JP2002279944A - Sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealed battery enofling a lid body to be surely fitted, in sealing a battery can of the sealed battery with the lid body. SOLUTION: In this sealed battery, formed by sealing the lid body fitted to the upper opening part of the battery can through welding, the lid body has a thin-walled part at the peripheral edge, and a stepped part positioned between the internal wall surfaces of the opening part of the battery can, and the opposed faces of the stepped part are provided with projecting parts, formed so that the distance connecting the tip parts is loner than the distance between the internal wall surfaces of the battery can, the lid body of such a constitution is placed on the opening part of the battery can, fitted to the battery can by the projecting parts formed at the stepped part, and welded in a state of the thin-walled part of the peripheral edge of the lid body abutting on the end face of the battery can.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery which has a lid fitted into an opening of a battery can and sealed by welding. The present invention relates to a sealed battery that does not cause poor sealing or the like.

[0002]

2. Description of the Related Art Batteries are used as power supplies for small electronic devices. In particular, non-aqueous electrolyte batteries such as lithium ion secondary batteries, which are small and large-capacity sealed batteries, are used as power sources for mobile phones, notebook computers, camera-integrated video recorders, and the like. In a battery-using device, a rectangular parallelepiped battery housing is generally used. However, in a battery housing of a device having a rectangular parallelepiped shape, there is a problem that an invalid volume is increased in a cylindrical battery. . Furthermore, since the diameter of the cylindrical battery is limited by the thickness of the battery housing, in a small or thin device, a thin prismatic sealed battery is used instead of the cylindrical battery. ing.

[0003] These rectangular sealed batteries are manufactured by welding a battery lid to an open end of a battery can made of stainless steel, nickel-plated steel plate, aluminum or the like containing a power generating element. In the process of assembling the prismatic sealed battery, the welding method of the lid is laser welding with higher positioning accuracy of the welded part and less thermal influence around the welded part compared to arc welding, resistance welding and gas welding. Is widely used.

In the sealing method using laser welding, a lid formed of a metal plate is fitted into an opening formed at one end of a rectangular metal can, and welding is performed by irradiating a laser to the fitting portion. ing. However, in the inspection of the battery after welding, leakage of the electrolyte from the welded portion and insufficient pressure resistance of the welded portion were sometimes found. The cause of the failure of the welded portion includes the problem of the processing accuracy of the battery can and the lid, but it has been difficult to manufacture all members with specific numerical values for mass-produced members. For this reason, when the lid was fitted to the fitting portion of the battery can, a sufficient fitting force could not be obtained. If the fitting force is insufficient, when the lid joined to the positive electrode conductive tab or the negative electrode conductive tab of the battery element housed in the battery can is fitted into the opening of the battery can, these bent tabs are used. The repulsive force sometimes caused a phenomenon such as a part of the lid body rising from the opening of the battery can.

When the battery can and the lid are sealed by laser welding in a state where the lid is partially raised, welding is insufficient at the portion where the lid is raised, resulting in poor sealing. Therefore, various methods have been proposed in order to solve such poor sealing between the battery can and the lid. For example, in Japanese Patent Application Laid-Open No. 10-269999, a thin edge portion and a step portion that fits inside the battery can are provided on the peripheral edge portion of the lid, and the thin edge portion is placed on the upper end of the battery can and fitted to the battery can. A battery can in which a plurality of press-fitting ribs having a straight portion and a tapered portion are provided on the lower surface of the lid, and the lid is fitted into the opening of the battery can by the press-fitting rib when the lid is press-fitted. Has been proposed.

However, since the press-fitting ribs are provided on the lower surface of the lid, the number of parts of the battery components increases, and it is necessary to provide a space for the press-fitting ribs inside the battery can. It cannot be said to be a practical solution, since it reduces the energy density per volume of the material.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a hermetic seal which has a sufficient fitting force when a lid is fitted into an opening of a battery can, and which does not cause defective sealing during subsequent welding. It is an object of the present invention to provide a battery.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sealed battery in which a lid fitted into an upper opening of a battery can is sealed by welding, and a thin wall portion is formed around the periphery of the battery can. A lid having a stepped portion located between the wall surfaces, and a lid having a protruding portion on the opposite surface of the stepped portion where the distance connecting the tip is larger than the distance between the inner wall surfaces of the battery can is an opening of the battery can. The battery is mounted on the battery case, and is fitted to the battery can by the convex portion formed at the step portion, and the thin portion of the peripheral edge of the lid is welded in a state of being in contact with the end surface of the battery can to solve the problem. be able to. Further, the convex portion is the above-mentioned sealed battery provided symmetrically with respect to a line passing through the center of the lid.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In a sealed battery according to the present invention, as a lid fitted into an opening of a battery can, a tip portion is connected to a step portion formed on the lid facing a wall surface of the battery can. When the lid is fitted into the opening of the battery can by forming a convex portion whose distance is larger than the distance of the opening of the battery can, a sufficient fitting force is applied between the battery can and the lid. It has been found that the sealing can be reliably performed by welding without occurrence of poor fitting of the lid and the like.

Hereinafter, a sealed battery of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a sealed battery according to the present invention. FIG. 1A is an upper cross-sectional view illustrating a state in which a lid is fitted, and FIG. 1B is an inner surface side of the lid. 1 (C) is a side view as viewed from a direction A in FIG. 1 (B). In a sealed battery 1 of the present invention, a lid 3 is fitted into an opening at the upper end of a battery can 2, and an electrode terminal 4 having a polarity opposite to that of the battery can is insulated at the center of the lid 3. Attached via body 5.

A thin portion 7 having a small thickness is formed on the peripheral edge 6 of the lid 2 in contact with the wall surface at the upper end of the battery can. The portion of the lid located on the inner surface of the battery can is , A stepped portion 8 is formed. The size of the step 8 is slightly smaller than the inner surface of the opening of the battery can 2, and the step 8 has four protrusions 9 a, 9 b, 9 c, and 9 d.
Individuals are formed.

When the cover 3 is pressed against the opening of the battery can 2 after the electrode tab 4 of the cover 2 and the conductive tab 11 connected to the battery element 10 are joined, the thin portion 7 on the outer periphery of the cover 3 becomes As a result of contacting the end surface of the battery can 2 and the convex portions 9a, 9b, 9c, 9d formed on the stepped portion 8 abutting on the inner surface of the battery can 2, the lid 3 is located between the opening of the battery can 2 Are fitted to each other with a predetermined fitting force. As a result, the lid 3 is securely fitted to the upper portion of the battery can 2 simply by placing the lid on the opening of the battery can and pressing it from above. Then, by irradiating the fitting portion with a laser, the sealed battery can be sealed without generating a poorly sealed battery.

FIG. 2 is a diagram for explaining another embodiment of the present invention. It is the figure which looked at the top view of the lid from the inside of the battery can. FIG. 2 (A) shows that convex portions 9a, 9b, 9c, 9d are formed at four positions at both ends of a step portion 8 provided on the inner surface of the lid 3, and FIG. The protrusions 9 a and 9 b are provided only on the short side of the step 8. FIG.
(C) shows convex portions 9a, 9b,
9c, 9d, 9e and 9f are formed. In the example shown above, a thin rectangular battery having a large ratio of the length of the long side and the length of the short side was shown. In the case of the same shape, two or more convex portions may be provided on each side.

The size of the convex portion provided on the lid is preferably 0.01 mm to 0.1 mm from the surface of the step, and more preferably 0.01 mm to 0.03 mm. The width is preferably 0.1 mm to 0.5 mm, more preferably 0.1 mm to 0.3 mm. If the height is larger than 0.1 mm, the battery can has a large force at the time of fitting and the battery can is deformed, which is not preferable. Further, it is preferable that the convex portion is formed on the entire surface of the height of the step portion. These convex parts are
By forming the concave portion corresponding to the convex portion in the press molding die for forming the step portion on the lid of the battery can, the convex portion can be formed simultaneously with the press molding.

Further, the sealed battery of the present invention can be used for any of iron and iron alloy battery cans, such as nickel-plated mild steel and stainless steel battery cans, and aluminum and aluminum alloy battery cans. Although it can be applied, it is suitable for a thick aluminum-based battery can.

[0016]

The present invention will be described below with reference to examples. Example 1 In FIG. 3, as shown in FIG. 3 (A) as a plan view from the inside of the lid, and FIG. 3 (B) as a side view, a vertical a: 4.8 m
m, width b: 29.6 mm, from the peripheral edge of the aluminum alloy lid to a portion having a width c: 0.3 mm and a thickness d: 0.
A thin portion of 7 mm was formed, and a step portion e: 0.3 mm was formed at the center portion from the thin portion of the peripheral portion. On the wall surface of the step portion e on the long side, a width g:
A lid having a convex part having a height of 0.2 mm and a height h of 0.01 mm was produced. After attaching the electrode terminal to the lid and joining it to the conductive tab connected to the battery element stored in the battery can,
It was press-fitted into the opening of a battery can made of an aluminum alloy having an inner size of 4.2 mm in length and 28.7 mm in width.

Next, when the battery can was fixed and the tab attached to the electrode terminal was pulled up vertically, the force at which the lid was removed from the battery can was measured by a tensile tester to determine the fitting force. As a result of measuring the fitting force for 100 batteries,
The average was 5.3 N, and the fitting force was 4.5 N or more for all the batteries.

Comparative Example 1 The fitting force was measured in the same manner as in Example 1 except that no convex portion was provided. The average of ten batteries was 3.8 N.

[0019]

According to the present invention, since the convex portion is formed on the surface of the lid that fits into the opening of the battery can and that is in contact with the inner surface of the opening of the battery can, the lid is pressed into the opening of the battery can. In this case, a sufficient fitting force is generated between the battery can and the lid, so that the conductive tab connected to the lid rebounds and so forth, thereby causing a gap between the battery can and the lid. The possibility of performing welding in a state is eliminated. As a result, occurrence of poor sealing can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a sealed battery of the present invention.

FIG. 2 is a diagram illustrating a manufacturing process of the sealed battery of the present invention.

FIG. 3 is a diagram illustrating a lid according to an embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sealed battery, 2 ... Battery can, 3 ... Lid, 4 ... Electrode terminal, 5 ... Insulator, 6 ... Peripheral part, 7 ... Thin part, 8 ... Step part, 9a, 9b, 9c, 9d, 9e , 9f ... convex part, 1
0: battery element, 11: conductive tab

Claims (1)

[Claims] 1. A sealed battery in which a lid fitted into an upper opening of a battery can is sealed by welding and has a stepped portion located at a periphery between a thin portion and an inner wall surface of the opening of the battery can. On the opposite surface of the step portion, a lid having a convex portion in which the distance connecting the tip portion is larger than the distance between the inner wall surfaces of the battery can was placed in the opening of the battery can, and formed on the step portion. A sealed battery characterized by being fitted to a battery can by a convex portion and being welded in a state where a thin portion on a peripheral edge of a lid is in contact with an end surface of the battery can.