US-20260128379-A1 - ELECTRODE ASSEMBLY

US20260128379A1US 20260128379 A1US20260128379 A1US 20260128379A1US-20260128379-A1

Abstract

An electrode assembly includes a first electrode portion including a plurality of first stack portions and a plurality of first curved portions and formed of a first electrode sheet, and a second electrode portion including a plurality of second stack portions. The plurality of first stack portions and the plurality of second stack portions are disposed alternately in a stacking direction. The first electrode sheet includes a first sheet portion including a portion formed of a first metal foil and forming the first stack portions and a portion formed of a first resin member and forming the plurality of first curved portions, and a first active material layer. The first stack portion includes a first metal foil and a first active material layer provided on the first metal foil. The first active material layer is not provided on the first resin member.

Inventors

Mitsuru Tateishi
Masashi Ueda
Jun Izumi
Shizuka MASUOKA
Aya Sato
Yuji Katayama
Tatsuya Yamamoto
Keitaro MACHIDA

Assignees

TOYOTA JIDOSHA KABUSHIKI KAISHA
Toyota Battery Co., Ltd.

Dates

Publication Date: 20260507
Application Date: 20251027
Priority Date: 20241106

Claims (5)

1 . An electrode assembly for a secondary battery, the electrode assembly comprising: a first electrode portion formed of a first electrode sheet; and a second electrode portion having a polarity different from that of the first electrode portion, wherein the first electrode sheet includes a plurality of first stack portions aligned in a stacking direction and a plurality of first curved portions, each of the plurality of first curved portions connects the first stack portions adjacent to each other in the stacking direction, the second electrode portion includes a plurality of second stack portions, the plurality of first stack portions and the plurality of second stack portions are disposed alternately in the stacking direction, the first electrode sheet includes a first sheet portion and a first active material layer provided on the first sheet portion, a portion of the first sheet portion forming the plurality of first stack portions is formed of a first metal foil, a portion of the first sheet portion forming the plurality of first curved portions is formed of a first resin member, each of the first stack portions includes the first metal foil and the first active material layer provided on the first metal foil, and the first active material layer is not provided on the first resin member.
2 . The electrode assembly according to claim 1 , wherein the second electrode portion is formed of a second electrode sheet, the second electrode sheet includes the plurality of second stack portions aligned in the stacking direction and a plurality of second curved portions, each of the plurality of second curved portions connects the second stack portions adjacent to each other in the stacking direction, the second electrode sheet includes a second sheet portion and a second active material layer provided on the second sheet portion, a portion of the second sheet portion forming the plurality of second stack portions is formed of a second metal foil, a portion of the second sheet portion forming the plurality of second curved portions is formed of a second resin member, each of the second stack portions includes the second metal foil and the second active material layer provided on the second metal foil, and the second active material layer is not provided on the second resin member.
3 . The electrode assembly according to claim 2 , wherein the second resin member has a thickness smaller than that of the second metal foil.
4 . The electrode assembly according to claim 1 , wherein the first resin member has a thickness smaller than that of the first metal foil.
5 . The electrode assembly according to claim 1 , further comprising an insulating film partially covering the plurality of first stack portions and the plurality of second stack portions, wherein the plurality of first curved portions are exposed from the insulating film.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This nonprovisional application is based on Japanese Patent Application No. 2024-194197 filed on Nov. 6, 2024 with the Japan Patent Office, the entire contents of which are hereby incorporated by reference. BACKGROUND Field The present disclosure relates to an electrode assembly for a secondary battery. Description of the Background Art Japanese National Patent Publication No. 2023-504474 discloses, as a conventional electrode assembly, a structure of an electrode assembly including a first electrode sheet and a second electrode sheet, in which the first electrode sheet is bent in a multilayer structure (zigzag shape). The first electrode sheet includes a plurality of first stack portions and a plurality of curved portions connecting the first stack portions adjacent to each other in a stacking direction. The first electrode sheet includes an insulating base member, an electrically conductive layer provided on the insulating base member, and an active material layer provided on the electrically conductive layer. SUMMARY In the electrode assembly with the first electrode sheet bent in the multilayer structure (zigzag pattern), a high stress is likely to be applied to the curved portion of the first electrode sheet. When the electrically conductive layer and the active material layer are provided on the insulating base member located at the curved portion, the curved portion becomes hard, and accordingly, the curved portion is easily broken when a stress is applied thereto. The present disclosure has been made in view of the above problem. An object of the present disclosure is to provide an electrode assembly that, in a structure including a first electrode sheet including a plurality of first stack portions and a plurality of curved portions connecting the first stack portions adjacent to each other in a stacking direction, can suppress damage to the curved portions. An electrode assembly according to the present disclosure is used for a secondary battery. The electrode assembly includes a first electrode portion formed of a first electrode sheet, and a second electrode portion having a polarity different from that of the first electrode portion. The first electrode sheet includes a plurality of first stack portions aligned in a stacking direction and a plurality of first curved portions. Each of the plurality of first curved portions connects the first stack portions adjacent to each other in the stacking direction. The second electrode portion includes a plurality of second stack portions. The plurality of first stack portions and the plurality of second stack portions are disposed alternately in the stacking direction. The first electrode sheet includes a first sheet portion and a first active material layer provided on the first sheet portion. A portion of the first sheet portion forming the plurality of first stack portions is formed of a first metal foil. A portion of the first sheet portion forming the plurality of first curved portions is formed of a first resin member. Each of the first stack portions includes the first metal foil and the first active material layer provided on the first metal foil. The first active material layer is not provided on the first resin member. With the configuration described above, the first curved portion is formed only of the resin member in the structure in which the first electrode sheet is curved in a zigzag pattern. Upon application of a stress to the first curved portion, thus, the resin member deforms by deflection, and accordingly, cracking or breakage of the first curved portion can be suppressed. In the electrode assembly according to the present disclosure, the second electrode portion may be formed of a second electrode sheet. The second electrode sheet may include the plurality of second stack portions aligned in the stacking direction and a plurality of second curved portions. Each of the plurality of second curved portions may connect the second stack portions adjacent to each other in the stacking direction. The second electrode sheet may include a second sheet portion and a second active material layer provided on the second sheet portion. A portion of the second sheet portion forming the plurality of second stack portions may be formed of a second metal foil. A portion of the second sheet portion forming the plurality of second curved portions may be formed of a second resin member. Each of the second stack portions may include the second metal foil and the second active material layer provided on the second metal foil. The second active material layer may not be provided on the second resin member. With the configuration described above, in the structure in which the second electrode sheet is bent in a zigzag pattern, the second curved portion is formed only of the resin member. Upon application of a stress to the second curved portion, thus, the resin member deforms by deflection, and accordingly, cracking o