Effects of nickel- and copper-coating of hydride alloys on the electrode reactions of metal-hydride electrodes

We have studied effects of Ni- and Cu-coating of hydride-forming metal alloys on their performance as the cathode material of an Ni/MHx cell. Ni or Cu (5-9 wt.%) was coated on alloy particles by an electroless coating technique prior to test electrode preparation. Mechanical stability of the alloy particles and the cycle life did not appear to be improved by such coatings. However, such coatings greatly improved the electrode rate capability and alloy activation time. The coating technique appears to be extremely useful for alloys which have other desirable properties, such as high specific capacity and long cycle life, but have low rate capability and long activation time.