JPH0492365A - Manufacture of alkaline storage battery - Google Patents

Abstract

PURPOSE:To maintain the preservable property of an alkaline storage battery and to improve the discharge performance extensively by adding a nickel hydroxide to an anode including a cadmium oxide as a main active substance, and carrying out a discharge in the formation process in a high temperature of alkaline water solution. CONSTITUTION:A nickel hydroxide is added to a cadmium oxide to be the main active substance of an anode plate to produce an electric plate, and after that, it is charged in a normal temperature of alkaline water solution in the formation process. And after discharging in a high temperature of alkaline water solution, it is washed in the water and dried to remove the alkaline component to make a completed electrode plate. The electrode plate is combined with a separator and a cathode plate to form an alkaline storage battery. Since it is charged in a normal temperature of alkaline water solution, the cadmium electrode is hardly corroded, and there is no density change of the alkaline water solution, making the handling, the temperature maintaining cost, and the like also excellent. Furthermore, since the discharging is carried out in a high temperature of alkaline water solution, it has an effect to reduce the active substance surface area as the temperature of the alkaline water solution is higher, in the discharge operation.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for manufacturing alkaline storage batteries such as sealed nickel-cadmium storage batteries, and particularly to improving discharge performance.

(B) Prior Art Conventionally, various studies have been made to improve the discharge performance of sealed nickel-cadmium storage batteries.

Particularly recently, the applications of sealed nickel-cadmium storage batteries for consumer use have expanded, and for example, for power tools, there is a demand for improved characteristics during high rate discharge. In this case, the performance of the cathode plate is reduced because the cathode plate is capacity limited,
Improving this performance is an important issue.

In order to increase the utilization rate of the active material, Japanese Patent Application Laid-Open No. 51-9231 proposes a method of performing charging and discharging at a high rate current value in a high-temperature alkaline aqueous solution.

Further, Japanese Patent Application Laid-Open No. 62-119861 proposes a method in which charging is performed at a high rate current value in an alkaline aqueous solution at a high temperature, and discharging is performed at a high rate current value in an alkaline aqueous solution at room temperature.

However, when a high-temperature alkaline aqueous solution is used, the cadmium electrode plate becomes extremely susceptible to corrosion, especially during charging, due to charging and discharging during chemical conversion treatment, which causes a problem that this becomes a cause of deterioration in battery performance.

In addition, with regard to improving the performance of cathode plates, studies are being conducted from two perspectives: improving conductivity (especially non-sintered cathodes) and adding additives to control the cadmium charge/discharge reaction (dissolution-precipitation reaction). . Regarding additives, for example,
There are many methods for adding organic substances such as lignin, CMC, and MC, but all of these decompose within the battery.
There is a risk of lowering the electrolyte concentration and reducing the charge reserve of the cathode.

On the other hand, when it comes to inorganic additives, it is effective to add nickel hydroxide as a counter electrode material, but in this case, the storage characteristics of the battery deteriorate, so the amount added is set to be effective in improving the discharge performance. There were some things I couldn't do.

(c) Problems to be Solved by the Invention The present invention solves the above-mentioned problems and provides a method that does not affect other properties while maintaining the effectiveness of adding nickel hydroxide. be.

(d) Means for Solving the Problems In the present invention, nickel hydroxide is added to cadmium oxide, which is the main active material of the cathode plate, and after the electrode plate is created, it is charged in an alkaline aqueous solution at room temperature in a chemical formation process. After discharging in a high-temperature alkaline aqueous solution, washing with water and drying to remove the alkaline content, the completed electrode plate is combined with a separator and an anode plate to form an alkano storage battery.

(E) Effect According to the manufacturing method of the present invention, charging is performed in an alkaline aqueous solution at room temperature during the chemical conversion process, so the cadmium electrode plate is is less likely to be corroded, there is no change in the aqueous alkaline solution concentration, and it has excellent handling properties, temperature maintenance cost, etc. Further, the discharge is performed in a high temperature alkaline aqueous solution. Here, it is thought that the smaller the surface area of the active material is, the better the storage characteristics are, and the higher the temperature of the alkaline aqueous solution during discharge, the more effective the active material surface area is to be reduced.

Therefore, the best results regarding storage properties can be obtained if the aqueous alkali solution temperature is near the boiling point. However, in practical terms, the temperature of the alkaline aqueous solution is desirably about 50 to 80° C. in consideration of changes in the concentration of the alkaline aqueous solution and ease of handling.

(F) Example A sintered nickel substrate with a porosity of 84% was immersed in an aqueous cadmium nitrate solution, dried and treated with alkali, and the sintered substrate was filled with cadmium hydroxide as an active material.

Nickel hydroxide was added by regulating the amount of nickel nitrate added to cadmium nitrate.

From the results of preliminary experiments, the Ni/Cd metal ratio was 3%.
Since the area near the area showed the highest utilization rate of cadmium hydroxide, an electrode plate with 3% nickel added was created. This electrode plate is further divided into two parts, one of which is made of caustic potassium (25%) at room temperature.
) Charged to 200% with a current of 0.2C (V, S, nominal capacity) in an aqueous solution, and discharged with a current of 0.2C in a caustic potash (25%) aqueous solution at 80°C to form the present invention. I created item a.

In addition, the chemically formed comparative amount was charged to 200% at a current of 0.2 C in a caustic potash (25%) aqueous solution at room temperature, and discharged at a current of 0.2 C in a caustic potash (25%) aqueous solution at room temperature. Created.

In addition, a comparative amount C was prepared under the same conditions except that nickel nitrate was not added.

Inventive battery A and comparative battery B with a nominal capacity of 1.2AH are made by combining the above three types of cathode plates, separators, and anode plates.
, C was created.

Table 1 shows the results of measuring the high rate discharge cycle characteristics and storage characteristics of the above battery. The cycle characteristics are O,
Charging with IC (120mA) current for 16 hours, 8
Discharged with a current of C (9.6 A), and the battery voltage reached 1. O.V.
The discharge time until reaching . The battery capacity before storage of storage characteristics is 0. Charged with a current of IC (120mA) for 16 hours, discharged with a current of IC (1.2A), and the battery voltage reached 1. The discharge time until reaching OV is shown.

The battery capacity after storage is measured at O
,, charged for 16 hours with the current of IC (120mA),
After being left in a constant temperature bath at 45°C for 172 months, IC (
It is discharged with a current of 1.2 A), and the battery voltage reaches 1.2 A). (Discharging time until reaching IV is shown.

Table 1 Table 2 Table 1 shows that Comparative Battery B has improved cycle characteristics, but on the other hand, storage characteristics have significantly deteriorated. The battery A of the present invention has improved storage characteristics comparable to those of the comparative battery C, and also has good cycle characteristics, and has the performance aimed at by the present invention.

Table 2 shows the surface area of each electrode plate of the present invention battery A and comparative batteries B and C (including the sintered body: the surface area of the sintered body alone is approximately 0.4 m"/
g) and the measurement results of residual nitrate radicals are shown. The surface area of the active material is determined by turning the formed electrode plate into fine powder and removing the core.
Measured using the method. The surface area of the sintered body alone is approximately 0.4 m'/
It is g. The amount of residual nitrate radicals was determined by baking each electrode plate at a temperature of 900° C. or higher, and measuring the air collected during that time using a milk gas detection tube.

From Table 2, it is thought that the larger the surface area of the active material, the lower the storage characteristics from the viewpoint of the reactivity of nitrate radicals, and it is expected that the surface area of the active material is a factor that determines the storage characteristics. It is thought that the battery A of the present invention had a smaller surface area, which led to improved performance.

(G) Effects of the Invention According to the production method of the present invention, nickel hydroxide is added to the cathode containing cadmium oxide as a living material, and the discharge in the chemical formation process is performed in a high-temperature alkaline aqueous solution, thereby preserving the cathode. Despite the addition of nickel hydroxide, which deteriorates the characteristics, the storage characteristics of the alkaline storage battery can be maintained and the discharge characteristics can also be greatly improved, and its industrial value is extremely large.

Claims (1)

[Claims] (1) A cathode plate containing cadmium oxide as the main active material and nickel hydroxide added thereto is charged in an aqueous alkaline solution at room temperature, then discharged in an aqueous alkaline solution at a high temperature, and then assembled into a battery. Method of manufacturing alkaline storage batteries.