| 摘要 |
PROBLEM TO BE SOLVED: To prevent deterioration of discharge characteristics, shortening of life, and lowering of energy density, by causing a nickel hydroxide powder to include a specific rate of zinc and cobalt, making its particles spherical, causing the zinc to be annularly distributed in particle cross-sections, causing the powder to have a specific tap density, and causing a diffraction peak of a specific surface by X-ray diffraction to have a specific half value width. SOLUTION: Swelling of an electrode due to massive generation of γ-NiOOH is prevented by causing a nickel hydroxide powder to contain 1 to 3 wt.% zinc and 0.5 to 2 wt.% cobalt. By making its particles spherical, its tap density becomes 2.05 g/ml or more, and also its energy density is raised, but normally it is 2.20 g/ml or less. Annular portions in particle cross-sections having a high zinc concentration prevent generation of γ-NiOOH, and therefore only a small amount of zinc is needed. The half value width of a diffraction peak on a (101) surface by X-ray diffraction is caused to be 0.9 degree or more, and crystallinity is obtained that is suitable for easy proton movement and the high tap density. It is preferable to produce this powder by simultaneous and continuous mixture of water solutions of nickel, of zinc/cobalt, and of a caustic alkali, and an ammonium-ion supplying body. |
