A fleeting glimpse of the dual roles of SiB4 in promoting the hydrogen storage performance of LiBH4

Abstract

In this study, the positive effects and dual roles of SiB₄ on the dehydrogenation and rehydrogenation performance of the LiBH₄–SiB₄ system are reported. Characterizations were performed through temperature programmed desorption mass spectrometry (TPD-MS), isothermal kinetics measurements, and XRD and FTIR analyses. For the hydrogen desorption from LiBH₄, SiB₄ played the role of a catalyst to kinetically facilitate the structural destabilization of LiBH₄ and its intermediate phase Li₂B₁₂H₁₂. Accordingly, a dehydrogenation capacity of 2.24 at. H/f.u. LiBH₄ (close to 10.3 wt% H) was attained at a relative temperature of 350 °C. For hydrogen absorption to generate LiBH₄, SiB₄ was unexpectedly found to act as a reactant to thermodynamically improve the rehydrogenation process by reacting with LiH under moderate conditions of 10 MPa H₂ and 400 °C, and a superior reversible capacity of 2.16 at. H/f.u. LiBH₄ was achieved. These experimental results remind us to take into account the explicit role(s) of the employed components during the dehydrogenation and rehydrogenation reactions when designing a desirable LiBH₄-based system.