JPS6074262A - Manufacture of nickel electrode - Google Patents

Abstract

PURPOSE:To reduce a number of cycles of processes by immersing a porous nickel substrate to be used for an alkali storage battery into a particular nickel nitrate solution and then converting it to active substance as the nickel hydroxide with a particular caustic soda solution. CONSTITUTION:A substrate consisting of sintered nickel powder to be used for alkali storage battery is immersed into the nickel nitrate solution in temperature of 65-85 deg.C and specific gravity of 1.65-1.75, allowing the substrate to be impregnated with nickel nitrate and a nickel electrode is converted into the nickel nitrate as the active substance in the caustic soda solution. Accordingly, impregnation is allowed up to the fine porosities by restricting the impregnation condition of the nickel nitrate, moreover density of nickel hydroxide to be precipitated can be set high and deep impregnation up to the fine porosities can be allowed by restricting the caustic soda solution and thereby processes can be simplified through reduction of processing cycles.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method of manufacturing nickel electrodes used in alkaline storage batteries.

Nickel electrodes use nickel hydroxide as the active material, and conventionally, a porous nickel substrate made from sintered nickel powder is placed in an aqueous solution of nickel nitrate or an organic solution of nickel nitrate (methanol solution, ethanol solution, etc.). immersion to impregnate nickel nitrate into the substrate, and then
The substrate was manufactured by dipping the substrate in a caustic soda solution and converting the nickel nitrate impregnated into the substrate into an active material as nickel hydroxide. Therefore, in the darning method, the process consisting of impregnation, heat treatment, formation of active material, washing, and drying is the cycle of impregnation. The active material cannot be sufficiently filled into /'2 at least 8 to 1.
It is necessary to repeat the 0 cycle, and the number of cycles is large.
It was time-consuming and labor-intensive to manufacture. For this reason,
A method of using a molten nickel Tit'i acid salt as a substitute for the Niracle nitrate solution has been devised, but it has not been possible to reduce the number of cycles vJ and a sufficient effect has not been obtained. To the heart, the actual situation (percentage) is 90-95.
%, it was low from the point of view of effective use of nickel.

The present invention has been developed in order to improve the drawbacks of the conventional method, and by selecting the conditions for impregnating nitrate with nitrate and the conditions for forming the active material with caustic soda to a specific value of 7.n4. , it is possible to both reduce the number of cycles and improve the utilization rate.

Specifically, the present invention provides a method in which a porous nickel substrate is immersed in a nickel nitrate solution to impregnate the substrate with nickel nitrate, and then the nickel nitrate is made into an active material as total nickel hydroxide in a caustic soda solution. , characterized in that the conditions for impregnation with the nickel nitrate solution are a temperature of 65 to 85°C and a specific gravity of 1.65 to 1°75, and the conditions for forming the active material in the caustic soda solution are a specific gravity of 1251 or more. be.

The porous nickel substrate in the present invention uses a nickel powder sintered body obtained by sintering nickel powder as in the conventional method, and the substrate made of this nickel powder sintered body is immersed in a nickel nitrate solution. Nickel nitrate is impregnated into the substrate. Here, as the nickel nitrate solution, an aqueous solution of nickel nitrate or an organic solution in which nickel nitrate is dissolved in methanol, ethanol, etc. can be used, but in the present invention, this solution has a temperature of 65 to 85°C, a specific gravity,
is required to be between 165 and 175. The temperature of the solution is 6
When the temperature is below 5℃, the viscosity of the d-liquid increases and the solution does not reach the pores of the nickel substrate, resulting in a decrease in the impregnation rate at the pores.On the other hand, when the temperature is above 85℃, the corrosion of the nickel substrate increases and the characteristics This is because it deteriorates. 1. In a thin solution with a specific gravity of 1,65 JJ or less, the amount of nickel nitrate impregnated in one immersion is small; on the other hand, with a specific gravity of 175 or more, the viscosity of the solution increases. It does not reach the pores of the body. Therefore, add 1 to the amount of nitric ethanol used for impregnation, and adjust accordingly (h) to meet the above conditions.
i, l order first.

After the nickel oxide film is impregnated with nickel nitrate in this manner, it is subjected to a prescribed heat treatment and then immersed in a caustic soda solution to undergo an active material treatment. Through this immersion ff, the impregnated nickel nitrate changes to water 11 nickel,
Nickel 11: As a pole! Caustic is published: l't-
The caustic nodal solution used here is
It is necessary that the k and i specific gravity be 1.25 or more. This seems to be because when the process is carried out in this manner, the density of the precipitated nickel hydroxide is high, sufficient pores are prepared for the next filling, and the nickel hydroxide penetrates deeply into the pores of the substrate.

In other words, as shown in Figure 1 (A), if the above conditions are followed, the contact area between nickel hydroxide, which is the active material 1, and nickel powder 2, which is the conductive material, will be as shown in Figure 1 (A). ) is larger than that of the conventional method, and this method also improves the utilization rate.

Figure 2 d shows the full A characteristics of the impregnated amount of nickel hydroxide for each number of impregnation cycles when manufactured under different impregnation conditions and active material forming conditions, where A is nickel nitrate. The specific mW of the solution is 1.609.When the temperature is 60°C and the specific gravity of the caustic soda solution is 1.30,
If B is the general purpose of the nickel nitrate solution, 1°75, the temperature is 60°C, and the specific gravity of the caustic soda solution is 1°20, C is the specific gravity of the nickel nitrate solution, 1.75°, the temperature is 70°C, and the ratio of the caustic soda solution is 7H [1]. , 20, D is the ratio of 7iFj nickel acid solution 31i, 1. , 75 V, the temperature is 60° C., and the ratio of the caustic soda solution is *J, , 3o. From the same figure, it is recognized that under conditions other than the conditions of the present invention, the number of cycles can be reduced in both cases of dl.

On the other hand, nickel 11-j produced by the method of the present invention
The utilization rate of the pole is approximately 100%, which is higher than that of the conventional method, and the number of cycles can be reduced to 4 to 5 times.

Next, the present invention will be described and explained based on examples.

A porous nickel substrate made of sintered nickel powder with a porosity of 80 cm was immersed in a nickel nitrate solution with a specific gravity of 1.72 and a temperature of 75°C for 40 minutes, and then in a caustic soda solution with a specific gravity of 13° and a temperature of 80°C. . This process is considered to be one cycle, and the amount of nickel hydroxide impregnated 1 at the end of each cycle is plotted, and the 31st threshold e) curve E is obtained.This song I%!Fj is at the end of 5 cycles. The finish was made good with %C, and then the product was charged for 16 hours with %C Tii', 1., KC, and the utilization rate was 100chi.).Curve F in Figure 3 shows the conventional method. When the utilization rate of all the electrode plates obtained by this method was measured in the same manner as above, the utilization rate was 92%.

From the above, when manufacturing according to the present invention, it is possible to not only reduce the number of cycles and reduce manufacturing time and labor, but also to improve the utilization rate and potency. Ru.

[Brief explanation of the drawing]

Figure 1) and (b) show the impregnated state of the nickel substrate.
- Sectional view 11 2nd In 1 and 3rd C'' - At the time of filling 15 plotting the amount of nickel hydroxide impregnated against the number of rifles
Tozu]. Number of patents (1 person, agent for Furukawa Battery Co., Ltd., patent attorney Tosa Fuji) (0)

Claims (1)

[Claims] Porous nickel substrate at temperature 65-85℃, specific gravity 1.65
The diagnostic substrate is impregnated with nickel nitrate by immersing it in a nickel nitrate solution with a concentration of ~175, and then the nickel nitrate is converted into nickel hydroxide into an active material in a caustic soda solution with a specific gravity of 1.25 or more. Method for manufacturing nickel electrodes.