Phase Transformation and Hydrogen Storage Properties of an La7.0Mg75.5Ni17.5 Hydrogen Storage Alloy

Abstract

X-ray diffraction showed that an La 7.0 Mg 75.5 Ni 17.5 alloy prepared via inductive melting was composed of an La 2 Mg 17 phase, an LaMg 2 Ni phase, and an Mg 2 Ni phase. After the first hydrogen absorption/desorption process, the phases of the alloy turned into an La-H phase, an Mg phase, and an Mg 2 Ni phase. The enthalpy and entropy derived from the van't Hoff equation for hydriding were −42.30 kJ·mol −1 and −69.76 J·K −1 ·mol −1 , respectively. The hydride formed in the absorption step was less stable than MgH 2 (−74.50 kJ·mol −1 and −132.3 J·K −1 ·mol −1 ) and Mg 2 NiH 4 (−64.50 kJ·mol −1 and −123.1 J·K −1 ·mol −1 ). Differential thermal analysis showed that the initial hydrogen desorption temperature of its hydride was 531 K. Compared to Mg and Mg 2 Ni, La 7.0 Mg 75.5 Ni 17.5 is a promising hydrogen storage material that demonstrates fast adsorption/desorption kinetics as a result of the formation of an La-H compound and the synergetic effect of multiphase.

Properties of Ti-Based Hydrogen Storage Alloy

“…As shown in Figure 1, after years of research, various of solid hydrogen storage materials have been researched, including metal alloys [8] [9] [10], chemical Figure 1. Overview of some MH with their volumetric and gravimetric H-density [17].…”

Crystal Dislocations: Their Impact on Physical Properties of Crystals

“…The importance of dislocations on phase transformation was examined by Hu et al [10], in which they studied phase transformation and hydrogen storage properties of an La 7.0 Mg 75.5 Ni 17.5 hydrogen storage alloy. Differential thermal analysis showed that the initial hydrogen desorption temperature of its hydride was 531 K and, compared to Mg and Mg 2 Ni, La 7.0 Mg 75.5 Ni 17.5 was found to be a promising hydrogen storage material that demonstrates fast adsorption/desorption kinetics as a result of the formation of an La − H compound.…”