Reversible De/hydriding Reactions between Two New Mg–In–Ni Compounds with Improved Thermodynamics and Kinetics

Abstract

Magnesium-based alloys show great potential for hydrogen storage because of their high capacity, excellent reversibility, and low cost. However, the sluggish hydrogen sorption kinetics and overhigh dehydrogenation temperature hinder their practical application. In this paper, we present the reversible de/hydriding reaction mechanism of two new Mg–In–Ni ternary intermetallic compounds, which shows improved thermodynamics and kinetics in comparison with pure Mg. These two new phases correspond to Mg2InNi and Mg14In3Ni3 stoichiometries, both with orthorhombic structure, as determined by combinational X-ray diffraction and electron diffraction tomography analysis. In the hydriding process, the Mg14In3Ni3 alloy decomposes into a mixture of MgH2 and Mg2InNi, which is fully reversible in the dehydrogenation with hydrogen storage capacity of 1.8 wt %. For the dehydriding of MgH2 and Mg2InNi, a decrease of the reaction enthalpy (70.1 kJ mol–1 H2) is obtained compared with pure MgH2 (72.2 kJ mol–1 H2), and the dehy...