周部
４０ＴＰ 内周部端面
４０Ｕ 負極中間部
４０ＵＰ 中間部端面
４１ 負極活物質層
４２，４２ＳＨ，４２ＴＨ 対向部
４４，４４ＳＨ，４４ＴＨ 他方側非対向部
４８ 負極箔
４８Ｆ （負極箔の）主面
５０ 電解液
ＡＸ 捲回軸
ＤＲ 径方向
ＤＲ１ （径方向の）外側
ＤＲ２ （径方向の）内側
ＤＸ 軸線方向
ＤＸ１ （軸線方向の）一方側
ＤＸ２ （軸線方向の）他方側 1 Battery (Lithium ion secondary battery)
10 Electrode body 20A Separator body 20AF Main body main surface (main surface of separator body)
20B Heat-resistant layer 20X First separator (separator)
20XB first pre-formation separator (separator not having a liquid retention reduction part)
20Y Second separator (separator)
20YB Second pre-formation separator (separator not having a liquid retention lowering portion)
22XT, 22XU, 22YS, 22YU Interposition part 26XB, 26YB Protrusion part 26XS, 26XT First heat contraction part (liquid retention lowering part)
26YS, 26YT second heat shrinkage part (liquid retention lowering part)
30 positive electrode plate 30S positive electrode outermost peripheral part 30T positive electrode innermost peripheral part 31 positive electrode active material layer 38 positive electrode foil 38F main surface 40 (negative electrode foil) main surface 40 negative electrode plate 40P other side end face 40S negative electrode outer peripheral part 40SP outer peripheral part end face 40T negative electrode inner peripheral part 40TP inner peripheral end face 40U negative electrode intermediate part 40UP intermediate end face 41 negative electrode active material layer 42, 42SH, 42TH facing part 44, 44SH, 44TH other side non-facing part 48 negative foil 48F (negative electrode foil) main surface 50 electrolyte AX Winding axis DR radial direction DR1 (radial) outer DR2 (radial) inner DX axial direction DX1 (axial) one side DX2 (axial) other side

Claims (6)

帯状の正極板と帯状の負極板とを帯状のセパレータを介して捲回してなる電極体、及び、上記セパレータに含浸された電解液を備え、
上記負極板は、
捲回された上記正極板のうち最外周に位置する正極最外周部に、上記セパレータを介して径方向外側から対向する負極外周部、及び、上記正極板のうち最内周に位置する正極最内周部に、上記セパレータを介して上記径方向内側から対向する負極内周部、を有する
リチウムイオン二次電池であって、
上記正極板は、
帯状の正極箔及びこの正極箔の両主面上で、捲回軸に沿う軸線方向の一方側に位置する正極活物質層を有し、
上記負極板は、
帯状の負極箔及びこの負極箔の両主面上で上記軸線方向の他方側に位置する負極活物質層を有し、
上記負極箔及び２つの上記負極活物質層は、上記他方側の端縁で共通の他方側端面をなし、
上記負極活物質層は、
上記セパレータを介して上記正極活物質層に対向する対向部と、この対向部の上記他方側に隣在し上記正極活物質層に対向しない他方側非対向部とを含み、
上記セパレータは、
上記正極活物質層とこれに対向する上記負極活物質層の上記対向部との間に介在する介在部及び上記介在部よりも上記電解液の保持性を低下させた液保持性低下部を有し、
上記負極板の上記他方側端面のうち、上記負極外周部に属する外周部端面及び上記負極内周部に属する内周部端面の少なくともいずれかは、
上記セパレータの上記液保持性低下部で覆われてなる
リチウムイオン二次電池。 An electrode body formed by winding a belt-like positive electrode plate and a belt-like negative electrode plate through a belt-like separator, and an electrolyte impregnated in the separator,
The negative electrode plate is
Of the wound positive electrode plate, the positive electrode outermost peripheral portion positioned on the outermost periphery of the positive electrode, the negative electrode outer peripheral portion facing from the radially outer side through the separator, and the positive electrode outermost portion positioned on the innermost periphery of the positive electrode plate A lithium ion secondary battery having a negative electrode inner peripheral portion facing from the radially inner side through the separator on an inner peripheral portion,
The positive plate is
On both main surfaces of the strip-like positive electrode foil and the positive electrode foil, a positive electrode active material layer located on one side in the axial direction along the winding axis,
The negative electrode plate is
It has a negative electrode active material layer located on the other side in the axial direction on both main surfaces of the strip-shaped negative electrode foil and the negative electrode foil,
The negative electrode foil and the two negative electrode active material layers form a common other side end face at the other side edge,
The negative electrode active material layer is
Including a facing portion that faces the positive electrode active material layer via the separator, and a non-facing portion on the other side that is adjacent to the other side of the facing portion and does not face the positive electrode active material layer,
The separator is
An interposition part interposed between the positive electrode active material layer and the facing part of the negative electrode active material layer opposite to the positive electrode active material layer, and a liquid retainability lowering part that lowers the electrolyte retention than the interposition part. And
Of the other end face of the negative electrode plate, at least one of an outer peripheral end face belonging to the negative electrode outer peripheral part and an inner peripheral end face belonging to the negative inner peripheral part is:
A lithium ion secondary battery covered with the liquid retention lowering portion of the separator. 請求項１に記載のリチウムイオン二次電池であって、
前記他方側端面のうち、少なくとも前記外周部端面及び前記内周部端面は、
前記セパレータの前記液保持性低下部で覆われてなる
リチウムイオン二次電池。 The lithium ion secondary battery according to claim 1,
Of the other side end face, at least the outer peripheral end face and the inner peripheral end face are:
A lithium ion secondary battery covered with the liquid retention lowering portion of the separator. 請求項２に記載のリチウムイオン二次電池であって、
前記負極板は、
前記負極外周部と前記負極内周部との間に位置する負極中間部を有し、
前記他方側端面のうち、前記外周部端面及び前記内周部端面は、
前記セパレータの前記液保持性低下部で覆われてなり、
上記他方側端面のうち、上記負極中間部に属する中間部端面は、
前記電極体の前記他方側に露出してなる
リチウムイオン二次電池。 The lithium ion secondary battery according to claim 2,
The negative electrode plate is
A negative electrode intermediate portion located between the negative electrode outer peripheral portion and the negative electrode inner peripheral portion;
Of the other end face, the outer peripheral end face and the inner peripheral end face are:
Covered with the liquid retention lowering portion of the separator,
Of the other side end surfaces, the intermediate end surface belonging to the negative electrode intermediate portion is:
A lithium ion secondary battery exposed on the other side of the electrode body. 請求項１〜３のいずれか１項に記載のリチウムイオン二次電池であって、
前記セパレータは、
多孔質の樹脂からなるセパレータ本体と、
上記セパレータ本体の片方の主面上に形成され、無機粒子を含む耐熱層と、を有し、
前記電極体において、上記セパレータ本体が前記負極活物質層側となる形態に配置されてなり、
前記液保持性低下部は、
加熱により上記セパレータ本体を熱収縮させてなる
リチウムイオン二次電池。 The lithium ion secondary battery according to any one of claims 1 to 3,
The separator is
A separator body made of porous resin;
Formed on one main surface of the separator body, and having a heat-resistant layer containing inorganic particles,
In the electrode body, the separator body is disposed in a form that is on the negative electrode active material layer side,
The liquid retention lowering part is
A lithium ion secondary battery obtained by thermally shrinking the separator body by heating. 帯状の正極板と帯状の負極板とを帯状のセパレータを介して捲回してなる電極体、及び、上記セパレータに含浸された電解液を備え、
上記負極板は、
捲回された上記正極板のうち最外周に位置する正極最外周部に、上記セパレータを介して径方向外側から対向する負極外周部、及び、上記正極板のうち最内周に位置する正極最内周部に、上記セパレータを介して上記径方向内側から対向する負極内周部、を有し、
上記正極板は、
帯状の正極箔及びこの正極箔の両主面上で、捲回軸に沿う軸線方向の一方側に位置する正極活物質層を有し、
上記負極板は、
帯状の負極箔及びこの負極箔の両主面上で上記軸線方向の他方側に位置する負極活物質層を有し、
上記負極箔及び２つの上記負極活物質層は、上記他方側の端縁で共通の他方側端面をなし、
上記負極活物質層は、
上記セパレータを介して上記正極活物質層に対向する対向部と、この対向部の上記他方側に隣在し上記正極活物質層に対向しない他方側非対向部とを含み、
上記セパレータは、
上記正極活物質層とこれに対向する上記負極活物質層の上記対向部との間に介在する介在部及び上記介在部よりも上記電解液の保持性を低下させた液保持性低下部を有し、
上記負極板の上記他方側端面のうち、上記負極外周部に属する外周部端面及び上記負極内周部に属する内周部端面の少なくともいずれかは、
上記セパレータの上記液保持性低下部で覆われてなる
リチウムイオン二次電池の製造方法であって、
帯状の上記正極板と帯状の上記負極板とを帯状で上記液保持性低下部を有さないセパレータを介して捲回して、電極体を作製する電極体作製工程と、
上記電極体をなして捲回された上記セパレータに、上記液保持性低下部を形成する低下部形成工程と、を備える
リチウムイオン二次電池の製造方法。 An electrode body formed by winding a belt-like positive electrode plate and a belt-like negative electrode plate through a belt-like separator, and an electrolyte impregnated in the separator,
The negative electrode plate is
Of the wound positive electrode plate, the positive electrode outermost peripheral portion positioned on the outermost periphery of the positive electrode, the negative electrode outer peripheral portion facing from the radially outer side through the separator, and the positive electrode outermost portion positioned on the innermost periphery of the positive electrode plate An inner peripheral portion having a negative electrode inner peripheral portion facing from the radially inner side via the separator,
The positive plate is
On both main surfaces of the strip-like positive electrode foil and the positive electrode foil, a positive electrode active material layer located on one side in the axial direction along the winding axis,
The negative electrode plate is
It has a negative electrode active material layer located on the other side in the axial direction on both main surfaces of the strip-shaped negative electrode foil and the negative electrode foil,
The negative electrode foil and the two negative electrode active material layers form a common other side end face at the other side edge,
The negative electrode active material layer is
Including a facing portion that faces the positive electrode active material layer via the separator, and a non-facing portion on the other side that is adjacent to the other side of the facing portion and does not face the positive electrode active material layer,
The separator is
An interposition part interposed between the positive electrode active material layer and the facing part of the negative electrode active material layer opposite to the positive electrode active material layer, and a liquid retainability lowering part that lowers the electrolyte retention than the interposition part. And
Of the other end face of the negative electrode plate, at least one of an outer peripheral end face belonging to the negative electrode outer peripheral part and an inner peripheral end face belonging to the negative inner peripheral part is:
A method for producing a lithium ion secondary battery covered with the liquid retention lowering portion of the separator,
An electrode body production step of producing an electrode body by winding the belt-like positive electrode plate and the belt-like negative electrode plate through a belt-like separator having no liquid retention lowering portion;
The manufacturing method of a lithium ion secondary battery provided with the reduced part formation process which forms the said liquid retention reduced part in the said separator wound by making the said electrode body. 請求項５に記載のリチウムイオン二次電池の製造方法であって、
前記セパレータは、
多孔質の樹脂からなるセパレータ本体と、
上記セパレータ本体の片方の主面上に形成され、無機粒子を含む耐熱層と、を有し、
前記電極体において、上記セパレータ本体が前記負極活物質層側となる形態に配置されてなり、
前記液保持性低下部は、加熱により上記セパレータ本体を熱収縮させてなり、
前記低下部形成工程は、
前記電極体をなして捲回された前記液保持性低下部を有さないセパレータのうち、前記他方側端面よりも、他方側に突出する突出部を加熱し、上記セパレータ本体を熱収縮させて上記液保持性低下部を形成する
リチウムイオン二次電池の製造方法。 It is a manufacturing method of the lithium ion secondary battery according to claim 5,
The separator is
A separator body made of porous resin;
Formed on one main surface of the separator body, and having a heat-resistant layer containing inorganic particles,
In the electrode body, the separator body is disposed in a form that is on the negative electrode active material layer side,
The liquid retention lowering portion is formed by thermally shrinking the separator body by heating,
The lowered portion forming step includes
Of the separator that does not have the liquid retainability lowered portion wound around the electrode body, the protruding portion protruding to the other side of the other side end surface is heated, and the separator main body is thermally contracted. The manufacturing method of the lithium ion secondary battery which forms the said liquid retainability fall part.
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