Platinum alloying effects on the behavior of a metal hydride electrode

This is a study of the alloy structure, cycling life, and reaction kinetics of LaNi4.7−xSn0.3Ptx (x=0 and 0.1) metal hydride electrodes, using X-ray diffraction, X-ray absorption spectroscopy, electrochemical charge/discharge cycling, and electrochemical impedance spectroscopy. It is seen that the presence of platinum in the alloy causes an increase of the cycle life and a decrease in the hydrogen equilibrium pressure, activation time, charge storage capacity, and the rate of capacity decay during multicycling. XANES results are consistent with a decrease in the Ni oxidation in the Pt-containing alloy after the electrode cycling, indicating a protection introduced by Pt against Ni oxidation. It was also found that the catalytic activity of charge/discharge is improved with Pt alloying, a factor exclusively related to an increase of the active area due to higher alloy pulverization.