LiBH4 hydrogen storage system with low dehydrogenation temperature and favorable reversibility promoted by metallocene additives

LiBH4 is of great potential as hydrogen storage material due to its high theoretical hydrogen storage capacity. However, it suffers from high thermal stability, sluggish dehydrogenation/hydrogenation kinetics and poor reversibility. Introduction of catalysts is an effective way to improve the hydrogen storage properties of LiBH4. In the present study, chromocene and nickelocene are used as catalytic additives to LiBH4 by a simple ball-milling. Nickelocene is mostly decomposed, forming CNTs (carbon nanotubes) cross-linking the LiBH4 particles, while chromocene maintains stable during the ball-milling process. But they are fully decomposed to Cr and Ni nanoparticles after the initial dehydrogenation and further transferred to CrB2 and Ni2B nanoparticles after initial hydrogenation. The in situ formed CrB2 and Ni2B show superfine nanoparticles and are uniformly dispersed in the matrix, acting as highly active catalysts. The dehydrogenation temperature of the combined system is evidently reduced, and the hydrogen storage kinetics and reversibility are significantly improved. The highly thermal conductive CNTs are considered helpful in heat transfer during dehydrogenation and hydrogenation. The method for the introduction of the catalysts is facile and low cost. The present work provides a new insight into the design of novel catalysts for LiBH4.