US-12620680-B2 - Joining method, joining structure, and battery

US12620680B2US 12620680 B2US12620680 B2US 12620680B2US-12620680-B2

Abstract

A joining method includes providing an electrode body that includes electrode plate end portions overlapping each other in a thickness-wise direction of the electrode plate end portions; providing a current collector including a folded portion, the folded portion includes two opposing holding walls that hold the electrode plate end portions of the electrode body in between, and a top portion that connects the two holding walls and includes an opening; and welding the electrode plate end portions to end surfaces of the two holding walls that define the opening by irradiating an edge of the electrode plate end portions with a laser beam in a state in which the edge of the electrode plate end portions held between the two holding walls projects into the opening.

Inventors

Shigeki Saito

Assignees

Toyota Battery Co., Ltd.

Dates

Publication Date: 20260505
Application Date: 20230627
Priority Date: 20220630

Claims (10)

1 . A joining method, comprising: providing an electrode body that includes electrode plate end portions overlapping each other in a thickness-wise direction of the electrode plate end portions; providing a current collector including a folded portion, wherein the folded portion includes two opposing holding walls that hold the electrode plate end portions of the electrode body in between, and a top portion that connects the two holding walls and includes an opening; and welding the electrode plate end portions to end surfaces of the two holding walls that define the opening by irradiating an edge of the electrode plate end portions with a laser beam in a state in which the edge of the electrode plate end portions held between the two holding walls projects into the opening, wherein the edge of the electrode plate end portions includes a ridge projecting into the opening, and the ridge increases in projecting amount toward a center of the opening from an end of the opening in a longitudinal direction of the opening that extends along the edge of the electrode plate end portions.
2 . The joining method according to claim 1 , wherein the electrode plate end portions include a slit at a position where the edge of the electrode plate end portions projects into the opening, the slit extending in a direction in which the edge of the electrode plate end portions projects and opening in a projection end of the edge.
3 . The joining method according to claim 1 , wherein the two holding walls include thin portions on the end surfaces of the two holding walls that define the opening.
4 . The joining method according to claim 1 , wherein the welding is performed by moving the laser beam in the thickness-wise direction of the electrode plate end portions relative to the edge of the electrode plate end portions.
5 . A joining structure, comprising: an electrode body that includes electrode plate end portions overlapping each other in a thickness-wise direction of the electrode plate end portions; a current collector that includes a folded portion, wherein the folded portion includes two opposing holding walls that hold the electrode plate end portions of the electrode body in between, and a top portion that connects the two holding walls and includes an opening; and a welded portion that connects an edge of the electrode plate end portions, held between the two holding walls, to end surfaces of the two holding walls in a state in which the welded portion projects into the opening from the end surfaces of the two holding walls that define the opening, wherein the edge of the electrode plate end portions includes a ridge projecting into the opening, and the ridge increases in projecting amount toward a center of the opening from an end of the opening in a longitudinal direction of the opening that extends along the edge of the electrode plate end portions.
6 . The joining structure according to claim 5 , wherein the welded portion has an arch-shaped cross section and connects the end surfaces of the two holding walls in a state in which the welded portion covers the edge of the electrode plate end portions projecting into the opening from the end surfaces of the two holding walls that define the opening.
7 . The joining structure according to claim 5 , wherein a portion where the electrode plate end portions are held between the two holding walls is free from the welded portion.
8 . The joining structure according to claim 5 , wherein the two holding walls include thin portions on the end surfaces of the two holding walls that define the opening.
9 . The joining structure according to claim 5 , wherein the electrode plate end portions include a slit at a position where the edge of the electrode plate end portions projects into the opening, the slit extending in a direction in which the edge of the electrode plate end portions projects and opening in a projection end of the edge.
10 . A battery comprising: the joining structure according to claim 5 .

Description

BACKGROUND 1. Field The following description relates to a joining method, a joining structure, and a battery. 2. Description of Related Art A battery, such as a lithium-ion rechargeable battery, includes an electrode body formed by a stack of positive and negative electrodes and a separator held between the positive and negative electrodes. The electrode body is, for example, accommodated in a case and connected to an external terminal by a current collector that serves as a connecting member. Japanese Laid-Open Patent Publication Nos. 11-317215 and 2000-200594 describe examples of a battery including an electrode body formed by a roll of electrodes and a separator. Each end of the electrode body is formed by an uncoated portion of an electrode plate where an electrode active material is not applied. Further, the electrode plate end of the positive electrode is arranged at one axial end side of the electrode body, and the electrode plate end of the negative electrode is arranged at the other axial end side of the electrode body. In such a battery, a current collector is joined to each axial end of the electrode body to connect a corresponding one of the positive and negative electrodes to an external terminal. The current collector includes a folded portion that holds the corresponding electrode plate end that is rolled into layers in a thickness-wise direction between two opposing holding walls. Further, the top of the folded portion includes an opening in the structures disclosed in Japanese Laid-Open Patent Publication Nos. 11-317215 and 2000-200594. The opening is used to laser-weld the electrode plate end held between the two holding walls in the structure disclosed in Japanese Laid-Open Patent Publication No. 2000-200594. SUMMARY When joining a current collector to an electrode body, it may be necessary to restrict thermal denaturation of the current collector and the electrode body in addition to maintaining a joining strength between the current collector and the electrode body. In this respect, there is room for improvement in the above described structures known in the art. This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. In one general aspect, a joining method includes providing an electrode body that includes electrode plate end portions overlapping each other in a thickness-wise direction of the electrode plate end portions; providing a current collector including a folded portion, the folded portion includes two opposing holding walls that hold the electrode plate end portions of the electrode body in between, and a top portion that connects the two holding walls and includes an opening; and welding the electrode plate end portions to end surfaces of the two holding walls that define the opening by irradiating an edge of the electrode plate end portions with a laser beam in a state in which the edge of the electrode plate end portions held between the two holding walls projects into the opening. With the above joining method, the electrode plate end portions may include a slit at a position where the edge of the electrode plate end portions projects into the opening. The slit may extend in a direction in which the edge of the electrode plate end portions projects and open in a projection end of the edge. With the above joining method, the edge of the electrode plate end portions may include a ridge projecting into the opening. The ridge may increase in projecting amount toward a center of the opening from an end of the opening in a longitudinal direction of the opening that extends along the edge of the electrode plate end portions. With the above joining method, the two holding walls may include thin portions on the end surfaces of the two holding walls that define the opening. With the above joining method, the welding may be performed by moving the laser beam in the thickness-wise direction of the electrode plate end portions relative to the edge of the electrode plate end portions. In another general aspect, a joining structure includes an electrode body, a current collector, and a welded portion. The electrode body includes electrode plate end portions overlapping each other in a thickness-wise direction of the electrode plate end portions. The current collector includes a folded portion and a top portion. The folded portion includes two opposing holding walls that hold the electrode plate end portions of the electrode body in between. The top portion connects the two holding walls and includes an opening. The welded portion connects an edge of the electrode plate end portions, held between the two holding walls, to end surfaces of the two holding walls in a state in which the welded portion pr