Hydrogen storage characteristics, kinetics and thermodynamics of Gd-Mg-Ni-based alloys

Gd5Mg95-xNix (x = 5,10,15) alloys were melted in a vacuum induction furnace, and the phase composition, microstructure and storage properties of gaseous hydrogen were investigated using scanning electron microscopy (SEM) and X-ray diffractometry (XRD). Hydrogen storage performance includes hydrogen absorption/desorption capacity, particle powder and platform pressure. The activation energy, entropy and enthalpy of the dehydrogena-tion reaction were calculated. The results show that GdMg5, Mg2Ni are the main phase and the secondary phase of the alloys respectively. After hydrogen absorption, the main phase transformation is MgH2, and the secondary phases are Mg2NiH4 and GdH3. After dehy-drogenation, the main phase transformation is Mg, and the secondary phases are Mg2Ni and GdH2. GdH3 has poor thermal stability and can be easily decomposed into GdH2. Hydrogen storage capacity gradually decreases as the nickel content increases, but the kinetic performance is significantly improved. The change in nickel content has no sig-nificant effect on the thermodynamic.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.