Enhanced kinetics for the LiBH4:MgH2 multi-component hydrogen storage system – The effects of stoichiometry and decomposition environment on cycling behaviour

In situ neutron diffraction was undertaken on stoichiometric 2LiBD4 : MgD2 and non-stoichiometric 0.3LiBD4:MgD2 with both ratios decomposed under 1 bar deuterium and under dynamic vacuum. The subsequent cycling behaviour under 100 bar D2 at 400 °C was investigated in situ. Analysis of the uptake through formation of deuterided products showed fast kinetics for the magnesium rich system, 0.3:1, with 90% deuteriding occurring within 10 min. This compares to only 60% deuteriding for the 2:1 sample after 4 h under similar conditions. These results demonstrate the strong influence of stoichiometry in the cycling kinetics compared to decomposition conditions, although the later determines the phase progression.