Complex Borohydride for Reversible Hydrogen Storage

Materials that are light weight, low cost and have high hydrogen storage capacity are essential for on-board vehicular applications.  Some reversible complex hydrides are alanates and amides but have low reversible capacity which is inadequate for onboard application.  High capacity, light weight, reversibility and fast kinetics at lower temperature are the primary desirable aspects for any type of hydrogen storage material.  Borohydride complexes as hydrogen storage materials have recently attracted great interest.  Understanding the above parameters for designing efficient complex borohydride materials requires modeling across different length and time scale.  In this study, a density functional theory study is performed to find the hydrogen storage properties for the reversible complex borohydride material (LiNH₂)₂ - LiBH₄ - (MgH₂) system.  The structural stability of the reactants and products involved in the reaction steps are confirmed and thermodynamic properties such as enthalpy of reactions and Gibbs energy are also calculated of these reactions.  These theoretically predicted reaction steps compare well with the experimental proposed reaction pathways.  Hydrogen storage capacity predicted for this complex borohydride will also be presented from the de-sorption behavior observed at different temperatures.