Kinetic enhancement of LiBH4-MgH2 composite by pre-milled MWCNTs observed by in situ X-ray diffraction measurements

LiBH4-MgH2 composite is one of the most promising solid-state hydrogen storage materials because it exhibits good reversibility as well as lower total reaction enthalpy. Nevertheless, its utilization for onboard hydrogen storage is hindered by poor reaction kinetics. In order to improve the kinetics, pre-milled multi-walled carbon nanotubes (MWCNTs) were added to LiBH4-MgH2 composite. Thereafter, we measured in situ X-ray diffraction patterns of LiBH4-MgH2 and LiBH4-MgH2-MWCNTs composites at various temperatures to study the decomposition process. The pre-milled MWCNTs played an effective role in reducing the MgH2 and LiBH4 dehydrogenation temperatures. In addition, MgH2 grain growth was inhibited by the formation of Mg in both the samples, and the inhibition started at a temperature lower by ∼50 °C in the composite with MWCNTs compared with the LiBH4-MgH2 composite.