JPS59128763A - Counter electrode for device used in formation of plate for alkaline storage battery - Google Patents

Abstract

PURPOSE:To suppress increase in IR loss caused when the current density of formation is increased, reduce the voltage of a container and obtain a formation counter electrode having a sufficient mechanical strength by packing the sintered body of nickel carbonyl powder in the holes of foamy nickel affixed to the surface of a nickel plate to be electrolysed. CONSTITUTION:After a part of foamy nickel 1 is pressed to increase its density, this is unified with a nickel plate 2 by spot welding. Next the unified body is washed with dilute nitric acid before being sufficiently washed with water in order to achieve higher close contact during sintering. Then slurry prepared by adding 4 parts CMC and 100 parts water to 100 parts nickel carbonyl powder is sufficiently rubbed into the unified body consisting of the foamy nickel 1 and the nickel plate 2. The thus obtained body is dried before being sintered in a reducing atmosphere at 1,000 deg.C for 15min thereby making a formation counter electrode consisting of the foamy nickel 1 and sintered nickel 3 packed in the foamy nickel 1. When current density is high, the thickness of the nickel plate 2 should be increased without any necessity of varying the thickness of the of the foamy nickel 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a counter electrode for a chemical conversion device for an electrode plate for an alkaline storage battery.

(b) Conventional Mokuzai Traditionally, in the manufacturing process of electrode plates for alkaline storage batteries,
After the live material filler culm, a chemical conversion treatment that mainly involves charging and discharging the electrode plate is performed for the purpose of activating the electrode plate and removing impurities. A continuous chemical conversion method is known. Patch type chemical treatment has 1 equity
1i1 (as shown in No. 55-89110, the electrode plate and counter electrode are wound through a separator and set in a chemical conversion container. Because the processing unit is large, the chemical conversion current density is set at 0.5 to 0. Formation is carried out for a long time with a small value of lA/drrP.In continuous formation, formation is carried out when the electrode plate faces the counter electrode in each tank while the electrode plate is continuously passed through the charging and discharging tanks. In order to complete the chemical formation in a short time,
Consideration has been given to increasing the chemical formation current density to an extremely high level of 10 to 40 A/d-. Both chemical conversion methods are opposite to chemical conversion,
A nickel smooth plate is generally used because it can withstand electrolysis in alkali, cost, electrical conductivity, etc. Of the two chemical conversion methods, the continuous chemical conversion method is often used from the viewpoint of workability.

Furthermore, when a smooth nickel plate is used as the chemically formed counter electrode, when the current density increases, the IR loss becomes noticeable, the effective area decreases due to bubbles generated on the counter electrode, the overvoltage increases significantly, and the sliding voltage It has the disadvantage of causing an increase in This increase in sliding voltage causes an increase in the electrolytic voltage and a rise in the temperature of the chemical solution.If the temperature of the chemical solution is high, crystals in cadmium electrodes etc. will become coarser, that is, capacity deterioration will occur. A cooling device is required.

In order to reduce the sliding voltage, it is effective to increase the surface area of the counter electrode and provide a gas vent on the opposite electrode, so punched plates or lath plates were used for the counter electrode, but sufficient effects were not obtained. In addition, the carbonyl nickel sintered body used in sintered batteries has a large surface area that can be used as a gas electrode, and is effective at reducing sliding voltages, but it does not occur under high current densities. The sintered body is easily damaged by the gas generated, which poses problems in terms of service life.

(c) Purpose In view of the above points, an object of the present invention is to provide a formed counter electrode that suppresses the increase in IR loss when the formed current density is increased, reduces the sliding voltage, and has sufficient strength. .

2) Structure The chemically formed counter electrode of the present invention is a carbonyl nickel sintered body with improved mechanical strength, and carbonyl nickel powder is injected into the pores of the foamed nick μ bonded to the electrolyzed surface of the nickel plate. It has a structure filled with sintered bodies.

Example) A partial sectional view of a chemically formed counter electrode of the present invention is shown in FIG. 1, and will be described below. Foamed nickel μ (2mm thick) manufactured by Sumitomo Electric ■
1) is partially pressurized to make it densified, and then the densified part of this foamed nickel/L/(1) is placed on a nickel plate (2
) and integrated by spot welding. This was washed with dilute nitric acid to improve adhesion during sintering, and then thoroughly washed with water. Next, add 100s of carboni pni'flV powder,
A slurry was prepared by adding 4 parts of CMC and 100 parts of water, and the slurry was thoroughly rubbed into the bonded material of the foamed nickel μ (1) and the nickel plate (2), dried, and sintered for 1000 minutes in a reducing atmosphere. C for 15 minutes to create a chemically formed counter electrode having a sintered nick μ (3) in the foamed nickel 1V (11).A chemically formed counter electrode was assembled using this counter electrode, and a sintered nickel anode plate was charged by changing the current density. Seven sliding voltages were measured.For comparison, a counter electrode made by applying slurry directly to a smooth nickel plate and sintering it under the same conditions as the above counter electrode was used. The sliding voltage was measured as follows.

The above-mentioned counter electrode of the present invention is A, and the electrolyte has a ratio of 1.1.
An aqueous potash solution of No. 28 was used. The results are shown in FIG. From Figure 2, it is clear that when counter electrodes A and B are used, the sliding voltage is lower than when counter electrodes B and C are used, and the larger the current @ skin, the larger the difference in sliding voltage, and the greater the effect. I know what will happen.

Further, using counter electrodes A and B, a continuous electrolytic test was conducted for 1000 hours at a current density of BOA/drn''.

As a result, damage to the sintered body was observed in counter electrode B, but
No abnormality was observed in the counter electrode A of the present invention. This is K
More foaming nickel! It can be seen that the strength was improved by using the nickel plate.

Regarding IR loss, although the foamed nick μ alone has conductivity, as the current density increases, the IR loss becomes noticeable. In order to reduce FiIR loss in the present invention,
It is supported by a nickel plate, and when the current density is high, the nickel plate can be made thicker, and there is no need to change the thickness of the foamed nickel μ.

(f) Effects According to the present invention, the increase in IR loss when the anodization current density is increased is suppressed, and the sliding voltage is reduced, so that electrolytic power can be saved, sufficient strength can be obtained, and the service life can be improved. This has the effect of eliminating the problem.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of a counter electrode of the present invention, and FIG. 2 is a drawing showing the relationship between chemical conversion current density and sliding voltage, showing a comparison between the present invention and a conventional counter electrode. (2)...nickel/l/fi+...foamed nickel/v(a)...sintered body.

Claims (1)

[Claims] +11 Carbonium nickel is inserted into the pores of the foamed nickel bonded to the electrolyzed figure of the nickel plate! A counter electrode for a chemical conversion device for an electrode plate for an alkaline storage battery having a structure filled with sintered powder.