JP2001126679A - Sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealed battery with a cap facilitating to cover the upper opening of a battery can. SOLUTION: A sealed battery is enclosed in a battery can with the upper opening covered by battery cap. At least one of the inside or outside of the battery cap is provided with a wavy portion parallel to its one side to absorb the distortion caused in the fitting of the cap.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery sealed with a lid fitted into an opening of a battery can and sealed by welding, and more particularly to a sealed battery characterized by a lid fitted into a fitting portion of a rectangular battery. About.

[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 battery-powered equipment, a rectangular parallelepiped battery housing is generally used.
In the battery storage section of the device having such a rectangular parallelepiped shape, there is a problem that an invalid volume is increased with 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. 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 generation element.

[0003] In the process of assembling a square sealed battery, the positioning accuracy of the welded portion is high and the thermal influence on the periphery of the welded portion is small as compared with arc welding, resistance welding and gas welding as a method of welding the battery lid. The method by laser welding is widely used. In the sealing method using laser welding, a lid formed from a metal plate is fitted into an opening formed at one end of a rectangular metal can, and the fitting portion is laser-welded. However, in the inspection of the sealed container after welding, leakage of the electrolyte from the welded portion and insufficient pressure resistance of the welded portion were sometimes found. The present inventors have found that such poor sealing is based on the following causes based on the decomposition of the defective welding product and the observation of the cross section.

FIG. 5 is a view for explaining a method of sealing an opening of a battery can. FIG. 5A is a perspective view showing the appearance of the battery can, and FIGS. 5B and 5C are FIGS.
2 is a cross-sectional view taken along the line AA ′, in which a power generation element inside the battery is omitted. The lid 3 is fitted into the open end 2 at the upper end of the battery can 1, and a state in which the outer peripheral edge of the lid 3 abuts against the inner periphery of the open end 2 of the battery can 1 as shown in FIG. The laser 4 is irradiated to a predetermined portion of these fitting portions while maintaining the same to perform laser welding. However, since the locking property of the lid of the battery can 1 at the welded portion is reduced, FIG.
As shown in (C), the lid 3 falls into the inside of the battery can 1 at the welding site, or the lid 3 is lifted out of the battery can 1 at the opposite side of the welding site due to the reaction, and the lid 3 is closed. Since the body 3 is displaced obliquely, the focal length of the laser 4 at the contact portion between the lid 3 and the battery can becomes inconsistent, and sufficient energy is not applied to a portion where the focus does not match. In addition, it has been found that, in the lifted portion, a shadow of a laser irradiation portion may occur due to the lifted portion, resulting in poor welding. It is also conceivable to manually retouch the lid that is not correctly attached, but it is practically impossible to manually rework the lid in an automated process for mass production.

[0005]

SUMMARY OF THE INVENTION According to the present invention, when a lid of a sealed battery is welded by laser welding or the like, the lid can be welded without causing displacement of the lid and the like. It is an object of the present invention to provide a sealed battery capable of performing the following.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a sealed battery in which a battery cover is provided at an upper opening of a battery can and sealed by welding, and at least one of the front surface and the back surface of the battery cover is provided. The problem was solved by forming a parallel wavy portion on either side of the lid of the battery can. Further, in the above battery, the corrugated portion is provided in parallel with the short side of the lid. The corrugated portion is the above battery formed by press molding. The battery according to the above, wherein the lid is a stainless steel containing copper and having good cold workability.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A sealed battery according to the present invention has a structure in which the lid is simply placed on the opening of the battery can and pressed from above when the lid is fitted into the opening of the battery can. It has been found that a sealed battery free from poor fitting can be obtained.

A sealed battery according to the present invention will be described with reference to the drawings. FIG. 1 is a view for explaining a sealed battery of the present invention, FIG. 1 (A) is a plan view, and FIG.
It is sectional drawing cut | disconnected by the A 'line. The lid 3 fitted to the open end 2 at the upper end of the battery can 1 absorbs the distortion in the corrugated portion 5 provided on the lid, and the outer peripheral edge of the lid 3 becomes the open end 2 of the battery can 1. Can be reliably butted against the inner periphery of the battery, and a sealed battery can be obtained that is securely sealed by irradiating a laser from above while maintaining the sealed state.

FIG. 2 is a view for explaining the manufacturing process of the battery of the present invention. As shown in FIG. 2A, when the lid 3 is placed on the open end 2 of the battery can 1 from above, the lid may not completely fit into the battery can. However, in the sealed battery of the present invention, since the lid 3 is provided with the corrugated portion 5 whose surface is not parallel to the surface of the lid, when a pressing force 6 is applied from above, FIG. As shown in the figure, the wall surface reaction force 7 from the wall surface of the opening of the battery can and the acting force 8 generated by the pressing force 6 act on the lid body as a force for distorting the wavy portion 5, and the opening end of the wavy portion is formed. The lid can be easily fitted to the opening end 2 of the battery can only by applying a pressing force 6 from above. As a result, as shown in FIG. 2C, there is no portion that blocks the laser light emitted from above, so that the battery can 1 and the lid 3 can be accurately sealed by welding.

FIG. 3 is a diagram for explaining another embodiment of the present invention. The corrugated portion provided on the battery lid is not limited to FIG. 1 and may be a lid provided with one corrugated portion as shown in FIG. 3 (A), as shown in FIG. 3 (B). As shown in FIG. 3, a wavy portion parallel to the long side may be provided.
As shown in (C), the corrugated portion may be provided in parallel with both the short side and the long side of the lid.

Although the formation of the corrugated portion is easy by press forming, the formation of the corrugated portion by press forming is preferably a stainless steel alloy having good cold forging properties and low cold hardening properties. . Specifically, SUS
XM7 (18Cr-9Ni-3.5Cu), NTKD
-8 (15.5 to 19.0 Cr-1 manufactured by Nippon Metal Industry)
1.54 to 12.50Ni-3.00 to 4.00Cu)
It is preferable to use an austenitic stainless steel containing copper or the like. By using these stainless steel alloys, when the corrugated part is formed by press working, the spreadability is large, the cold hardenability is small, so the occurrence of cracks is less likely to occur, and when it is fitted to the open end, It also becomes easy to follow the shape of the opening end.

When the corrugated portion is formed by press molding,
The wavy part is thinner than the other parts, but if the wavy part is too thin, cracks may occur from the wavy part when the internal pressure increases, so do not form the wavy part too deeply Preferably, in the case of the stainless steel plate described above, the thin portion formed in the corrugated portion has a thickness of 20 μm.
m to 30 μm.

Further, since the corrugated portion of the lid shrinks at the time of fitting, the size of the lid is slightly larger than the size of the opening end, and the size of the opening is shrunk by the contraction of the corrugated portion at the time of fitting. It is preferable to match the size. Further, it is preferable that the position where the corrugated portion is formed is such that the distance between the lid and the fitting portion on the wall surface of the battery can is short because the amount of distortion generated in the corrugated portion is large.

Further, the entirety or a part of the thin portion formed in the corrugated portion may be thinned to be used as a safety valve for releasing the internal pressure when the pressure inside the battery is abnormally increased.

FIG. 4 illustrates a specific example of the lid according to the present invention. FIG. 4A is a plan view of the lid, and FIG.
FIG. 4C is a cross-sectional view taken along line AA ′, and FIG. 4C is a diagram illustrating the size of each part in FIG. 4B when the lid is fitted into the opening. A corrugated portion is formed on a stainless steel plate (NTK D-8 manufactured by Nippon Metal Industry) having a thickness c of 0.5 mm by press molding, and the short side a is 8.45 mm and the long side b
A lid member having a thickness of 32.90 mm was produced. The thin portion d of the wavy portion is 25 μm, the distance e from the end of the wavy portion is 1.0 mm, and the width of the wavy portion is 0.2 mm in the opening width f on the upper surface.
It was 25 mm. Such a lid is used as the opening width of the battery can.
When fitted to the opening end of 4 mm, the size of each part of the lid becomes 8.40 mm in width g and 0.20 mm in opening width h on the upper surface of the corrugated part, as shown in FIG. 4C. As the opening width of the corrugated portion became smaller, it was securely fitted to the opening of the battery can.

[0016]

By using the lid of the present invention,
Since the lid can be easily fitted into the opening of the battery can in the assembling process, it is possible to prevent a laser welding defect due to a defective mounting of the lid.

[Brief description of the drawings]

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

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

FIG. 3 is a diagram for explaining another embodiment of the present invention.

FIG. 4 is a diagram illustrating a specific example of the battery of the present invention.

FIG. 5 is a diagram illustrating a method of sealing an opening of a battery can.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Battery can, 2 ... Open end part, 3 ... Lid, 4 ... Laser,
5: wavy portion, 6: pressing force, 7: wall reaction force, 8: acting force,
a: short side, b: long side, c: thickness, d: thin portion, e: distance from end, f: opening width of upper surface, g: width, h: opening width of upper surface

Continued on the front page F term (reference) 5H011 AA09 AA13 AA17 CC06 DD03 DD05 DD13 FF03 GG09 5H029 AJ12 AJ14 AJ15 AM01 BJ02 CJ03 CJ05 DJ02 DJ14 EJ01 HJ12

Claims (2)

[Claims] 1. A sealed battery in which a battery lid is provided in an upper opening portion of a battery can and sealed by welding, at least one of a front surface and a back surface of the battery lid, and one side of a lid of the battery can. A sealed battery characterized by forming a wave-like portion parallel to. 2. The sealed battery according to claim 1, wherein the corrugated portion is formed by press-molding a material having low cold work hardening property.