| 摘要 |
PROBLEM TO BE SOLVED: To display a high utilization factor of active material over a long period by adding metal yttrium and/or its compound to active material powder. SOLUTION: Active material powder consists of a compound particle formed with a coating layer comprising a sodium contained cobalt compound on a surface of nickel hydroxide particle. By this coating layer, conductivity of a particle surface is enhanced, a utilization factor of active material in the beginning of a charge/discharge cycle is increased. By adding metal yttrium and/or its compound powder to the active material powder, at charge/discharge cycle time, cobalt of the coating layer is prevented from easily diffusing in the inside of the nickel hydroxide particle. In this way, not only in the beginning of a charge/discharge cycle but also over a long period, a high utilization factor of active material is realized. Additive ratio of metal yttrium or the like relating to the active material powder is suited for 0.05 to 5 pts.wt. relating to 100 pts.wt. the latter. |
