Effect of LiBH4 on hydrogen storage property of MgH2

The effect of lithium borohydride (LiBH4) on the hydriding/dehydriding kinetics and thermodynamics of magnesium hydride (MgH2) was investigated. It was found that LiBH4 played both positive and negative effects on the hydrogen sorption of MgH2. With 10 mol.% LiBH4 content, MgH2-10 mol.% LiBH4 had superior hydrogen absorption/desorption properties, which could absorb 6.8 wt.% H within 1300 s at 200 °C under 3 MPa H2 and completed desorption within 740 s at 350 °C. However, with the increasing amount of LiBH4, the hydrogenation/dehydrogenation kinetics deteriorated, and the starting desorption temperature increased and the hysteresis of the pressure-composition isotherm (PCI) became larger. Our results showed that the positive effect of LiBH4 was mainly attributed to the more uniform powder mixture with smaller particle size, while the negative effect of LiBH4 might be caused by the H-H exchange between LiBH4 and MgH2.