JPS5873962A - Manufacture of negative plate for alkaline storage battery - Google Patents

Abstract

PURPOSE:To make uniform formation in a short time by polarizing cathodically a paste type negative plate in a cadmium salt solution to deposit cadmium in a dendrite state, and utilizing increase of solubility of cadmium compound in a paste resulting in decrease of pH in an electrode. CONSTITUTION:100pts. cadmium oxide powder is mixed with 1 pts. synthetic fiber, and ''teflon'' dispersion is added thereto. This mixture is kneaded with a kneader for about 30min to form a paste. The both surfaces of a nickel plate iron porous plate are coated with this paste. After drying, this coated plate is polarized cathodically in a 5wt% cadmium sulfate solution for one hour. A cadmium plate is used as a counter electrode in a cathodic polarization. After completion of cathodeic polarization, the negative electrode is discharged in a 20% potassium hydroxide solution for one hour, then washed and dried to form a negative plate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a paste-type cadmium negative electrode plate for an alkaline storage battery, and its purpose is to perform chemical formation uniformly and in a short time.

In general, paste-type cadmium negative electrode plates have the major advantages of a simple manufacturing process and high energy density, but compared to sintered-type cadmium negative electrode plates, they have lower mechanical strength and the active material is removed during the manufacturing process. It has the disadvantage of poor workability, such as falling off. Especially when cadmium hydroxide or cadmium oxide is used as an active material raw material.

Charge acceptance during formation was poor, and hydrogen gas was generated between the substrate and the active material, resulting in an interlayer in which the active material peeled off and fell off.

In order to eliminate this drawback, various methods have been proposed in the past. for example.

(1) Add neutralized fiber to the active material to increase the strength of the active material.

(2) Adding a metal or other conductive material to the active material and immersing it in a cadmium salt aqueous solution to chemically replace it.

There are other methods.

The present invention utilizes the fact that a paste-type negative electrode plate is cathodically polarized in a cadmium salt to precipitate cadmium in a dendrite shape, and at the same time, the pH decreases in the electrode and the solubility of the cadmium compound in the paste increases. Wait, for a short time? It is an attempt to create a sophisticated chemical formation.

An embodiment of the present invention is shown below.

100 parts of cadmium oxide powder and synthetic fiber (vinyl chloride)
Mix 1 part of acrylic (3 lengths). Then add Teflon Disbergeron so that the amount of Teflon is 1.
Mix the wires by crushing them for about 2 minutes to make a paste. This paste is applied to a thickness of Ka3 on both sides of a porous piece made of nickel plated iron. After drying, cathode polarization is performed for 1 hour in an Ifill cadmium sulfate aqueous solution at a current equivalent to one person.A cadmium plate is used as the counter electrode for cathode polarization. After cathodic polarization, '
tav! Transfer the electrode plate to potassium hydroxide ± aqueous solution and LIQm
It was discharged for a time equivalent to A, washed with water, and press dried to obtain a negative electrode plate.

During the above process, the state of the electrode plate during cathodic polarization is compared with that when cathodic polarization was performed in a 20-potassium hydroxide aqueous solution. In an aqueous solution of potassium hydroxide, it is possible to prevent the occurrence of hydrogen failure unless the current is kept below αIQIIIA.1 In the case of the present invention, overcurrent of up to about 10Qs+A can be suppressed without generating hydrogen gas. I was able to do it. Further, although the chemical conversion progresses uniformly in the case of the present invention, it is uneven in the potassium hydroxide water droplet, and the electrode plate surface has a mottled pattern in the early and middle stages of chemical formation.

The negative electrode plate manufactured according to the present invention was assembled into a circular sealed battery, but the mechanical strength was 1 and there were no problems in the process. Furthermore, the battery characteristics were also equivalent to those using sintered cadmium electrode plates.

In this example, cathodic polarization was performed in an aqueous solution of cadmium sulfate until the end of chemical charging, but if 10 minutes or more have passed after the start of charging, the same effect can be obtained by performing cathodic polarization in potassium hydroxide. There is.

As described above, the present invention solves the defective formation of paste-type cadmium negative electrode plates, and also shortens the formation time.
This has great industrial effects.

Patent applicant.

Claims (1)

[Claims] A method for producing a negative electrode plate for an alkaline storage battery, which comprises forming a paste-type negative electrode plate containing cadmium or its compound as the main active material in an aqueous solution containing a cadmium salt.