Hydrogen storage properties of LiBH4 destabilized by SrH2

In this work, we have succeeded in destabilizing LiBH4 by the addition of SrH2, via the reaction 6LiBH4 + SrH2 → SrB6 + 6LiH + 10H2 with a theoretical hydrogen capacity of 9.1 wt.%. According to the van’t Hoff and Arrhenius equations, the dehydrogenation enthalpy change and activation energy for the LiBH4/SrH2 system were experimentally determined to be 48 kJ/mol H2 and 64 kJ/mol, respectively. Both are remarkably reduced in comparison with the pristine LiBH4, which is responsible for the improved dehydrogenation property of the LiBH4/SrH2 system. The dehydrogenated products SrB6 + 6LiH can be rehydrogenated to form LiBH4 and LiSrH3 at 723 K under an initial hydrogen pressure of 8.0 MPa.

► Thermal stability of LiBH4 can be remarkably reduced by the addition of SrH2. ► Dehydrogenation enthalpy change for the LiBH4/SrH2 system is 48 kJ/mol H2. ► Dehydrogenation process of the LiBH4/SrH2 system is rate-limited by a three-dimension phase boundary mechanism. ► LiBH4 can be regenerated upon rehydrogenation at 723 K under an initial hydrogen pressure of 8.0 MPa.