Dynamical stabilization and H-vacancy diffusion kinetics of lightweight complex hydrides: Ab initio study for hydrogen storage improvement

Abstract

We present structural stability of new lightweight complex hydrides: Li2BeMgH6, LiNaMg2H6, and LiNaBeMgH6, which correlated to the LiMgH3 (R3c) phase. Lattice dynamic stability, mechanical stability, electronic structure, and hydrogen vacancy mechanism are investigated using ab initio calculation. Remarkably, calculation results show the enhancement of the internal mechanism for hydrogen storage in the lightweight complex hydrides. The stable phase (R3) of the new complex hydrides exhibits high gravimetric density and low heat capacity. The Li2BeMgH6 in the R3 phase systematically indicates the remarkable improvement of the hydrogen storage mechanism compared with the LiMgH3-based system.