Functionalized Boranes for Hydrogen Storage

Using density functional theory, the generalized gradient approximation for the exchange-correlation potential and Møller–Plesset 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.