JPH09129201A - Sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide sufficient leakage-resistant properties even if a sealing plate integrally molded with an insulating gasket is used by roughing a peripheral vertical part of the sealing plate and then integrally molding the insulating gasket in the periphery of the roughed side surface. SOLUTION: Both sides of a part, corresponding to the peripheral vertical part of a sealing plate, of a steel plate 11 are concentrically roughed, then the steel plate 11 is press worked to form the sealing plate. The side both surfaces of the sealing plate are roughed in the range of 10-100μm to form the outside roughed region 12 of the peripheral vertical part of the sealing plate and the inside roughed region 13 of the peripheral vertical part, and an insulating gasket is integrally molded to the side surfaces. The roughed regions 12, 13 coming in contact with the insulating gasket have large surface area compared with a smooth surface, and a path through which an electrolyte leaks is lengthened. Time required to electrolyte leakage is also lengthened, and electrolyte leakage resistance is increased. The gap in a part coming in contact with the inside surface of the peripheral vertical part is not generated by the anchoring effect, and the electrolyte leakage path is lengthened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed battery including a battery case such as a coin type lithium battery, a button type air battery and a silver oxide battery, a sealing plate and an insulating gasket and hermetically sealing a power generating element.

[0002]

2. Description of the Related Art A coin-type manganese dioxide / lithium battery will be described below as an example of a conventional technique in which an insulating gasket is integrally molded with a sealing plate having no fold-back. FIG. 2 shows the structure of a conventional coin type manganese dioxide / lithium battery.

As shown in FIG. 2 (A), a positive electrode is obtained by pressure-molding a mixed powder of manganese dioxide, graphite, a binder, etc. on the inner bottom surface of a battery case 21 which also serves as a positive electrode terminal made of a cylindrical metal having a bottom. A mixture 22 is arranged, a positive electrode mixture 22 is covered with a cup-shaped separator 23, and the mixture is impregnated with an organic electrolytic solution.
A negative electrode metallic lithium 24 is placed on the separator 23, and an insulating gasket 25 integrally molded with a non-folded sealing plate 26 (mold sealing plate) is arranged, and the opening of the battery case 21 is caulked inward. It is sealed.

Conventionally, as for the integral molding of the insulating gasket and the sealing plate, the sealing plate was integrally molded without any treatment as described in JP-A-4-34837.

The insulating gasket is generally made of a polymer resin, and if it is simply integrally molded (insert mold molding) with a metallic sealing plate, the both will not physically or chemically adhere to each other. As shown in FIG. 2 (b), the inside of the side surface of the plate is contracted by the insulating gasket, so that a space 27 is formed to allow the electrolyte solution to easily penetrate.
There is an inconvenience that the leakage resistance of the battery is insufficient.

[0006]

As described above, in the conventional structure, the leakage resistance of the battery is insufficient. It is an object of the present invention to develop a sealed battery having sufficient leakage resistance even if an insulating gasket and a sealing plate are integrally molded.

[0007]

The present inventors mechanically improve the adhesion between the insulating gasket and the sealing plate and, at the same time, increase the distance until the electrolyte leaks out of the battery to prevent leakage. In order to improve the liquid characteristics, the vertical portion of the peripheral edge of the sealing plate is roughened.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION One of the leakage phenomena of a battery is that the electrolyte solution inside penetrates the interface between the insulating gasket and the sealing plate and leaks to the outside of the battery. Prolonging the path through which the electrolyte leaks out of the battery and prolonging the time until the electrolyte leaks are effective means for improving the leak-proof property. It is considered to be particularly effective when using an integrally molded insulating gasket and a sealing plate without using a sealant.

Roughening the surface of the periphery of the sealing plate that contacts the insulating gasket to make it uneven has a larger surface area than a smooth surface, and as a result, the path through which the electrolyte leaks becomes longer, leading to leakage. The time also becomes longer and the liquid leakage resistance is improved.

Further, a portion of the insulating gasket that abuts on the inner surface of the peripheral portion of the sealing plate is formed with a void due to the inward contraction force. However, if the inner surface of the peripheral portion of the sealing plate is also rough, the anchor is used. Due to the improved adhesiveness due to the effect, no void is formed, and the inner surface of the peripheral portion of the peripheral edge of the sealing plate can be kept in close contact with the insulating gasket, and the path through which the electrolytic solution leaks can be lengthened.

[0011]

Embodiments of the present invention will be described below with reference to the drawings using a coin type lithium battery. FIG. 1 (a) is a schematic view of a sealing plate prepared by press working using a steel plate 11 in which a portion corresponding to the peripheral vertical portion of the sealing plate is concentrically roughened on both sides in advance. In the figure, 12 and 13 are roughened areas. FIG. 2B is a schematic view of the sealing plate insert-molded with an insulating gasket.

A leak resistance test was carried out on a battery A made using this sealing plate and a battery B prepared by a conventional method. The results are shown in (Table 1). This table shows the number of batteries in which 100 batteries were stored in an environment of a temperature of 60 ° C. and a relative humidity of 90%, and liquid leakage occurred with the lapse of the storage period. For the battery of the present invention, three types of rough surfaces were prepared and tested.

[0013]

[Table 1]

As can be seen from this table, 10 μm to 10 μm
By providing a rough surface of 0 μm in the vertical portion of the peripheral edge of the sealing plate, the liquid leakage resistance can be significantly improved.

[0015]

As is apparent from the above description of the embodiments,
When using an integrally molded insulating gasket and sealing plate, by roughening the peripheral part of the sealing plate peripheral edge, it is possible to lengthen the path through which the electrolyte inside the battery permeates and leaks out, resulting in leakage resistance. The liquid characteristics can be improved.

[Brief description of the drawings]

FIG. 1A is a view showing a sealing plate having a roughened peripheral edge vertical portion. FIG. 1B is a view showing a sealing plate integrally molded with an insulating gasket.

FIG. 2A is a half sectional view of a coin type manganese dioxide / lithium battery. FIG. 2B is a view showing a sealing plate integrally molded with an insulating gasket.

[Explanation of symbols]

 11 Steel Plates Preliminarily Concentrically Processed 12 Roughened Area Outside Peripheral Vertical Peripheral of Sealing Plate 13 Roughened Area Inside Vertical Perimeter of Sealing Plate 21 Battery Case 22 Positive Electrode Mixture 23 Separator 24 Negative Lithium Metal 25 Insulation Gasket 26 Sealing plate 27 Void between the inside of the vertical portion of the sealing plate and the insulating gasket

Claims (1)

[Claims] 1. A sealed battery comprising a battery case also serving as a positive electrode terminal, a cup-shaped sealing plate also serving as a negative electrode terminal, and an insulating gasket arranged between the cup-shaped sealing plate and the cup-shaped sealing plate. ~ 100 μm (Rma x display)
A sealed battery in which the surface is roughened in the range of, and the insulating gasket is integrally molded around the side surface.