Phase evolution, thermodynamics and kinetics property of transition metal (TM = Zr, Ti, V) catalyzed Mg–Ce–Y–Ni hydrogen storage alloys

Abstract

To improve hydrogen storage property of Mg-based alloy, the Mg–Ce–Y–Ni + 10 wt % M (M = Zr, Ti, V) composites were prepared by the combination of alloying and ball-milling, and their microstructure, phase evolution, as well as hydrogen storage thermodynamic and kinetic properties, were investigated by XRD, PCT, and DSC methods. The result shows that the hydrogenated samples are composed of MgH2, Mg2NiH4 and corresponding ZrH2, TiH2 and VH1.9 phases. In comparison, the |ΔH| value of M = Ti sample is larger than that of M = Zr and M = V samples, and the M = Ti sample has the highest the peak temperatures and lowest plateau pressure, which indicates that Zr and V elements are more efficient to reduce the thermodynamic stability of RE-Mg-Ni hydrogen storage alloys. Besides, the DSC curve of the M = V sample has another endothermic peak which corresponds to the decomposition reaction between VH1.9 and VH0.8, which has a contribution to desorption kinetic property for the M = V sample. The apparent activation energies (Ede) show an increasing trend in the following order: M = Zr (87.7 kJ/mol) < M = V (89.1 kJ/mol) < M = Ti (99.3 kJ/mol).