Reversible Hydrogen Storage Composite Based on 6LiBH4 + CaF2

In this work, we report a new reversible hydrogen storage composite based on 6LiBH4+CaF2. It has a theoretical hydrogen capacity of 9.6 wt % (0.09 g·ml−1) and a slightly reduced thermodynamic stability compared with pure LiBH4. The dehydrogenation of 6LiBH4 + CaF2 yielded CaB6 and a solid solution of LiH and LiF that can be rehydrogenated to form LiBH4 and CaF2. The composite revealed good reversibility of hydrogen storage regardless of the hydrogen back pressure applied during the dehydrogenation. Catalysts like TiF3, CeF3, and NbCl5 were found to enhance its dehydriding kinetics. XRD and FT-IR analyses revealed that hydrogen uptake of the composite proceeded through a reaction path involving CaH2 as the main intermediate.