A Combined Hydrogen Storage System of Mg(BH₄)₂−LiNH₂with Favorable Dehydrogenation

The decomposition properties of Mg(BH 4 ) 2 −LiNH 2 mixtures were investigated. Apparent NH 3 release appeared from 50 to 300 °C for the Mg(BH 4 ) 2 −LiNH 2 mixtures with mole ratios of 1:1.5, 1:2, and 1:3, while only hydrogen release was detected for the mixture with a mole ratio of 1:1. In the case of the Mg(BH 4 ) 2 −LiNH 2 (1:1) sample, the onset of the first-step dehydrogenation starts at 160 °C, with a weight loss of 7.2 wt % at ∼300 °C, which is improved significantly compared to the pure Mg(BH 4 ) 2 alone. From Kissinger’s method, the activation energy, E a, for the first and second step dehydrogenation in Mg(BH 4 ) 2 −LiNH 2 (1:1) was estimated to be about 121.7 and 236.6 kJ mol −1, respectively. The improved dehydrogenation in the combined system may be ascribed to a combination reaction between [BH 4 ] and [NH 2 ], resulting in the formation of Li−Mg alloy and amorphous B−N compound.