Discovery of novel hydrogen storage materials: an atomic scale computationalapproach

Abstract

Practical hydrogen storage for mobile applications requires materials that exhibit highhydrogen densities, low decomposition temperatures, and fast kinetics for absorption anddesorption. Unfortunately, no reversible materials are currently known that possess all ofthese attributes. Here we present an overview of our recent efforts aimed at developing afirst-principles computational approach to the discovery of novel hydrogen storagematerials. Such an approach requires several key capabilities to be effective: (i) accurateprediction of decomposition thermodynamics, (ii) prediction of crystal structures forunknown hydrides, and (iii) prediction of preferred decomposition pathways. Wepresent examples that illustrate each of these three capabilities: (i) prediction ofhydriding enthalpies and free energies across a wide range of hydride materials,(ii) prediction of low energy crystal structures for complex hydrides (such asCa(AlH4)2 CaAlH5,and Li2NH), and (iii) predicted decomposition pathways forLi4BN3H10 and destabilized systems based on combinations ofLiBH4,Ca(BH4)2 and metal hydrides. For the destabilized systems, we propose a set of thermodynamicguidelines to help identify thermodynamically viable reactions. These capabilities have ledto the prediction of several novel high density hydrogen storage materials and reactions.