JPS60182656A - Sealed type alkaline battery - Google Patents

Abstract

PURPOSE:To increase leakage resistance by arranging an insulating film comprising metal oxide and silicon dioxide powder having a specified particle size on the surface, which is to be in contact with a gasket, of an anode can. CONSTITUTION:An insulating film 7 of metal oxide such as alumina or chromate is formed on the surface, which is to be contact with a gasket, of an anode can by vapor deposition or chemical treatment process. Silicon dioxide particles 8 having a particle size of 10-150Angstrom (silica sol) are embedded into 100-300Angstrom defects or micro pores of the insulating film 7. When chromate film is formed by chemical treatment, silica sol is added into chromate treatment solution, and silica particles are embedded into a chromate film when chromate is deposited. For example, the anode can with insulating film is subjected to heat treatment at 150 deg.C or more (400-600 deg.C). By this heat treatment, silica particles become insoluble in water and alkali resistant.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in sealed alkaline batteries used in small devices such as wristwatches, cameras, and pocket calculators.

An example of a conventional sealed alkaline battery of this type will be explained with reference to longitudinal cross-sectional half-mounted views shown in FIGS. 1 and 2. In Figure 1, 1 is a cathode can with a curled portion 1a, the inner surface is made of a metal that is easily amalgamated, such as a copper plate, and the outer surface is a corrosion-resistant stainless steel plate, and 2 is a synthetic cathode can such as a knife. A gasket made of resin, 3 a cathode active material made of a mixture of amalgamated zinc powder and an electrolytic solution with shelving material added;
4 is a separator consisting of a semipermeable membrane such as cellophane and a liquid retaining layer such as nonwoven fabric, 5 is an anode active material made by compression molding a mixed powder of silver oxide or silver peroxide powder and graphite powder, and 6 is nickel plated. This is an anode can made of metal material.

Conventionally, a drawback of this type of sealed alkaline battery is that the electrolyte creeps up the surface of the cathode can 1 of the battery, resulting in leakage. This creeping up of the electrolyte occurs when water adhering to the surface of the cathode can 10 is polarized due to the electrode potential of the cathode active material 3 and generates a force that attracts the electrolyte.

In order to prevent this, the rising part 6a of the anode can 6 is bent inward, and the gasket 2 is compressed (35 to 65% of the thickness) and held by the curled part I El of the cathode can 1. 1 and the gasket 2, but at that time, the curled portion 1a of the cathode can 10 was also pushed inward and deformed, making it impossible to obtain the desired compression amount and the desired leakage resistance. Increase the internal pressure and remove the cathode can 1. This has the disadvantage that the bottom surface of the anode can 6 swells significantly and leakage resistance cannot be obtained from this point as well.

Furthermore, in order to prevent this, as shown in FIG. 2, alumina (A
1203) Alternatively, the insulating film 7 made of a metal oxide such as ljA acid (Cr203) is coated by vapor deposition or chemical treatment to prevent the electrode potential from being applied to the water adhering to the surface and prevent the electrolyte from creeping up. An attempt was also made.

However, as shown in the partially enlarged detailed view of FIG. 3, the insulating film 7 made of metal oxide has 100 to 300 defects and minute holes A due to the surface condition of the surface of the cathode can 10 and attached impurities. Therefore, it was difficult to ensure insulation over the entire surface of the cathode can 1.

Therefore, the moisture remaining in the defects and the fine pores A is polarized by the electrode potential and attracts the electrolyte, which causes the electrolyte to creep up, resulting in a drawback that leakage cannot be reduced.

The present invention was developed in view of the above drawbacks, and improves leakage resistance by disposing an insulating film made of metal oxide and silicon dioxide powder of 10 to 150 A on the surface of the cathode can that contacts the gas get. It is intended for this purpose.

A vertical cross-sectional half-mounted view of the sealed alkaline battery according to the present invention is the same as FIG. 2. FIG. 4 is a partially enlarged detailed view of a sealed alkaline battery according to the present invention. The surface of the cathode can 1 in contact with the gasket 2 is coated with 10θ to 3OO defects in the insulating film 7 made of a metal oxide such as alumina (7v203) or chromic acid (Cr203) by vapor deposition or chemical treatment. In the minute hole, 10
~15oA silicon dioxide powder 8 is buried. 10～
150's silicon dioxide powder is commonly called silica sol, and will be described by its common name in the following text.

It is preferable to add silica particles into the chromic acid film during chromic acid precipitation.

In addition, when the film is created by vapor deposition or chemical processing, it is preferable to coat the film with silica sol and fill the defects and fine pores with silica particles.

The cathode can filled with silica particles is heated to 150℃ or higher (especially 4℃).
The silica particles are heat-treated at a temperature of 00 to 600° C.) so that the silica particles do not dissolve in water, do not change in quality over time, and have strong alkali resistance before use.

In the battery of the present invention, defects and minute holes are eliminated over the entire surface of the cathode can, so an insulating film can be ensured over the entire surface, and moisture adhering to the insulating film will not be polarized. , the ability to attract the electrolyte is eliminated, the tendency of the electrolyte to creep up is eliminated, and leakage resistance is improved. Furthermore, since the insulating film material is a material that has long-term alkali resistance, leakage resistance is maintained over a long period of time.

As explained above, the present invention improves leakage resistance by disposing an insulating film made of metal oxide and silicon dioxide powder (commonly known as silica sol) of 10 to 150λ on the surface of the cathode can that contacts the gasket. , its leakage resistance can be maintained for a long period of time, and its practical effects are extremely large.

[Brief explanation of the drawing]

Figures 1 and 2 are longitudinal cross-sectional views of conventional sealed alkaline batteries, Figure 3 is a partially enlarged detailed view of Figure 2, and Figure 4 is
FIG. 1 is a partially enlarged detailed view of the sealed alkaline battery of the present invention. DESCRIPTION OF SYMBOLS 1... Cathode can, 2... Gasket, 3... Cathode active material, 4... Separator, 5... Anode active material. 6...Anode can, 7...Insulating film, 8...Silicon dioxide grains III Otsu No. 2 Figure 3 Cabinet No. 411

Claims (1)

[Claims] Contents such as cathode active material, separator, anode active material, etc.
In a closed type alkaline 11E pond sealed by a cathode can and an anode can made of a metal material through a gasket, metal oxide and 10 to 150 silicon dioxide particles are added to the surface of the cathode can that contacts the gasket. Sealed alkaline battery characterized by an insulating film