Enhancement of hydrogen storage properties of Li12+xMg3-xSi4-ySny (x=y=0.48) phase by modification with LixZnO/La2O3-CNT composites

Abstract Two kinds of LixZnO-CNT and La2O3-CNT composite additives (CA) are employed to improve the hydrogen absorption/desorption processes of Li12+xMg3-xSi4-ySny phase. The effect of the addition of composite additives on the improvement of hydrogen sorption kinetics of intermetallic phase is due to the following factors: CA are more stable than Li contain intermetallic; CA provides diffusion pathways to most of the grains inside the material, where the dissociation of H2 molecules into H atoms takes place; CA surface has a relatively higher reactivity to H2 dissociation. The substituted (Si atoms by Sn) and doped by La2O3-CNT composite Li12+xMg3-xSi4-ySny alloy have the highest uptake and release capability (9.8 wt%). LixZnO-CNT give 9.3 wt% hydrogen uptake and release, which are still much better than undoped Li12+xMg3-xSi4-ySny (8.9 wt%). Li12+xMg3-xSi4-ySny is a maximally disordered intermetallic phase (MD-IP) with a cubic structure (I-43d, a = 10.7409(8) A) related to Cu15Si4-type.