Synthesis and hydrogen storage properties of lithium borohydride amidoborane complex

A series of mixtures of LiAB/LiBH4 with different molar ratios were prepared and their hydrogen storage properties were investigated in this study. Among them, a new structure was found in the LiAB/LiBH4 sample with a molar ratio of 1/1. It is of orthorhombic structure and composed of alternative layers of LiAB and LiBH4. It shows similar hydrogen desorption behaviors of LiAB–LiBH4 and LiAB–0.5LiBH4. For use in hydrogen storage, high hydrogen capacity and low operation temperature are demanded, thus, the dehydrogenation properties of LiAB–0.5LiBH4 were subsequently measured. Three steps of desorption were observed during the heating process, with a total release of 11.5 wt% H2 at 500 °C. The reaction path was identified using a combined investigation of XRD and 11B solid state NMR. Dehydrogenation kinetic analyses show that the complex has lower activation energy (61 ± 4 kJ mol−1 H2) than that of LiAB (71 ± 5 kJ mol−1 H2). It is likely that dehydrogenation process was promoted due to the presence of LiBH4.