Carbon Support Effects on the Hydrogen Storage Properties of LiBH4 Nanoparticles: A First-Principles Study

LiBH4 nanoparticles confined in nanoporous carbon materials show improved hydrogen storage properties. Using density functional theory calculations, we study how the thermodynamics of the decomposition reactions of LiBH4 nanoparticles is affected by the chemical interactions between the reactant or products and the nanoporous carbon host. We find that the reversible intercalation of Li as one of the reaction products into the graphitic carbon host has a large effect on the reaction enthalpies of small clusters. Explicit calculations show that small (LiBH4)(n), n less than or similar to 12, clusters decompose at much lower temperatures in the presence of graphite, leading to the formation of intercalated Li. This route becomes unfavorable for larger (LiBH4)(n) clusters, where dehydrogenation leads to the formation of (LiH)(n) clusters.