EFFECTS OF RARE-EARTH-OXIDES ON PASTED CA DMIUM ELECTRODE FOR ALKALINE STORAGE BATTERY

Rare earth oxides (oxide of Y, La, Ce, Pr and Nd) were investigated as additive for pasted cadmium electrodes to improve its discharge effic iency. It was found that Y-2 O-3 powder is effective for the high util ization of cadmium active material at high rate discharge and at, high loading density. The discharged active material with Y-2 O-3 was fine and porous with high specific surface area, which contained needle-li ke gamma -Cd(OH)(2) in addition to a normal beta-phase. Y-2 O-3 powder showed higher solubility in KOH solution campared to other rate earth oxides, and yttrium ions absorbed on Cd surface. The cyclic voltammet ry showed the anodic oxidation of Cd plate was easier in KOH solution with yttrium ions than in pure KOH solution. The precipitated Cd(OH)(2 ) on the Cd plate, which was formed in KOH solution with yttrium ions, had same structure as the active material of pasted electrode with Y- 2 O-3. These results indicate that Y-2 O-3 powder in the pasted electr ode is dissolved KOH solution, the precipitation of Cd(OH)(2) to form affects diffusions of cadmium complex ions from Cd surface are the por ous surface and accelerated.