Effect of alkali-treatment of hydrogen storage alloy on the degradation ofNi/MH batteries

Alkali-treatment at high temperature of the hydrogen storage alloy which wa s used as the negative electrode of nickel/metal-hydride batteries could en hance the cycle life. Al dissolves from the alloy surface, rare earth metal hydroxides form on the alloy surface, while Ni and Co exist as metals near the surface. Mn dissolves first and then deposits again as an oxide on the alloy surface. The corrosion reaction caused by alkali-treatment of the al loy stops at a certain stage. The above three points can be considered as t he main factors for the long cycle life for the alkali-treated alloys. (C) 1999 Elsevier Science S.A. All rights reserved.