Hydrogen storage properties of equiatomic Li–Mg alloy with and without additives

In this study, the hydrogen storage properties of an equiatomic body-centered cubic Li–Mg alloy with and without additives are investigated. The Li–Mg alloy without additives absorbs 0.4 wt% of H 2 (H/M = 0.067) in 4 h at 200 °C under 1.0 MPa. Among the additives (Nb, NbF 5 , Nb 2 O 5 , Ni, and Pd), only NbF 5 enhances the hydrogen absorption kinetics of the Li–Mg alloy, resulting in 1.9 wt% of H 2 (H/M = 0.31) in 4 h, which is 4.6 times that of the Li–Mg alloy without additives. The XPS measurements indicated that NbF 5 was reduced to an intermediate valence state between +4 and + 5 by ball milling with Li–Mg alloy. The catalytic mechanism of NbF 5 in the Li–Mg alloy is likely similar to that observed in Mg, where the interactions between the d-electrons in the additives and the antibonding electrons of hydrogen molecules facilitate hydrogen dissociation on the Mg surface. • NbF 5 additive drastically enhances the hydrogen absorption kinetics of the Li–Mg alloy. • Li–Mg alloy with NbF 5 absorb 1.9 wt % hydrogen in 4 h, which is 4.6 times that of Li–Mg alloy without additives. • The catalytic mechanism of NbF 5 in the Li–Mg alloy is likely similar to that in Mg alloys.