PURPOSE: To aim at improved charging efficiency at a high temperature by securing 0.01∼0.05g/cm3 of lithium hydroxide in pores of positive plate active substance.
CONSTITUTION: Slurry consisting of caking agent solution of methyl cellulose and metallic powder of carbonyl nickel for sintering is subjected to coating on porous metal plate, which is then sintered in a reducing hydrogen atmosphere. The sintered substrate is immersed in water solution of nickel nitrate (in nickel concentration of 10∼20%, at a temperature of 60∼70°C) and then in water solution of potassium hydroxide (in concentration of 10∼15%, at a temperature of 40∼50°C), thereby depositing nickel hydroxide. After the above cycle is repeated until the prescribed quantity of active substance is secured, the resultant deposit is submitted to washing by water and subsequent air drying, thus giving the positive plate, which is again immersed in a water solution of more than 10wt% of lithium hydroxide at a temperature of 60∼70°C for 10∼15min, and then exposed to hot air at 70∼80°C for 30min so as to evaporate up water content. By repeating this cycle, the prescribed quantity of 0.01∼0.05g/cm3 of lithium hydroxide is secured in pores of positive active substance.
SHIMODA MASAKAZU
TAKAHASHI KATSURO
OGURA TAKAO
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