Single-pot solvothermal strategy toward support-free nanostructured LiBH4 featuring 12 wt% reversible hydrogen storage at 400 °C

Abstract

Lithium borohydride (LiBH4) exhibits poor hydrogen storage reversibility because of phase separation between LiH and B due to foaming during thermal dehydrogenation. Herein, we report that by synthesizing nanostructured LiBH4 without any supports, the foaming and phase separation can be effectively suppressed, and consequently, the hydrogen storage reversibility of LiBH4 can be considerably improved. Using a facile single-pot solvothermal approach, a hierarchical porous nanostructured LiBH4 composed of 50–60 nm-sized primary nanoparticles is synthesized. The resulting neat nano-LiBH4 reversibly desorbs and absorbs approximately 12 wt% of H at 400 °C and under 100 bar H2. The superior hydrogen storage performance is attributed to the effective inhibition of foaming upon heating. The formation of LiH and B prior to melting, which can be associated with the largely reduced particle sizes and porous agglomeration structure, plays a crucial role in suppressing foaming. Our findings offer a new strategy for the preparation of nanoscaled freestanding borohydrides, and also important insights into the development of highly reversible metal borohydrides for hydrogen storage applications.