Hydrogen storage alloys as the anode materials of the direct borohydride fuel cell

Abstract

The direct borohydride fuel cell (DBFC) employs an alkaline borohydride solution as the anodic fuel. In this study, several Ni-based hydrogen storage alloys were studied as the anode materials for the DBFC. It was proved that hydrogen storage materials can absorb hydrogen during immersing in the borohydride solution. When used as the anode catalysts, these alloys usually showed less negative potentials than the pure nickel electrode. It was observed that hydrogen evolution was partially depressed through the electrochemical oxidation of the absorbed hydrogen at low borohydride concentrations. However, at high borohydride concentrations, the electrochemical reaction starting from borohydride species seems to be kinetically more favorable than the oxidation of the absorbed hydrogen. It was also found that the increases in specific surface area, surface activity and temperature improved the polarization properties of the alloy electrodes but hydrogen evolution was also increased.