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 LiB 6H 7, LiB 12H 13, Li 2B 6H 6, Li 2B 12H 12, MgB 6H 6, and MgB 12H 12. Up to three H 2 molecules can be bound quasi-molecularly to each of the metal cations with binding energies per H 2 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. Li- and Mg-functionalized boranes (see picture) are promising materials for hydrogen storage. They can store up to 12 wt % hydrogen with a desorption energy of 0.07 eV-0.27 eV per H 2 molecule. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.