Microstructural evolution and improved hydrogen storage properties for the Li 3 N–MgH 2 system by addition of LiNH 2 during the hydrogenation/dehydrogenation

Abstract The Li–Mg–N–H system consists of lightweight materials with high hydrogen capacity and thus it is of interest for hydrogen storage application. In this work, different amount of LiNH 2 in the Li 3 N–MgH 2 (1:1) system was added to enhance the hydrogen storage properties. The mixtures of LiMgN, LiH and LiNH 2 were obtained after ball milling of Li 3 N–MgH 2 -xLiNH 2 (x = 0, 0.13, 1 and 2 mol). The addition of LiNH 2 results in the microstructural change of dispersion of the particles with the refined grains, shortening of the diffusion distance of hydrogen. The hydrogen absorption/desorption capacities of all samples were greatly improved by the addition of LiNH 2 . The hydrogen storage capacity was improved from 3.2 wt% to approximately 5.1 wt% at 250 °C by the addition of LiNH 2 from 0 to 2 mol. The microstructural evolution and hydrogen storage mechanisms during the hydrogenation/dehydrogenation process for the Li 3 N–MgH 2 –2LiNH 2 sample are discussed.