Effect of Y partially substituting La on the phase structure and hydrogen storage property of La–Mg–Ni alloys

Abstract

Hydrogen is one of the most promising ideal energy vectors for solving the current environmental pollution and energy crisis. Safe and efficient hydrogen storage and transportation technology is a key to the commercial application of hydrogen energy. Mg-based alloys have high hydrogen storage capacity, but the slow rates for absorbing and desorbing hydrogen limit their application. To improve the hydriding and dehydriding thermodynamics and kinetics of La2Mg17-type alloys, Y was selected to partially replace La in this study, and La2-xYxMg16Ni (x = 0, 0.1, 0.2, 0.3, 0.4) alloys were made through vacuum induction melting. Through the characterization and hydriding and dehydriding performance testing of the alloys, it was found that replacing La with Y does not create any new phases, but it refines the structure of alloys significantly. The hydrogen storage capacity of all experimental alloys changes a little after adding Y. The substitution of Y for La ameliorates the de-/hydriding kinetics of the alloys obviously. The dehydriding activation energies of La2-xYxMg16Ni (x = 0–0.4) alloys are 84.5, 80.8, 78.2, 77.4 and 77.2 kJ/mol respectively, which is thought to be the reason for the accelerated dehydriding rate with increasing Y content. The absolute value of ΔH decreases a little after adding Y.