Hydrogen storage in a Li–Al–N ternary system

Abstract

Abstract Hydrogen-storage properties and mechanisms of a novel Li–Al–N ternary system were systematically investigated by a series of performance evaluation and structural examinations. It is found that ca. 5.2 wt% of hydrogen is reversibly stored in a Li 3 N–AlN (1:1) system, and the hydrogenated product is composed of LiNH 2 , LiH, and AlN. A stepwise reaction is ascertained for the dehydrogenation of the hydrogenated Li 3 N–AlN sample, and AlN is found reacting only in the second step to form the final product Li 3 AlN 2 . The calculation of the reaction enthalpy change indicates that the two-step dehydrogenation reaction is more thermodynamically favorable than any one-step reaction. Further investigations exhibit that the presence of AlN in the LiNH 2 –2LiH system enhances the kinetics of its first-step dehydrogenation with a 10% reduction in the activation energy due likely to the higher diffusivity of lithium and hydrogen within AlN.