Enhanced kinetics for the LiBH_4:MgH_2 multi-component hydrogen storage system - The effects of stoichiometry and decomposition environment on cycling behaviour

摘要

In situ neutron diffraction was undertaken on stoichiometric 2LiBD_4 : MgD_2 and non-stoichiometric 0.3LiBD_4:MgD_2 with both ratios decomposed under 1 bar deuterium and under dynamic vacuum. The subsequent cycling behaviour under 100 bar D_2 at 400 ℃ 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 10min. This compares to only 60% deuteriding for the 2:1 sample after 4h 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.