Effects of Metal Borohydrides on the Dehydrogenation Kinetics of the Li–Mg–N–H Hydrogen-Storage System

The combination of magnesium amide and lithium hydride represents a category of solid hydrogen-storage system with moderate hydrogen-storage conditions and good reversibility. At a molar ratio of 1:2 for the amide and hydride [Mg(NH2)2-2LiH], the dehydrogenation kinetics of the system can be effectively accelerated by LiBH4. In this paper, the effects of kinetic enhancement were studied by doping the amide-hydride system at 1:2 molar ratio with NaBH4 and Mg(BH4)2 along with LiBH4. Compared to the pristine system, the activation energies for the dehydrogenation were decreased by all three metal hydrides in the order of Mg(BH4)2 > LiBH4 > NaBH4. The mechanism for the kinetic improvement of Mg(BH4)2 and NaBH4 was investigated.