JPH0619989B2 - Manufacturing method of nickel electrode for alkaline battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a nickel electrode for an alkaline battery.

Configuration of Conventional Example and Its Problems In recent years, demand for nickel-cadmium storage batteries (hereinafter referred to as Ni-Cd batteries) has increased as a power source for emergency lights or electronic devices. Conventionally, a sintered nickel electrode and a pocket nickel electrode have been used for the positive electrode of a Ni-Cd battery, but a typical one is a sintered type. The sintered nickel electrode is a porous metal plate of nickel or nickel-plated iron, coated with carbonyl nickel powder and sintered to form a substrate, which is impregnated with the active material salt of the sintered substrate and heated or chemically treated. It is converted into an active material by a reaction to obtain an electrode. This method has good electrode plate performance, long life, and excellent high-rate discharge characteristics, but the problem is that the porosity of the sintered substrate is low and an electrode with high capacity density cannot be obtained, and the electrode process is complicated. was there. On the other hand, a non-sintered electrode in which a foamed metal porous body having a high porosity is directly filled with an active material powder has attracted attention as an electrode that can obtain a high capacity density in a simple process. However, in this electrode, since it is necessary to press the metal porous body having a relatively low strength with the active material powder and then pressing it at a high pressure, there is a problem that the electrode is cracked or bent.

An object of the present invention is to provide a non-sintered nickel electrode, which comprises directly filling or coating a porous substrate with a battery active material,
Particularly in the pressing process, the purpose is to increase the capacity density of the nickel electrode and prevent cracks and bending of the electrode.

Configuration of the Invention The present invention is characterized in that, in the method for producing a non-sintered nickel electrode, the water content of the nickel electrode paste during the pressing step is controlled in a high humidity atmosphere.

Description of Examples Hereinafter, details of the present invention will be described using a Ni-Cd battery.

Nickel hydroxide passed through a 200 mesh screen,
Carbonyl nickel and metallic cobalt powder in a weight ratio of 8
After mixing at a ratio of 0: 15: 5, water containing 0.5% by weight of carboxymethyl cellulose was added to obtain a water content of 22.
% Paste made.

Next, a nickel metal porous body with a thickness of 0.13cm at a porosity of 95% was filled with the paste, per 1 cm ^2, 0.
A filled electrode plate containing 18 g of paste and having dimensions of 24 cm in length, 8 cm in width and 0.13 cm in thickness was obtained. From various studies, it was found that the active material powder should be in a wet state rather than a completely dry state in order to press the filled electrode plate to obtain a high packing density. It is considered that this is because the water present on the surface of the active material powder acts as a lubricant. However, if the water content is too high, the active material powder flows out during pressing, which is not preferable. Proper value of water content is 5-10%
However, when the water distribution is non-uniform, bending occurs. The water content of the paste in this plate is 7-8%
4 adjustment methods were examined and classified as shown in the following table.

The electrode plates A to D were passed between press rolls having an interval of 0.4 mm to obtain an electrode plate having an average thickness of 0.60 mm. However, the electrode plates that have been subjected to the treatments A and B suffer from bending and distortion, which makes it difficult to cut and process the electrode plates. It is considered that this is because the distribution of water in the electrode plate is non-uniform. Further, in the method A, it was confirmed that the drying started from the peripheral portion of the electrode plate, which was the cause of nonuniform water content. Also B
In the above method, a method such as spraying water was also examined, but it was found that a large amount was distributed on the surface of the electrode plate and did not enter the inside. In the methods C and D, if a large volume of atmosphere is secured, the water content preferable for the press is 7 to 7.
It is possible to maintain a uniform amount of 8% and the relative humidity is 7
If the atmosphere is 0 to 100%, a water content of 5 to 10% of the active material suitable for pressing can be obtained. In addition, it is possible to perform cutting and processing without any trouble after the roll pressing without any bending or distortion. Next, each of the electrode plates according to the method of A and C is 150
FIG. 1 and FIG. 2 show the variation in the thickness of the electrode plate after pressing when the sheet is rolled. As shown in this figure, there is a difference in the variation of the electrode plate thickness due to the difference in the method of adjusting the water content, and the method of adjusting in the high humidity atmosphere of the relative humidity of 70 to 100% of the present invention is It was also confirmed that it was excellent in that there was little variation in electrode plate thickness.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to obtain an electrode plate having a uniform electrode plate thickness after roll pressing and less deflection and distortion.

[Brief description of drawings]

FIG. 1 is a frequency distribution diagram showing the thickness of the electrode plate after roll pressing after being filled with paste and adjusted by a drying method, and FIG. 2 is a frequency diagram showing the electrode plate thickness after roll pressing according to an embodiment of the present invention. It is a distribution map.

Claims (2)

[Claims] 1. A method for producing a nickel electrode in which a paste containing at least an active material for a battery is directly filled in a foamed metal porous body or coated on a metal porous plate and then pressed to form an electrode. A method for producing a nickel electrode for an alkaline battery, wherein the water content of the active material paste of the electrode during pressing is adjusted in an atmosphere having a relative humidity of 70 to 100%. 2. The method for producing a nickel electrode for an alkaline battery according to claim 1, wherein the water content of the active material paste in the electrode during pressing is 5 to 10%.