Effect of gas back pressure on hydrogen storage properties and crystal structures of Li2Mg(NH)2.

The ternary imide Li 2 Mg(NH) 2 is considered to be one of the most promising on-board hydrogen storage materials due to its high reversible hydrogen capacity of 5.86 wt%, favorable thermodynamic properties and good cycling stability. In this work, Li 2 Mg(NH) 2 was synthesized by dynamically dehydrogenating a mixture of Mg(NH 2 ) 2 –2LiH up to 280 °C under different gas (Ar and H 2 ) and pressures (0–9.0 bar). The crystal structure of Li 2 Mg(NH) 2 was found to depend on the gas back pressure in the dehydrogenation process. The crystal structure of Li 2 Mg(NH) 2 and the dehydrogenation/rehydrogenation properties of the Mg(NH 2 ) 2 –2LiH system strongly depend on the gas back pressure in the dehydrogenation process due to the effect of the pressure on the dehydrogenation kinetics. This study provides a new approach for improving the hydrogen storage properties of the amide–hydride systems. [ABSTRACT FROM AUTHOR]