Functionalized Boranes for Hydrogen Storage

Using density functional theory, the generalized gradient approximation for the exchange-correlation potential and MollerPlesset perturbation theory we study the hydrogen uptake of Li- and Mg-doped boranes. Specifically, we calculate the structures and binding energies of hydrogen molecules sequentially attached to LiB6H7, LiB12H13, Li2B6H6, Li2B12H12, MgB6H6, and MgB12H12. Up to three H2 molecules can be bound quasi-molecularly to each of the metal cations with binding energies per H2 molecule ranging between 0.07 eV and 0.27 eV. The corresponding gravimetric densities lie in the range of 3.49 to 12 wt %, not counting the H atoms bound chemically to the B atoms.