Effect of cobalt on the physicochemical properties of a simple LaB5 metal hydride alloy

This work reports the results of a systematic study on the effect of Co as substituent for Ni on several physical and electrochemical properties of LaNi4.7−xSn0.3Cox metal hydride alloys, where 0≤x≤0.7. These included the unit cell lattice parameters measured using X-ray diffraction (XRD) and the electronic properties obtained using X-ray absorption spectroscopy (XAS). In general, the presence of cobalt in the alloys causes a decrease on the hydrogen equilibrium pressure and on the rate of capacity decay, and an increase in the cycle life and on the alloy activation time. A negligible effect of Co is observed in the maximum charge storage capacity and on the catalytic activity with respect to the hydrogen oxidation reaction (HOR).