LiAl-substitution into the MgH 2 structure may improve the hydrogen storage processes

Abstract

When Li,Al is coupled-substituted into the MgH 2 structure to assume the composition of LiAlMg 10H 24, the resulted structure was found to retain that of the parent material but assumes substantial differences in bonding and associated properties. Density functional theory (DFT) method was used in deriving the stable structure, computing the thermochemical parameters and evaluating the reaction/activation energies of dehydriding. The stability of the optimized LiAl-substituted structure was verified through the lattice dynamics calculations of the density functional perturbation theory (DFPT) method. The coupled substitution weakens the H-metal bonds that results in reductions in the reaction energy and potentially the activation barriers of dehydriding of the materials.