Computational Discovery of Novel Hydrogen Storage Materials and Reactions

Practical hydrogen storage for mobile applications requires materials that exhibit high hydrogen densities, low decomposition temperatures, and fast kinetics for absorption and desorption. Unfortunately, no reversible materials are currently known that possess all of these attributes. Here we present an overview of our recent efforts aimed at developing a first-principles computational approach to the discovery of novel hydrogen storage materials. We have developed computational tools which enable accurate prediction of decomposition thermodynamics, crystal structures for unknown hydrides, and thermodynamically preferred decomposition pathways. We present examples that illustrate each of these three capabilities. Specifically, we focus on recent work on crystal structure and dehydriding reactions of borohydride materials, such as Mg(BH$_4$)$_2$, MgB$_{12}$H$_{12}$, and mixtures of complex hydrides such as the ternary LiBH$_4$/LiNH$_2$/MgH$_2$ system.\\ \\ {\textbf References:}\\[0pt] (1) V. Ozolins, E. H. Majzoub, and C. Wolverton, ``First-Principles Prediction of a Ground State Crystal Structure of Magnesium Borohydride'', Phys. Rev. Lett. {\textbf 100}, 135501 (2008).\\ (2) C. Wolverton, D. J. Siegel, A. R. Akbarzadeh, and V. Ozolins, ``Discovery of Novel Hydrogen Storage Materials: An Atomic Scale Computational Approach'', J. Phys. Condens. Matt. {\textbf 20}, 064228 (2008).\\ (3) J. Yang, et al., ``A Self-Catalyzing Hydrogen Storage Material'' Angew. Chem. Int. Ed., {\textbf 47}, 882 (2008).\\ (4) A. R. Akbarzadeh, V. Ozolins, and C. Wolverton, ``First-Principles Determination of Multicomponent Hydride Phase Diagrams: Application to the Li-Mg-N-H System'', Advanced Materials {\textbf 19}, 3233 (2007).\\ (5) D. J. Siegel, C. Wolverton, and V. Ozolins, ``Thermodynamic Guidelines for the Prediction of Hydrogen Storage Reactions and their Application to Destabilized Hydride Mixtures'', Phys. Rev. B {\textbf 76}, 134102 (2007).