Electronic structure and decomposition pathways of monoammoniate of lithium borohydride (Li(NH_3)BH_4): A first-principles investigation

摘要

The monoammoniate of lithium borohydride (Li(NH_3)BH_4) is a potential candidate for hydrogen storage owing to its high hydrogen capacity (18 wt). In this work, electronic structure, bonding characters, and decomposition pathways of Li(NH_3)BH_4 are investigated from first-principles calculations. We find that NH_3 molecules are covalently attached to Li atoms through N atoms and the ionization of Li atoms plays an essential role in stabilizing the compound. A general correlation between the stability of X(NH_3)BH_4 (X=H,Li,Na,K) and the electronegativities of X atoms is established. The thermal stability of X(NH_3)BH_4 could be modulated by manipulating the cation electronegativities. Free energy computations indicate that Li(NH _3)BH_4→LiBH_4+NH_3 is the most likely thermal decomposition route.