First principles screening of destabilized metal hydrides for high capacity H2 storage using scandium

Favorable thermodynamics are a prerequisite for practical H-2 storage materials for vehicular applications. Destabilization of metal hydrides is a versatile route to finding materials that reversibly store large quantities of H-2. First principles calculations have proven to be a useful tool for screening large numbers of potential destabilization reactions when tabulated thermodynamic data are unavailable. We have used first principles calculations to screen potential destabilization schemes that involve Sc-containing compounds. Our calculations use a two-stage strategy in which reactions are initially assessed based on their reaction enthalpy alone, followed by more detailed free energy calculations for promising reactions. Our calculations indicate that mixtures of ScH2 + 2LiBH(4), which will release 8.9 wt.% H-2 at completion and will have an equilibrium pressure of 1 bar at around 330 K, making this compound a promising target for experimental study. Along with thermodynamics, favorable kinetics are also of enormous importance for practical usage of these materials. Experiments would help identify possible kinetic barriers and modify them by developing suitable catalysts. (C) 2006 Elsevier B.V. All rights reserved.