Effect of Al substitution for Co on the hydrogen storage characteristics of Ml0.8Mg0.2Ni3.2Co0.6−xAlx (x=0–0.6) alloys

Ml0.8Mg0.2Ni3.2Co0.6−xAlx (x=0–0.6) hydrogen storage alloys were prepared by induction melting and the effect of Al substitution for Co on the structure and hydrogen storage characteristics was investigated. These alloys are confirmed to be composed of LaNi5 as matrix and (LaMg)Ni3 as the secondary phase. The Al substitution leads to an expansion of the unit cell volume of matrix and an enhancement of the stability of the alloy hydrides. The thermodynamic properties such as ΔH and ΔS and the diffusion coefficient of hydrogen in these alloys were also evaluated.