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EP-4742328-A1 - WOUND ELECTRODE ASSEMBLY

EP4742328A1EP 4742328 A1EP4742328 A1EP 4742328A1EP-4742328-A1

Abstract

A wound electrode assembly (10) has a positive electrode (11) and a negative electrode (12) wound in a flat shape with a separator (13) in between, and includes a pair of flat portions (91) facing each other with a winding center in between and a pair of curved portions (92) connecting ends of the pair of flat portions (91) to each other. The positive electrode (11) includes a first base member including a first metal foil (111) and a first resin member (112) alternately joined along a winding direction of the wound electrode assembly (10). The negative electrode (12) includes a second base member including a second metal foil (121) and a second resin member (122) alternately joined along the winding direction. In each of the pair of flat portions (91), the first metal foil (111) and the second metal foil (121) are alternately arranged in a direction in which the pair of flat portions (91) face each other. In each of the pair of curved portions (92), the first resin member (112) and the second resin member (122) are alternately arranged in a radial direction of the wound electrode assembly (10).

Inventors

  • TATEISHI, MITSURU
  • UEDA, MASASHI
  • IZUMI, JUN
  • MASUOKA, SHIZUKA
  • SATO, AYA
  • KATAYAMA, YUJI
  • YAMAMOTO, TATSUYA
  • MACHIDA, Keitaro

Assignees

  • TOYOTA JIDOSHA KABUSHIKI KAISHA

Dates

Publication Date
20260513
Application Date
20251009

Claims (7)

  1. A wound electrode assembly (10, 10X, 10Y) having a positive electrode (11) and a negative electrode (12) wound in a flat shape with a separator (13) in between, the wound electrode assembly (10, 10X, 10Y) comprising a pair of flat portions (91) facing each other with a winding center in between and a pair of curved portions (92) connecting ends of the pair of flat portions (91) to each other, wherein the positive electrode (11) includes a first base member (110) including a first metal foil (111) and a first resin member (112) alternately joined along a winding direction of the wound electrode assembly (10, 10X, 10Y), the negative electrode (12) includes a second base member (120) including a second metal foil (121) and a second resin member (122) alternately joined along the winding direction, in each of the pair of flat portions (91), the first metal foil (111) and the second metal foil (121) are alternately arranged in a direction in which the pair of flat portions (91) face each other, and in each of the pair of curved portions (92), the first resin member (112) and the second resin member (122) are alternately arranged in a radial direction of the wound electrode assembly (10, 10X, 10Y).
  2. The wound electrode assembly (10, 10X, 10Y) according to claim 1, wherein in a cross section perpendicular to a winding axis of the wound electrode assembly (10, 10X, 10Y), a first boundary (P1) is located at boundaries (B1, B2) between the pair of flat portions (91) and the pair of curved portions (92), the first boundary (P1) being a boundary (B1, B2) between the first metal foil (111) and the first resin member (112), and a second boundary (P2) is located at the boundaries (B1, B2) between the pair of flat portions (91) and the pair of curved portions (92), the second boundary (P2) being a boundary between the second metal foil (121) and the second resin member (122).
  3. The wound electrode assembly (10) according to claim 2, wherein in the cross section perpendicular to the winding axis, at each of the boundaries (B1, B2) between the pair of flat portions (91) and the pair of curved portions (92), the first boundary (P1) and the second boundary (P2) are alternately disposed side by side in an arrangement direction in which the first metal foil (111) and the second metal foil (121) are alternately aligned.
  4. The wound electrode assembly (10X) according to claim 2, wherein when a direction orthogonal to the winding axis and to a direction in which the pair of flat portions (91) face each other is a width direction, in the cross section perpendicular to the winding axis, at each of the boundaries (B1, B2) between the pair of flat portions (91) and the pair of curved portions (92), the first boundary (P1) and the second boundary (P2) are alternately disposed as to be positioned toward inward in the width direction from an outer peripheral side to an inner peripheral side of the wound electrode assembly (10X).
  5. The wound electrode assembly (10Y) according to claim 2, wherein when a direction orthogonal to the winding axis and to a direction in which the pair of flat portions (91) face each other is a width direction, in the cross section perpendicular to the winding axis, at each of the boundaries (B1, B2) between the pair of flat portions (91) and the pair of curved portions (92), the first boundary (P1) and the second boundary (P2) are alternately disposed as to be positioned toward outward in the width direction from an outer peripheral side to an inner peripheral side of the wound electrode assembly (10Y).
  6. The wound electrode assembly (10, 10X, 10Y) according to any one of claims 1 to 5, wherein the first resin member (112) has a thickness smaller than that of the first metal foil (111).
  7. The wound electrode assembly (10, 10X, 10Y) according to claim 6, wherein the second resin member (122) has a thickness smaller than that of the second metal foil (121).

Description

CROSS REFERENCE TO RELATED APPLICATIONS This nonprovisional application is based on Japanese Patent Application No. 2024-194198 filed on November, 6, 2024 with the Japan Patent Office, the entire contents of which are hereby incorporated by reference. BACKGROUND Field The present disclosure relates to a wound electrode assembly. Description of the Background Art Japanese Patent Laying-Open No. 2016-042433 discloses, as a conventional electrode assembly, a wound electrode assembly including a positive electrode having a first metal foil and a positive-electrode active material layer formed on the first metal foil and a negative electrode having a second metal foil and a negative-electrode active material layer formed on the second metal foil, wherein the positive electrode and the negative electrode are wound with a separator in between. SUMMARY The wound electrode assembly has a pair of flat portions facing each other with a winding center in between, and a pair of curved portions connecting ends of the pair of flat portions to each other. In the wound electrode, the pair of curved portions are maintained in a bent state, and a higher stress is applied to the pair of curved portions than to the pair of flat portions. The present disclosure has been made in view of the problem described above. An object of the present disclosure is to provide a wound electrode assembly that can suppress damage to the curved portion. A wound electrode assembly according to the present disclosure is a wound electrode assembly that has a positive electrode and a negative electrode wound in a flat shape with a separator in between and that includes a pair of flat portions facing each other with a winding center in between and a pair of curved portions connecting ends of the pair of flat portions to each other. In the wound electrode assembly, the positive electrode includes a first base member including a first metal foil and a first resin member alternately joined along a winding direction of the wound electrode assembly. The negative electrode includes a second base member including a second metal foil and a second resin member alternately joined along the winding direction. In each of the pair of flat portions, the first metal foil and the second metal foil are alternately arranged in a direction in which the pair of flat portions face each other. In each of the pair of curved portions, the first resin member and the second resin member are alternately arranged in a radial direction of the wound electrode assembly. With the configuration described above, in each of the pair of curved portions, the first resin member and the second resin member are alternately disposed in the radial direction of the wound electrode assembly, thus, the curved portion easily deforms by deflection and is less easily bent compared with the configuration in which the metal foil is disposed in the curved portion. This can suppress damage to the curved portion even when a high stress is applied to the curved portion. In the wound electrode assembly according to the present disclosure, in a cross section perpendicular to a winding axis of the wound electrode assembly, a first boundary, which is a boundary between the first metal foil and the first resin member, may be located at boundaries between the pair of flat portions and the pair of curved portions. A second boundary, which is a boundary between the second metal foil and the second resin member, may be located at the boundaries between the pair of flat portions and the pair of curved portion. With the configuration described above, the curved portion is entirely formed of a resin member. This can further suppress damage to the curved portion. In the wound electrode assembly according to the present disclosure, in the cross section perpendicular to the winding axis, at each of the boundaries between the pair of flat portions and the pair of curved portions, the first boundary and the second boundary may be alternately disposed side by side in an arrangement direction in which the first metal foil and the second metal foil are alternately aligned. Also in the configuration described above, the curved portion is entirely formed of a resin member. This can further suppress damage to the curved portion. In the wound electrode assembly according to the present disclosure, when a direction orthogonal to the winding axis and to a direction in which the pair of flat portions face each other is a width direction, in the cross section perpendicular to the winding axis, at each of the boundaries between the pair of flat portions and the pair of curved portions, the first boundary and the second boundary may be alternately disposed as to be positioned toward inward in the width direction from an outer peripheral side to an inner peripheral side of the wound electrode assembly. With the configuration described above, the curved portion can be formed in a fan shape, and accordingly, deforms easily. This can su