Rare earth hydrogen storage alloy used in borohydride fuel cells

Fuel cell using the borohydride as the fuel has attracted much attentions because of high energy density and working potential. In this work, LaNi4.5Al0.5 hydrogen storage alloy used as the anodic material to replace noble metals has been investigated. Experimental results showed that H2 evolution was unavoidable during discharge process because of the hydrolysis of BH4-, but the utilization of the fuel increased with the increasing current densities. At high discharge current, the alloy electrode showed the lowest hydrogen generation rate and higher utilization of the fuel because, the generated hydrogen was absorbed and oxidized to produce electric energy similar to the behavior of hydrogen storage alloy in nickel-metal hydride batteries. The reaction mechanism of borohydride on the surface of electrode made of hydrogen storage alloy also has been discussed. Hydrogen storage alloy would be a promising material as the anodic catalyst in borohydride fuel cell.