CN-122000409-A - Wound electrode body

CN122000409ACN 122000409 ACN122000409 ACN 122000409ACN-122000409-A

Abstract

The invention provides a wound electrode body. The wound electrode body is formed by winding a positive electrode and a negative electrode in a flat shape with a separator interposed therebetween, and has a pair of flat portions facing each other with a winding center therebetween and a pair of bent portions connecting end portions of the pair of flat portions, wherein the positive electrode includes a1 st base material obtained by alternately joining a1 st metal foil and a1 st resin member in a winding direction of the wound electrode body, the negative electrode includes a2 nd base material obtained by alternately joining a2 nd metal foil and a2 nd resin member in the winding direction, the 1 st metal foil and the 2 nd metal foil are alternately arranged in a direction facing the pair of flat portions in each of the pair of flat portions, and the 1 st resin member and the 2 nd resin member are alternately arranged in a radial direction of the wound electrode body in each of the pair of bent portions.

Inventors

TATEISHI TAKASHI
UEDA MASASHI
He Quanrun
Mashioka Shizuka
SATO REI
KATAYAMA YUJI
YAMAMOTO YASUNARI
MACHIDA KEITARO

Assignees

丰田自动车株式会社
丰田电池有限公司

Dates

Publication Date: 20260508
Application Date: 20251103
Priority Date: 20241106

Claims (7)

1. A wound electrode body in which a positive electrode and a negative electrode are wound in a flat shape with a separator interposed therebetween, the wound electrode body having a pair of flat portions facing each other across a winding center and a pair of bent portions connecting end portions of the pair of flat portions to each other, The positive electrode includes a1 st base material in which a1 st metal foil and a1 st resin member are alternately joined along a winding direction of the wound electrode body, The negative electrode includes a2 nd base material in which a2 nd metal foil and a2 nd resin member are alternately joined along the winding direction, In each of the pair of flat portions, the 1 st metal foil and the 2 nd metal foil are alternately arranged in a direction in which the pair of flat portions oppose each other, In each of the pair of bent portions, the 1 st resin member and the 2 nd resin member are alternately arranged in the radial direction of the wound electrode body.
2. The rolled electrode body according to claim 1, In a section of the wound electrode body perpendicular to the winding axis, The 1 st boundary being the boundary between the 1 st metal foil and the 1 st resin member is located at the boundary between the pair of flat portions and the pair of curved portions, The 2 nd boundary, which is a boundary between the 2 nd metal foil and the 2 nd resin member, is located at a boundary between the pair of flat portions and the pair of curved portions.
3. The rolled electrode body according to claim 2, In the section perpendicular to the winding axis, At each boundary of the pair of flat portions and the pair of curved portions, the 1 st boundary and the 2 nd boundary are alternately arranged in an arrangement direction in which the 1 st metal foil and the 2 nd metal foil are alternately arranged.
4. The rolled electrode body according to claim 2, When the direction orthogonal to the direction in which the winding shaft and the pair of flat portions face each other is the width direction, In the section perpendicular to the winding axis, At each boundary of the pair of flat portions and the pair of curved portions, the 1 st boundary and the 2 nd boundary are alternately arranged so as to go inward in the width direction from the outer peripheral side to the inner peripheral side of the wound electrode body.
5. The rolled electrode body according to claim 2, When the direction orthogonal to the direction in which the winding shaft and the pair of flat portions face each other is the width direction, In the section perpendicular to the winding axis, At each boundary of the pair of flat portions and the pair of curved portions, the 1 st boundary and the 2 nd boundary are alternately arranged so as to go to the outer side in the width direction from the outer peripheral side to the inner peripheral side of the wound electrode body.
6. The rolled electrode body according to any one of claim 1 to 5, The 1 st resin member has a thickness smaller than that of the 1 st metal foil.
7. The rolled electrode body according to claim 6, The thickness of the 2 nd resin member is thinner than the thickness of the 2 nd metal foil.

Description

Wound electrode body Technical Field The present disclosure relates to a rolled electrode body. Background In Japanese patent application laid-open No. 2016-042433, a conventional electrode body is disclosed in which a positive electrode having a 1 st metal foil and a positive electrode active material layer formed on the 1 st metal foil and a negative electrode having a 2 nd metal foil and a negative electrode active material layer formed on the 2 nd metal foil are wound with a separator interposed therebetween. Disclosure of Invention A pair of flat portions facing each other across the winding center and a pair of curved portions connecting the ends of the pair of flat portions to each other are formed in the wound electrode body. In the wound electrode, a pair of bent portions is maintained in a bent state, and a stress is applied to the pair of bent portions higher than to the pair of flat portions. The present disclosure has been made in view of the above-described problems, and an object of the present disclosure is to provide a wound electrode body capable of suppressing breakage of a bent portion. The wound electrode body according to the present disclosure is a wound electrode body in which a positive electrode and a negative electrode are wound in a flat shape with a separator interposed therebetween, and which has a pair of flat portions facing each other with a winding center therebetween, and a pair of bent portions connecting end portions of the pair of flat portions to each other. In the wound electrode body, the positive electrode includes a1 st base material in which a1 st metal foil and a1 st resin member are alternately bonded along a winding direction of the wound electrode body. The negative electrode includes a2 nd base material in which a2 nd metal foil and a2 nd resin member are alternately bonded along the winding direction. In each of the pair of flat portions, the 1 st metal foil and the 2 nd metal foil are alternately arranged in a direction in which the pair of flat portions face each other. In each of the pair of bent portions, the 1 st resin member and the 2 nd resin member are alternately arranged in the radial direction of the wound electrode body. According to the above configuration, the 1 st resin member and the 2 nd resin member are alternately arranged in the radial direction of the wound electrode body in each of the pair of bent portions, and therefore, the bent portions are more likely to flex and be less likely to break as compared with the configuration in which the metal foil is arranged in the bent portions. Thus, even when a high stress is applied to the bending portion, breakage of the bending portion can be suppressed. In the wound electrode body according to the present disclosure, in a cross section of the wound electrode body perpendicular to a winding axis, a1 st boundary, which is a boundary between the 1 st metal foil and the 1 st resin member, may be located at a boundary between the pair of flat portions and the pair of curved portions. The 2 nd boundary, which is the boundary between the 2 nd metal foil and the 2 nd resin member, may be located at the boundary between the pair of flat portions and the pair of curved portions. According to the above configuration, the bending portion is entirely made of the resin member. This can further suppress breakage of the bent portion. In the wound electrode body according to the present disclosure, the 1 st boundary and the 2 nd boundary may be alternately arranged in an arrangement direction in which the 1 st metal foil and the 2 nd metal foil are alternately arranged, at each boundary of the pair of flat portions and the pair of curved portions in the cross section perpendicular to the winding axis. In the above configuration, the bending portion is also entirely made of the resin member. This can further suppress breakage of the bent portion. In the wound electrode body according to the present disclosure, when a direction orthogonal to a direction in which the winding shaft and the pair of flat portions face each other is a width direction, the 1 st boundary and the 2 nd boundary may be alternately arranged at each boundary between the pair of flat portions and the pair of curved portions in the cross section perpendicular to the winding shaft so as to go inward in the width direction from the outer peripheral side to the inner peripheral side of the wound electrode body. According to the above configuration, the bending portion can be formed in a fan shape, and the bending portion is easily deformed. This can suppress bending of the bending portion when stress is applied to the bending portion. In the wound electrode body according to the present disclosure, when a direction orthogonal to a direction in which the winding shaft and the pair of flat portions face each other is a width direction, the 1 st boundary and the 2 nd boundary may be alternately arranged at each boundary between the pair of flat por