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 less than or equal to x less than or equal to 0.7. These included the unit cell lattice parameters measured using Xray 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). (C) 2002 Elsevier Science B.V All rights reserved.