JPS59181457A - Manufacture of negative plate of nickel-cadmium storage battery - Google Patents

Abstract

PURPOSE:To increase amount of impregnation of active substance of sintered negative plate by previously filling pores of sintered body with water on the occasion of dipping a negative plate into cadmium salt solution during the chemical dipping process. CONSTITUTION:In case a negative plate is dipped into the cadmium salt solution in the chemical dipping process, a substrate for impregnation is filled water for each cycle, the cadmium salt is diffused into the substrate and influence by clogging of pores by adhesion to surface can be reduced. Thereby, since the fine pores of sintered body 4 are filled with water, the ions such as Cd<2+>, NO<3-> etc. in the dipping solution 3 can be diffused easily and amount of impregnation can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing cathode plates for nickel-cadmium storage batteries, and in particular to increasing the impregnation level of sintered cathode plates in chemical impregnation.

Chemical impregnation methods, electrolytic impregnation methods, and melt impregnation methods are generally known as methods for manufacturing sintered cathode plates. In the chemical impregnation method, the active material is fixed in the form of cadmium hydroxide in the sintered body, whereas in the electrolytic impregnation method and the melt impregnation method, the active material is fixed in the form of metallic cadmium. Although the chemical impregnation method has many advantages such as active material utilization rate and productivity, it has the disadvantage that the amount of active material impregnated is small. The reason for this is largely due to the principle of the impregnation method itself, but we cannot overlook the fact that it is also due to clogging of pores on the surface of the sintered body due to surface adhesion.

The object of the present invention is that when immersing in a cadmium salt bath, the impregnated substrate is filled with water in advance for each cycle, and the cadmium salt is diffused into the substrate and the pores are clogged due to surface adhesion. The objective is to reduce the influence and increase the amount of active material impregnated. (Hereinafter, this impregnation method will be referred to as "water displacement impregnation method.") Next, one embodiment of the present invention will be described.

Figure 1 shows the cycle change of the active material layer.

1 is a case where the water displacement impregnation method of the present invention is used, and 2 is a case where the impregnation is carried out by a conventional method. It does not increase at all until the second cycle.

On the other hand, in case 1, there is almost no tendency to plateau even in the 6th cycle. The reason for this will be explained with reference to FIGS. 3 and 4. Figure 3 is a schematic diagram of the case of impregnation in a dry state.
This shows that it is difficult for ions such as cadmium ions (cd'') and nitrate ions (No''-) in the immersion liquid 3 to replace the air 5 in the pores of the sintered body 4.

On the other hand, FIG. 4 shows the case of water displacement impregnation according to the present invention, in which the pores of the sintered body 4 are filled with water 6, so that (d4-, N0s-, etc.) in the immersion liquid 3 are This shows that ions can easily diffuse.

Note that 7 is a cadmium hydroxide crystal.

Next, FIG. 2 shows the dependence of the immersion time on the amount of active material impregnated.

In No. 2, extension of the immersion time has almost no effect on the amount of active material impregnated, whereas l increases rapidly until about 10 minutes and becomes almost constant at about 60 minutes. As mentioned above, in case 1, this is due to the diffusion of the immersion liquid, and in case 2, this is due to the diffusion of the immersion liquid.
clarified that this is due to the replacement of air in the pores with the immersion liquid.

As described above, the present invention has great industrial value in that it can increase the amount of impregnation in chemical impregnation.

[Brief explanation of the drawings] Figure 1 is a comparative curve diagram showing changes in the amount of active material impregnated with the number of impregnation cycles between the method of the present invention and the conventional method, and Figure 2 similarly shows the dependence of the amount of active material impregnated on immersion time. Comparative curve diagrams, FIG. 3 are schematic diagrams showing the impregnated state in the conventional method, and FIG. 4 is a schematic diagram showing the impregnated state in the method of the present invention. 1 is the method of the present invention, 2 is the conventional method, 3 is the immersion liquid, 4 is the sintered body,
5 is air in the pores of the sintered body, 6 is water in the pores of the sintered body, 7 is cadmium hydroxide crystal patent applicant Figure 1 Immersion time (0)

Claims (1)

[Claims] A method for producing a cathode plate for a nickel-cadmium storage battery, which comprises filling the pores of a sintered body with water in advance when immersing the cathode plate in a cadmium salt bath in chemical impregnation of the cathode plate.