In-situ introduction of highly active TiO for enhancing hydrogen storage performance of LiBH4

LiBH4 is a promising candidate for solid state hydrogen storage, however, it still suffers from high hydrogen desorption temperature, harsh hydrogen absorption conditions, and poor reversibility, which hinder its practical development. In this paper, a novel synthetic strategy of heat treating a LiBH4 and Ti(OEt)4 mixture is employed to prepare LiBH4 system with TiO in-situ introduced. With an optimized TiO content of 0.06 in molar fraction, the LiBH4-0.06TiO system shows onset and peak dehydrogenation temperatures of 240 °C and 340 °C, respectively, which are 140 °C and 90 °C lower than those of the pure LiBH4. The LiBH4-0.06TiO system can rapidly release 9 wt% H2 after dwelling at 400 °C for 10 min. The hydrogenation of the dehydrogenation product initiates at 150 °C, and a capacity of 9 wt% is reached after isothermal dwelling at 500 °C under 50 bar of H2 for 100 min. The capacity retention of the system can reach 74.4% after 10 cycles, indicating a favorable reversibility. With the introduction of TiO, the apparent dehydrogenation activation energy of the system is evidently reduced, and the formation of Li2B12H12, a highly thermal stable intermediate phase, is greatly suppressed. In addition, the aggregation is evidently alleviated. All of these contribute to the enhanced dehydrogenation kinetics and reversibility. TiO reacts with LiBH4, forming Li3BO3 and TiH2 after the initial dehydrogenation, which play significant catalytic effect to LiBH4.