The enhanced hydrogen storage performance of (Mg-B-N-H)-doped Mg(NH2)-2LiH system

Doping Mg(NH2)2-2LiH by Mg2(BH4)2(NH2)2 compound exhibits enhanced hydrogen de/re-hydrogenation performance. The peak width in temperature-programmed desorption (TPD) profile for the Mg(NH2)2-2LiH-0.1Mg2(BH4)2(NH2)2 was remarkably shrunk by 60 °C from that of pristine Mg(NH2)2-2LiH, and the peak temperature was lowered by 12 °C from the latter. Its isothermal dehydrogenation rate was greatly improved by five times from the latter at 200 °C. XRD, FTIR and NMR analyses revealed that a series of reactions occurred in the dehydrogenation of the composite. The prior interaction between LiH and Mg-B-N-H yielded intermediate LiBH4, which subsequently reacted with Mg(NH2)2 and LiH in molar ratio of 1:6:9 to form Li2Mg2(NH)3 and Li4BN3H10 phases. The observed 6Mg(NH2)2-9LiH-LiBH4 combination dominated the hydrogen release and soak in the composite system, and enhanced the kinetics of the system.