Hydrogen storage properties of mechanically alloyed Mg-8 mol% LaNi0.5 composite

摘要

A new nano-ternary Mg-8 mol% LaNi0.5 was prepared by melted and subsequent mechanical alloying technique for hydrogen storage. It was found from our experiments that, this kind of alloy had superior hydriding/dehydriding characteristics in comparison with conventional materials for hydrogen storage. It possessed large hydrogen capacity at a lower temperature, which could absorb 4.55-7.01 mass% H under 3 MPa hydrogen pressure and desorb 4.40-6.90 mass% H under 0.0133 MPa in 600 s above 423 K without any activation requirement drawn from our pressure-composition isotherm and kinetic experiments. Through the x-ray diffraction and transmission electron microscopy experiments, we further found that these superior characteristics could be attributed to the multiphase structure and a catalytic effect of LaH3 and Mg2Ni that were formed in the material preparation of mechanical alloying process. Finally, based on these data the relationships between equilibrium pressure of hydrogen and temperature were obtained, they were Igp(0.1 MPa) = -3985/T + 7.188(553 K less than or equal to T less than or equal to 573K) for hydriding and Igp(0.1 MPa) = -3804/T + 6.770 (553 K less than or equal to T less than or equal to 573 K) for dehydriding.