| 摘要 |
PROBLEM TO BE SOLVED: To improve an effect to suppress expansion of an electrode plate while effectively utilizing properties such as the high use efficiency of an active material and the excellent over-discharging property of an active material which is produced by forming higher valence cobalt oxide on the surface of nickel hydroxide particles by alkaline thermal treatment. SOLUTION: An aqueous solution of nickel sulfate is prepared and while the solution being stirred, a sodium hydroxide solution is gradually dropped to precipitate nickel hydroxide crystal. Then, while the aqueous solution in which the crystal is precipitated being stirred, a cobalt sulfate solution and a sodium hydroxide solution are dropped to deposit cobalt hydroxide on the surface of the nickel hydroxide crystal. The produced granular material is separated and taken out, washed with water, dried, and the granular material is treated by an alkaline thermal treatment in which the resultant granular material is impregnated with an aqueous solution of sodium hydroxide in a prescribed concentration by adding the solution while being stirred in a beaker and then the material is heated while being stirred further. A prescribed amount of a cobalt hydroxide powder on the market is then added to the granular material treated by alkaline thermal treatment to produce the active material. |
