JPH0622114B2 - Manufacturing method of sintered positive plate for alkaline storage battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a sintered positive electrode plate for an alkaline storage battery, particularly a nickel-cadmium storage battery.

Structure of Conventional Example and Problems Thereof In general, this type of positive electrode plate of the type has a nickel powder having a particle diameter of several microns adhered to a nickel-plated iron core material of 800 to 800 in a reducing or inert gas atmosphere. Sintering is performed at a temperature of 1000 ° C. to form a porous substrate, and the sintered substrate is impregnated with a required amount of active material to form a positive electrode plate. Conventionally,
In this type of positive electrode plate, it is already known that the coexistence of nickel hydroxide as the active material with cobalt hydroxide improves the utilization rate of the active material. However, the positive electrode obtained by the above method has a 30-hour rate (1/30
When the charging method of charging an amount of electricity equivalent to 150% of the discharge capacity in C) was adopted, the utilization rate was about 40%, and satisfactory performance could not be obtained. With respect to such problems, JP-A-53-88929 and JP-A-53-1261
In No. 31, a substrate is filled with a cobalt salt, and then an alkali hydroxide is caused to act on the salt to fill a hydroxide or oxide of cobalt, and then a nickel hydroxide or a hydroxide of nickel and cobalt. By filling the mixture of the above, the conventional defects are eliminated, and
It has been proposed to improve the utilization rate when charging with a minute current of 1/30 C or less at a high temperature of 65 ° C.
However, this method has a drawback that a series of steps including immersion in an active material aqueous solution, immersion in an alkali hydroxide aqueous solution, water washing, and drying is added as compared with the conventional method, and when discharging at a current of 1 C or more. However, there is a drawback that the battery voltage decreases.

OBJECT OF THE INVENTION The present invention eliminates the above-mentioned drawbacks and reduces the number of steps, and at the high temperature of 45 to 65 ° C., 1/30
It is an object of the present invention to improve the utilization factor when charging with a minute current of C or less and further improve the battery voltage characteristic when discharging with a current of 1C or more.

Structure of the Invention That is, according to the present invention, a cobalt compound which is insoluble or sparingly soluble in water, for example, cobalt carbonate or cobalt oxide powder is mixed with nickel powder in an amount of 2 to 15 wt% to sinter a powder to prepare a substrate. 90-100 mol% nickel hydroxide and 10-0 mol% cobalt hydroxide on this substrate.
Is a method for producing a sintered positive electrode plate for an alkaline storage battery, which is characterized in that it is filled with an active material of

Description of Embodiments The details will be described below with reference to embodiments.

A predetermined amount of a cobalt compound which is insoluble or sparingly soluble in water, such as cobalt carbonate or cobalt oxide, is mixed with nickel powder.
A 100 wt% aqueous solution is mixed to form a slurry, and a nickel-plated perforated plate core material is passed through the slurry to adhere the slurry to both surfaces of the core material, which is pre-dried at 100 ° C. and then in an inert atmosphere. , And sintered at 870 ° C. for 15 minutes to prepare a sintered substrate having a thickness of 0.8 mm. After that, the sintered substrate is immersed in an aqueous solution of nickel nitrate mixed with a predetermined amount of cobalt nitrate, the mixed aqueous solution is impregnated into the pores of the sintered substrate, then immersed in an alkali hydroxide, washed with water and dried. A positive electrode plate was obtained by repeating the above process. A sealed type nickel-nickel-cadmium storage battery A having a nominal capacity of 1800 mAh prepared by using the positive electrode plate thus obtained.
The following tables show the substrates and active material compositions of the positive electrode plates of to F.

Figure 1 shows the various batteries in this table at 1/30 at 55 ° C.
It is the active material utilization rate when it was charged for 45 hours by the current of C. The battery A according to the conventional method has a utilization rate of about 70%, but the batteries C, D and E according to the present invention can secure a utilization rate of 80% or more. On the other hand, in the battery B in which the amount of the cobalt compound added to the substrate is less than 2 wt%, the active material utilization rate is not sufficiently improved when charged with a small current at a high temperature.

Next, FIG. 2 shows the discharge characteristics of the batteries in the table. 55
After charging for 45 hours at a current of 1 / 30C at a temperature of 55 ° C, discharge was performed at a current of 1C at 55 ° C. The batteries C, D, and E according to the method of the present invention have a higher battery voltage during discharge of 50 to 10 mv and a longer discharge time than the battery A according to the conventional method. On the other hand, the cobalt compound in the substrate is 20 wt%
In the battery F described above, the battery voltage at the time of discharging decreases, and as a result, the discharging time up to 1.0 V becomes short. In the case of B in which the amount of cobalt hydroxide in the active material is 10 mol% or more, the battery F is the same.

Further, metallic cobalt or cobalt hydroxide was tried as an additive to the substrate, but the discharge voltage was almost the same as that of the conventional method, and the effect of improving the battery voltage characteristic during discharge as obtained by the method of the present invention was not obtained. . The reason for this is not clear, but when metallic cobalt or cobalt hydroxide is added to the substrate, the added cobalt compound becomes an active material by charge and discharge, and especially Co ^III → Co ^II during discharge, which lowers the battery voltage. It is thought to be because.

On the other hand, when the additive is cobalt carbonate or cobalt oxide, it is considered that the additive is stable even when charged and discharged and does not become an active material, so that the discharge voltage increases. FIG. 3 shows the relationship between the amount of cobalt compound added to the substrate and the expansion coefficient of the positive electrode plate after 100 cycles of charge and discharge. When the amount of the cobalt compound added to the substrate is 15 wt% or less, the expansion coefficient slightly increases but is 2% or less. on the other hand,
When the amount of cobalt compound added to the substrate is about 20 wt%, the expansion coefficient of the positive electrode plate sharply increases, and the electrode plate becomes brittle.

EFFECTS OF THE INVENTION As described above, according to the present invention, a positive electrode plate having an improved utilization rate of an active material at the time of charging with a small current at a high temperature and excellent battery voltage characteristics when discharged at a current of 1 C or more is obtained. In addition, the number of manufacturing processes can be reduced.

[Brief description of drawings]

FIG. 1 shows the relationship between the amount of cobalt compound added to the substrate and the active material and the utilization rate of the active material when charged with a small current at high temperature, and FIG. 2 shows the discharge characteristics of the battery. FIG. 3 is a graph showing the relationship between the amount of cobalt compound added to the substrate and the expansion coefficient of the positive electrode plate.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiromi Maruyama 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Minor Yamaga, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A substrate is prepared by sintering a powder in which a cobalt compound powder insoluble or hardly soluble in water is mixed in an amount of 2 to 15 wt% with respect to a nickel powder. A method for producing a sintered positive electrode plate for an alkaline storage battery, which comprises filling an active material comprising 100 mol% and 10 to 0 mol% cobalt hydroxide.