JP7117944B2 - secondary battery - Google Patents

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JP7117944B2
JP7117944B2 JP2018161007A JP2018161007A JP7117944B2 JP 7117944 B2 JP7117944 B2 JP 7117944B2 JP 2018161007 A JP2018161007 A JP 2018161007A JP 2018161007 A JP2018161007 A JP 2018161007A JP 7117944 B2 JP7117944 B2 JP 7117944B2
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positive electrode
negative electrode
current collector
separator
electrode current
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JP2020035641A (en
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佳士 飯塚
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Vehicle Energy Japan Inc
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • Connection Of Batteries Or Terminals (AREA)

Description

本開示は、二次電池に関する。 The present disclosure relates to secondary batteries.

従来からセパレータの収縮に基づく短絡の発生を防止した安全性の高い非水二次電池に関する発明が知られている（下記特許文献１を参照。）。特許文献１に記載された発明は、厚みが２０μｍ以下のセパレータを用いる場合に生じる問題点を解決し、セパレータの収縮に基づく内部短絡の発生を防止した安全性の高い非水二次電池を提供することを目的としている（同文献、第０００５段落－第００１１段落等を参照。）。 Conventionally, there has been known an invention relating to a highly safe non-aqueous secondary battery that prevents the occurrence of a short circuit due to shrinkage of the separator (see Patent Document 1 below). The invention described in Patent Document 1 solves the problem that occurs when using a separator with a thickness of 20 μm or less, and provides a highly safe non-aqueous secondary battery that prevents the occurrence of internal short circuits due to shrinkage of the separator. (See Ibid., paragraphs 0005 to 0011, etc.).

上記目的を達成するために、特許文献１は、以下の発明を開示している（同文献、請求項１等を参照。）。非水二次電池は、導電性基体上に正極合剤層が形成された正極と、導電性基体上に負極合剤層が形成された負極とを、厚みが２０μｍ以下のセパレータを介して巻回した電極巻回体を有する。セパレータの周辺部の一部または全部は、正極または負極の一部分に固定されている。 In order to achieve the above object, Patent Document 1 discloses the following invention (see the same document, claim 1, etc.). In a non-aqueous secondary battery, a positive electrode having a positive electrode mixture layer formed on a conductive substrate and a negative electrode having a negative electrode mixture layer formed on a conductive substrate are wound with a separator having a thickness of 20 μm or less interposed therebetween. It has a wound electrode winding. A part or all of the periphery of the separator is fixed to a part of the positive electrode or the negative electrode.

この従来の発明によれば、セパレータの周辺部の一部を正極に固定しているので、加熱時のセパレータの収縮による内部短絡を防止することができる（同文献、第００４７段落等を参照。）。したがって、この従来の発明によれば、セパレータの収縮による内部短絡の発生を防止した安全性の高い非水二次電池を提供することができる（同文献、第００４８段落等を参照。）。 According to this conventional invention, since a part of the periphery of the separator is fixed to the positive electrode, it is possible to prevent an internal short circuit due to contraction of the separator during heating (see paragraph 0047 of the same document, etc.). ). Therefore, according to this conventional invention, it is possible to provide a highly safe non-aqueous secondary battery that prevents the occurrence of an internal short circuit due to shrinkage of the separator (see paragraph 0048 of the same document).

特開２００３－１６８４１１号公報Japanese Patent Application Laid-Open No. 2003-168411

前記した従来の非水二次電池のような電極巻回体を備える二次電池では、一般に、正極の終端部の外側にセパレータを介して負極の終端部が巻回され、その外側の電極巻回体の最外周にセパレータの終端部が巻回される場合がある。この場合、最外周のセパレータの終端部の内周側に巻回された負極の終端部と、その負極の終端部の内周側にセパレータを介して巻回された正極の終端部との間に、隙間が生じやすくなる。電極巻回体の負極と正極との間に隙間が生じると、その隙間から電解液とともに異物が流入し、二次電池の性能を低下させるおそれがある。 In a secondary battery including an electrode wound body such as the conventional non-aqueous secondary battery, generally, the terminal end of the negative electrode is wound outside the terminal end of the positive electrode with a separator interposed therebetween, and the electrode winding on the outside is wound. The end portion of the separator may be wound around the outermost circumference of the winding body. In this case, between the terminal end of the negative electrode wound on the inner peripheral side of the terminal end of the outermost separator and the terminal end of the positive electrode wound on the inner peripheral side of the terminal end of the negative electrode with the separator interposed therebetween. , gaps are likely to occur. If a gap is formed between the negative electrode and the positive electrode of the electrode-wound body, foreign matter may flow into the gap together with the electrolytic solution, degrading the performance of the secondary battery.

本開示は、負極電極と正極電極とをセパレータを介在させて巻回した巻回体に流入する異物を抑制することが可能な二次電池を提供する。 The present disclosure provides a secondary battery capable of suppressing foreign matter from entering a wound body in which a negative electrode and a positive electrode are wound with a separator interposed therebetween.

本開示の一態様は、巻回軸方向の一端と他端に正極集電部と負極集電部が位置するように配置した正極電極と負極電極とを第１セパレータと第２セパレータを介在させて巻回軸を中心に巻回した巻回体を備えた二次電池であって、前記巻回体は、最外周に前記第１セパレータの終端部が巻回され、前記第１セパレータの前記終端部の内側に前記負極電極の終端部が巻回され、前記負極電極の前記終端部の内側に前記第２セパレータの終端部を介在させて前記正極電極の終端部が巻回されており、少なくとも前記第１セパレータと前記正極集電部との間を跨いで前記巻回体の外表面の一部を覆う熱可塑性成形材からなる被覆部を有することを特徴とする二次電池である。 In one aspect of the present disclosure, a positive electrode and a negative electrode are arranged such that the positive current collector and the negative current collector are positioned at one end and the other end in the winding axial direction, with a first separator and a second separator interposed therebetween. A secondary battery comprising a wound body wound around a winding axis, wherein the wound body has an end portion of the first separator wound around the outermost circumference of the wound body, and the first separator of the first separator The terminal portion of the negative electrode is wound inside the terminal portion, and the terminal portion of the positive electrode is wound inside the terminal portion of the negative electrode with the terminal portion of the second separator interposed, The secondary battery is characterized in that it has a covering portion made of a thermoplastic molding material that covers a part of the outer surface of the winding body across at least the first separator and the positive electrode current collecting portion.

上記一態様によれば、被覆部によって第１セパレータと正極集電部との間を跨いで巻回体の外表面の一部を覆うことで、巻回体の最外周に位置する第１セパレータの終端部を、正極集電部に近接させることができる。これにより、第１セパレータの終端部の内周に巻回された負極電極と第２セパレータとを正極電極の終端部に近接させ、巻回体の負極電極と正極電極との間に隙間が生じるのを抑制することができる。したがって、上記一態様によれば、負極電極と正極電極とを第１セパレータと第２セパレータを介在させて巻回した巻回体に流入する異物を抑制することが可能な二次電池を提供することができる。 According to the above aspect, the first separator located on the outermost periphery of the wound body is partially covered by the covering portion across the first separator and the positive electrode current collecting portion. can be brought close to the positive current collector. As a result, the negative electrode and the second separator wound on the inner periphery of the end portion of the first separator are brought close to the end portion of the positive electrode, and a gap is formed between the negative electrode and the positive electrode of the wound body. can be suppressed. Therefore, according to the above aspect, there is provided a secondary battery capable of suppressing foreign matter from flowing into a wound body in which a negative electrode and a positive electrode are wound with a first separator and a second separator interposed therebetween. be able to.

本開示の実施形態１に係る二次電池の一例を示す斜視図。1 is a perspective view showing an example of a secondary battery according to Embodiment 1 of the present disclosure; FIG. 図１に示す二次電池の分解斜視図。FIG. 2 is an exploded perspective view of the secondary battery shown in FIG. 1; 図２に示す二次電池の巻回体の分解斜視図。3 is an exploded perspective view of the wound body of the secondary battery shown in FIG. 2; FIG. 図２に示す二次電池の集電板が巻回体に接合された状態を示す正面図。FIG. 3 is a front view showing a state in which a collector plate of the secondary battery shown in FIG. 2 is joined to a wound body; 図４に示す巻回体および正極集電板のVA‐VA線に沿う模式的な断面図。FIG. 5 is a schematic cross-sectional view along line VA-VA of the wound body and the positive current collector plate shown in FIG. 4; 図５Ａに示す巻回体の変形部の一点鎖線で囲まれたVB部の模式的な拡大図。A schematic enlarged view of the VB portion surrounded by the dashed-dotted line of the wound body shown in FIG. 5A. 図４に示す巻回体のVI‐VI線に沿う模式的な拡大断面図。5 is a schematic enlarged cross-sectional view along line VI-VI of the wound body shown in FIG. 4; FIG. 図４に示す巻回体に被覆部を形成した状態を示す正面図。The front view which shows the state which formed the covering part in the winding body shown in FIG. 図７に示す巻回体のVIIIA‐VIIIA線に沿う模式的な拡大断面図。8 is a schematic enlarged cross-sectional view along line VIIIA-VIIIA of the wound body shown in FIG. 7; FIG. 図８Ａに示す巻回体の変形部のVIIIB部の模式的な拡大図。FIG. 8B is a schematic enlarged view of the VIIIB portion of the deformed portion of the wound body shown in FIG. 8A; 実施形態１に係る二次電池の変形例を示す図７に対応する正面図。FIG. 8 is a front view corresponding to FIG. 7 showing a modification of the secondary battery according to Embodiment 1; 本開示の実施形態２に係る二次電池の図７に対応する正面図。FIG. 7 is a front view corresponding to FIG. 7 of the secondary battery according to Embodiment 2 of the present disclosure; 図１０Ａに示す巻回体のXB‐XB線に沿う模式的な断面図。A schematic cross-sectional view along line XB-XB of the wound body shown in FIG. 10A.

以下、図面を参照して本開示に係る二次電池の実施形態を説明する。 Hereinafter, embodiments of a secondary battery according to the present disclosure will be described with reference to the drawings.

［実施形態１］
図１は、本開示の実施形態１に係る二次電池１００の一例を示す斜視図である。図２は、図１に示す二次電池１００の分解斜視図である。図３は、図２に示す二次電池１００の電池容器１０の内部に収容された巻回体３０の一部を展開した状態を示す分解斜視図である。 [Embodiment 1]
FIG. 1 is a perspective view showing an example of a secondary battery 100 according to Embodiment 1 of the present disclosure. FIG. 2 is an exploded perspective view of secondary battery 100 shown in FIG. FIG. 3 is an exploded perspective view showing a state in which a part of the wound body 30 housed inside the battery container 10 of the secondary battery 100 shown in FIG. 2 is unfolded.

本実施形態の二次電池１００は、たとえば、電気自動車（ＥＶ）やハイブリッド電気自動車（ＨＥＶ）の蓄電装置に使用される角形二次電池であり、より詳細には、たとえば、角形のリチウムイオン二次電池である。詳細については後述するが、本実施形態の二次電池１００は、次の構成を主要な特徴としている。 The secondary battery 100 of the present embodiment is, for example, a prismatic secondary battery used in a power storage device for an electric vehicle (EV) or a hybrid electric vehicle (HEV). Next battery. Although the details will be described later, the main features of the secondary battery 100 of the present embodiment are as follows.

二次電池１００は、巻回体３０を備えている。巻回体３０は、正極電極３１と、負極電極３２と、第１セパレータ３３と、第２セパレータ３４とを備えている。巻回体３０は、正極電極３１と負極電極３２とを、巻回軸方向Ｄの一端と他端に正極集電部３１ｃと負極集電部３２ｃが位置するように配置し、第１セパレータ３３と第２セパレータ３４を介在させて巻回軸３０Ａを中心に巻回することによって構成されている。巻回体３０は、最外周に第１セパレータ３３の終端部３３ｅが巻回され、その内側に負極電極３２の終端部３２ｅが巻回され、その内側に第２セパレータ３４の終端部３４ｅを介在させて正極電極３１の終端部３１ｅが巻回されている。二次電池１００は、少なくとも第１セパレータ３３と正極集電部３１ｃとの間を跨いで巻回体３０の外表面の一部を覆う熱可塑性成形材からなる被覆部３７を有する（図７、図８Ａおよび図８Ｂを参照。）。 A secondary battery 100 includes a wound body 30 . The wound body 30 includes a positive electrode 31 , a negative electrode 32 , a first separator 33 and a second separator 34 . In the wound body 30, the positive electrode 31 and the negative electrode 32 are arranged such that the positive electrode current collector 31c and the negative electrode current collector 32c are positioned at one end and the other end in the winding axial direction D, and the first separator 33 and the second separator 34 are interposed and wound around the winding shaft 30A. The wound body 30 has the terminal end portion 33e of the first separator 33 wound on the outermost periphery, the terminal end portion 32e of the negative electrode 32 wound inside thereof, and the terminal end portion 34e of the second separator 34 interposed therebetween. The end portion 31e of the positive electrode 31 is wound. The secondary battery 100 has a covering portion 37 made of a thermoplastic molding material that covers a part of the outer surface of the wound body 30 across at least the first separator 33 and the positive current collecting portion 31c (FIGS. 7 and 7). See Figures 8A and 8B.).

以下、本実施形態の二次電池１００の各部の構成を詳細に説明する。なお、各図面では、扁平角形の二次電池１００の幅方向に平行なＸ軸、厚さ方向に平行なＹ軸、高さ方向に平行なＺ軸からなるＸＹＺ直交座標系を用いて、二次電池１００の各部の構成を説明する場合がある。また、以下の説明における上下左右の方向は、図面に基づいて二次電池１００の各部の構成を説明するための便宜的な方向であり、鉛直方向や水平方向に限定されない。 The configuration of each part of the secondary battery 100 of this embodiment will be described in detail below. In each drawing, an XYZ orthogonal coordinate system including an X axis parallel to the width direction of the flat prismatic secondary battery 100, a Y axis parallel to the thickness direction, and a Z axis parallel to the height direction is used. The configuration of each part of the secondary battery 100 may be described. In addition, the directions of up, down, left and right in the following description are directions for convenience in describing the configuration of each part of the secondary battery 100 based on the drawings, and are not limited to vertical or horizontal directions.

電池容器１０は、たとえば扁平な矩形箱形の形状を有する金属製の容器である。電池容器１０は、幅方向（Ｘ方向）に沿う一対の広側面１０ｗと、厚さ方向（Ｙ方向）に沿う一対の狭側面１０ｎと、細長い長方形の上面１０ｔおよび底面１０ｂを有している。これら広側面１０ｗ、狭側面１０ｎ、上面１０ｔおよび底面１０ｂのうち、広側面１０ｗが最大の面積を有している。 Battery container 10 is, for example, a metal container having a flat rectangular box shape. The battery container 10 has a pair of wide side surfaces 10w along the width direction (X direction), a pair of narrow side surfaces 10n along the thickness direction (Y direction), and an elongated rectangular top surface 10t and bottom surface 10b. Among these wide side 10w, narrow side 10n, top 10t and bottom 10b, the wide side 10w has the largest area.

電池容器１０は、たとえば、高さ方向（Ｚ方向）の一端が開放された扁平角形の電池缶１１と、その電池缶１１の開口部１１ａを閉塞する長方形板状の電池蓋１２とを有している。電池容器１０は、電池缶１１の開口部１１ａから蓄電要素である巻回体３０が内部に挿入されている。電池容器１０は、たとえば、レーザ溶接によって電池缶１１の開口部１１ａの全周にわたって電池蓋１２が溶接されることで、電池缶１１の開口部１１ａが電池蓋１２によって封止されている。 The battery container 10 has, for example, a flat rectangular battery can 11 with one end in the height direction (Z direction) open, and a rectangular plate-like battery lid 12 that closes the opening 11 a of the battery can 11 . ing. The battery container 10 has a wound body 30 as a power storage element inserted through the opening 11 a of the battery can 11 . In the battery container 10 , the opening 11 a of the battery can 11 is sealed by the battery lid 12 by welding the battery lid 12 along the entire circumference of the opening 11 a of the battery can 11 by laser welding, for example.

電池蓋１２は、二次電池１００の幅方向（Ｘ方向）である長手方向の両端部に外部端子２０の一部を挿通させる貫通孔１２ａを有している。また、電池蓋１２は、長手方向の中央部にガス排出弁１５を有している。ガス排出弁１５は、たとえば、電池蓋１２の一部をプレス加工して薄肉化し、スリットを形成した部分であり、電池蓋１２と一体的に設けられている。ガス排出弁１５は、電池容器１０の内圧が所定の圧力まで上昇したときに開裂して、電池容器１０の内部のガスを排出することで、電池容器１０の内圧を低減して二次電池１００の安全性を確保する。 The battery lid 12 has through holes 12 a through which a part of the external terminal 20 is inserted at both ends in the longitudinal direction, which is the width direction (X direction) of the secondary battery 100 . In addition, the battery cover 12 has a gas exhaust valve 15 in the central portion in the longitudinal direction. The gas exhaust valve 15 is, for example, a portion formed by pressing a portion of the battery lid 12 to make it thinner and forming a slit, and is provided integrally with the battery lid 12 . The gas discharge valve 15 is opened when the internal pressure of the battery container 10 rises to a predetermined pressure to discharge the gas inside the battery container 10 , thereby reducing the internal pressure of the battery container 10 and discharging the secondary battery 100 . ensure the safety of

電池蓋１２は、たとえば貫通孔１２ａとガス排出弁１５との間に注液孔１６を有している。注液孔１６は、電池蓋１２の内部に電解液を注入するために設けられ、電解液の注入後に、たとえばレーザ溶接によって注液栓１７を接合することによって封止される。電池容器１０内に注入される電解液としては、たとえば、エチレンカーボネート等の炭酸エステル系の有機溶媒に６フッ化リン酸リチウム（ＬｉＰＦ６）等のリチウム塩が溶解された非水電解液を使用することができる。 Battery lid 12 has, for example, liquid injection hole 16 between through hole 12 a and gas exhaust valve 15 . The injection hole 16 is provided for injecting the electrolyte into the battery lid 12, and is sealed by joining the injection plug 17 by laser welding, for example, after the injection of the electrolyte. As the electrolytic solution to be injected into the battery container 10, for example, a non-aqueous electrolytic solution in which a lithium salt such as lithium hexafluorophosphate ( LiPF6 ) is dissolved in a carbonate-based organic solvent such as ethylene carbonate is used. can do.

一対の外部端子２０は、電池蓋１２の外面すなわち電池容器１０の上面１０ｔの長手方向に離隔して配置され、電池蓋１２を貫通して電池容器１０の内部でそれぞれ一対の集電板４０の基部４１に接続されている。外部端子２０は、正極外部端子２０Ｐと負極外部端子２０Ｎを含んでいる。正極外部端子２０Ｐの素材は、たとえばアルミニウムまたはアルミニウム合金である。負極外部端子２０Ｎの素材は、たとえば銅または銅合金である。 The pair of external terminals 20 are arranged separately in the longitudinal direction of the outer surface of the battery lid 12 , that is, the upper surface 10 t of the battery container 10 . It is connected to the base 41 . The external terminal 20 includes a positive external terminal 20P and a negative external terminal 20N. The material of positive electrode external terminal 20P is, for example, aluminum or an aluminum alloy. The material of negative external terminal 20N is, for example, copper or a copper alloy.

外部端子２０は、たとえばバスバーに接合される接合部２１と、集電板４０に接続される接続部２２とを有している。接合部２１は、おおむね直方体形状の矩形のブロック状の形状を有し、電気絶縁性を有するガスケット１３を介して電池蓋１２の外面すなわち電池容器１０の上面１０ｔに配置される。接続部２２は、電池蓋１２に対向する接合部２１の底面から電池蓋１２を貫通する方向に延びる円柱状または円筒状の部分である。 The external terminal 20 has, for example, a joint portion 21 that is joined to a bus bar and a connection portion 22 that is connected to the current collector plate 40 . The joint portion 21 has a substantially rectangular block-like shape and is arranged on the outer surface of the battery lid 12 , that is, the upper surface 10 t of the battery container 10 via an electrically insulating gasket 13 . Connecting portion 22 is a columnar or cylindrical portion extending from the bottom surface of joint portion 21 facing battery lid 12 in a direction penetrating battery lid 12 .

集電板４０は、図２に示すように、所定の形状に屈曲された板状の部材であり、巻回体３０に接続されている。集電板４０は、正極電極３１と正極外部端子２０Ｐとを接続する正極集電板４０Ｐと、負極電極３２と負極外部端子２０Ｎとを接続する負極集電板４０Ｎとを含む。正極集電板４０Ｐの素材は、たとえばアルミニウムまたはアルミニウム合金である。負極集電板４０Ｎの素材は、たとえば銅または銅合金である。 The collector plate 40 is a plate-like member bent into a predetermined shape, and is connected to the wound body 30, as shown in FIG. The collector plate 40 includes a positive collector plate 40P that connects the positive electrode 31 and the positive external terminal 20P, and a negative collector plate 40N that connects the negative electrode 32 and the negative external terminal 20N. The material of positive electrode current collector plate 40P is, for example, aluminum or an aluminum alloy. The material of the negative electrode current collector plate 40N is, for example, copper or a copper alloy.

集電板４０は、外部端子２０に接続された基部４１と、その基部４１に交差する方向に延びる延在部４２と、巻回体３０に接合された延在部４２の接合部４２ａと基部４１との間に設けられた屈曲部４３と、を有している。基部４１は、電池蓋１２の内面に沿って配置され、延在部４２は、電池蓋１２の内面に直交する方向へ向けて延びている。延在部４２の接合部４２ａは、巻回体３０の正極集電部３１ｃまたは負極集電部３２ｃが巻回されて扁平に積層された積層部３５に対して、たとえば、超音波接合によって接合されている。 The current collector plate 40 includes a base portion 41 connected to the external terminal 20, an extension portion 42 extending in a direction intersecting the base portion 41, a joint portion 42a of the extension portion 42 joined to the wound body 30, and the base portion. , and a bent portion 43 provided between 41 and . Base portion 41 is arranged along the inner surface of battery lid 12 , and extension portion 42 extends in a direction orthogonal to the inner surface of battery lid 12 . The joint portion 42a of the extension portion 42 is joined, for example, by ultrasonic bonding to the laminated portion 35 in which the positive electrode collector portion 31c or the negative electrode collector portion 32c of the wound body 30 is wound and laminated flat. It is

巻回体３０は、たとえば、正極電極３１と、負極電極３２と、これらの電極を絶縁する絶縁体である第１セパレータ３３と、第２セパレータ３４とを備えている。巻回体３０は、第１セパレータ３３、正極電極３１、第２セパレータ３４、および負極電極３２が積層されて巻回された構成を有する巻回電極群である。巻回体３０において、たとえば、最内周と最外周に巻回された電極は負極電極３２であり、最外周に巻回された負極電極３２の外周にさらに第１セパレータ３３が巻回されている。 The wound body 30 includes, for example, a positive electrode 31, a negative electrode 32, and a first separator 33 and a second separator 34, which are insulators for insulating these electrodes. The wound body 30 is a wound electrode group having a configuration in which a first separator 33, a positive electrode 31, a second separator 34, and a negative electrode 32 are laminated and wound. In the wound body 30, for example, the electrodes wound on the innermost circumference and the outermost circumference are the negative electrode 32, and the first separator 33 is further wound around the outer circumference of the negative electrode 32 wound on the outermost circumference. there is

負極電極３２は、負極集電体３２ａと、その表裏両面に形成された負極合剤層３２ｂと、その負極合剤層３２ｂから負極集電体３２ａが露出した部分である負極集電部３２ｃとを有している。負極電極３２の負極集電部３２ｃは、長尺帯状の負極電極３２の幅方向（Ｘ方向）、すなわち巻回体３０の巻回軸方向Ｄの一側に設けられている。負極集電体３２ａは、たとえば厚さが約１０μｍ程度の銅箔である。 The negative electrode 32 includes a negative electrode current collector 32a, negative electrode mixture layers 32b formed on both front and back surfaces of the negative electrode current collector 32a, and a negative electrode current collector 32c that is a portion where the negative electrode current collector 32a is exposed from the negative electrode mixture layer 32b. have. The negative current collecting portion 32 c of the negative electrode 32 is provided on one side of the long band-shaped negative electrode 32 in the width direction (X direction), that is, in the winding axial direction D of the wound body 30 . The negative electrode current collector 32a is, for example, a copper foil having a thickness of approximately 10 μm.

負極合剤層３２ｂは、たとえば、負極集電体３２ａの表裏両面に、負極集電部３２ｃを除いてスラリー状の負極合剤を塗布し、塗布された負極合剤を乾燥させてプレスすることで形成されている。その後、負極合剤層３２ｂが形成された負極集電体３２ａを、適宜、裁断することによって負極電極３２を製作することができる。負極集電体３２ａを含まない負極合剤層３２ｂの厚さは、たとえば約７０μｍ程度である。負極合剤のスラリーとしては、たとえば、負極活物質である１００重量部の非晶質炭素粉末に対し、結着剤である１０重量部のポリフッ化ビニリデン（ＰＶＤＦ）を添加し、さらに分散溶媒としてＮ－メチルピロリドン（ＮＭＰ）を添加して混練したものを用いることができる。 The negative electrode mixture layer 32b is formed, for example, by applying slurry-like negative electrode mixture to both the front and back surfaces of the negative electrode current collector 32a except for the negative electrode current collecting portion 32c, drying the applied negative electrode mixture, and pressing. is formed by Thereafter, the negative electrode 32 can be manufactured by appropriately cutting the negative electrode current collector 32a on which the negative electrode mixture layer 32b is formed. The thickness of the negative electrode mixture layer 32b that does not include the negative electrode current collector 32a is, for example, about 70 μm. As the slurry of the negative electrode mixture, for example, 10 parts by weight of polyvinylidene fluoride (PVDF) as a binder is added to 100 parts by weight of amorphous carbon powder as the negative electrode active material, and further, as a dispersion solvent, A mixture obtained by adding N-methylpyrrolidone (NMP) and kneading can be used.

なお、負極合剤層３２ｂに含まれる負極活物質は、前述の非晶質炭素に限定されない。たとえば、負極活物質として、リチウムイオンを挿入、脱離可能な天然黒鉛や、人造の各種黒鉛材、コークスなどの炭素質材料やＳｉやＳｎなどの化合物（たとえば、ＳｉＯ、ＴｉＳｉ２など）、またはこれらの複合材料を用いてもよい。また、負極活物質の粒子形状は特に制限されず、たとえば、鱗片状、球状、繊維状、塊状などであってもよい。 Note that the negative electrode active material contained in the negative electrode mixture layer 32b is not limited to the amorphous carbon described above. For example, as the negative electrode active material, natural graphite capable of intercalating and deintercalating lithium ions, various artificial graphite materials, carbonaceous materials such as coke, compounds such as Si and Sn (for example, SiO, TiSi 2 , etc.), or Composite materials of these may also be used. Moreover, the particle shape of the negative electrode active material is not particularly limited, and may be, for example, scale-like, spherical, fibrous, or block-like.

正極電極３１は、正極集電体である正極集電体３１ａと、その表裏両面に形成された正極合剤層３１ｂと、その正極合剤層３１ｂから正極集電体３１ａが露出した部分である正極集電部３１ｃとを有している。正極電極３１の正極集電部３１ｃは、長尺帯状の正極電極３１の幅方向（Ｘ方向）、すなわち巻回体３０の巻回軸方向Ｄにおいて、負極電極３２の負極集電部３２ｃと反対側の一側に設けられている。正極集電体３１ａは、たとえば厚さが約２０μｍ程度のアルミニウム箔である。 The positive electrode 31 includes a positive current collector 31a as a positive current collector, positive electrode mixture layers 31b formed on both front and back surfaces of the positive electrode current collector 31a, and a portion where the positive electrode current collector 31a is exposed from the positive electrode mixture layer 31b. and a positive current collector 31c. The positive current collecting portion 31c of the positive electrode 31 is opposite to the negative current collecting portion 32c of the negative electrode 32 in the width direction (X direction) of the long strip-shaped positive electrode 31, that is, in the winding axial direction D of the wound body 30. provided on one side. The positive electrode current collector 31a is, for example, an aluminum foil having a thickness of approximately 20 μm.

正極合剤層３１ｂは、たとえば、正極集電体３１ａの表裏両面に、正極集電部３１ｃを除いてスラリー状の正極合剤を塗布し、塗布された正極合剤を乾燥させてプレスすることで形成されている。その後、正極合剤層３１ｂが形成された正極集電体３１ａを、適宜、裁断することによって正極電極３１を製作することができる。正極集電体３１ａを含まない正極合剤層３１ｂの厚さは、たとえば約９０μｍ程度である。正極合剤のスラリーとしては、たとえば、正極活物質である１００重量部のマンガン酸リチウム（化学式ＬｉＭｎ２Ｏ４）に対し、導電材である１０重量部の鱗片状黒鉛と、結着剤である１０重量部のＰＶＤＦとを添加し、さらに分散溶媒としてＮＭＰを添加して混練したものを用いることができる。 The positive electrode mixture layer 31b is formed, for example, by applying a slurry-like positive electrode mixture to both the front and back surfaces of the positive electrode current collector 31a except for the positive electrode current collector portion 31c, drying the applied positive electrode mixture, and pressing the applied positive electrode mixture. is formed by Thereafter, the positive electrode 31 can be manufactured by appropriately cutting the positive electrode current collector 31a on which the positive electrode mixture layer 31b is formed. The thickness of the positive electrode mixture layer 31b that does not include the positive electrode current collector 31a is, for example, about 90 μm. As the slurry of the positive electrode mixture, for example, 100 parts by weight of lithium manganate (chemical formula LiMn 2 O 4 ), which is the positive electrode active material, is mixed with 10 parts by weight of flake graphite, which is a conductive material, and a binder. 10 parts by weight of PVDF and NMP as a dispersing solvent are added and kneaded.

なお、正極合剤層３１ｂに含まれる正極活物質は、前述のマンガン酸リチウムに限定されない。たとえば、正極活物質として、スピネル結晶構造を有する他のマンガン酸リチウム、一部を金属元素で置換またはドープしたリチウムマンガン複合酸化物を用いることができる。また、正極活物質として、層状結晶構造を有するコバルト酸リチウムやチタン酸リチウム、一部を金属元素で置換またはドープしたリチウム－金属複合酸化物を用いてもよい。 Note that the positive electrode active material contained in the positive electrode mixture layer 31b is not limited to lithium manganate described above. For example, other lithium manganese oxides having a spinel crystal structure and lithium-manganese composite oxides partially substituted or doped with metal elements can be used as the positive electrode active material. As the positive electrode active material, lithium cobaltate or lithium titanate having a layered crystal structure, or a lithium-metal composite oxide partially substituted or doped with a metal element may be used.

また、負極合剤および正極合剤に用いられる結着剤は、ＰＶＤＦに限定されない。結着剤としては、たとえば、ポリテトラフルオロエチレン（ＰＴＦＥ）、ポリエチレン、ポリスチレン、ポリブタジエン、ブチルゴム、ニトリルゴム、スチレンブタジエンゴム、多硫化ゴム、ニトロセルロース、シアノエチルセルロース、各種ラテックス、アクリロニトリル、フッ化ビニル、フッ化ビニリデン、フッ化プロピレン、フッ化クロロプレン、アクリル系樹脂などの重合体およびこれらの混合体などを用いることができる。 Moreover, the binder used for the negative electrode mixture and the positive electrode mixture is not limited to PVDF. Examples of binders include polytetrafluoroethylene (PTFE), polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, styrene-butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethyl cellulose, various latexes, acrylonitrile, vinyl fluoride, Vinylidene fluoride, propylene fluoride, chloroprene fluoride, polymers such as acrylic resins, mixtures thereof, and the like can be used.

図示は省略するが、巻回体３０は、負極電極３２、第１セパレータ３３、正極電極３１、および第２セパレータ３４を積層させて巻回するための軸芯を有してもよい。軸芯としては、たとえば、正極集電体３１ａ、負極集電体３２ａ、第１セパレータ３３および第２セパレータ３４よりも曲げ剛性の高い樹脂シートを巻回したものを用いることができる。また、巻回体３０は、巻回軸方向Ｄ（Ｘ方向）において負極合剤層３２ｂの寸法が正極合剤層３１ｂの寸法よりも大きく、正極合剤層３１ｂが必ず負極合剤層３２ｂの間に挟まれるように構成されている。 Although not shown, the wound body 30 may have a core for winding the negative electrode 32, the first separator 33, the positive electrode 31, and the second separator 34 in layers. As the core, for example, a wound resin sheet having bending rigidity higher than that of the positive electrode current collector 31a, the negative electrode current collector 32a, the first separator 33, and the second separator 34 can be used. Further, in the wound body 30, the dimension of the negative electrode mixture layer 32b is larger than the dimension of the positive electrode mixture layer 31b in the winding axial direction D (X direction), and the positive electrode mixture layer 31b is always larger than the negative electrode mixture layer 32b. configured to be sandwiched between

巻回体３０において、正極電極３１の正極集電部３１ｃと負極電極３２の負極集電部３２ｃは、それぞれ、図３に示すように巻回軸方向Ｄ（Ｘ方向）の一端と他端で巻回されて積層されている。さらに、正極集電部３１ｃ、負極集電部３２ｃは、それぞれ、図２に示すように扁平に束ねられ、たとえば超音波接合や抵抗溶接によって集電板４０の延在部４２の接合部４２ａに接合されている。 In the wound body 30, the positive collector portion 31c of the positive electrode 31 and the negative collector portion 32c of the negative electrode 32 are respectively connected at one end and the other end in the winding axial direction D (X direction) as shown in FIG. It is wound and laminated. Further, the positive electrode current collector 31c and the negative electrode current collector 32c are each flatly bundled as shown in FIG. are spliced.

なお、巻回軸方向Ｄ（Ｘ方向）において、第１セパレータ３３、第２セパレータ３４の寸法は、負極合剤層３２ｂの寸法よりも大きい。しかし、第１セパレータ３３、第２セパレータ３４の端部は、それぞれ、正極集電部３１ｃ、負極集電部３２ｃの端部よりも、巻回軸方向Ｄ（Ｘ方向）における内側の位置に配置されている。そのため、正極集電部３１ｃおよび負極集電部３２ｃを束ねて、それぞれ、正極集電板４０Ｐおよび負極集電板４０Ｎの延在部４２の接合部４２ａに接合する際に支障はない。 In addition, in the winding axis direction D (X direction), the dimensions of the first separator 33 and the second separator 34 are larger than the dimensions of the negative electrode mixture layer 32b. However, the ends of the first separator 33 and the second separator 34 are located inside the ends of the positive current collector 31c and the negative current collector 32c, respectively, in the winding axis direction D (X direction). It is Therefore, there is no problem in bundling the positive electrode current collector 31c and the negative electrode current collector 32c and joining them to the joint portions 42a of the extension portions 42 of the positive electrode current collector 40P and the negative electrode current collector 40N, respectively.

集電板４０の基部４１は、板状の絶縁部材１４を介して電池蓋１２に固定され、外部端子２０に電気的に接続されている。より詳細には、外部端子２０の接続部２２が、たとえば、ガスケット１３の貫通孔１３ａと、電池蓋１２の貫通孔１２ａと、絶縁部材１４の貫通孔１４ａと、集電板４０の基部４１の貫通孔４１ａに挿通され、集電板４０の基部４１の下面で先端を拡径させるように塑性変形させてかしめられている。 A base portion 41 of the current collector plate 40 is fixed to the battery lid 12 via a plate-like insulating member 14 and electrically connected to the external terminal 20 . More specifically, the connection portion 22 of the external terminal 20 is formed by, for example, through-hole 13 a of gasket 13 , through-hole 12 a of battery lid 12 , through-hole 14 a of insulating member 14 , and base 41 of collector plate 40 . It is inserted into the through-hole 41a and crimped by plastically deforming so as to expand the diameter of the tip on the lower surface of the base portion 41 of the current collector plate 40 .

これにより、外部端子２０と集電板４０とが、互いに電気的に接続され、電池蓋１２に対してガスケット１３と絶縁部材１４を介して電気的に絶縁された状態で固定されている。また、集電板４０の延在部４２の接合部４２ａが、巻回体３０の正極集電部３１ｃ、負極集電部３２ｃのそれぞれの積層部３５に接合されることで、巻回体３０を構成する正極電極３１および負極電極３２が、集電板４０を介して外部端子２０に電気的に接続されている。ガスケット１３および絶縁部材１４の素材は、たとえばポリブチレンテレフタレート、ポリフェニレンサルファイド、ペルフルオロアルコキシフッ素樹脂などの電気絶縁性を有する樹脂である。 As a result, the external terminal 20 and the current collector plate 40 are electrically connected to each other and fixed to the battery lid 12 in an electrically insulated state via the gasket 13 and the insulating member 14 . In addition, the joint portion 42a of the extension portion 42 of the current collector plate 40 is joined to the laminated portions 35 of the positive electrode current collector portion 31c and the negative electrode current collector portion 32c of the wound body 30, so that the wound body 30 are electrically connected to the external terminal 20 via the collector plate 40 . Gasket 13 and insulating member 14 are made of electrically insulating resin such as polybutylene terephthalate, polyphenylene sulfide, and perfluoroalkoxy fluororesin.

図４は、図２に示す電池蓋１２に外部端子２０および集電板４０がガスケット１３および絶縁部材１４を介して固定され、集電板４０が巻回体３０に接合された状態を示す正面図である。集電板４０は、巻回体３０を構成する正極電極３１の正極集電部３１ｃと負極電極３２の負極集電部３２ｃに対し、超音波接合される場合がある。この場合、アンビルの上に正極集電板４０Ｐおよび負極集電板４０Ｎを配置し、その上に正極集電部３１ｃおよび負極集電部３２ｃをそれぞれ配置する。 FIG. 4 is a front view showing a state in which the external terminal 20 and the collector plate 40 are fixed to the battery lid 12 shown in FIG. It is a diagram. The collector plate 40 may be ultrasonically bonded to the positive collector portion 31 c of the positive electrode 31 and the negative collector portion 32 c of the negative electrode 32 that constitute the wound body 30 . In this case, the positive current collector 40P and the negative current collector 40N are arranged on the anvil, and the positive current collector 31c and the negative current collector 32c are respectively arranged thereon.

そして、ホーンによって、正極集電部３１ｃおよび負極集電部３２ｃを、それぞれ、正極集電板４０Ｐおよび負極集電板４０Ｎに対して押し当てて、ホーンに超音波振動を発生させる。これにより、正極集電板４０Ｐと正極集電部３１ｃの積層部３５との間、および、負極集電板４０Ｎと負極集電部３２ｃの積層部３５との間が冶金結合によって接合され、それぞれ接合部Ｊが形成される。 Then, the horn presses the positive current collecting portion 31c and the negative current collecting portion 32c against the positive current collecting plate 40P and the negative current collecting plate 40N, respectively, thereby causing the horn to generate ultrasonic vibration. As a result, the positive collector plate 40P and the laminate 35 of the positive collector 31c and the negative collector 40N and the laminate 35 of the negative collector 32c are joined by metallurgical bonding. A junction J is formed.

たとえば、この超音波接合の過程で、集電板４０、正極集電部３１ｃ、負極集電部３２ｃが削られることなどにより、金属異物が発生する場合がある。発生した金属異物の一部は、たとえば、電池容器１０に電解液を注入する過程で、電解液とともに巻回体３０の内部に流入するおそれがある。金属異物は、巻回体３０の内部に侵入すると、大きさや形状によっては、第１セパレータ３３または第２セパレータ３４を貫通して、正極電極３１と負極電極３２を短絡させるおそれがある。 For example, in the process of this ultrasonic bonding, metal foreign matter may be generated due to scraping of the current collecting plate 40, the positive electrode current collecting portion 31c, and the negative electrode current collecting portion 32c. Some of the generated metallic foreign matter may flow into the wound body 30 together with the electrolytic solution, for example, during the process of injecting the electrolytic solution into the battery container 10 . If foreign metal enters the wound body 30 , depending on its size and shape, it may penetrate the first separator 33 or the second separator 34 and short-circuit the positive electrode 31 and the negative electrode 32 .

たとえば、巻回体３０の内部に侵入した金属異物が、負極集電体３２ａや負極集電板４０Ｎを構成する銅または銅合金であるとする。この場合、金属異物が正極電位で酸化されて電解液中に拡散し、負極電極３２で還元析出することで、正極電極３１と負極電極３２との間に微小な短絡回路が形成されるおそれがある。金属異物の析出や成長形態は、金属の種類などによって異なる。たとえば、金属異物は、多孔質の第１セパレータ３３または第２セパレータ３４の空隙内を樹枝状に成長する場合がある。この場合、物理的にセパレータを貫通しない小さな金属異物であっても、正極電極３１と負極電極３２との間に短絡を生じさせるおそれがある。 For example, it is assumed that the metal foreign matter that has entered the wound body 30 is copper or a copper alloy that constitutes the negative electrode current collector 32a and the negative electrode current collector plate 40N. In this case, the metal foreign matter is oxidized at the positive electrode potential, diffuses into the electrolytic solution, and is reduced and precipitated at the negative electrode 32, which may form a minute short circuit between the positive electrode 31 and the negative electrode 32. be. The deposition and growth forms of metallic foreign matter differ depending on the type of metal and the like. For example, metallic foreign matter may grow like a tree in the voids of the porous first separator 33 or second separator 34 . In this case, even a small metallic foreign matter that does not physically penetrate the separator may cause a short circuit between the positive electrode 31 and the negative electrode 32 .

すなわち、異物に起因する二次電池１００の内部短絡の要因としては、以下の二つの要因がある。第１の要因は、二次電池１００の負極側の金属部材から発生した金属異物が電解液中を移動して正極側から巻回体３０の内部へ流入し、第１セパレータ３３または第２セパレータ３４を貫通することによるものである。第２の要因は、二次電池１００の正極側の金属部材から発生した金属異物が、巻回体３０の正極側の端部から巻回体３０の内部へ流入し、第１セパレータ３３または第２セパレータ３４を貫通することによるものである。このような巻回体３０の内部への異物の流入を防止する対策は容易ではない。 That is, there are the following two factors for the internal short circuit of the secondary battery 100 caused by the foreign matter. The first factor is that foreign metal particles generated from the metal member on the negative electrode side of the secondary battery 100 migrate in the electrolytic solution and flow into the wound body 30 from the positive electrode side, and the first separator 33 or the second separator 34 by penetrating. The second factor is that metallic foreign matter generated from the positive electrode side metal member of the secondary battery 100 flows into the wound body 30 from the positive electrode side end of the wound body 30, and the first separator 33 or the second separator 33 2 separator 34 is penetrated. It is not easy to take measures to prevent foreign matter from entering the wound body 30 as described above.

図５Ａは、図４に示す巻回体３０および正極集電板４０ＰのVA-VA線に沿う模式的な断面図である。図５Ｂは、図５Ａに示す巻回体３０の変形部３６の一点鎖線で囲まれたVB部の模式的な拡大図である。 FIG. 5A is a schematic cross-sectional view along line VA-VA of wound body 30 and positive electrode current collector plate 40P shown in FIG. FIG. 5B is a schematic enlarged view of the VB portion surrounded by the dashed-dotted line of the deformed portion 36 of the wound body 30 shown in FIG. 5A.

巻回体３０を構成する正極電極３１の正極集電部３１ｃは、巻回軸方向Ｄの一端で巻回軸３０Ａを中心に巻回されて積層され、扁平な形状に成形されている。巻回体３０は、正極集電部３１ｃが巻回された巻回軸方向Ｄの端部において、第１セパレータ３３が負極電極３２よりも巻回軸方向Ｄに突出しており、正極集電部３１ｃが第１セパレータ３３よりも巻回軸方向Ｄに突出している。巻回されて積層した正極集電部３１ｃは、図２に示すように、平坦部３０ａに対応する部分が厚さ方向（Ｙ方向）に圧縮されて束ねられ、巻回体３０の他の部分よりも厚さが薄い積層部３５が形成されている。 The positive electrode current collecting portion 31c of the positive electrode 31 constituting the wound body 30 is wound around the winding axis 30A at one end in the winding axis direction D and stacked to form a flat shape. In the wound body 30, the first separator 33 protrudes in the winding axial direction D from the negative electrode 32 at the end portion in the winding axial direction D around which the positive electrode current collecting portion 31c is wound. 31 c protrudes in the winding axis direction D from the first separator 33 . As shown in FIG. 2, the wound and laminated positive electrode current collecting portion 31c is bundled with the portion corresponding to the flat portion 30a compressed in the thickness direction (Y direction), and the other portion of the wound body 30 is bundled. A laminated portion 35 having a thickness smaller than that is formed.

これにより、巻回体３０の平坦部３０ａと、正極集電部３１ｃの積層部３５との間に、湾曲した形状の変形部３６が形成される。すなわち、正極電極３１の正極集電部３１ｃは、巻回体３０の内周側の巻き始め部分である始端部から、巻回体３０の外周側の巻き終わり部分である終端部３１ｅまで巻回され、扁平に成形されて巻回軸方向Ｄの先端部の積層部３５で束ねられ、巻回体３０の巻回軸方向Ｄの一端に変形部３６を形成している。 Thereby, a deformed portion 36 having a curved shape is formed between the flat portion 30a of the wound body 30 and the laminated portion 35 of the positive electrode collector portion 31c. That is, the positive current collecting portion 31c of the positive electrode 31 is wound from the starting end, which is the winding start portion on the inner peripheral side of the wound body 30, to the terminal end portion 31e, which is the winding end portion on the outer peripheral side of the wound body 30. It is formed flat and bundled at a laminated portion 35 at the tip in the winding axial direction D, and a deformed portion 36 is formed at one end in the winding axial direction D of the wound body 30 .

これにより、変形部３６において、正極電極３１の終端部３１ｅの内周側に巻回された第１セパレータ３３、負極電極３２、および第２セパレータ３４は、正極集電部３１ｃとともに、巻回軸方向Ｄに積層部３５に近づくほど、電池容器１０の厚さ方向（Ｙ方向）に巻回軸３０Ａに近づくように集束されている。これにより、正極集電部３１ｃを含む変形部３６においては、正極電極３１の終端部３１ｅおよびその内周側で、正極電極３１と負極電極３２との間の隙間Ｇが狭くなる。 As a result, the first separator 33, the negative electrode 32, and the second separator 34 wound on the inner peripheral side of the terminal end portion 31e of the positive electrode 31 in the deformed portion 36, together with the positive electrode current collecting portion 31c, are wound around the winding axis. The closer to the laminated portion 35 in the direction D, the closer to the winding axis 30A in the thickness direction (Y direction) of the battery container 10 . As a result, in the deformed portion 36 including the positive current collecting portion 31c, the gap G between the positive electrode 31 and the negative electrode 32 is narrowed at the end portion 31e of the positive electrode 31 and its inner peripheral side.

一方、変形部３６において、正極電極３１の終端部３１ｅの外周側に巻回された第２セパレータ３４、負極電極３２、および最外周の第１セパレータ３３は、巻回および積層された正極集電部３１ｃを集束させて積層部３５で束ねることによる影響をほとんど受けない。そのため、正極集電部３１ｃを含む変形部３６において、正極電極３１の終端部３１ｅの外周側に巻回された第２セパレータ３４、負極電極３２、および最外周の第１セパレータ３３は、巻回軸３０Ａに向けて集束せず、おおむね巻回軸方向Ｄに沿う方向に延びている。これにより、正極集電部３１ｃを含む変形部３６においては、正極電極３１の終端部３１ｅの外周側で、正極電極３１と負極電極３２との間の隙間Ｇが広くなる。 On the other hand, in the deformed portion 36, the second separator 34, the negative electrode 32, and the outermost first separator 33, which are wound around the outer peripheral side of the terminal end portion 31e of the positive electrode 31, are the wound and laminated positive electrode current collectors. It is hardly affected by converging the portion 31c and bundling it with the laminated portion 35. FIG. Therefore, in the deformed portion 36 including the positive electrode current collecting portion 31c, the second separator 34, the negative electrode 32, and the outermost first separator 33, which are wound around the outer peripheral side of the terminal end portion 31e of the positive electrode 31, are wound It does not converge toward the axis 30A and extends generally along the winding axis direction D. As a result, in the deformed portion 36 including the positive current collecting portion 31c, the gap G between the positive electrode 31 and the negative electrode 32 is widened on the outer peripheral side of the terminal end portion 31e of the positive electrode 31 .

さらに、正極電極３１の終端部３１ｅの正極集電部３１ｃとその外周に巻回された第２セパレータ３４との間には、広い隙間Ｇｗが形成される。この隙間Ｇｗは、巻回軸方向Ｄに開放されている。そのため、この隙間Ｇｗを介して正極電極３１と負極電極３２との間に金属異物が流入および侵入しやすくなるおそれがある。 Further, a wide gap Gw is formed between the positive current collecting portion 31c of the terminal end portion 31e of the positive electrode 31 and the second separator 34 wound around the positive electrode current collecting portion 31c. This gap Gw is open in the winding axis direction D. As shown in FIG. Therefore, there is a possibility that metallic foreign matter may easily flow into or enter between the positive electrode 31 and the negative electrode 32 through the gap Gw.

図６は、図４に示す巻回体３０のVI‐VI線に沿う模式的な拡大断面図である。正極電極３１の巻き終わり端部である終端部３１ｅの外周には、第２セパレータ３４、負極電極３２および第１セパレータ３３が巻回されている。そのため、正極電極３１の終端部３１ｅの巻回方向Ｒの末端において、正極電極３１の終端部３１ｅの内周側に巻回された第１セパレータ３３および負極電極３２と、正極電極３１の終端部３１ｅの外周側に巻回された第２セパレータ３４および負極電極３２との間に隙間Ｇａが形成される。この隙間Ｇａに、巻回体３０の巻回軸方向Ｄ（Ｘ方向）の端部から金属異物が流入および侵入するおそれがある。 FIG. 6 is a schematic enlarged cross-sectional view of the wound body 30 shown in FIG. 4 taken along line VI-VI. A second separator 34 , a negative electrode 32 , and a first separator 33 are wound around the outer circumference of a terminal portion 31 e that is a winding end portion of the positive electrode 31 . Therefore, at the end in the winding direction R of the end portion 31e of the positive electrode 31, the first separator 33 and the negative electrode 32 wound on the inner peripheral side of the end portion 31e of the positive electrode 31, and the end portion of the positive electrode 31 A gap Ga is formed between the second separator 34 wound around the outer circumference of 31e and the negative electrode 32 . Metallic foreign matter may flow into or enter this gap Ga from the end of the wound body 30 in the winding axial direction D (X direction).

図７は、図４に示す巻回体３０に被覆部３７を形成した状態を示す正面図である。図８Ａは、図７に示す巻回体３０のVIIIA‐VIIIA線に沿う模式的な拡大断面図である。図８Ｂは、図８Ａに示す巻回体３０の変形部３６の一点鎖線で囲まれたVIIIB部の模式的な拡大図である。 FIG. 7 is a front view showing a state in which the covering portion 37 is formed on the wound body 30 shown in FIG. 8A is a schematic enlarged cross-sectional view along line VIIIA-VIIIA of the wound body 30 shown in FIG. 7. FIG. FIG. 8B is a schematic enlarged view of a portion VIIIB surrounded by a dashed line of the deformed portion 36 of the wound body 30 shown in FIG. 8A.

たとえば、図５Ｂに示す隙間Ｇｗや、図６に示す隙間Ｇａを介した巻回体３０の内部への金属異物の流入および侵入を抑制するために、本実施形態の二次電池１００は、少なくとも第１セパレータ３３と正極集電部３１ｃとの間を跨いで巻回体３０の外表面の一部を覆う熱可塑性成形材からなる被覆部３７を有している。 For example, in order to suppress the inflow and penetration of metallic foreign matter into the wound body 30 through the gap Gw shown in FIG. 5B and the gap Ga shown in FIG. It has a covering portion 37 made of a thermoplastic molded material that covers a part of the outer surface of the wound body 30 across the gap between the first separator 33 and the positive electrode current collecting portion 31c.

被覆部３７は、たとえば、熱可塑性接着剤、すなわちホットメルト接着剤である。熱可塑性接着剤は、たとえば、エチレン酢酸ビニル（ＥＶＡ）などの熱可塑性樹脂を含む。被覆部３７は、たとえば、グルーガンによって加熱されて可塑化した状態で、巻回体３０の最外周の第１セパレータ３３と正極集電部３１ｃとの間を跨ぐように巻回体３０の外表面に塗布される。 The covering portion 37 is, for example, a thermoplastic adhesive, ie hot-melt adhesive. Thermoplastic adhesives include, for example, thermoplastic resins such as ethylene vinyl acetate (EVA). The covering portion 37 is, for example, heated by a glue gun and is in a plasticized state. applied to the

このとき、正極電極３１の終端部３１ｅの外周側に巻回された第２セパレータ３４、負極電極３２、および最外周の第１セパレータ３３の巻回軸方向Ｄの端部は、熱可塑性接着剤の重量により、正極電極３１の終端部３１ｅの正極集電部３１ｃへ向けて変形する。その結果、たとえば、巻回体３０の最外周に巻回された第１セパレータ３３の終端部３３ｅの巻回軸方向Ｄの端部が、その内周側に巻回された第２セパレータ３４の終端部３４ｅの巻回軸方向Ｄの端部に接する。 At this time, the ends in the winding axis direction D of the second separator 34, the negative electrode 32, and the outermost first separator 33 wound around the outer peripheral side of the terminal end 31e of the positive electrode 31 are coated with the thermoplastic adhesive. , the positive electrode 31 is deformed toward the positive collector portion 31c of the end portion 31e. As a result, for example, the end portion 33e of the first separator 33 wound on the outermost periphery of the wound body 30, in the winding axial direction D, becomes the end portion of the second separator 34 wound on the inner peripheral side. It touches the end in the winding axial direction D of the terminal end 34e.

また、第２セパレータ３４の終端部３４ｅの巻回軸方向Ｄの端部が、その内周側に巻回された正極電極３１の正極集電部３１ｃの巻回軸方向Ｄの端部に接近し、または接する。その後、熱可塑性接着剤が冷却されて固化することで、変形部３６の形状に倣う形状の被覆部３７が形成される。すなわち、被覆部３７は、集電板４０に接合された正極集電部３１ｃの外形に沿う形状に成形されている。 In addition, the end portion 34e of the second separator 34 in the winding axial direction D approaches the end portion in the winding axial direction D of the positive current collecting portion 31c of the positive electrode 31 wound on the inner peripheral side thereof. to or in contact with. After that, the thermoplastic adhesive is cooled and solidified to form the covering portion 37 having a shape that follows the shape of the deformed portion 36 . That is, the covering portion 37 is formed in a shape that follows the outer shape of the positive electrode current collecting portion 31 c joined to the current collecting plate 40 .

また、前述のように、巻回体３０は、扁平な形状に成形され、平板状の平坦部３０ａと、その平坦部３０ａの両端に設けられた半円筒状の湾曲部３０ｂとを有している。被覆部３７は、たとえば、巻回体３０の平坦部３０ａに位置している。また、被覆部３７は、たとえば、巻回体３０の正極集電部３１ｃが積層された積層部３５において、正極集電板４０Ｐの延在部４２の接合部４２ａが接合された面に設けられている。 Further, as described above, the wound body 30 is formed into a flat shape, and has a flat plate-like flat portion 30a and semi-cylindrical curved portions 30b provided at both ends of the flat portion 30a. there is The covering portion 37 is positioned, for example, on the flat portion 30a of the wound body 30 . The covering portion 37 is provided, for example, on the surface of the laminated portion 35 in which the positive electrode current collector portion 31c of the wound body 30 is laminated, to which the joint portion 42a of the extension portion 42 of the positive electrode current collector plate 40P is joined. ing.

また、被覆部３７は、巻回体３０の巻回軸方向Ｄの正極集電部３１ｃが巻回された端部において、正極電極３１の正極合剤層３１ｂおよび負極電極３２の巻回軸方向Ｄの端部を覆う位置に配置されている。また、被覆部３７は、正極電極３１の終端部３１ｅの巻回方向Ｒの端縁を正極電極３１の巻回方向Ｒに跨ぐように配置されている。また、被覆部３７は、正極電極３１の巻回方向Ｒにおいて、正極集電板４０Ｐと正極集電部３１ｃの積層部３５との間に接合部Ｊが形成されている範囲に位置している。 In addition, the coating portion 37 is provided at the end portion of the wound body 30 in the winding axial direction D around which the positive electrode collector portion 31c is wound, and the positive electrode mixture layer 31b of the positive electrode 31 and the negative electrode 32 in the winding axial direction. It is arranged in a position covering the end of D. In addition, the covering portion 37 is arranged so as to straddle the winding direction R edge of the terminal end portion 31 e of the positive electrode 31 in the winding direction R of the positive electrode 31 . In addition, the covering portion 37 is positioned in a range in the winding direction R of the positive electrode 31 where the joint portion J is formed between the positive current collecting plate 40P and the laminated portion 35 of the positive current collecting portion 31c. .

集電板４０に接合され、被覆部３７が設けられた巻回体３０は、集電板４０を介して電池蓋１２に固定された状態で、電気絶縁性を有する樹脂製の絶縁シート５０によって覆われて、電池缶１１の開口部１１ａから電池缶１１内に挿入される。絶縁シート５０は、たとえばポリプロピレンなどの合成樹脂を素材とする一枚のシートまたは複数のフィルム部材からなる。絶縁シート５０は、集電板４０が接合された巻回体３０のおおむね全体を集電板４０とともに覆うことができる寸法および形状を有している。 The wound body 30 joined to the current collector plate 40 and provided with the covering portion 37 is fixed to the battery lid 12 via the current collector plate 40 and is protected by the resin insulating sheet 50 having electrical insulation. It is covered and inserted into the battery can 11 through the opening 11 a of the battery can 11 . The insulating sheet 50 is composed of one sheet or a plurality of film members made of synthetic resin such as polypropylene. The insulating sheet 50 has a size and shape that can cover substantially the entire wound body 30 to which the current collector plate 40 is joined together with the current collector plate 40 .

巻回体３０は、巻回軸方向Ｄが二次電池１００の幅方向（Ｘ方向）に沿うように、一方の湾曲部３０ｂから電池缶１１内に挿入され、他方の湾曲部３０ｂが電池蓋１２に対向して配置される。その後、前述のように、電池蓋１２を電池缶１１の開口部１１ａの全周にわたって接合して電池容器１０を構成する。その後、注液孔１６を介して電池容器１０内に電解液を注入し、注液孔１６に注液栓１７を接合して封止する。このとき、電池容器１０の内部の圧力と外部の圧力とを適切に調整すると、巻回体３０内の空気と電解液の置換が促進されて、電池容器１０内に電解液を効率的に注入することができる。 The wound body 30 is inserted into the battery can 11 from one curved portion 30b so that the winding axis direction D is along the width direction (X direction) of the secondary battery 100, and the other curved portion 30b is inserted into the battery lid. 12 are arranged opposite to each other. After that, as described above, the battery lid 12 is joined to the entire circumference of the opening 11a of the battery can 11 to form the battery container 10 . Thereafter, an electrolytic solution is injected into the battery container 10 through the injection hole 16, and the injection plug 17 is joined to the injection hole 16 for sealing. At this time, if the internal pressure and the external pressure of the battery container 10 are appropriately adjusted, replacement of the air in the wound body 30 with the electrolytic solution is promoted, and the electrolytic solution is efficiently injected into the battery container 10. can do.

以上の構成により、二次電池１００は、外部端子２０と外部機器とが、外部端子２０に接合された図示を省略するバスバーを介して接続される。二次電池１００は、外部端子２０と集電板４０を介して巻回体３０の正極電極３１および負極電極３２に電力を供給することで充電され、巻回体３０の正極電極３１および負極電極３２から集電板４０および外部端子２０を介して外部へ電力を供給することができる。 With the above configuration, in the secondary battery 100 , the external terminal 20 and an external device are connected via a bus bar (not shown) joined to the external terminal 20 . The secondary battery 100 is charged by supplying power to the positive electrode 31 and the negative electrode 32 of the wound body 30 through the external terminal 20 and the collector plate 40 , and the positive electrode 31 and the negative electrode 32 of the wound body 30 are charged. Electric power can be supplied from 32 to the outside through the current collector plate 40 and the external terminal 20 .

以下、本実施形態の二次電池１００の作用について説明する。 The operation of the secondary battery 100 of this embodiment will be described below.

本実施形態の二次電池１００は、前述のように、巻回軸方向Ｄの一端と他端に正極集電部３１ｃと負極集電部３２ｃが位置するように配置した正極電極３１と負極電極３２とを第１セパレータ３３と第２セパレータ３４を介在させて巻回軸３０Ａを中心に巻回した巻回体３０を備えている。巻回体３０は、最外周に第１セパレータ３３の終端部３３ｅが巻回され、第１セパレータ３３の終端部３３ｅの内側に負極電極３２の終端部３２ｅが巻回されている。さらに、負極電極３２の終端部３２ｅの内側に第２セパレータ３４の終端部３４ｅを介在させて正極電極３１の正極電極３１が巻回されている。二次電池１００は、少なくとも第１セパレータ３３と正極集電部３１ｃとの間を跨いで巻回体３０の外表面の一部を覆う熱可塑性成形材からなる被覆部３７を有している。 As described above, the secondary battery 100 of the present embodiment has a positive electrode 31 and a negative electrode arranged such that the positive current collector 31c and the negative current collector 32c are positioned at one end and the other end in the winding axial direction D. 32 are wound around a winding shaft 30A with a first separator 33 and a second separator 34 interposed. The wound body 30 has the terminal end portion 33e of the first separator 33 wound around the outermost circumference thereof, and the terminal end portion 32e of the negative electrode 32 wound inside the terminal end portion 33e of the first separator 33 . Further, the positive electrode 31 of the positive electrode 31 is wound inside the terminal portion 32e of the negative electrode 32 with the terminal portion 34e of the second separator 34 interposed therebetween. The secondary battery 100 has a covering portion 37 made of a thermoplastic molding material that covers a part of the outer surface of the wound body 30 across at least the first separator 33 and the positive electrode collector portion 31c.

この構成により、前述のように、たとえば、巻回体３０の最外周に巻回された第１セパレータ３３の終端部３３ｅの巻回軸方向Ｄの端部が、その内周側に巻回された第２セパレータ３４の終端部３４ｅの巻回軸方向Ｄの端部に接する。また、第２セパレータ３４の終端部３４ｅの巻回軸方向Ｄの端部が、その内周側に巻回された正極電極３１の正極集電部３１ｃの巻回軸方向Ｄの端部に接近し、または接する。 With this configuration, as described above, for example, the end portion in the winding axial direction D of the terminal end portion 33e of the first separator 33 wound around the outermost circumference of the wound body 30 is wound on the inner circumference side. It is in contact with the end portion in the winding axis direction D of the terminal end portion 34 e of the second separator 34 . In addition, the end portion 34e of the second separator 34 in the winding axial direction D approaches the end portion in the winding axial direction D of the positive current collecting portion 31c of the positive electrode 31 wound on the inner peripheral side thereof. to or in contact with.

これにより、図５Ｂに示す正極電極３１の終端部３１ｅの正極集電部３１ｃとその外周に巻回された第２セパレータ３４の終端部３４ｅとの間の広い隙間Ｇｗが縮小する。また、この隙間Ｇｗは、正極電極３１の終端部３１ｅの正極集電部３１ｃとその外周の第２セパレータ３４の終端部３４ｅとが接近し、または接することで、図８Ｂに示すように閉鎖された狭い隙間Ｇｎとなる。したがって、巻回体３０の内部の正極電極３１と負極電極３２との間への金属異物の流入および侵入を抑制することができる。 As a result, the wide gap Gw between the positive current collecting portion 31c of the terminal end portion 31e of the positive electrode 31 shown in FIG. 5B and the terminal end portion 34e of the second separator 34 wound around the positive electrode collector portion 31c is reduced. In addition, the gap Gw is closed as shown in FIG. 8B when the positive current collecting portion 31c of the terminal end portion 31e of the positive electrode 31 and the terminal end portion 34e of the second separator 34 on the outer circumference of the positive electrode current collecting portion 31c approach or come into contact with each other. It becomes a narrow gap Gn. Therefore, it is possible to suppress the inflow and penetration of metallic foreign matter between the positive electrode 31 and the negative electrode 32 inside the wound body 30 .

また、本実施形態の二次電池１００の巻回体３０は、正極集電部３１ｃが巻回された巻回軸方向Ｄの端部において、第１セパレータ３３が負極電極３２よりも巻回軸方向Ｄに突出している。また、正極集電部３１ｃが第１セパレータ３３よりも巻回軸方向Ｄに突出している。 In addition, in the wound body 30 of the secondary battery 100 of the present embodiment, the first separator 33 is positioned closer to the winding axis than the negative electrode 32 at the end portion in the winding axis direction D around which the positive electrode collector portion 31c is wound. It protrudes in direction D. Further, the positive electrode current collecting portion 31c protrudes in the winding axial direction D from the first separator 33. As shown in FIG.

この構成により、第１セパレータ３３と正極集電部３１ｃとの間を跨ぐ被覆部３７を設けることで、巻回体３０の最外周に巻回された第１セパレータ３３の終端部３３ｅを正極集電部３１ｃへ向けて変形させることができる。さらに、変形させた第１セパレータ３３の終端部３３ｅによって、負極電極３２の終端部３２ｅおよび第２セパレータ３４の終端部３４ｅを正極集電部３１ｃへ向けて変形させることができる。したがって、巻回体３０の内部への金属異物の流入および侵入をより効果的に抑制することができる。 With this configuration, by providing the covering portion 37 that straddles between the first separator 33 and the positive electrode collector portion 31c, the end portion 33e of the first separator 33 wound around the outermost circumference of the wound body 30 is covered with the positive electrode collector. It can be deformed toward the electric part 31c. Furthermore, the deformed end portion 33e of the first separator 33 can deform the end portion 32e of the negative electrode 32 and the end portion 34e of the second separator 34 toward the positive current collecting portion 31c. Therefore, the inflow and penetration of metallic foreign matter into the wound body 30 can be more effectively suppressed.

また、本実施形態の二次電池１００は、正極外部端子２０Ｐおよび正極集電板４０Ｐと、負極外部端子２０Ｎおよび負極集電板４０Ｎとを備えている。正極集電部３１ｃと負極集電部３２ｃは、それぞれ、正極集電板４０Ｐと負極集電板４０Ｎを介して、正極外部端子２０Ｐと負極外部端子２０Ｎに接続されている。そして、被覆部３７は、正極集電板４０Ｐに接合された正極集電部３１ｃの外形に沿う形状に成形されている。 Further, the secondary battery 100 of the present embodiment includes a positive electrode external terminal 20P and a positive electrode collector plate 40P, and a negative electrode external terminal 20N and a negative electrode collector plate 40N. The positive current collector 31c and the negative current collector 32c are connected to the positive external terminal 20P and the negative external terminal 20N via the positive current collector 40P and the negative current collector 40N, respectively. The covering portion 37 is formed in a shape that follows the outer shape of the positive electrode current collecting portion 31c joined to the positive electrode current collecting plate 40P.

この構成により、巻回体３０において、正極電極３１の終端部３１ｅよりも外周に巻回された第１セパレータ３３の終端部３３ｅ、負極電極３２の終端部３２ｅ、および第２セパレータ３４の終端部３４ｅを正極集電部３１ｃへ向けて変形させることができる。これにより、正極電極３１の終端部３１ｅの正極集電部３１ｃとその外周に巻回された第２セパレータ３４の終端部３４ｅとの間の広い隙間Ｇｗを縮小させ、閉鎖された狭い隙間Ｇｎとすることができる。 With this configuration, in the wound body 30, the terminal end portion 33e of the first separator 33, the terminal end portion 32e of the negative electrode 32, and the terminal end portion of the second separator 34 are wound around the terminal end 31e of the positive electrode 31. 34e can be deformed toward the positive current collecting portion 31c. As a result, the wide gap Gw between the positive current collecting portion 31c of the terminal end portion 31e of the positive electrode 31 and the terminal end portion 34e of the second separator 34 wound around it is reduced, and the closed narrow gap Gn and can do.

また、本実施形態の二次電池１００の巻回体３０は、扁平な形状に成形され、平板状の平坦部３０ａと、その平坦部３０ａの両端に設けられた半円筒状の湾曲部３０ｂとを有している。そして、被覆部３７は、平坦部３０ａに位置している。 In addition, the wound body 30 of the secondary battery 100 of the present embodiment is formed into a flat shape, and includes a flat plate-like flat portion 30a and semi-cylindrical curved portions 30b provided at both ends of the flat portion 30a. have. The covering portion 37 is positioned on the flat portion 30a.

この構成により、巻回体３０の正極集電部３１ｃが巻回された端部において、平坦部３０ａで束ねられて圧縮された積層部３５に連続する変形部３６の最外周に生じやすい隙間Ｇｗを効果的に縮小させることができる。 With this configuration, at the end of the wound body 30 around which the positive electrode current collector 31c is wound, a gap Gw is likely to occur in the outermost periphery of the deformed portion 36 that is continuous with the laminated portion 35 bundled and compressed by the flat portion 30a. can be effectively reduced.

また、本実施形態の二次電池１００において、被覆部３７は、正極電極３１の終端部３１ｅの巻回方向Ｒの端縁を正極電極３１の巻回方向Ｒに跨ぐように配置されている。 Further, in the secondary battery 100 of the present embodiment, the covering portion 37 is arranged so as to straddle the winding direction R edge of the terminal end portion 31 e of the positive electrode 31 in the winding direction R of the positive electrode 31 .

この構成により、巻回体３０の巻回軸方向Ｄの正極集電部３１ｃが巻回された端部において、図６に示すような正極電極３１の終端部３１ｅの巻回方向Ｒの端縁に生じる隙間Ｇａを、被覆部３７によって縮小させ、隙間Ｇａの巻回軸方向Ｄの端部を閉鎖することができる。したがって、この隙間Ｇａに、巻回体３０の巻回軸方向Ｄ（Ｘ方向）の端部から金属異物が流入および侵入するのを抑制することができる。 With this configuration, at the end portion of the wound body 30 in the winding axial direction D where the positive electrode current collector portion 31c is wound, the end edge in the winding direction R of the terminal portion 31e of the positive electrode 31 as shown in FIG. The gap Ga generated in the winding can be reduced by the covering portion 37, and the end portion of the gap Ga in the winding axial direction D can be closed. Therefore, it is possible to suppress the inflow and penetration of metallic foreign matter from the end of the wound body 30 in the winding axial direction D (X direction) into the gap Ga.

また、本実施形態の二次電池１００において、被覆部３７は、熱可塑性接着剤である。 Moreover, in the secondary battery 100 of the present embodiment, the covering portion 37 is a thermoplastic adhesive.

この構成により、熱可塑性接着剤を加熱して可塑化させ、巻回体３０の最外周の第１セパレータ３３と正極集電部３１ｃとの間を跨ぐように巻回体３０の外表面に塗布して被覆部３７を形成することができる。これにより、たとえば粘着テープを用いる場合と比較して、正極集電部３１ｃを含む変形部３６の外形に沿う被覆部３７を容易に形成することができ、被覆部３７を形成する工程の生産性を向上させ、コストを低減することができる。 With this configuration, the thermoplastic adhesive is heated and plasticized, and applied to the outer surface of the wound body 30 so as to straddle between the first separator 33 on the outermost periphery of the wound body 30 and the positive electrode current collector 31c. Then, the covering portion 37 can be formed. This makes it possible to easily form the covering portion 37 along the outer shape of the deforming portion 36 including the positive electrode current collecting portion 31c, compared with the case of using an adhesive tape, for example, and improves the productivity of the process of forming the covering portion 37. can be improved and costs can be reduced.

また、本実施形態の二次電池１００において、正極電極３１は、帯状の正極集電体３１ａと、その正極集電体３１ａの幅方向の一側を除いてその正極集電体３１ａに塗工された正極合剤層３１ｂと、正極集電体３１ａの一側を露出させた正極集電部３１ｃとを有している。負極電極３２は、帯状の負極集電体３２ａと、その負極集電体３２ａの幅方向の一側を除いてその負極集電体３２ａに塗工された負極合剤層３２ｂと、負極集電体３２ａの一側を露出させた負極集電部３２ｃとを有している。 Further, in the secondary battery 100 of the present embodiment, the positive electrode 31 includes a strip-shaped positive electrode current collector 31a, and the positive electrode current collector 31a except for one side in the width direction of the positive electrode current collector 31a. and a positive electrode current collector 31c exposing one side of the positive electrode current collector 31a. The negative electrode 32 includes a strip-shaped negative electrode current collector 32a, a negative electrode mixture layer 32b coated on the negative electrode current collector 32a except for one side in the width direction of the negative electrode current collector 32a, and a negative electrode current collector. and a negative electrode collector 32c with one side of the body 32a exposed.

この構成により、巻回軸方向Ｄの一端と他端に正極集電部３１ｃと負極集電部３２ｃが位置するように配置した正極電極３１と負極電極３２とを、第１セパレータ３３と第２セパレータ３４を介在させて巻回軸３０Ａを中心に巻回することができる。これにより、巻回軸方向Ｄの一端と他端に、それぞれ、正極集電部３１ｃと負極集電部３２ｃが巻回された巻回体３０を構成することができる。 With this configuration, the positive electrode 31 and the negative electrode 32 are arranged such that the positive current collecting portion 31c and the negative electrode current collecting portion 32c are positioned at one end and the other end in the winding axial direction D, and the first separator 33 and the second separator 33 are arranged. It can be wound around the winding shaft 30A with the separator 34 interposed therebetween. As a result, the wound body 30 can be formed by winding the positive current collector 31c and the negative current collector 32c at one end and the other end in the winding axial direction D, respectively.

以上説明したように、本実施形態によれば、内部短絡を生じさせるおそれがある上記二つの要因に対処することができ、負極電極３２と正極電極３１とをセパレータ３３、３４を介在させて巻回した巻回体３０に流入する異物を抑制することが可能な二次電池１００を提供することができる。なお、本開示に係る二次電池は、本実施形態の二次電池１００に構成に限定されない。 As described above, according to the present embodiment, it is possible to deal with the above two factors that may cause an internal short circuit, and the negative electrode 32 and the positive electrode 31 are wound with the separators 33 and 34 interposed. It is possible to provide the secondary battery 100 capable of suppressing foreign matter from flowing into the wound wound body 30 . Note that the configuration of the secondary battery according to the present disclosure is not limited to the configuration of the secondary battery 100 of the present embodiment.

図９は、実施形態１に係る二次電池１００の変形例を示す図７に対応する正面図である。本変形例において、被覆部３７は、巻回体３０の最外周に巻回された第１セパレータ３３の終端部３３ｅの巻回方向Ｒにおいて、巻回体３０の平坦部３０ａの全域にわたって設けられている。 9 is a front view corresponding to FIG. 7 showing a modification of the secondary battery 100 according to Embodiment 1. FIG. In this modification, the covering portion 37 is provided over the entire flat portion 30a of the wound body 30 in the winding direction R of the end portion 33e of the first separator 33 wound on the outermost periphery of the wound body 30. ing.

この構成により、巻回体３０の平坦部３０ａの全域にわたって巻回体３０の最外周に巻回された第１セパレータ３３の終端部３３ｅの巻回軸方向Ｄの端部が、正極集電部３１ｃに接近するように変形する。これにより、前述の実施形態１に係る二次電池１００と同様の効果を奏することができるだけでなく、図８Ｂに示すような閉鎖された隙間Ｇｎを巻回体３０の平坦部３０ａの全域にわたって形成することができる。したがって、巻回体３０の内部の正極電極３１と負極電極３２との間への金属異物の流入および侵入をより確実に抑制することができる。 With this configuration, the end portion in the winding axis direction D of the end portion 33e of the first separator 33 wound around the outermost periphery of the wound body 30 over the entire flat portion 30a of the wound body 30 is the positive electrode current collecting portion. Transform to approach 31c. As a result, not only can the same effect as the secondary battery 100 according to the first embodiment described above be obtained, but also the closed gap Gn as shown in FIG. can do. Therefore, it is possible to more reliably suppress the inflow and penetration of metallic foreign matter between the positive electrode 31 and the negative electrode 32 inside the wound body 30 .

［実施形態２］
次に、図１から図６を援用し、図１０Ａおよび図１０Ｂを参照して、本開示に係る二次電池の実施形態２を説明する。図１０Ａは、実施形態２に係る二次電池の図７に対応する正面図である。図１０Ｂは、図１０Ａに示す巻回体３０のXB‐XB線に沿う模式的な断面図である。 [Embodiment 2]
Next, Embodiment 2 of the secondary battery according to the present disclosure will be described with reference to FIGS. 1 to 6 and FIGS. 10A and 10B. 10A is a front view corresponding to FIG. 7 of the secondary battery according to Embodiment 2. FIG. FIG. 10B is a schematic cross-sectional view along line XB-XB of wound body 30 shown in FIG. 10A.

本実施形態の二次電池は、被覆部３７が熱収縮フィルムである点で、前述の実施形態１に係る二次電池１００と異なっている。本実施形態の二次電池のその他の点は、前述の実施形態１に係る二次電池１００と同様であるので、同様の部分には同一の符号を付して説明を省略する。 The secondary battery of this embodiment differs from the secondary battery 100 of Embodiment 1 described above in that the covering portion 37 is a heat-shrinkable film. Other points of the secondary battery of this embodiment are the same as those of the secondary battery 100 according to Embodiment 1 described above, so that the same parts are denoted by the same reference numerals, and descriptions thereof are omitted.

被覆部３７は、たとえば、柔軟性を有する薄い筒状に形成されている。被覆部３７は、たとえば、加熱前の非収縮状態の周長が、正極電極３１、負極電極３２、第１セパレータ３３、および第２セパレータ３４の巻回方向Ｒと直交する方向の巻回体３０の周長よりも長い。そのため、集電板４０に接合されて電池蓋１２に固定された巻回体３０の一方の湾曲部３０ｂを筒状の被覆部３７に挿入し、被覆部３７を巻回体３０の周囲に被せることができる。被覆部３７は、たとえば、電池容器１０の高さ方向（Ｚ方向）の寸法が、同方向の巻回体３０の平坦部３０ａの寸法とおおむね等しく、平坦部３０ａの全体を覆っている。 The covering portion 37 is formed, for example, in a flexible thin tubular shape. The covering portion 37 is, for example, the wound body 30 whose circumferential length in a non-shrinking state before heating is perpendicular to the winding direction R of the positive electrode 31, the negative electrode 32, the first separator 33, and the second separator 34. longer than the perimeter of Therefore, one curved portion 30b of the wound body 30 joined to the current collecting plate 40 and fixed to the battery lid 12 is inserted into the cylindrical covering portion 37, and the covering portion 37 is put around the wound body 30. be able to. For example, the covering portion 37 has a dimension in the height direction (Z direction) of the battery container 10 that is substantially equal to the dimension of the flat portion 30a of the wound body 30 in the same direction, and covers the entire flat portion 30a.

被覆部３７の熱収縮フィルムの素材としては、たとえば、ポリ塩化ビニル（ＰＶＣ）、ポリスチレン（ＰＳ）、ポリエチレンテレフタレート（ＰＥＴ）、ポリエチレン（ＰＥ）、ポリプロピレン（ＰＰ）、ポリオレフィン（ＰＯ）などの樹脂材料を用いることができる。特に、ＰＶＣは、低温で収縮させることができるため、被覆部３７の素材として好適である。 Examples of materials for the heat-shrinkable film of the covering portion 37 include resin materials such as polyvinyl chloride (PVC), polystyrene (PS), polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), and polyolefin (PO). can be used. In particular, PVC is suitable as a material for the covering portion 37 because it can be shrunk at a low temperature.

被覆部３７は、たとえば、前述のように巻回体３０の周囲に被せた後に、熱風を吹き付けたり、金型の内部に配置して加熱したりすることによって、収縮させることができる。このとき、正極電極３１の終端部３１ｅの外周側に巻回された第２セパレータ３４、負極電極３２、および最外周の第１セパレータ３３の巻回軸方向Ｄの端部は、熱収縮フィルムの収縮により、正極電極３１の終端部３１ｅの正極集電部３１ｃへ向けて変形する。 For example, after covering the wound body 30 as described above, the covering portion 37 can be shrunk by blowing hot air or placing it inside a mold and heating it. At this time, the ends in the winding axis direction D of the second separator 34, the negative electrode 32, and the outermost first separator 33 wound on the outer peripheral side of the terminal end 31e of the positive electrode 31 are covered with the heat-shrinkable film. Due to the contraction, the end portion 31e of the positive electrode 31 is deformed toward the positive collector portion 31c.

その結果、たとえば、巻回体３０の最外周に巻回された第１セパレータ３３の終端部３３ｅの巻回軸方向Ｄの端部が、その内周側に巻回された第２セパレータ３４の終端部３４ｅの巻回軸方向Ｄの端部に接する。また、第２セパレータ３４の終端部３４ｅの巻回軸方向Ｄの端部が、その内周側に巻回された正極電極３１の正極集電部３１ｃの巻回軸方向Ｄの端部に接近し、または接する。被覆部３７は、熱収縮することによって集電板４０に接合された正極集電部３１ｃの外形に沿う形状に成形されている。 As a result, for example, the end portion 33e of the first separator 33 wound on the outermost periphery of the wound body 30, in the winding axial direction D, becomes the end portion of the second separator 34 wound on the inner peripheral side. It touches the end in the winding axial direction D of the terminal end 34e. In addition, the end portion 34e of the second separator 34 in the winding axial direction D approaches the end portion in the winding axial direction D of the positive current collecting portion 31c of the positive electrode 31 wound on the inner peripheral side thereof. to or in contact with. The covering portion 37 is formed into a shape that conforms to the outer shape of the positive electrode current collecting portion 31c that is joined to the current collecting plate 40 by thermal contraction.

このように、本実施形態の二次電池は、前述の実施形態１に係る二次電池１００と同様に少なくとも第１セパレータ３３と正極集電部３１ｃとの間を跨いで巻回体３０の外表面の一部を覆う熱可塑性成形材からなる被覆部３７を有している。したがって、本実施形態の二次電池によれば、前述の実施形態１に係る二次電池１００と同様の効果を奏することができる。 As described above, in the secondary battery of the present embodiment, as in the secondary battery 100 of Embodiment 1 described above, at least the first separator 33 and the positive current collecting portion 31c are straddled to the outside of the wound body 30. It has a covering portion 37 made of a thermoplastic molded material covering part of the surface. Therefore, according to the secondary battery of the present embodiment, it is possible to achieve the same effects as the secondary battery 100 according to the first embodiment described above.

また、本実施形態の二次電池によれば、被覆部３７によって、巻回体３０の平坦部３０ａを、正極電極３１、負極電極３２、第１セパレータ３３、および第２セパレータ３４の巻回方向Ｒと直交する方向の全周にわたって覆うことができる。この構成により、巻回体３０の平坦部３０ａの巻回軸方向Ｄの両端部を被覆部３７によって全体的に覆うことができ、巻回体３０の内部への異物の流入および侵入をより確実に抑制することができる。 Further, according to the secondary battery of the present embodiment, the flat portion 30a of the wound body 30 is covered by the covering portion 37 in the winding direction of the positive electrode 31, the negative electrode 32, the first separator 33, and the second separator 34. It can be covered over the entire circumference in the direction orthogonal to R. With this configuration, both end portions of the flat portion 30a of the wound body 30 in the winding axial direction D can be entirely covered with the covering portion 37, so that the inflow and penetration of foreign matter into the wound body 30 can be more reliably prevented. can be suppressed to

以上、図面を用いて本開示に係る二次電池の実施形態を詳述してきたが、具体的な構成はこれらの実施形態に限定されるものではなく、本開示の要旨を逸脱しない範囲における設計変更等があっても、それらは本開示に含まれるものである。 The embodiments of the secondary battery according to the present disclosure have been described in detail above with reference to the drawings, but the specific configuration is not limited to these embodiments, and the design within the scope of the present disclosure All such modifications are intended to be included in this disclosure.

たとえば前述の実施形態では、正極電極と負極電極とがセパレータを介して巻回された巻回体を有する二次電池を例示した。しかし、本開示は、矩形シート状の正極電極と矩形シート状の負極電極とを、セパレータを介して平坦状に積層した電極群を備える二次電池に適用することができる。また、前述の実施形態では、二次電池をリチウムイオン二次電池として例示した。しかし、本開示は、ニッケル・カドミウム電池やニッケル水素電池等、他の二次電池に適用することができる。 For example, in the above embodiments, the secondary battery has a wound body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween. However, the present disclosure can be applied to a secondary battery including an electrode group in which a rectangular sheet-like positive electrode and a rectangular sheet-like negative electrode are flatly laminated via a separator. Moreover, in the above-described embodiments, the secondary battery is exemplified as a lithium ion secondary battery. However, the present disclosure can be applied to other secondary batteries such as nickel-cadmium batteries and nickel-metal hydride batteries.

２０Ｎ 負極外部端子
２０Ｐ 正極外部端子
３０ 巻回体
３０ａ 平坦部
３０ｂ 湾曲部
３０Ａ 巻回軸
３１ 正極電極
３１ａ 正極集電体
３１ｂ 正極合剤層
３１ｃ 正極集電部
３１ｅ 終端部
３２ 負極電極
３２ａ 負極集電体
３２ｂ 負極合剤層
３２ｃ 負極集電部
３２ｅ 終端部
３３ 第１セパレータ
３３ｅ 終端部
３４ 第２セパレータ
３４ｅ 終端部
３７ 被覆部
４０Ｎ 負極集電板
４０Ｐ 正極集電板
１００ 二次電池
Ｄ 巻回軸方向
Ｒ 巻回方向 20N negative electrode external terminal 20P positive electrode external terminal 30 wound body 30a flat portion 30b curved portion 30A winding shaft 31 positive electrode 31a positive electrode current collector 31b positive electrode mixture layer 31c positive electrode current collector 31e terminal portion 32 negative electrode 32a negative electrode current collector Body 32b Negative electrode mixture layer 32c Negative electrode current collector 32e Termination portion 33 First separator 33e Termination portion 34 Second separator 34e Termination portion 37 Coating portion 40N Negative electrode current collector 40P Positive electrode current collector 100 Secondary battery D Winding axial direction R winding direction

Claims (6)

巻回軸方向の一端と他端に正極集電部と負極集電部が位置するように配置した正極電極と負極電極とを第１セパレータと第２セパレータを介在させて巻回軸を中心に巻回した巻回体を備えた二次電池であって、
前記巻回体は、最外周に前記第１セパレータの終端部が巻回され、前記第１セパレータの前記終端部の内側に前記負極電極の終端部が巻回され、前記負極電極の前記終端部の内側に前記第２セパレータの終端部を介在させて前記正極電極の終端部が巻回されており、
少なくとも前記第１セパレータと前記正極集電部との間を跨いで前記巻回体の外表面の一部を覆う熱可塑性成形材からなる被覆部を有し、
前記被覆部は、熱可塑性接着剤であることを特徴とする二次電池。 A positive electrode and a negative electrode are arranged such that the positive current collecting portion and the negative current collecting portion are positioned at one end and the other end in the direction of the winding axis. A secondary battery comprising a wound body,
In the wound body, the end portion of the first separator is wound around the outermost periphery, the end portion of the negative electrode is wound inside the end portion of the first separator, and the end portion of the negative electrode is wound. The end portion of the positive electrode is wound with the end portion of the second separator interposed inside the
a covering portion made of a thermoplastic molding material covering a part of the outer surface of the wound body across at least the first separator and the positive electrode current collecting portion;
The secondary battery, wherein the covering portion is a thermoplastic adhesive. 前記巻回体は、前記正極集電部が巻回された前記巻回軸方向の端部において、前記第１セパレータが前記負極電極よりも前記巻回軸方向に突出しており、前記正極集電部が前記第１セパレータよりも前記巻回軸方向に突出していることを特徴とする請求項１に記載の二次電池。 In the wound body, the first separator protrudes in the winding axial direction more than the negative electrode at an end portion in the winding axial direction around which the positive electrode current collector is wound, and the positive electrode current collector 2. The secondary battery according to claim 1, wherein a portion protrudes further in the winding axis direction than the first separator. 正極外部端子および正極集電板と、負極外部端子および負極集電板とを備え、
前記正極集電部と前記負極集電部は、それぞれ、前記正極集電板と前記負極集電板を介して、前記正極外部端子と前記負極外部端子に接続され、
前記被覆部は、前記正極集電板に接合された前記正極集電部の外形に沿う形状に成形されていることを特徴とする請求項２に記載の二次電池。 A positive electrode external terminal and a positive electrode current collector, and a negative electrode external terminal and a negative electrode current collector,
The positive electrode current collecting portion and the negative electrode current collecting portion are connected to the positive electrode external terminal and the negative electrode external terminal via the positive electrode current collecting plate and the negative electrode current collecting plate, respectively,
3. The secondary battery according to claim 2 , wherein the covering portion is formed in a shape that conforms to the outer shape of the positive electrode current collecting portion joined to the positive electrode current collecting plate. 前記巻回体は、扁平な形状に成形され、平板状の平坦部と、該平坦部の両端に設けられた半円筒状の湾曲部とを有し、
前記被覆部は、前記平坦部に位置していることを特徴とする請求項３に記載の二次電池。 The wound body is formed in a flat shape and has a flat flat portion and semi-cylindrical curved portions provided at both ends of the flat portion,
4. The secondary battery according to claim 3 , wherein the covering portion is positioned on the flat portion. 前記被覆部は、前記正極電極の終端部の巻回方向の端縁を該巻回方向に跨ぐように配置されていることを特徴とする請求項４に記載の二次電池。 5. The secondary battery according to claim 4 , wherein the covering portion is arranged so as to straddle an edge in the winding direction of the end portion of the positive electrode in the winding direction. 前記正極電極は、帯状の正極集電体と、該正極集電体の幅方向の一側を除いて該正極集電体に塗工された正極合剤層と、前記正極集電体の前記一側を露出させた前記正極集電部とを有し、
前記負極電極は、帯状の負極集電体と、該負極集電体の幅方向の一側を除いて該負極集電体に塗工された負極合剤層と、前記負極集電体の前記一側を露出させた前記負極集電部とを有することを特徴とする請求項１に記載の二次電池。 The positive electrode includes a strip-shaped positive electrode current collector, a positive electrode mixture layer coated on the positive electrode current collector except for one side in the width direction of the positive electrode current collector, and the positive electrode current collector described above. and the positive electrode current collector with one side exposed,
The negative electrode includes a strip-shaped negative electrode current collector, a negative electrode mixture layer coated on the negative electrode current collector except for one side in the width direction of the negative electrode current collector, and the negative electrode current collector described above. 2. The secondary battery according to claim 1, further comprising the negative electrode current collector with one side exposed.
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