Manufacturing method for external terminals for batteries

Abstract

This invention provides a method for manufacturing an external terminal for a battery, which involves joining metal components coated with a plated film to obtain an external terminal for the negative electrode of a battery. [Solution] A method for manufacturing an external terminal for a battery, comprising fitting a recess of a metal member to be joined into a protrusion of a metal joining member and applying pressure in a compressive direction to both members, thereby flattening the outer circumference of the end face of the protrusion of the joining member outward to form an undercut portion and joining the two members together, characterized in that, before joining, the surface of the protrusion of the joining member and the inner surface of the recess of the member to be joined are subjected to plasma treatment.

Description

Technical Field

[0001] The present invention particularly relates to a method for manufacturing an external terminal for a battery of a negative electrode.

Background Art

[0002] Conventionally, when manufacturing a composite member by joining a joining member made of a metal material and a joined member, depending on the use of the composite member, a high degree of adhesion is required at the joining location. For example, in a lithium battery, since a lead wire or the like is attached to an electrode terminal by welding or the like, a composite member in which a copper member having high conductivity and an aluminum member having high corrosion resistance are joined with enhanced adhesion so that the electrical resistance does not increase is required for the electrode terminal. As a joining method of metal members corresponding to this kind of requirement, the diffusion joining method described in Japanese Patent Publication No. Sho 59-52031 (Patent Document 1), Japanese Patent Publication No. Sho 64-4581 (Patent Document 2), etc. is known as the most suitable method.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in diffusion joining, when an oxide film or impurities adhere to the joining interface, since these cannot be removed, there is a problem that diffusion joining cannot be performed. Further, when one of these members is coated with a plating film of a metal that is difficult to perform diffusion joining, similarly, in a general integral joining method, since the plating film remains without being peeled off at the joining portion of both members, there is a problem that diffusion joining cannot be performed.

[0005] The present invention was invented to solve the above problems, and aims to provide a method for manufacturing an external terminal for a battery, which involves joining metal members coated with a plated film to obtain an external terminal for a negative electrode battery. [Means for solving the problem]

[0006] The above problem can be solved by a method for manufacturing an external battery terminal, in which the protrusions of a metal joining member are fitted into the recesses of a metal member to be joined, and both members are compressed by applying pressure in a compressive direction, thereby flattening the outer circumference of the end face of the protrusions of the joining member outward to form an undercut portion, and joining the two members together, characterized in that plasma treatment is applied to the surface of the protrusions of the joining member and the inner surface of the recesses of the member to be joined before joining. [Effects of the Invention]

[0007] As described above, by irradiating the joint and the joined members with plasma, the oxide film on the surface is removed, exposing a new surface on the surface of these members, and the new surfaces come into contact with each other at the joint interface. As a result, the two members are in a metallic bond state, making it possible to manufacture an external terminal for batteries with low electrical resistance and excellent conductivity. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows a method for manufacturing an external terminal for a battery according to an embodiment of the present invention. [Figure 2] This is an explanatory diagram showing the steps of a method for manufacturing an external terminal for a battery according to an embodiment of the present invention. [Modes for carrying out the invention]

[0009] The method for manufacturing an external terminal for a battery, which is the present invention, will be described below with reference to the drawings.

[0010] In Figure 1, 1 is a joining member made of copper material having a shaft portion 1a, a flange portion 1b, and a protrusion portion 1c, and 2 is a member to be joined made of columnar aluminum alloy material having a recess 2a that abuts against the flange portion 1b and fits into the protrusion portion 1c. The surfaces of these joining member 1 and member to be joined 2 are coated with nickel plating, an oxide film, etc.

[0011] Furthermore, the surfaces (end faces and outer circumferential faces) of the protruding portions of the joining member 1 are treated with plasma by irradiating them with plasma. Similarly, the inner surfaces (bottom faces and inner circumferential faces) of the recessed portions of the member to be joined are also treated with plasma.

[0012] These two members 1 and 2 are placed in the receiving mold 3, and the member to be joined 2 is integrally joined to the joining member 1 by the pressure of the pressing mold 4 to manufacture the battery external terminal CC. The battery external terminal CC may also be formed into a desired outer shape by trimming the outer circumference of the member to be joined 2.

[0013] The receiving mold 3 has an enlarged hole 3a that guides a part of the member to be joined 2 and a positioning hole 3b that communicates with the enlarged hole 3a and positions the shaft portion 1a of the joining member 1. A knockout pin 5 extending concentrically is positioned to protrude from the positioning hole 3b, and the end face of the knockout pin 5 is configured to close the bottom of the positioning hole 3b. The knockout pin 5 is also configured to position the flange portion 1b of the joining member 1 within the positioning hole 3b in the enlarged hole 3a of the receiving mold 3, and to expose the protrusion 1c of the joining member 1 from the receiving mold 3. Furthermore, when the knockout pin 5 protrudes into the positioning hole 3b after the push die 4 has retracted, the shaft portion 1a of the joining member 1 located in the positioning hole 3b is removed from the receiving mold 3 together with the member to be joined 2 to which it is integrally joined.

[0014] Preferably, as shown in Figure 2(a), the pre-molding die 6 has a pre-molding hole 6a. The pre-molding die 6 is configured to pre-form the member to be joined 2, which fits into the protrusion 1c of the joining member 1, into a pan-head shaped portion 2b. The pre-molding hole 6a of this pre-molding die 6 allows the excess material of the member to be joined 2 to extend in a direction intersecting its pressurizing direction. Furthermore, when pre-molding the member to be joined 2, the pre-molding die 6 is configured to form a part of the member to be joined 2 that fits into the protrusion 1c of the joining member 1 into a shape along the enlarged hole 3a of the receiving die 3, and to make it tightly adhere to the flange portion 1b of the joining member 1.

[0015] As shown in Figures 2(b) and (c), the press mold 4 is configured to plastically deform the pre-formed pan-head-shaped molded portion 2b into a flat plate-like head 2d of a predetermined thickness after the pre-formed member to be joined 2, thereby joining the two members together as a single unit. Furthermore, similar to the pre-forming mold 6, the press mold 4 is configured to increase the hardness of the member to be joined 2 by work hardening the member to be joined 2, which has low hardness, during the molding process, and to press the convex portion 1c of the joining member 1, which has high hardness, through the inner wall of its concave portion 2a.

[0016] Although the joining member 1 is made of copper, it may be made of a harder metal material such as iron.

[0017] According to the above-described method for manufacturing an external battery terminal, the oxide film on the surface of the bonding member 1 and the member to be bonded 2 is removed by irradiating them with plasma. As a result, a new surface is exposed on the surfaces of the bonding member 1 and the member to be bonded 2, and these new surfaces come into contact with each other at the bonding interface, resulting in a metallic bond. The external battery terminal CC with a metallic bond at the bonding interface has low electrical resistance and excellent conductivity.

[0018] The specific configuration of each part of the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0019] CC battery external terminal 1. Joining member 1a shaft portion 1b flange portion 1c convex portion 1ca undercut portion 2 joined member 2a concave portion 3 receiving mold 4 pressing mold

Claims

[Claim 1] In a method for manufacturing an external terminal for a battery, in which the protrusions of a metal joining member are fitted into the recesses of a metal member to be joined, and both members are compressed by applying pressure in a compressive direction, thereby flattening the outer circumference of the end face of the protrusions of the joining member outward to form an undercut portion and joining the two members together as a single unit, A method for manufacturing an external terminal for a battery, characterized by applying plasma treatment to the surface of the protrusions of the joining member and the inner surface of the recesses of the member to be joined before joining.

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