In Situ Introduction of Li₃BO₃ and NbH Leads to Superior Cyclic Stability and Kinetics of a LiBH₄-Based Hydrogen Storage System

Abstract

LiBH4 is a high-capacity hydrogen storage material; however, it suffers from high dehydrogenation temperature and poor reversibility. To tackle those issues, we introduce a new LiBH4-based system with in situ formed superfine and well-dispersed Li3BO3 and NbH as co-reactants. Those are synthesized by the addition of niobium ethoxide [Nb­(OEt)5] to LiBH4, heat treatment of the mixture, and then hydrogenation, where Li3BO3 and NbH are generated from the reaction of Nb­(OEt)5 and LiBH4. After optimization, the system with a normalized composition of LiBH4-0.04­(Li3BO3 + NbH) in molar fraction shows superior hydrogen storage reversibility and kinetics. The initial and main dehydrogenation temperatures of the system are 200 and 90 °C lower than those of the pristine LiBH4, respectively, and 8.2 wt % H2 is released upon heating to 400 °C. A capacity of 7.2 wt % H2, corresponding to a capacity retention of 91%, is sustained after 30 cycles in an isothermal cyclic regime of dwelling at 400 °C for 60 min for dehydrogenation and dwelling at 500 °C and 50 bar H2 pressure for 20 min for hydrogenation. Such a high cyclic stability for a LiBH4-based system has never been reported to date. The in situ introduced Li3BO3 and NbH have a synergistic catalysis effect on the improvement of the hydrogen storage performance of LiBH4, showing highly effective bidirectional action on both dehydrogenation and hydrogenation.

LiAlH4 as a “Microlighter” on the Fluorographite Surface Triggering the Dehydrogenation of Mg(BH4)2: Toward More than 7 wt % Hydrogen Release below 70 °C

“…Hydrogen is a totally clean and renewable energy source. , The growing demand of finding efficient, low-cost hydrogen storage materials with high capacity has stimulated great effort in developing metal hydride composites for hydrogen storage. − Light metal borohydrides have received extensive interest due to their high gravimetric and volumetric hydrogen capacities. − Among these borohydrides, Mg­(BH 4 ) 2 exhibits the lowest dehydrogenation temperature (∼300 °C) and favorable hydrogen capacity (14.7 wt %) . However, the dehydrogenation temperature of Mg­(BH 4 ) 2 is still too high for actual use, since the covalent B–H bonds are thermodynamically stable .…”

Reaction Route Optimized LiBH4 for High Reversible Capacity Hydrogen Storage by Tunable Surface-Modified AlN

“…For the composite of LiBH 4 and surface-modified AlN, the characteristic vibrational peaks of [BO 3 ] 3– units at 746, 1265 and 1315 cm –1 are observed. , The in situ-formed Li 3 BO 3 could facilitate the decomposition and formation of [BH 4 ] − to accelerate the de/rehydrogenation of LiBH 4. , The O element on the surface-modified AlN effectively prevents LiBH 4 from forming a Li 2 B 12 H 12 intermediate. The oxidation layer on the interface of LiBH 4 could significantly reduce the desorption of diborane and modulate the dehydrogenation pathway of LiBH 4.…”

LiBH4 Nanoconfined in Porous Hollow Carbon Nanospheres with High Loading, Low Dehydrogenation Temperature, Superior Kinetics, and Favorable Reversibility

“…A custom-designed temperature-programmed desorption (TPD) instrument coupled with a mass spectrometer (HidenQIC-20, England) was used to evaluate the temperature-dependent dehydrogenation behaviors of the confined systems. Mass spectra (MS) were measured at different heating rates (1, 2, 3, 5, and 7.5 °C min –1 ) to evaluate the apparent dehydrogenation activation energies ( E a ) of the systems based on the Kissinger method where β is the heating rate, T p is the absolute temperature corresponding to the maximum desorption rate, and R is the gas constant. In this work, T p is the peak temperature of the MS curves of different heating rates.…”

“…A customdesigned temperature-programmed desorption (TPD) instrument coupled with a mass spectrometer (HidenQIC-20, England) was used to evaluate the temperature-dependent dehydrogenation behaviors of the confined systems. Mass spectra (MS) were measured at different heating rates (1, 2, 3, 5, and 7.5 °C min −1 ) to evaluate the apparent dehydrogenation activation energies (E a ) of the systems based on the Kissinger method59…”