JPH01648A - Method for manufacturing sintered electrodes for alkaline storage batteries - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION B) Industrial Application Field The present invention relates to a method for manufacturing a sintered electrode for an alkaline storage battery, which uses a nickel sintered substrate and fills it with an active material by a chemical impregnation method.

Conventional technology Generally, this cypress sintered electrode is made by mixing carbonyl nickel powder with a small apparent specific gravity with a thickener such as methyl cellulose and water to obtain a slurry, and then applying nickel or a nickel-plated wire mesh on top of the slurry. Alternatively, after applying it to a conductive core such as punching metal, apply it to a conductor core body such as punched metal, and then
It was heated to 1000'C to decompose the thickener and water to form a porous nickel sintered substrate, and the porous portions of the substrate were impregnated with predetermined amounts of anode and anode active materials to form cathode and anode electrode plates. It is what you do. In this impregnation process, an aqueous solution of metal salts of the anode active material (cadmium salt on the cathode side, nickel salt on the anode side, etc.), such as nitrate salt, sulfate, and chloride, is used as the impregnating liquid. The impregnation process is repeated several times by impregnating the substrate, then converting the above salt #A into a hydroxide as an active material by chemical substitution, ilysis, or thermal decomposition in an alkaline solution, and washing and drying this with water. This is to obtain a predetermined amount of active W material.

In each of the above impregnation steps, an active layer, ie, a hydroxide such as cadmium hydroxide on the cathode side and nickel hydroxide on the Pa electrode side, is deposited on the surface of the sintered substrate. This precipitate covers the pores of the porous sintered substrate, and since these deposits are insoluble, they remain unremoved even in the next washing with water, and in the ninth impregnation step, the impregnating solution is removed. This makes it difficult for the active material to penetrate, causing variations in the amount of impregnation, making it difficult to obtain a uniform filling amount of the active material.

Therefore, in order to eliminate this drawback, conventional methods have been adopted in which the deposits on the surface of the sintered substrate are removed by brushing when washing the hydroxide formed by chemical substitution etc. in the above impregnation process with water. .

However, with this method, it takes many man-hours to brush each time during valley water washing, which complicates the impregnation process, and there is a concern that not only will the electrode surface be stained, but also the active material in the holes of the sintered substrate may be removed. Garuru.

Another method is to impregnate a sintered substrate with a salt of a predetermined active material, as shown in IFB No. 60-8585. It has been proposed that the salt fA, which adheres to the substrate surface by immersion in a certain salt solution and diffuses due to the concentration difference, is removed from the substrate surface by reducing the a degree. However, this method requires time and
There is a problem in that when a strongly attached active material is formed, a sufficient removal effect cannot be obtained.

e→ Problems to be Solved by the Invention The present invention has been made to address the above-mentioned problems, and is aimed at suppressing the clogging V of the pores of a sintered substrate due to unnecessary adhering active material during active material impregnation. The purpose is to make it easier for the impregnating liquid to penetrate and to fill the active material with high efficiency. In addition, the present invention allows the water washing step to be omitted, and the electrode manufacturing process can be simplified.
This is simplified to □.

2) Means for Solving Problems In the method for manufacturing opaque sintered electrodes for alkaline storage batteries, a sintered nickel substrate is immersed in an aqueous solution of metal salts, and then subjected to alkali treatment to hydrate the metal salts (9). Of course, after changing i
This is characterized by immersing the metal salt aqueous solution again in a state in which a portion of the alkali σ remains.

In addition, at the same time as the alkali treatment and the immersion process in the aqueous Meng salt solution, the Alkali-F that was saved during the a) v-potash treatment process is also immersed in low-1 degree alkali or v-water. Since the elyalkali can be sufficiently diffused, the active material can be planted more efficiently.

(E) Function Contrary to the conventional chemical impregnation method in which a nickel sintered substrate is impregnated with a metal salt solution and made into an active material in an alkali, the substrate is impregnated with an alkali and held therein. It is possible to turn this metal salt into an active material by immersing it in a salt solution and using VC processing. In addition, in order to maximize this effect, it is necessary to remove a certain amount of alkali on the surface of the nickel sintered substrate, or to sufficiently remove moisture inside the porous body of the substrate, to prevent adhesion and clogging. Become. For example, drying is a good way to remove moisture. By doing so, the metal 4 solution is easily permeated into the inside of the sintered substrate. Here, it is safe to pay sufficient attention to changes in pH and concentration due to the introduction of alkali into the salt solution, since this affects not only the impregnating properties but also the performance.

(F) Example Using a sintered nickel substrate with a porosity of about 85%, nickel nitrate (cooked to a temperature of 80'C, lj, 5-tE, 1/1) was used. (Metal salt) After immersing in an aqueous solution, it was dried and soaked in 25% tetrahydric soda at 80'C. Further, after this, about 5 pieces of paper were soaked in water for 1stDt, dried, and immersed in the nickel nitrate aqueous solution again. The above operation is regarded as one cycle, and the extension of the living body Sadamitsu dodo when this operation is repeated is shown on the back of the figure. One pole obtained in this manner is referred to as the kick pole a of the present invention.

As a comparative example, the same substrate was immersed in the nickel nitrate aqueous solution, dried in the same manner, and immersed in 25% caustic soda at 80°C. After this, as usual, wash with water and alkali' (
r Thoroughly remove and dry. With the above operations as one cycle, you can create this masterpiece 'km! The increase in the amount of active material purchased when the sample was returned is shown in the figure.

The polarization obtained in this way (1.) is taken as comparison tib.

In addition, in each cycle of the impregnation process, the active material was immersed in alkali in both the light and valley cycles, and the sample was taken out, thoroughly exposed to water, dried, and the air flow rate was measured. This is something that was brought out from the perspective of the board's gravity and weakness. This active @mass filling amount (
%) rC, expressed by the following formula.

From the figure, it can be seen that in the present invention, the awakening electrode a is
Although it is sufficient to repeat the impregnation process twice, the predetermined active material filling amount was not obtained in the comparison electrode even after six impregnations. Therefore, it can be seen that in the manufacturing method of the present invention, the impregnation cycle for filling the predetermined active material can be reduced.

Furthermore, the water washing step required in conventional chemical impregnation methods can be completely omitted.

In addition, in the example, after performing alkaline treatment with 25% caustic soda, it was immersed in water for 5 seconds, but this process differs from the conventional water washing process in that it was completely immersed in water. The point is that alkali is not removed. Therefore, when immersing in water that does not contain alkali, 5
If the time is maintained at about 0 seconds or less, the active material can be impregnated while the alkali is maintained. Further, after the alkali treatment, the alkali can be efficiently diffused by performing the alkali treatment with an alkali having a lower a degree than the alkali used in the alkali treatment.

(G) Effects of the Invention According to the method for producing a sintered polarizer for alkaline storage batteries of the present invention, the active material can be filled efficiently, thereby simplifying the 11L electrode production process, and its industrial value is 11i[ Extremely large. −

[Brief explanation of the drawing]

The figure shows the change in the amount of active material filled every 81 cycles of the active anatomy impregnation process. a... Electrode of the present invention, b... Comparative polarization.

Claims (4)

[Claims] (1) After immersing the nickel sintered substrate in a metal salt aqueous solution,
A method for producing a sintered electrode for an alkaline storage battery, which comprises converting the metal salt into a hydroxide through alkali treatment, and then immersing it in an aqueous metal salt solution again with some of the alkali remaining. . (2) Between the alkali treatment step and the immersion step in the aqueous metal salt solution, the product is immersed in an alkali or water having a lower concentration than the alkali used in the alkali treatment step. A method for producing a sintered electrode for an alkaline storage battery according to scope (1). (3) A sintered electrode for an alkaline storage battery according to claim (1), characterized in that a drying step is provided between the alkali treatment step and the step of dipping into the metal salt aqueous solution again. manufacturing method. (4) Between the alkali treatment step and the re-immersion step in the aqueous metal salt solution, a step is provided in which the alkali is immersed in an alkali or water with a lower concentration than the alkali used in the alkali treatment step, and then dried. A method for manufacturing a sintered electrode for an alkaline storage battery according to claim (1).