Electrochemical investigation of hydrogen-storage alloy electrode with duplex surface modification

摘要

The alloy electrode with duplex surface treatment (i.e., the alloy was treated with hot KOH solution first and then coated with metallic nickel) performs satisfactorily in both fast activation and long cycle life. AC impedance data show that the contact resistance between particles and the charge-transfer resistance on electrolyte/electrode interface have been reduced markedly by the duplex surface treatment. The amount of nickel deposited on the alloy surface influences not only the electrochemical kinetics but also cycle-life stability. The optimal amount of deposited nickel is found to be around 15 wt% in terms of the electrode's highest exchange current and limiting current densities obtained from the anodic polarization curves. The electrode with higher exchange current density and limiting current density has an increased high-rate dischargeability.