JPS59181456A - Manufacture of negative plate of alkali storage battery - Google Patents

Abstract

PURPOSE:To ease the clogging during repeated impregnations and obtain a negative plate having high energy density by dipping a nickel porous materials impregnated with nitric acid cadmium into the aqueous solution of caustic alkali and executing the processing by dilute acid to the activated negative plate. CONSTITUTION:On the occasion of activating nitric acid cadmium in the aqueous solution of alkali, clogging of fine entrance is eliminated by eliminating a layer of a large amount of cadmium hydroxide generated at the area near the surface, deviation from the theoretical impregnation curve obtained by repeating the cycles is compressed, and amount of impregnation is acquired easily while increasing productivity. For example, after the nickel porous sintered body in the thickness of 0.8mm. is dipped into cadmium nitric acid with a specific gravity of 2.0 and PH of 4.0 for 5min, an extra solution is eliminated by stationary setting. Thereafter, such material is dipped into the 20% aqueous solution of sodium hydroxide at 30 deg.C. After removing the alkali by washing with water, such material is then dipped into the nitric acid of 1mol/l at 60 deg.C for 10sec. The negative plate can be obtained beating such process for six times.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the filling of a cadmium active material into a nickel porous ceramic body used in an alkaline battery cathode plate.

Conventionally, as a method for producing a cadmium cathode plate for an alkaline τ battery, a nickel porous sintered body obtained by sintering carbonyl nickel powder or its slurry at a temperature of 700 to 1000°C in a hydrogen or nitrogen atmosphere is used. The active material is filled by immersing it in a solution of cadmium chain acid, electrolytically reducing the impregnated cadmium nitrate in an alkaline solution using a nickel plate as the counter electrode, and then washing and drying it 5 to 6 times. Was.

However, in the above method, when converting cadmium nitrate into an active material, it is necessary to apply a current of about IOA/dmt, making it difficult to reduce costs and increase production in terms of electrolytic equipment and costs such as electric power.

Note that thermal decomposition or a method using cadmium formate have been proposed as a method to eliminate the above-mentioned drawbacks, but the former method tends to cause the nickel sintered body to melt due to the high heat during decomposition, and has a lifespan of 1. The latter method has the disadvantage that the raw material salt is more expensive than nitrate. A method has also been proposed in which cadmium nitrate impregnated into a nickel sintered body is chemically replaced with caustic alkali. Therefore, the active material tends to concentrate near the pore entrances of the porous body. This large amount of active material layer near the surface prevents the diffusion of cadmium nitrate into the pores, so even after repeated cycles, 40 to 50% of the pore volume was the limit that could be filled with active material. .

The present invention has been made to eliminate the above-mentioned drawbacks.
The purpose is to manufacture a cathode plate with a sufficient amount of effective active material while maintaining high productivity.

The present invention eliminates clogging near the entry of pores by using dilute acid to remove the multi-legged cadmium hydroxide layer that is generated near the surface when cadmium nitrate is made into an active material in an alkaline aqueous solution. This is a method for manufacturing an alkaline τ1 battery IeITi plate that can easily secure the amount of impregnation while increasing productivity by reducing the deviation from the theoretical impregnation curve when repeated cycles.

In the present invention, an example is shown.

Length: 200mm, Medium: 33mm, I! Tsao, s v, vq
After soaking the nickel porous sintered body in cadmium nitrate with a specific gravity of 2.0 and pH of 4.0 for 5 minutes, the excess vagina was removed by allowing it to stand still, and the body was immersed in a 20% sodium hydroxide aqueous solution at 30°C. do. After removing alkali by washing with water,
Immerse in 1 m o I/l nitric acid for 10 seconds at °C. This process was repeated 6 times.

The amount of impregnation of the cathode plate impregnated in this way was as shown in the drawing, and was closer to the theoretical impregnation curve than that of the cathode plate that was not treated, and the active material utilization rate was also almost the same.

As described above, according to the present invention, it is possible to alleviate the clogging phenomenon that occurs when the impregnation operation is repeated, so that it is possible to obtain a cathode plate with high energy density without reducing productivity unlike the electrolytic method. There are effects such as being able to.

[Brief explanation of the drawing]

The drawing is a curve diagram showing the deviation from the theoretical impregnation curve of a cathode plate according to an embodiment of the present invention and a cathode plate according to a conventional method. patent applicant

Claims (1)

[Claims] An alkaline storage battery cathode plate characterized in that the cathode plate obtained by chemically converting it into an active material by immersing a porous nickel body impregnated with cadmium nitrate in an aqueous caustic alkali solution is treated with dilute acid. Manufacturing method.