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JP7616276B2 - Energy storage element - Google Patents
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JP7616276B2 - Energy storage element - Google Patents

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JP7616276B2
JP7616276B2 JP2023101703A JP2023101703A JP7616276B2 JP 7616276 B2 JP7616276 B2 JP 7616276B2 JP 2023101703 A JP2023101703 A JP 2023101703A JP 2023101703 A JP2023101703 A JP 2023101703A JP 7616276 B2 JP7616276 B2 JP 7616276B2
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active material
positive electrode
tab
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insulating layer
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JP2023126819A (en
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好浩 山本
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GS Yuasa International Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/10—Multiple hybrid or EDL capacitors, e.g. arrays or modules
    • H01G11/12—Stacked hybrid or EDL capacitors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/172—Arrangements of electric connectors penetrating the casing
    • H01M50/174—Arrangements of electric connectors penetrating the casing adapted for the shape of the cells
    • H01M50/176—Arrangements of electric connectors penetrating the casing adapted for the shape of the cells for prismatic or rectangular cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/74—Terminals, e.g. extensions of current collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/74—Terminals, e.g. extensions of current collectors
    • H01G11/76—Terminals, e.g. extensions of current collectors specially adapted for integration in multiple or stacked hybrid or EDL capacitors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/536—Electrode connections inside a battery casing characterised by the method of fixing the leads to the electrodes, e.g. by welding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/538—Connection of several leads or tabs of wound or folded electrode stacks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/54—Connection of several leads or tabs of plate-like electrode stacks, e.g. electrode pole straps or bridges
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • 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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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Secondary Cells (AREA)
  • Materials Engineering (AREA)
  • Connection Of Batteries Or Terminals (AREA)
  • Electric Double-Layer Capacitors Or The Like (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Cell Electrode Carriers And Collectors (AREA)

Description

本発明は、セパレータを介して積層される正極シートおよび負極シートを有する蓄電素子に関する。 The present invention relates to an energy storage element having a positive electrode sheet and a negative electrode sheet stacked with a separator interposed therebetween.

リチウムイオン電池のような蓄電素子には、セパレータを介して交互に積層された正極シート及び負極シートを有する電極体が用いられることがある。一般に、正極シート及び負極シートは、金属箔の両面に活物質層が塗工されることで形成される。 In energy storage devices such as lithium-ion batteries, an electrode assembly having positive and negative electrode sheets alternately stacked with a separator between them may be used. In general, positive and negative electrode sheets are formed by coating both sides of a metal foil with an active material layer.

特許文献１に開示されているように、蓄電素子の正極シート及び負極シートには、該シートの幅方向の一方側における直線状の縁部から幅方向の外側に突出したタブが設けられることがある。タブの少なくとも一部は、活物質層が形成されていない活物質非形成部とされ、該活物質非形成部は、集電体を介して外部端子に電気的に接続される。 As disclosed in Patent Document 1, the positive electrode sheet and the negative electrode sheet of the energy storage element may be provided with a tab that protrudes outward in the width direction from a linear edge on one side of the sheet in the width direction. At least a part of the tab is an active material non-forming part where no active material layer is formed, and the active material non-forming part is electrically connected to an external terminal via a current collector.

この種の蓄電素子において、正極シートには、タブだけでなく、該タブ側の縁部に沿った部分にも活物質非形成部が形成されることがある。また、このように正極シートの縁部に沿って形成された活物質非形成部は、セパレータを介して負極シートの活物質層に対向配置されることがある。 In this type of energy storage element, the positive electrode sheet may have an active material non-forming portion formed not only on the tab but also along the edge of the tab. In addition, the active material non-forming portion formed along the edge of the positive electrode sheet in this manner may be disposed opposite the active material layer of the negative electrode sheet via a separator.

特許第５３５４０４２号公報Patent No. 5354042

しかしながら、上記のように正極シートのタブ側の縁部に沿って形成された活物質非形成部がセパレータを介して負極活物質層に対向配置された蓄電素子では、セパレータの位置ずれ、収縮又は破損のような何らかの原因によって、正極活物質非形成部と負極活物質層が直接対向する状態になった場合に、これらの間で短絡が生じる可能性がある。 However, in a storage element in which the active material non-forming portion formed along the edge of the tab side of the positive electrode sheet as described above is disposed opposite the negative electrode active material layer via a separator, if the positive electrode active material non-forming portion and the negative electrode active material layer come to face each other directly due to some cause such as misalignment, shrinkage, or breakage of the separator, a short circuit may occur between them.

そこで、本発明は、電極シートのタブ側の縁部に沿って活物質非形成部が設けられた蓄電素子において、前記活物質非形成部における短絡の発生を抑制することを目的とする。 The present invention aims to prevent the occurrence of short circuits in an active material non-forming portion of an energy storage element that has an active material non-forming portion along the edge of the tab side of the electrode sheet.

本発明に係る蓄電素子は、電極体を備えた蓄電素子であって、前記電極体は、第１電極シートと前記第１電極シートとは異なる極性を有する第２電極シートとを有し、かつ、前記第１電極シートと前記第２電極シートとが重ねられて巻回されることで形成され、前記第１電極シートは、金属箔と、前記金属箔に設けられた活物質層と、前記金属箔に設けられた絶縁層と、を備え、前記金属箔は、前記活物質層が設けられていない活物質非形成部を有し、前記活物質非形成部は、前記金属箔の所定方向の縁部に沿って延びる第１活物質非形成部と、前記第１活物質非形成部から突出した第１タブと、を有し、前記絶縁層は、前記活物質層上、及び、前記活物質非形成部における前記第１タブの基部を含む領域に形成されており、前記第１タブは、前記基部においてアールが付けられており、前記絶縁層は、前記第１タブの前記アールを含む領域に形成されていることを特徴とする。または、第１電極シートと、セパレータを介して前記第１電極シートに積層され、前記第１電極シートとは異なる極性を有する第２電極シートと、を備えた蓄電素子であって、前記第１電極シートは、第１方向に延びる縁部、及び、該縁部から前記第１方向に交差する第２方向に突出した第１タブを有する金属箔と、前記金属箔の表面に形成された活物質層と、前記金属箔の表面に形成された絶縁層と、を備え、前記第２電極シートは、前記第１方向に延びる縁部、及び、該縁部から前記第２方向に延びる第２タブを有し、前記第１タブと前記第２タブは、前記第２方向の同じ側に突出しており、前記金属箔における前記縁部に沿う部分及び前記第１タブは、前記活物質層が形成されていない活物質非形成部とされ、前記絶縁層は、前記活物質非形成部における前記第１タブの基部を含む領域に設けられ、前記第１タブは、前記基部においてアールが付けられており、前記絶縁層は、前記第１タブの前記アールを含む領域に形成されていることを特徴とする。または、本発明に係る蓄電素子は、電極体を備えた蓄電素子であって、前記電極体は、第１電極シートと、前記第１電極シートとは異なる極性を有する第２電極シートと、を有し、前記第１電極シートは、金属箔と、前記金属箔に設けられた活物質層と、前記金属箔に設けられた絶縁層と、を備え、前記金属箔は、前記活物質層が設けられていない活物質非形成部を有し、前記活物質非形成部は、前記金属箔の縁部に沿って延びる第１活物質非形成部と、前記第１活物質非形成部から突出した第１タブと、を有し、前記絶縁層は、前記活物質非形成部における前記第１タブの基部を含む領域に設けられ、前記第２電極シートは、縁部、及び、該縁部から突出した第２タブを有し、前記第１タブと前記第２タブは、前記電極体の同一端面部から突出しており、前記第１タブは、前記基部においてアールが付けられており、前記絶縁層は、前記アールに沿って形成されていることを特徴とする。 The energy storage element according to the present invention is an energy storage element including an electrode body, the electrode body having a first electrode sheet and a second electrode sheet having a polarity different from that of the first electrode sheet, and being formed by stacking and rolling the first electrode sheet and the second electrode sheet, the first electrode sheet including a metal foil, an active material layer provided on the metal foil, and an insulating layer provided on the metal foil, the metal foil having an active material non-forming portion where the active material layer is not provided, the active material non-forming portion including a first active material non-forming portion extending along an edge of the metal foil in a predetermined direction and a first tab protruding from the first active material non-forming portion, the insulating layer being formed on the active material layer and in a region including a base of the first tab in the active material non-forming portion, the first tab being rounded at the base, and the insulating layer being formed in a region including the rounded edge of the first tab. Alternatively, an energy storage element comprising a first electrode sheet and a second electrode sheet laminated on the first electrode sheet via a separator and having a different polarity from the first electrode sheet, wherein the first electrode sheet comprises a metal foil having an edge extending in a first direction and a first tab protruding from the edge in a second direction intersecting the first direction, an active material layer formed on a surface of the metal foil, and an insulating layer formed on the surface of the metal foil, the second electrode sheet has an edge extending in the first direction and a second tab extending from the edge in the second direction, the first tab and the second tab protruding on the same side in the second direction, a portion of the metal foil along the edge and the first tab are active material non-forming portions in which the active material layer is not formed, the insulating layer is provided in a region including a base of the first tab in the active material non-forming portion, the first tab is radiused at the base, and the insulating layer is formed in a region including the radius of the first tab. Alternatively, the energy storage element according to the present invention is an energy storage element having an electrode body, the electrode body having a first electrode sheet and a second electrode sheet having a polarity different from that of the first electrode sheet, the first electrode sheet having a metal foil, an active material layer provided on the metal foil, and an insulating layer provided on the metal foil, the metal foil having an active material non-forming portion where the active material layer is not provided, the active material non-forming portion having a first active material non-forming portion extending along the edge of the metal foil and a first tab protruding from the first active material non-forming portion, the insulating layer being provided in a region including the base of the first tab in the active material non-forming portion, the second electrode sheet having an edge and a second tab protruding from the edge, the first tab and the second tab protruding from the same end surface portion of the electrode body, the first tab having a radius at the base, and the insulating layer being formed along the radius.

これにより、セパレータの位置ずれ、収縮又は破損等によって第１電極シートが第２電極シートに直接対向する状態になった場合でも、第１電極シートの活物質非形成部と第２電極シートとの間に絶縁層が介在することで、第１電極シートの活物質非形成部における短絡の発生を抑制できる。 As a result, even if the first electrode sheet comes directly opposite the second electrode sheet due to misalignment, shrinkage, or damage of the separator, the insulating layer is interposed between the active material non-forming portion of the first electrode sheet and the second electrode sheet, thereby preventing a short circuit from occurring in the active material non-forming portion of the first electrode sheet.

本発明において、前記絶縁層は、前記活物質層上、及び、前記活物質非形成部における前記第１タブの基部を含む領域に設けられるため、第１タブの基部における短絡の発生を抑制しつつ、該基部を絶縁層によって補強することができる。 In the present invention, the insulating layer is provided on the active material layer and in a region including the base of the first tab in the active material non-forming portion, so that the base can be reinforced by the insulating layer while suppressing the occurrence of a short circuit at the base of the first tab.

本発明において、前記第１タブは、前記基部においてアールが付けられているため、第１タブの基部にかかる応力を分散させて、第１タブの強度を向上させることができる。 In the present invention, the first tab has a radius at the base, which distributes the stress on the base of the first tab and improves the strength of the first tab.

本発明に係る蓄電素子が、前記第１電極シートを外部端子に電気的に接続させる集電体を更に備える場合、前記第１タブは、折り曲げられた状態で前記集電体に接続されてもよい。この場合、折り曲げによって応力が集中する第１タブの基部が絶縁層によって補強されていることで、第１タブの剛性、耐久性の向上を図ることができる。 When the energy storage element according to the present invention further includes a current collector that electrically connects the first electrode sheet to an external terminal, the first tab may be connected to the current collector in a folded state. In this case, the base of the first tab, where stress is concentrated due to bending, is reinforced by an insulating layer, thereby improving the rigidity and durability of the first tab.

本発明において、前記絶縁層における前記第１タブの表面に形成された部分は、前記第２方向において前記セパレータの縁部よりも突出していることが好ましい。これにより、セパレータの位置ずれ、収縮又は破損等によって第１タブがセパレータを介することなく第２電極シートに対向する状態になった場合でも、第１タブの金属箔と第２電極シートとの間に絶縁層が介在することで、第１タブにおける短絡の発生を抑制できる。 In the present invention, it is preferable that the portion of the insulating layer formed on the surface of the first tab protrudes in the second direction beyond the edge of the separator. As a result, even if the first tab faces the second electrode sheet without the separator in between due to misalignment, shrinkage, or damage of the separator, the insulating layer is interposed between the metal foil of the first tab and the second electrode sheet, thereby suppressing the occurrence of a short circuit in the first tab.

本発明では、前記活物質非形成部において、前記金属箔の端面にも前記絶縁層が形成されていることが好ましい。これにより、第１電極シートの活物質非形成部における短絡の発生をより効果的に抑制できる。また、第１電極シートの前記縁部の端面が絶縁層で被覆されていることにより、この縁部の端面での短絡の抑制を図りつつ、第１電極シートの縁部よりも第２方向の外側に位置するセパレータの縁部に対して、第１電極シートの縁部を近づけて配置しやすくなる。そのため、第１電極シートを第２方向に拡大することができ、これにより、電池容量の増大を図ることができる。 In the present invention, it is preferable that the insulating layer is also formed on the end face of the metal foil in the active material non-forming portion. This makes it possible to more effectively suppress the occurrence of short circuits in the active material non-forming portion of the first electrode sheet. In addition, since the end face of the edge portion of the first electrode sheet is covered with an insulating layer, it is easy to arrange the edge portion of the first electrode sheet close to the edge portion of the separator located outside the edge portion of the first electrode sheet in the second direction while suppressing short circuits at the end face of this edge portion. Therefore, the first electrode sheet can be expanded in the second direction, which can increase the battery capacity.

本発明において、前記第２電極シートが、前記第１方向に直線状に延びる縁部、及び、該縁部から前記第２方向に延びる第２タブを有する場合、前記第１タブと前記第２タブは、前記第２方向の同じ側に突出すると共に、前記第１方向に間隔を空けて配置されてもよい。この場合、この種の蓄電素子において上述の効果を得ることができる。 In the present invention, when the second electrode sheet has an edge portion that extends linearly in the first direction and a second tab that extends from the edge portion in the second direction, the first tab and the second tab may protrude to the same side in the second direction and be spaced apart in the first direction. In this case, the above-mentioned effects can be obtained in this type of energy storage element.

本発明において、前記第１電極シートが、前記第１方向に間隔を空けて配置された複数の前記第１タブを備え、前記第１電極シートと前記第２電極シートが、前記セパレータを介して相互に重ねられながら前記第２方向に平行な軸周りに巻回されることで、巻回体を形成している場合、前記巻回体は、前記複数の第１タブを積層してなる第１タブ束を備えてもよい。この場合、第１タブの基部の剛性が絶縁層によって高められていることにより、第１電極シートを巻回する際に、該第１電極シートの厚み方向に反るような第１タブの撓みが抑制される。そのため、第１電極シートを巻回して複数の第１タブを重ねるときに、第１タブ同士が引っ掛かり難くなり、これにより、各第１タブの折れが抑制される。 In the present invention, when the first electrode sheet includes a plurality of the first tabs arranged at intervals in the first direction, and the first electrode sheet and the second electrode sheet are stacked on each other via the separator and wound around an axis parallel to the second direction to form a wound body, the wound body may include a first tab bundle formed by stacking the plurality of first tabs. In this case, the rigidity of the base of the first tab is increased by the insulating layer, so that when the first electrode sheet is wound, the first tab is prevented from bending in the thickness direction of the first electrode sheet. Therefore, when the first electrode sheet is rolled to stack the plurality of first tabs, the first tabs are less likely to get caught on each other, and thus bending of each first tab is prevented.

本発明において、前記巻回体が、前記軸の延びる方向から見て相互に平行な直線状に延びる一対のフラット部と、該一対のフラット部間を繋ぐ一対の湾曲部とを備える場合、前記第１タブ束は、前記フラット部に設けられてもよい。この場合、この種の蓄電素子において上述の効果を得ることができる。 In the present invention, when the wound body has a pair of flat portions that extend linearly parallel to each other when viewed in the direction in which the axis extends, and a pair of curved portions that connect the pair of flat portions, the first tab bundle may be provided on the flat portions. In this case, the above-mentioned effects can be obtained in this type of energy storage element.

本発明に係る蓄電素子が、複数の前記第１電極シートと複数の前記第２電極シートが前記セパレータを介して交互に積層されてなる積層体を備える場合、前記積層体は、前記複数の第１電極シートのそれぞれに設けられた前記第１タブを積層してなる第１タブ束を備えてもよい。この場合、この種の蓄電素子において上述の効果を得ることができる。 When the energy storage element according to the present invention includes a laminate in which a plurality of the first electrode sheets and a plurality of the second electrode sheets are alternately stacked with the separator interposed therebetween, the laminate may include a first tab bundle in which the first tabs provided on each of the plurality of first electrode sheets are stacked. In this case, the above-mentioned effects can be obtained in this type of energy storage element.

本発明によれば、セパレータの位置ずれ、収縮又は破損等によって第１電極シートが第２電極シートに直接対向する状態になった場合でも、第１電極シートの活物質非形成部と第２電極シートとの間に絶縁層が介在することで、第１電極シートの活物質非形成部における短絡の発生を抑制できる。 According to the present invention, even if the first electrode sheet is placed directly opposite the second electrode sheet due to misalignment, shrinkage, or damage of the separator, the insulating layer is interposed between the active material non-forming portion of the first electrode sheet and the second electrode sheet, thereby preventing a short circuit from occurring in the active material non-forming portion of the first electrode sheet.

本発明の実施形態に係る蓄電素子を示す斜視図である。1 is a perspective view showing an energy storage element according to an embodiment of the present invention; 図１のＡ－Ａ線で破断して蓄電素子の内部を示す一部破断斜視図である。2 is a partially cutaway perspective view taken along line AA in FIG. 1 and showing the inside of the energy storage element. FIG. 図１に示す蓄電素子の電極体の斜視図である。2 is a perspective view of an electrode body of the energy storage element shown in FIG. 1 . 図３に示す電極体の展開図である。FIG. 4 is a development view of the electrode body shown in FIG. 3 . 正極シートの正極タブ及びその周辺部を示す図４の拡大図である。5 is an enlarged view of FIG. 4 showing the positive electrode tab of the positive electrode sheet and its surrounding area. FIG. 正極シートの絶縁層の第１絶縁部及びその周辺部を正極シートの長手方向から見た図５のＢ－Ｂ線断面図である。6 is a cross-sectional view taken along line BB in FIG. 5 , showing the first insulating portion of the insulating layer of the positive electrode sheet and its surrounding area, viewed from the longitudinal direction of the positive electrode sheet. 正極シートの絶縁層の第２絶縁部及びその周辺部を正極シートの長手方向から見た図５のＣ－Ｃ線断面図である。6 is a cross-sectional view taken along line CC of FIG. 5 , showing the second insulating portion of the insulating layer of the positive electrode sheet and its surrounding area, viewed from the longitudinal direction of the positive electrode sheet. 正極シートの絶縁層の第２絶縁部及びその周辺部を正極タブの突出方向から見た図５のＤ－Ｄ線断面図である。6 is a cross-sectional view taken along line DD in FIG. 5 , showing the second insulating portion of the insulating layer of the positive electrode sheet and its surrounding area, viewed from the protruding direction of the positive electrode tab. 本発明の別の実施形態に係る蓄電素子の電極体を模式的に示す分解斜視図である。13 is an exploded perspective view showing a schematic diagram of an electrode body of an energy storage element according to another embodiment of the present invention. FIG.

以下、添付図面を参照して本発明の実施形態を説明する。なお、本願明細書において方向を示すために使用される「上」及び「下」を含む用語及びこれらに関連する方向を示す用語は、添付図面に図示された蓄電素子の姿勢における方向を示すものであり、必ずしも実際の使用状態における方向と一致するものでない。 Hereinafter, an embodiment of the present invention will be described with reference to the attached drawings. Note that terms including "up" and "down" used to indicate directions in this specification and terms indicating directions related to these indicate directions in the attitude of the storage element shown in the attached drawings, and do not necessarily coincide with directions in the actual state of use.

図１は、本発明の実施形態に係る蓄電素子１を示している。蓄電素子１は、例えばリチウムイオン電池等の非水電解質二次電池である。ただし、本発明は、リチウムイオン電池以外にも、キャパシタを含む種々の蓄電素子に適用できる。 Figure 1 shows an energy storage element 1 according to an embodiment of the present invention. The energy storage element 1 is, for example, a non-aqueous electrolyte secondary battery such as a lithium ion battery. However, the present invention can be applied to various energy storage elements, including capacitors, in addition to lithium ion batteries.

図１に示すように、蓄電素子１は、例えば略直方体のケース２を有する。ケース２は、上面開口部を有するケース本体３と、ケース本体３の上面開口部を塞ぐ蓋体４とを有する。 As shown in FIG. 1, the energy storage element 1 has a case 2 that is, for example, a substantially rectangular parallelepiped. The case 2 has a case body 3 that has an opening on the top surface, and a lid body 4 that closes the opening on the top surface of the case body 3.

ケース本体３の材料には、例えばアルミニウム又はアルミニウム合金等の金属が用いられる。なお、ケース本体３の表面は、例えば樹脂からなる絶縁層（図示せず）で全体的に覆われるようにしてもよい。 The case body 3 is made of a metal such as aluminum or an aluminum alloy. The surface of the case body 3 may be entirely covered with an insulating layer (not shown) made of, for example, resin.

蓋体４は例えば矩形の金属板である。蓋体４は、ケース本体３の開口縁部に溶接されている。蓋体４の表面には、正極の外部端子１１と負極の外部端子１２が固定されている。 The lid 4 is, for example, a rectangular metal plate. The lid 4 is welded to the edge of the opening of the case body 3. A positive external terminal 11 and a negative external terminal 12 are fixed to the surface of the lid 4.

各外部端子１１，１２は、蓋体４の上面に上ガスケット１３を介して例えばかしめによって固定されている。外部端子１１，１２の材料には、例えば、アルミニウム、銅、ニッケル等の金属が用いられる。 Each external terminal 11, 12 is fixed to the upper surface of the lid 4 via an upper gasket 13, for example by crimping. The external terminals 11, 12 are made of a metal such as aluminum, copper, or nickel.

また、蓋体４には、ケース本体３内で発生したガスをケース２の外側へ排出するためのガス排出弁８と、注液口（図示せず）が設けられている。注液口は、注液栓１０にて閉鎖されている。 The lid 4 is also provided with a gas exhaust valve 8 for discharging gas generated within the case body 3 to the outside of the case 2, and a liquid filling port (not shown). The liquid filling port is closed by a liquid filling plug 10.

図２に示すように、ケース２には、少なくとも１つの電極体２０（特許請求の範囲の「巻回体」に相当）と、電極体２０を正極及び負極の外部端子１１，１２に電気的に接続する集電体１５と、電解液（図示せず）とが収容される。 As shown in FIG. 2, the case 2 contains at least one electrode body 20 (corresponding to the "wound body" in the claims), a current collector 15 that electrically connects the electrode body 20 to the positive and negative external terminals 11, 12, and an electrolyte (not shown).

図２に図示された集電体１５は、正極の外部端子１１に接続される正極集電体であり、図２を参照する以下の説明は、正極集電体１５の構成について行われ、負極の外部端子１２に接続される負極集電体の図示及び説明は省略される。 The current collector 15 shown in FIG. 2 is a positive electrode current collector connected to the positive electrode external terminal 11, and the following description with reference to FIG. 2 focuses on the configuration of the positive electrode current collector 15, and the illustration and description of the negative electrode current collector connected to the negative electrode external terminal 12 is omitted.

なお、負極集電体は、以下に説明される正極集電体１５と同様に構成されているが、正極集電体１５とは異なる構成を有してもよい。また、正極集電体１５及び負極集電体は互いに異なる材料で構成されてもよい。具体的に、正極集電体１５の材料には、例えば、アルミニウム等の金属が用いられ、負極集電体の材料には、例えば、銅等の金属が用いられる。 The negative electrode collector is configured in the same manner as the positive electrode collector 15 described below, but may have a different configuration from the positive electrode collector 15. The positive electrode collector 15 and the negative electrode collector may be configured from different materials. Specifically, the positive electrode collector 15 is made of a metal such as aluminum, and the negative electrode collector is made of a metal such as copper.

集電体１５は、蓋体４の下面に下ガスケット１４を介して例えばかしめによって固定されている。集電体１５は、例えば、蓋体４に固定された第１平板部１５ａと、該第１平板部１５ａの縁部から湾曲しながら下方へ延びる連絡部１５ｂと、該連絡部１５ｂを介して第１平板部１５ａに連なり、該第１平板部１５ａの下方に対向配置される第２平板部１５ｃとを備えている。 The current collector 15 is fixed to the underside of the lid 4 via a lower gasket 14, for example by crimping. The current collector 15 includes, for example, a first flat portion 15a fixed to the lid 4, a connecting portion 15b extending downward while curving from the edge of the first flat portion 15a, and a second flat portion 15c connected to the first flat portion 15a via the connecting portion 15b and disposed opposite the lower side of the first flat portion 15a.

第１平板部１５ａは、例えば外部端子１１から下方に延びるリベット部（図示せず）を介して、外部端子１１に電気的に接続されている。第２平板部１５ｃの下面には、電極体２０に設けられた後述のタブ３５が例えば超音波溶接により接合されており、これにより、電極体２０に電気的に接続されている。 The first flat plate portion 15a is electrically connected to the external terminal 11, for example, via a rivet portion (not shown) extending downward from the external terminal 11. A tab 35 (described later) provided on the electrode body 20 is joined to the underside of the second flat plate portion 15c, for example, by ultrasonic welding, and is thus electrically connected to the electrode body 20.

図３及び図４を併せて参照すると、電極体２０は、いずれも一定幅の長尺な帯状である正極シート（特許請求の範囲の「第１電極シート」に相当）２１、負極シート２２（特許請求の範囲の「第２電極シート」に相当）及び微多孔性樹脂シートからなる２枚のセパレータ２３，２３を重ね合わせて、概ね高平率の長円状に巻回したものである。正極シート２１の一つの層と、それに隣接する負極シート２２の一つの層との間には、２枚のセパレータ２３，２３のうちのいずれか一方が介在している。セパレータ２３，２３は、正極シート２１及び負極シート２２よりも長尺である。これにより、電極体２０の最外層は、いずれか一方のセパレータ２３で構成されている。 3 and 4, the electrode body 20 is made by stacking a positive electrode sheet (corresponding to the "first electrode sheet" in the claims) 21, a negative electrode sheet 22 (corresponding to the "second electrode sheet" in the claims), and two separators 23, 23 made of a microporous resin sheet, all of which are long and strip-like with a constant width, and winding them into an elliptical shape with a high flatness. One of the two separators 23, 23 is interposed between one layer of the positive electrode sheet 21 and one layer of the adjacent negative electrode sheet 22. The separators 23, 23 are longer than the positive electrode sheet 21 and the negative electrode sheet 22. As a result, the outermost layer of the electrode body 20 is composed of one of the separators 23.

正極シート２１、負極シート２２及び２枚のセパレータ２３，２３の巻回の軸線（巻回軸）は、図３において符号Ｘで概念的に示されている。電極体２０は、巻回軸Ｘが概ね、図１に示すケース本体３の底壁部と上面開口部が対向する方向（図１における上下方向）に延びる姿勢で、ケース本体３内に収容されている。 The axis of winding (winding axis) of the positive electrode sheet 21, the negative electrode sheet 22, and the two separators 23, 23 is conceptually indicated by the symbol X in FIG. 3. The electrode body 20 is housed in the case body 3 with the winding axis X extending generally in the direction in which the bottom wall and the top opening of the case body 3 shown in FIG. 1 face each other (the up-down direction in FIG. 1).

図３に示すように、巻回軸Ｘの延びる方向における電極体２０の各端部は、正極シート２１、負極シート２２及びセパレータ２３，２３の幅方向（短手方向）の端部が配置された端面部２０ａ，２０ｂとなっている。電極体２０は、巻回軸Ｘを挟んで対向配置され、巻回軸Ｘの延びる方向から見て相互に平行な直線状に延びる一対のフラット部２０ｃ，２０ｃと、巻回軸Ｘの延びる方向から見て半円状に湾曲するように延びて一対のフラット部２０ｃ，２０ｃ間を繋ぐ一対の湾曲部２０ｄ，２０ｄとを有する。 As shown in FIG. 3, each end of the electrode body 20 in the direction in which the winding axis X extends is an end surface portion 20a, 20b where the ends in the width direction (short direction) of the positive electrode sheet 21, the negative electrode sheet 22, and the separators 23, 23 are arranged. The electrode body 20 has a pair of flat portions 20c, 20c arranged opposite each other across the winding axis X and extending in a straight line parallel to each other when viewed from the direction in which the winding axis X extends, and a pair of curved portions 20d, 20d extending in a semicircular curve when viewed from the direction in which the winding axis X extends and connecting the pair of flat portions 20c, 20c.

なお、フラット部２０ｃは、設計上において直線状に延びる部分である。実際にケース２に電極体２０が収容された状態において、フラット部２０ｃは、完全な直線状に配置されるとは限らず、全体的には直線に近い形状となるように撓んだ状態で配置されることもある。 The flat portion 20c is designed to extend in a straight line. When the electrode body 20 is actually housed in the case 2, the flat portion 20c is not necessarily arranged in a completely straight line, and may be arranged in a bent state so that the overall shape is close to a straight line.

図３及び図４に示すように、正極シート２１は、帯状の正極金属箔２４と、この正極金属箔２４の両面に形成された正極活物質層２５とを備える。正極金属箔２４の幅方向（短手方向）両側の縁部は、正極金属箔２４の長手方向に沿って直線状に延びるように形成されている。正極金属箔２４の幅方向の一方側（図３及び図４において下側）においては、正極金属箔２４の縁部まで正極活物質層２５が設けられている。正極金属箔２４の幅方向の他方側（図３及び図４において上側）の縁部には、正極活物質層２５を設けずに、正極金属箔２４を露出させた第１活物質非形成部３４が設けられている。正極金属箔２４の第１活物質非形成部３４は、後述する絶縁層４０（図５～図８参照）で覆われている。なお、図３においては絶縁層４０の図示が省略されている。 3 and 4, the positive electrode sheet 21 includes a strip-shaped positive electrode metal foil 24 and a positive electrode active material layer 25 formed on both sides of the positive electrode metal foil 24. The edges of the positive electrode metal foil 24 on both sides in the width direction (short side direction) are formed to extend linearly along the longitudinal direction of the positive electrode metal foil 24. On one side of the width direction of the positive electrode metal foil 24 (lower side in Figs. 3 and 4), the positive electrode active material layer 25 is provided up to the edge of the positive electrode metal foil 24. On the edge of the other side of the width direction of the positive electrode metal foil 24 (upper side in Figs. 3 and 4), a first active material non-forming portion 34 is provided in which the positive electrode metal foil 24 is exposed without providing the positive electrode active material layer 25. The first active material non-forming portion 34 of the positive electrode metal foil 24 is covered with an insulating layer 40 (see Figs. 5 to 8) described later. Note that the insulating layer 40 is omitted from Fig. 3.

正極金属箔２４の材料には、例えばアルミニウムが用いられるが、これ以外の金属を用いてもよい。正極活物質としては、例えば、マンガン酸リチウム（ＬｉＭｎ２Ｏ４）、ニッケルコバルトマンガン酸リチウム（ＬｉＮｉｘＣｏｙＭｎ１－ｘ－ｙＯ２）、コバルト酸リチウム（ＬｉＣｏＯ２）、ニッケル酸リチウム（ＬｉＮｉＯ２）、リン酸鉄リチウム（ＬｉＦｅＰＯ４）、リン酸マンガンリチウム（ＬｉＭｎＰＯ４）、これらに置換添加物を用いたもの、又は、これらの混合物などが用いられるが、他のリチウム含有遷移金属酸化物を用いてもよい。 The material of the positive electrode metal foil 24 is, for example, aluminum, but other metals may be used. The positive electrode active material may be, for example, lithium manganese oxide (LiMn2O4), lithium nickel cobalt manganese oxide (LiNixCoyMn1-x-yO2), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium iron phosphate (LiFePO4), lithium manganese phosphate (LiMnPO4), or a combination of these with a substitution additive, or a mixture of these, but other lithium-containing transition metal oxides may also be used.

負極シート２２は、帯状の負極金属箔２６と、この負極金属箔２６の両面に形成された負極活物質層２７とを備える。負極金属箔２６の幅方向（短手方向）両側の縁部は、負極金属箔２６の長手方向に沿って直線状に延びるように形成されている。負極金属箔２６の幅方向の両側（図３及び図４において上側及び下側）において、負極活物質層２７は負極金属箔２６の縁部まで設けられている。これにより、負極金属箔２６の各面の全体が負極活物質層２７で被覆されている。 The negative electrode sheet 22 comprises a strip-shaped negative electrode metal foil 26 and a negative electrode active material layer 27 formed on both sides of the negative electrode metal foil 26. The edges on both sides in the width direction (short direction) of the negative electrode metal foil 26 are formed to extend linearly along the longitudinal direction of the negative electrode metal foil 26. On both sides in the width direction of the negative electrode metal foil 26 (upper and lower sides in Figures 3 and 4), the negative electrode active material layer 27 is provided up to the edges of the negative electrode metal foil 26. As a result, the entire surfaces of the negative electrode metal foil 26 are covered with the negative electrode active material layer 27.

負極金属箔２６の材料には、例えば銅が用いられるが、これ以外の金属を用いてもよい。負極活物質としては、例えばグラファイトが用いられるが、他の炭素材料、リチウム金属、リチウム合金、チタン酸リチウム（Ｌｉ４Ｔｉ５Ｏ１２）、ケイ素、一酸化ケイ素、スズ等のリチウム吸蔵可能な材料、またはこれらの混合物を用いてもよい。 The material of the negative electrode metal foil 26 is, for example, copper, but other metals may be used. The negative electrode active material is, for example, graphite, but other carbon materials, lithium metal, lithium alloys, lithium titanate (Li4Ti5O12), silicon, silicon monoxide, tin, or other materials capable of absorbing lithium, or mixtures of these, may also be used.

以下の説明では、正極シート２１、負極シート２２及びセパレータ２３の長手方向（図４～図８における矢印Ｐ方向）を単に「長手方向Ｐ」、正極シート２１、負極シート２２及びセパレータ２３の短手方向（図４～図８における矢印Ｑ方向）を単に「短手方向Ｑ」、正極シート２１、負極シート２２及びセパレータ２３の厚み方向（図５～図８における矢印Ｒ方向）を単に「厚み方向Ｒ」という。なお、長手方向Ｐは、特許請求の範囲の「第１方向」に相当するものである。短手方向Ｑは、特許請求の範囲の「第２方向」に相当するものであり、電極体２０の巻回軸Ｘ（図３参照）に平行な幅方向である。 In the following description, the longitudinal direction of the positive electrode sheet 21, the negative electrode sheet 22, and the separator 23 (the direction of the arrow P in Figs. 4 to 8) is simply referred to as the "longitudinal direction P", the transverse direction of the positive electrode sheet 21, the negative electrode sheet 22, and the separator 23 (the direction of the arrow Q in Figs. 4 to 8) is simply referred to as the "transverse direction Q", and the thickness direction of the positive electrode sheet 21, the negative electrode sheet 22, and the separator 23 (the direction of the arrow R in Figs. 5 to 8) is simply referred to as the "thickness direction R". The longitudinal direction P corresponds to the "first direction" in the claims. The transverse direction Q corresponds to the "second direction" in the claims, and is the width direction parallel to the winding axis X of the electrode body 20 (see Fig. 3).

図４に示すように、正極シート２１及び負極シート２２の短手方向Ｑにおいて、負極シート２２の幅は、正極シート２１の幅よりも大きい。負極シート２２は、短手方向Ｑの両側において正極シート２１の縁部よりも外側に突出している。セパレータ２３の幅は、負極シート２２の幅よりも大きい。セパレータ２３は、短手方向Ｑの両側において負極シート２２の縁部よりも外側に突出している。 As shown in FIG. 4, in the short-side direction Q of the positive electrode sheet 21 and the negative electrode sheet 22, the width of the negative electrode sheet 22 is greater than the width of the positive electrode sheet 21. The negative electrode sheet 22 protrudes outward beyond the edges of the positive electrode sheet 21 on both sides of the short-side direction Q. The width of the separator 23 is greater than the width of the negative electrode sheet 22. The separator 23 protrudes outward beyond the edges of the negative electrode sheet 22 on both sides of the short-side direction Q.

図３及び図４に示すように、正極金属箔２４には、短手方向Ｑの一方側（図３及び図４における上側）の縁部に沿って直線状に延びる上記の第１活物質非形成部３４から短手方向Ｑ外向きに突出する複数の正極タブ（特許請求の範囲の「第１タブ」に相当）３５が、長手方向Ｐに間隔をあけて設けられている。第１活物質非形成部３４と複数の正極タブ３５は、１枚の正極金属箔２４で構成されており、各正極タブ３５は、第１活物質非形成部３４に一体に連なっている。正極タブ３５は、正極金属箔２４の表面に活物質層が形成されていない第２活物質非形成部とされている。 As shown in Figures 3 and 4, the positive electrode metal foil 24 has a plurality of positive electrode tabs (corresponding to the "first tab" in the claims) 35 that protrude outward in the short direction Q from the first active material non-forming portion 34 that extends linearly along the edge on one side (upper side in Figures 3 and 4) of the short direction Q, and are provided at intervals in the longitudinal direction P. The first active material non-forming portion 34 and the plurality of positive electrode tabs 35 are formed from a single sheet of positive electrode metal foil 24, and each positive electrode tab 35 is integrally connected to the first active material non-forming portion 34. The positive electrode tabs 35 are second active material non-forming portions on which no active material layer is formed on the surface of the positive electrode metal foil 24.

図５に示すように、正極タブ３５の基部３５ａにおいて、長手方向Ｐにおける正極タブ３５の縁部と短手方向Ｑにおける第１活物質非形成部３４の縁部とのコーナ部にアール３５ｆが付けられている。アール３５ｆ，３５ｆは、長手方向Ｐにおける基部３５ａの両縁部に設けられている。これにより、長手方向Ｐにおける基部３５ａの幅は、第１活物質非形成部３４に近づくにつれて次第に大きくなっている。このようなアール３５ｆ，３５ｆが設けられていることにより、正極タブ３５の基部３５ａ、特にコーナ部にかかる応力集中を分散させることができ、基部３５ａでの破断が抑制される。つまり、正極タブ３５の基部３５ａの強度が高められている。 As shown in FIG. 5, in the base 35a of the positive electrode tab 35, a radius 35f is provided at the corner between the edge of the positive electrode tab 35 in the longitudinal direction P and the edge of the first active material non-forming portion 34 in the lateral direction Q. The radiuses 35f, 35f are provided at both edges of the base 35a in the longitudinal direction P. As a result, the width of the base 35a in the longitudinal direction P gradually increases as it approaches the first active material non-forming portion 34. By providing such radiuses 35f, 35f, it is possible to disperse stress concentration on the base 35a of the positive electrode tab 35, particularly on the corners, and fracture at the base 35a is suppressed. In other words, the strength of the base 35a of the positive electrode tab 35 is increased.

図３及び図４に示すように、負極金属箔２６にも、正極タブ３５と同様の複数の負極タブ（特許請求の範囲の「第２タブ」に相当）３７が設けられている。負極タブ３７は、短手方向Ｑにおいて、正極タブ３５と同じ側に突出して設けられている。負極タブ３７における基端部を除く大部分は、負極金属箔２６の表面に活物質層が形成されていない活物質非形成部とされている。 As shown in Figures 3 and 4, the negative electrode metal foil 26 is also provided with a plurality of negative electrode tabs (corresponding to "second tabs" in the claims) 37 similar to the positive electrode tabs 35. The negative electrode tabs 37 are provided protruding on the same side as the positive electrode tabs 35 in the short-side direction Q. Most of the negative electrode tabs 37, except for the base end, are active material non-forming portions where no active material layer is formed on the surface of the negative electrode metal foil 26.

図３に示すように、正極シート２１と負極シート２２がセパレータ２３，２３を介して重ね合わされて巻回されてなる電極体２０は、複数の正極タブ３５を積層してなる正極タブ束（特許請求の範囲の「第１タブ束」に相当）５５を備えている。正極タブ束５５は、電極体２０の一方のフラット部２０ｃに設けられている。 As shown in FIG. 3, the electrode body 20, which is formed by stacking and winding a positive electrode sheet 21 and a negative electrode sheet 22 with separators 23, 23 between them, is provided with a positive electrode tab bundle 55 (corresponding to the "first tab bundle" in the claims) which is formed by stacking a plurality of positive electrode tabs 35. The positive electrode tab bundle 55 is provided on one flat portion 20c of the electrode body 20.

負極タブ３７は、長手方向Ｐにおいて正極タブ３５から間隔を空けて配置されており、正極タブ３５と負極タブ３７が相互に重なり合うことはない。巻回状態の電極体２０において、複数の負極タブ３７は互いに重ね合わされ、これにより、第２タブ束としての負極タブ束５７が形成されている。 The negative electrode tab 37 is spaced apart from the positive electrode tab 35 in the longitudinal direction P, and the positive electrode tab 35 and the negative electrode tab 37 do not overlap each other. In the electrode body 20 in a wound state, the multiple negative electrode tabs 37 are overlapped with each other, thereby forming a negative electrode tab bundle 57 as a second tab bundle.

正極タブ束５５と負極タブ束５７は、電極体２０の一方の端面部２０ａ（図３において上側の端面部）から突出している。また、電極体２０の端面部２０ａを巻回軸Ｘの延びる方向から見たときの長手方向の中心線Ｙに対し、一対のフラット部２０ｃ，２０ｃのうちの一方側（図３において手前側）から、正極タブ束５５と負極タブ束５７が突出している。 The positive electrode tab bundle 55 and the negative electrode tab bundle 57 protrude from one end surface 20a (the upper end surface in FIG. 3) of the electrode body 20. In addition, the positive electrode tab bundle 55 and the negative electrode tab bundle 57 protrude from one side (the front side in FIG. 3) of the pair of flat portions 20c, 20c with respect to the center line Y in the longitudinal direction when the end surface 20a of the electrode body 20 is viewed from the direction in which the winding axis X extends.

図２に示すように、電極体２０の一方のフラット部２０ｃから突出した正極タブ束５５は、電極体２０の厚み方向Ｚ（巻回軸Ｘと中心線Ｙに直角な方向）における他方のフラット部２０ｃ側に倒されるように折り曲げられた状態で正極集電体１５に接続されている。 As shown in FIG. 2, the positive electrode tab bundle 55 protruding from one flat portion 20c of the electrode body 20 is bent toward the other flat portion 20c in the thickness direction Z of the electrode body 20 (direction perpendicular to the winding axis X and center line Y) and is connected to the positive electrode current collector 15.

この状態において、正極タブ束５５を構成する各正極タブ３５は、その基部（基端から中間部に亘る部分）３５ａにおいて湾曲しており、各正極タブ３５の先端側部分（先端３５ｃから中間部に亘る部分）３５ｂは、電極体２０の端面部２０ａの上方に対向すると共に、正極集電体１５の第２平板部１５ｃの下面に沿って配置されている。 In this state, each positive electrode tab 35 constituting the positive electrode tab bundle 55 is curved at its base (portion extending from the base end to the middle portion) 35a, and the tip side portion (portion extending from the tip 35c to the middle portion) 35b of each positive electrode tab 35 faces the upper side of the end surface portion 20a of the electrode body 20 and is disposed along the underside of the second flat portion 15c of the positive electrode current collector 15.

正極タブ束５５は、正極集電体１５の第２平板部１５ｃの下面に例えば超音波溶接により接合されている。これにより、各正極タブ３５は、正極集電体１５を介して正極の外部端子１１に電気的に接続されている。 The positive electrode tab bundle 55 is joined to the underside of the second flat plate portion 15c of the positive electrode collector 15, for example, by ultrasonic welding. As a result, each positive electrode tab 35 is electrically connected to the positive electrode external terminal 11 via the positive electrode collector 15.

図示は省略するが、負極タブ３７も同様に折り曲げられた状態で、負極集電体（図示せず）を介して負極の外部端子１２（図１参照）に電気的に接続されている。 Although not shown in the figure, the negative electrode tab 37 is also bent in a similar manner and is electrically connected to the negative electrode external terminal 12 (see FIG. 1) via the negative electrode current collector (not shown).

以下、図５～図８を参照しながら、正極シート２１の絶縁層４０及びこれに関連する構成について説明する。 The insulating layer 40 of the positive electrode sheet 21 and related configurations will be described below with reference to Figures 5 to 8.

図５は、正極シート２１の一方の面側から見た正極タブ３５及びその周辺部を示す拡大図、図６は、長手方向Ｐにおいて正極タブ３５からずれた部分における第１活物質非形成部３４及びその周辺部を長手方向Ｐから見た図５のＢ－Ｂ線断面図、図７は、正極タブ３５及びその周辺部を長手方向Ｐから見た図５のＣ－Ｃ線断面図、図８は、正極タブ３５及びその周辺部を正極タブ３５の突出方向（短手方向Ｑ）から見た図５のＤ－Ｄ線断面図である。 Figure 5 is an enlarged view of the positive electrode tab 35 and its surroundings as viewed from one side of the positive electrode sheet 21, Figure 6 is a cross-sectional view of the first active material non-forming portion 34 and its surroundings in a portion displaced from the positive electrode tab 35 in the longitudinal direction P, taken along line B-B in Figure 5, as viewed from the longitudinal direction P, Figure 7 is a cross-sectional view of the positive electrode tab 35 and its surroundings as viewed from the longitudinal direction P, taken along line C-C in Figure 5, as viewed from the longitudinal direction P, and Figure 8 is a cross-sectional view of the positive electrode tab 35 and its surroundings as viewed from the protruding direction of the positive electrode tab 35 (short direction Q), taken along line D-D in Figure 5.

図６及び図７に示すように、短手方向Ｑにおいて、負極活物質層２７は、正極活物質層２５よりも外側に突出して配置されている。これにより、蓄電素子１がリチウムイオン電池である場合、充電時に正極活物質層２５から放出されたリチウムイオンを負極活物質層２７に吸蔵させやすくなっている。 As shown in Figures 6 and 7, in the short-side direction Q, the negative electrode active material layer 27 is disposed so as to protrude outward from the positive electrode active material layer 25. This makes it easier for the lithium ions released from the positive electrode active material layer 25 during charging to be absorbed in the negative electrode active material layer 27 when the energy storage element 1 is a lithium ion battery.

図５～図８に示すように、絶縁層４０は、短手方向Ｑにおける正極活物質層２５の一方の縁部に沿って、正極活物質層２５の縁部に隣接するように、正極金属箔２４の表面に設けられている。絶縁層４０は、正極金属箔２４の両面に設けられている。絶縁層４０は、正極金属箔２４の第１活物質非形成部３４に設けられた第１絶縁層部４１と、第２活物質非形成部である正極タブ３５に設けられた第２絶縁層部４２とを備えている。 As shown in Figures 5 to 8, the insulating layer 40 is provided on the surface of the positive electrode metal foil 24 along one edge of the positive electrode active material layer 25 in the short-side direction Q, adjacent to the edge of the positive electrode active material layer 25. The insulating layer 40 is provided on both sides of the positive electrode metal foil 24. The insulating layer 40 includes a first insulating layer portion 41 provided on the first active material non-forming portion 34 of the positive electrode metal foil 24, and a second insulating layer portion 42 provided on the positive electrode tab 35, which is the second active material non-forming portion.

図５及び図６に示すように、第１絶縁層部４１は、第１活物質非形成部３４の両側の表面において同様に設けられている。第１活物質非形成部３４の各表面において、第１絶縁層部４１は、短手方向Ｑにおける正極活物質層２５の上縁部に沿って形成されており、該正極活物質層２５の上縁部を覆っている。 As shown in Figures 5 and 6, the first insulating layer portion 41 is provided in the same manner on both surfaces of the first active material non-forming portion 34. On each surface of the first active material non-forming portion 34, the first insulating layer portion 41 is formed along the upper edge portion of the positive electrode active material layer 25 in the short-side direction Q, and covers the upper edge portion of the positive electrode active material layer 25.

第１絶縁層部４１は、短手方向Ｑにおいて正極金属箔２４の上端面２４ａよりも突出して形成されており、該上端面２４ａを覆っている。第１絶縁層部４１は、長手方向Ｐにおいて第１活物質非形成部３４の全長に亘って設けられている。これにより、第１活物質非形成部３４の両側の表面及び上端面２４ａは、第１絶縁層部４１によって完全に覆われている。 The first insulating layer portion 41 is formed to protrude from the upper end surface 24a of the positive electrode metal foil 24 in the short direction Q, and covers the upper end surface 24a. The first insulating layer portion 41 is provided over the entire length of the first active material non-forming portion 34 in the longitudinal direction P. As a result, both side surfaces and the upper end surface 24a of the first active material non-forming portion 34 are completely covered by the first insulating layer portion 41.

図５に示すように、第２絶縁層部４２は、正極タブ３５の基部３５ａを含む領域に設けられている。より具体的に、第２絶縁層部４２は、正極タブ３５の基端から中間部に亘って設けられている。正極タブ３５の先端側部分３５ｂは、絶縁層４０に覆われることなく露出しており、これにより、先端側部分３５ｂにおける上述の集電体１５との接続が可能となっている。 As shown in FIG. 5, the second insulating layer portion 42 is provided in a region including the base portion 35a of the positive electrode tab 35. More specifically, the second insulating layer portion 42 is provided from the base end to the middle portion of the positive electrode tab 35. The tip portion 35b of the positive electrode tab 35 is exposed without being covered by the insulating layer 40, which allows connection to the above-mentioned current collector 15 at the tip portion 35b.

図７に示すように、第２絶縁層部４２は、正極タブ３５の両側の表面において同様に設けられている。正極タブ３５の各表面において、第２絶縁層部４２は、短手方向Ｑにおいて第１絶縁層部４１の外側に一体に連なっている。短手方向Ｑにおいて、第２絶縁層部４２の上縁部４２ａは、負極シート２２の上縁部２２ａ及びセパレータ２３の上縁部２３ａよりも外側に位置している。 As shown in FIG. 7, the second insulating layer portion 42 is provided in the same manner on both sides of the surface of the positive electrode tab 35. On each surface of the positive electrode tab 35, the second insulating layer portion 42 is integrally connected to the outside of the first insulating layer portion 41 in the short direction Q. In the short direction Q, the upper edge portion 42a of the second insulating layer portion 42 is located outside the upper edge portion 22a of the negative electrode sheet 22 and the upper edge portion 23a of the separator 23.

このように、正極タブ３５の基部３５ａが絶縁層４０によって被覆されていることにより、短絡の発生を抑制しつつ、該基部３５ａを絶縁層４０によって補強することができる。正極タブ３５は、上述のように集電体１５との接続のために折り曲げられることから（図２参照）、該折り曲げによって湾曲した基部３５ａに応力が集中しやすいが、該基部３５ａが絶縁層４０によって補強されていることで、正極タブ３５の剛性を高め、耐久性の向上を図ることができる。 In this way, by covering the base 35a of the positive electrode tab 35 with the insulating layer 40, the occurrence of a short circuit can be suppressed while the base 35a can be reinforced by the insulating layer 40. Since the positive electrode tab 35 is bent to connect to the current collector 15 as described above (see FIG. 2), stress tends to concentrate on the curved base 35a due to the bending. However, by reinforcing the base 35a with the insulating layer 40, the rigidity of the positive electrode tab 35 can be increased, and durability can be improved.

また、正極タブ３５の基部３５ａの剛性が絶縁層４０によって高められていることにより、正極シート２１を巻回する際に、厚み方向Ｒに反るような正極タブ３５の撓みが抑制される。そのため、正極シート２１を巻回して複数の正極タブ３５を重ねるときに、正極タブ３５同士が引っ掛かり難くなり、これにより、各正極タブ３５の折れが抑制される。さらに、上述のように、基部３５ａにアール３５ｆ，３５ｆが付いているため、巻回時に正極シート２１にテンションがかかっても、基部３５ａへの応力集中が緩和され、基部３５ａの強度が更に向上する。 In addition, because the rigidity of the base 35a of the positive electrode tab 35 is increased by the insulating layer 40, bending of the positive electrode tab 35 in the thickness direction R is suppressed when the positive electrode sheet 21 is rolled. Therefore, when the positive electrode sheet 21 is rolled to stack multiple positive electrode tabs 35, the positive electrode tabs 35 are less likely to get caught on each other, which suppresses bending of each positive electrode tab 35. Furthermore, as described above, because the base 35a has radii 35f, 35f, even if tension is applied to the positive electrode sheet 21 during rolling, stress concentration on the base 35a is mitigated, and the strength of the base 35a is further improved.

図８に示すように、絶縁層４０の第２絶縁層部４２は、長手方向Ｐの両側において正極タブ３５よりも外側に突出しており、正極タブ３５の両側の側端面３５ｄ，３５ｅを覆っている。これにより、正極タブ３５の基部３５ａは、正極タブ３５の両側の表面及び両側の側端面３５ｄ，３５ｅが第２絶縁層部４２によって覆われている。 As shown in FIG. 8, the second insulating layer portion 42 of the insulating layer 40 protrudes outward from the positive electrode tab 35 on both sides in the longitudinal direction P, covering both side end faces 35d, 35e of the positive electrode tab 35. As a result, both sides of the surface of the positive electrode tab 35 and both side end faces 35d, 35e of the base 35a of the positive electrode tab 35 are covered by the second insulating layer portion 42.

絶縁層４０の材料には、電気抵抗率が高い絶縁材料が用いられる。絶縁層４０の具体的な材料としては、例えば、無機および／または有機の粒子と結着剤とを混合したものが用いられる。無機物粒子としては、例えば、アルミナ（Ａｌ２Ｏ３）、ＳｉＯ２、ＺｒＯ２、ＴｉＯ２、ＭｇＯが用いられ、有機物粒子としては、例えば、ポリイミド粉末が用いられる。結着剤としては、例えば、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）、ポリイミド、ポリアミドイミドが用いられる。 The insulating layer 40 is made of an insulating material with high electrical resistivity. Specific materials for the insulating layer 40 include, for example, a mixture of inorganic and/or organic particles and a binder. Examples of inorganic particles include alumina (Al2O3), SiO2, ZrO2, TiO2, and MgO, and examples of organic particles include polyimide powder. Examples of binders include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyimide, and polyamideimide.

図６及び図７に示すように、絶縁層４０は、セパレータ２３を介して負極活物質層２７に対向配置されている。特に、絶縁層４０の第２絶縁層部４２は、短手方向Ｑにおいて、セパレータ２３の上縁部２３ａよりも突出している。そのため、セパレータ２３の位置ずれ、収縮又は破損を含む何らかの原因により正極シート２１における第１活物質非形成部３４及び正極タブ３５の基部３５ａと負極活物質層２７との間にセパレータ２３が介在しない部分が生じて、万一、正極シート２１と負極シート２２が接触しても、正極シート２１の金属部分を覆う絶縁層４０が、第１活物質非形成部３４及び正極タブ３５における金属箔２４と負極活物質層２７との間に介在することにより、短絡の防止が図られる。 6 and 7, the insulating layer 40 is disposed opposite the negative electrode active material layer 27 via the separator 23. In particular, the second insulating layer portion 42 of the insulating layer 40 protrudes from the upper edge portion 23a of the separator 23 in the short direction Q. Therefore, even if the separator 23 is not interposed between the first active material non-forming portion 34 of the positive electrode sheet 21 and the base portion 35a of the positive electrode tab 35 and the negative electrode active material layer 27 due to some cause including misalignment, shrinkage, or breakage of the separator 23, and the positive electrode sheet 21 and the negative electrode sheet 22 come into contact with each other, the insulating layer 40 covering the metal portion of the positive electrode sheet 21 is interposed between the metal foil 24 of the first active material non-forming portion 34 and the positive electrode tab 35 and the negative electrode active material layer 27, thereby preventing a short circuit.

また、図６及び図８に示すように、絶縁層４０は、第１活物質非形成部３４及び正極タブ３５の基部３５ａの両側の表面だけでなく、これらの端面２４ａ，３５ｄ，３５ｅも被覆しているため、短絡の発生をより効果的に抑制できる。 In addition, as shown in Figures 6 and 8, the insulating layer 40 covers not only both sides of the first active material non-forming portion 34 and the base 35a of the positive electrode tab 35, but also the end faces 24a, 35d, and 35e of these, so that the occurrence of a short circuit can be more effectively suppressed.

仮に正極金属箔２４上に、正極電位で溶解する銅のような金属が混入した場合、該金属は、正極金属箔２４上で溶解する。このように溶解した金属が負極シート２２上に析出し、該金属の析出物が成長して正極シート２１に接触すると短絡を引き起こす。 If a metal such as copper that dissolves at the positive electrode potential is mixed onto the positive electrode metal foil 24, the metal will dissolve on the positive electrode metal foil 24. The dissolved metal will deposit on the negative electrode sheet 22, and if the metal deposit grows and comes into contact with the positive electrode sheet 21, it will cause a short circuit.

しかしながら、本実施形態によれば、図６及び図７に示すように正極金属箔２４が絶縁層４０で覆われていることにより、負極シート２２の近傍に位置する正極金属箔２４上での金属の溶解が防止され、ひいては負極シート２２上での金属の析出を抑制でき、これにより、金属の析出物を起因とする短絡を防止できる。 However, in this embodiment, as shown in Figures 6 and 7, the positive metal foil 24 is covered with an insulating layer 40, which prevents dissolution of metal on the positive metal foil 24 located near the negative electrode sheet 22, thereby suppressing metal precipitation on the negative electrode sheet 22, thereby preventing short circuits caused by metal precipitation.

さらに、第１活物質非形成部３４の上端面２４ａが絶縁層４０で被覆されることにより、この上端面２４ａでの短絡の抑制を図りつつ、該上端面２４ａよりも短手方向Ｑの外側に位置するセパレータ２３の上縁部２３ａに対して、上端面２４ａを近づけて配置しやすくなる。そのため、正極金属箔２４を短手方向Ｑに拡大することができ、これにより、電池容量の増大を図ることができる。 Furthermore, by covering the upper end surface 24a of the first active material non-forming portion 34 with the insulating layer 40, it is possible to suppress short circuits at this upper end surface 24a, while making it easier to position the upper end surface 24a closer to the upper edge portion 23a of the separator 23, which is located outside the upper end surface 24a in the short direction Q. Therefore, the positive electrode metal foil 24 can be expanded in the short direction Q, thereby increasing the battery capacity.

ところで、正極タブ３５は、正極金属箔２４を所定形状にカットすることで形成される。より具体的には、正極金属箔２４における短手方向Ｑの一端部において、正極タブ３５に相当する部分を除いた残りの部分を切除することで、正極タブ３５が形成される。 The positive electrode tab 35 is formed by cutting the positive electrode metal foil 24 into a predetermined shape. More specifically, the positive electrode tab 35 is formed by cutting off the remaining part of the positive electrode metal foil 24 at one end in the short direction Q, except for the part that corresponds to the positive electrode tab 35.

このような正極金属箔２４のカットにより、上記の第１活物質非形成部３４の上端面２４ａ及び正極タブ３５の側端面３５ｄ，３５ｅが形成され、その後、絶縁層４０の形成が行われる。このように、絶縁層４０の形成が、正極金属箔２４のカットの後に行われることにより、第１活物質非形成部３４及び正極タブ３５の端面２４ａ，３５ｄ，３５ｅを絶縁層４０によって被覆することができる。 By cutting the positive electrode metal foil 24 in this way, the upper end surface 24a of the first active material non-forming portion 34 and the side end surfaces 35d, 35e of the positive electrode tab 35 are formed, and then the insulating layer 40 is formed. In this way, by forming the insulating layer 40 after cutting the positive electrode metal foil 24, the first active material non-forming portion 34 and the end surfaces 24a, 35d, 35e of the positive electrode tab 35 can be covered with the insulating layer 40.

絶縁層４０の形成は、例えばスロットダイ方式によるペースト状材料の塗布によって行われる。ただし、絶縁層４０の形成方法はこれに限定されるものでなく、例えば、静電粉体塗装によって、絶縁層４０を形成するようにしてもよい。 The insulating layer 40 is formed, for example, by applying a paste-like material using a slot die method. However, the method of forming the insulating layer 40 is not limited to this, and the insulating layer 40 may be formed, for example, by electrostatic powder coating.

以上、上述の実施形態を挙げて本発明を説明したが、本発明は上述の実施形態に限定されるものではない。 Although the present invention has been described above using the above-mentioned embodiments, the present invention is not limited to the above-mentioned embodiments.

例えば、上述の実施形態では、いわゆる巻回型の電極体２０を有する蓄電素子１について説明したが、本発明は、例えば図９に示すような所謂スタック型の電極体１２０（特許請求の範囲の「積層体」に相当）を有する蓄電素子にも適用できる。 For example, in the above embodiment, the energy storage element 1 having a so-called wound type electrode body 20 was described, but the present invention can also be applied to an energy storage element having a so-called stack type electrode body 120 (corresponding to the "laminated body" in the claims) as shown in FIG. 9.

図９に示す電極体１２０は、複数の正極シート（特許請求の範囲の「第１電極シート」に相当）１２１と複数の負極シート（特許請求の範囲の「第２電極シート」に相当）１２２がセパレータ１２３を介して交互に積層されてなる積層体である。各正極シートは、上記と同様の第１活物質非形成部３４と第２活物質非形成部である正極タブ３５とを備え、各負極シート１２２は、上記と同様の負極タブ３７を備えている。電極体１２０は、各正極シート１２１に設けられた正極タブ３５を積層してなる正極タブ束と、各負極シート１２２に設けられた負極タブ３７を積層してなる負極タブ束とを備えている。 The electrode body 120 shown in FIG. 9 is a laminate in which multiple positive electrode sheets (corresponding to the "first electrode sheet" in the claims) 121 and multiple negative electrode sheets (corresponding to the "second electrode sheet" in the claims) 122 are alternately laminated with separators 123 in between. Each positive electrode sheet has a first active material non-forming portion 34 and a positive electrode tab 35 which is a second active material non-forming portion similar to those described above, and each negative electrode sheet 122 has a negative electrode tab 37 similar to those described above. The electrode body 120 has a positive electrode tab bundle formed by laminating the positive electrode tabs 35 provided on each positive electrode sheet 121, and a negative electrode tab bundle formed by laminating the negative electrode tabs 37 provided on each negative electrode sheet 122.

このようなスタック型の電極体１２０においても、各正極シート１２１の第１活物質非形成部３４及び正極タブ３５に上記と同様の絶縁層４０が形成されることで、正極タブ３５の折り曲げによって応力が集中しやすい該タブ３５の基部を絶縁層によって補強できるなど、上述の実施形態と同様の効果を得ることができる。 Even in such a stacked electrode body 120, the insulating layer 40 similar to that described above is formed on the first active material non-forming portion 34 and the positive electrode tab 35 of each positive electrode sheet 121, so that the base of the positive electrode tab 35, where stress is likely to concentrate due to bending of the positive electrode tab 35, can be reinforced by the insulating layer, thereby obtaining the same effects as the above-mentioned embodiment.

また、上述の実施形態では、第１活物質非形成部３４を構成する正極シート２１の縁部が延びる「第１方向」と、該縁部から正極タブ３５が突出する「第２方向」とが直角である例を説明したが、本発明において、第２方向は、第１方向に直角な方向に対して傾斜していてもよい。 In the above embodiment, an example was described in which the "first direction" in which the edge of the positive electrode sheet 21 constituting the first active material non-forming portion 34 extends is perpendicular to the "second direction" in which the positive electrode tab 35 protrudes from the edge, but in the present invention, the second direction may be inclined with respect to the direction perpendicular to the first direction.

さらに、上述の実施形態では、絶縁層が設けられる第１電極シートが正極シートである例を説明したが、本発明は、第１電極シートが負極シートである場合にも適用可能である。 Furthermore, in the above-described embodiment, an example was described in which the first electrode sheet on which the insulating layer is provided is a positive electrode sheet, but the present invention is also applicable to cases in which the first electrode sheet is a negative electrode sheet.

本発明において、第１電極シートの金属箔は、必ずしも金属のみで構成されたものでなくてもよく、樹脂等からなる導電性のコート層（被膜）が金属の表面に形成されたものであってもよい。 In the present invention, the metal foil of the first electrode sheet does not necessarily have to be composed of metal only, but may have a conductive coating layer (film) made of resin or the like formed on the surface of the metal.

また、本発明において、第１電極シートの金属箔の表面に形成される絶縁層は、活物質層の縁部の表面に重なって形成されてもよく、或いは、活物質層の表面全体にオーバコートされてもよい。 In addition, in the present invention, the insulating layer formed on the surface of the metal foil of the first electrode sheet may be formed to overlap the surface of the edge of the active material layer, or may be overcoated on the entire surface of the active material layer.

さらに、上述の実施形態では、第１電極シートの金属箔の表面だけでなく端面にも絶縁層が形成される例を説明したが、本発明において、絶縁層は、必ずしも金属箔の端面に形成されなくてもよい。金属箔の端面に絶縁層を形成しない場合は、金属箔の表面に絶縁層を形成した後に、第１タブを形成するための第１電極シートのカットを行ってもよい。 In addition, in the above embodiment, an example was described in which an insulating layer is formed not only on the surface but also on the end faces of the metal foil of the first electrode sheet, but in the present invention, the insulating layer does not necessarily have to be formed on the end faces of the metal foil. If an insulating layer is not formed on the end faces of the metal foil, the first electrode sheet may be cut to form the first tab after forming an insulating layer on the surface of the metal foil.

またさらに、上述の実施形態では、第１タブの基部にアールが付けられる例を説明したが、本発明において、第１タブの基部には、必ずしもアールを付けなくてもよい。 Furthermore, in the above embodiment, an example was described in which a radius was added to the base of the first tab, but in the present invention, the base of the first tab does not necessarily have to be radiused.

１ ：蓄電素子
１１ ：正極外部端子
１５ ：正極集電体
２０ ：電極体（巻回体）
２０ｃ ：フラット部
２０ｄ ：湾曲部
２１ ：正極シート（第１電極シート）
２２ ：負極シート（第２電極シート）
２２ａ ：負極シートの縁部
２３ ：セパレータ
２３ａ ：セパレータの縁部
２４ ：正極金属箔
２４ａ ：正極金属箔の端面
２５ ：正極活物質層
３４ ：第１活物質非形成部
３５ ：正極タブ（第１タブ）（第２活物質非形成部）
３５ａ ：正極タブの基部
３５ｃ ：正極タブの先端
３５ｄ，３５ｅ ：正極タブの側端面
３７ ：負極タブ（第２タブ）
４０ ：絶縁層
４１ ：第１絶縁層部
４２ ：第２絶縁層部
４２ａ ：第２絶縁層部の縁部
５５ ：正極タブ束（第１タブ束）
５７ ：負極タブ束（第２タブ束）
１２０ ：電極体（積層体）
１２１ ：正極シート（第１電極シート）
１２２ ：負極シート（第２電極シート）
１２３ ：セパレータ
Ｐ ：シートの長手方向（第１方向）
Ｑ ：シートの短手方向（第２方向）
Ｘ ：巻回軸 1: Electric storage element 11: Positive electrode external terminal 15: Positive electrode current collector 20: Electrode body (wound body)
20c: Flat portion 20d: Curved portion 21: Positive electrode sheet (first electrode sheet)
22: Negative electrode sheet (second electrode sheet)
22a: Edge of negative electrode sheet 23: Separator 23a: Edge of separator 24: Positive electrode metal foil 24a: End surface of positive electrode metal foil 25: Positive electrode active material layer 34: First active material non-forming portion 35: Positive electrode tab (first tab) (second active material non-forming portion)
35a: Base of positive electrode tab 35c: Tip of positive electrode tab 35d, 35e: Side end surfaces of positive electrode tab 37: Negative electrode tab (second tab)
40: Insulating layer 41: First insulating layer portion 42: Second insulating layer portion 42a: Edge portion of second insulating layer portion 55: Positive electrode tab bundle (first tab bundle)
57: Negative electrode tab bundle (second tab bundle)
120: Electrode body (laminate)
121: Positive electrode sheet (first electrode sheet)
122: Negative electrode sheet (second electrode sheet)
123: Separator P: Longitudinal direction of sheet (first direction)
Q: Short side direction of the sheet (second direction)
X: Winding axis

Claims (5)

電極体を備えた蓄電素子であって、
前記電極体は、第１電極シートと前記第１電極シートとは異なる極性を有する第２電極シートとを有し、かつ、前記第１電極シートと前記第２電極シートとが重ねられて巻回されることで形成され、
前記第１電極シートは、
金属箔と、
前記金属箔に設けられた活物質層と、
前記金属箔に設けられた絶縁層と、
を備え、
前記金属箔は、前記活物質層が設けられていない活物質非形成部を有し、
前記活物質非形成部は、前記金属箔の所定方向の縁部に沿って延びる第１活物質非形成部と、前記第１活物質非形成部から突出した第１タブと、を有し、
前記絶縁層は、前記第１電極シートの厚み方向において前記活物質層と接触し、かつ、前記活物質非形成部における前記第１タブの基部を含む領域に形成されており、
前記第１タブは、前記基部の縁部のコーナ部にアールが付けられており、
前記絶縁層は、前記第１タブの前記アールを含む領域に形成されていることを特徴とする蓄電素子。 An electric storage element including an electrode body,
the electrode body has a first electrode sheet and a second electrode sheet having a polarity different from that of the first electrode sheet, and is formed by overlapping and winding the first electrode sheet and the second electrode sheet,
The first electrode sheet is
Metal foil;
An active material layer provided on the metal foil;
An insulating layer provided on the metal foil;
Equipped with
the metal foil has an active material non-forming portion where the active material layer is not provided,
the active material-free portion has a first active material-free portion extending along an edge portion of the metal foil in a predetermined direction, and a first tab protruding from the first active material-free portion,
the insulating layer is in contact with the active material layer in a thickness direction of the first electrode sheet , and is formed in a region of the active material non-forming portion including a base of the first tab,
the first tab has a radiused corner at an edge of the base;
The energy storage element, characterized in that the insulating layer is formed in a region including the radius of the first tab. 前記第１電極シートと前記第２電極シートとの間にセパレータが介されており、
前記絶縁層における前記第１タブの表面に形成された部分は、前記所定方向において前記セパレータの縁部よりも突出していることを特徴とする請求項１に記載の蓄電素子。 A separator is interposed between the first electrode sheet and the second electrode sheet,
The energy storage element according to claim 1 , wherein a portion of the insulating layer formed on the surface of the first tab protrudes beyond an edge of the separator in the predetermined direction. 前記活物質非形成部において、前記金属箔の端面にも前記絶縁層が形成されていることを特徴とする請求項１又は請求項２に記載の蓄電素子。 The energy storage element according to claim 1 or 2, characterized in that the insulating layer is also formed on the end faces of the metal foil in the active material non-forming portion. 前記絶縁層は、さらに、前記第１活物質非形成部に形成されており、
前記第１活物質非形成部及び前記基部に設けられた前記絶縁層は、一体に連なっていることを特徴とする請求項１から請求項３のいずれか１項に記載の蓄電素子。 The insulating layer is further formed on the first active material non-formed portion,
4 . The energy storage element according to claim 1 , wherein the insulating layer provided on the first active material non-forming portion and the insulating layer provided on the base are integrally connected. 前記第１電極シートを外部端子に電気的に接続させる集電体を更に備え、
前記第１タブは、折り曲げられた状態で前記集電体に接続されていることを特徴とする請求項１から請求項４のいずれか１項に記載の蓄電素子。 The first electrode sheet further includes a current collector for electrically connecting the first electrode sheet to an external terminal.
The energy storage element according to claim 1 , wherein the first tab is connected to the current collector in a bent state.
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