Structure, thermal analysis and dehydriding kinetic properties of Na1−xLixMgH3 hydrides

•NaMgH3 and Li0.5Na0.5MgH3 have been synthesized by ball milling.•Two decomposition steps have been detected for NaMgH3.•In comparison with NaMgH3, Li0.5Na0.5MgH3 hydride has better kinetic properties.•As for LiMgH3, LiH is a good catalyst for the dehydrogenation process.

NaMgH3 hydride with perovskite structure has been synthesized by high-energy ball milling, the maximum hydrogen-desorbed amount of which is 3.42 wt.% at 638 K. Two decomposition steps have been detected for perovskite-type NaMgH3 hydride, calculated values of activation energy for the two steps are 180.25 ± 8.25 kJ/mol and 156.23 ± 18.54 kJ/mol by Kissinger method. In comparison with NaMgH3 hydride, Li0.5Na0.5MgH3 hydride has better dehydriding kinetic properties and higher hydrogen-desorbed amount (4.11 wt.%) due to partial replacement of Na by Li. LiMgH3 hydride with perovskite structure cannot be synthesized by milling of the mixture of LiH and MgH2 hydrides. However, the maximum hydrogen-desorbed amount of this milled mixture is 5.54 wt.% at 638 K, this may suggest that LiH is a good catalyst for dehydrogenation of MgH2, but further research is needed.