Dehydrogenation Thermodynamics of Hydrogen Storage Material Manganese Borohydride: First-Principles Study

Ab initio calculations using DFT were performed to establish a stable crystal structure of Mn(BH4)2. The crystal structure of Mn(BH4)2 is found to be orthorhombic with space group Fddd (No. 70). The electronic density of states shows that manganese borohydride is of metallic nature without a band gap. Our calculations showed that the interaction between Mn atoms and BH4 complexes has an ionic character while the internal bonding of BH4 is essentially covalent. The reaction enthalpy was also found for the reaction Mn(BH4)2 = Mn + 2B + 4H2(g) to be 135.026 kJ/f.u. at 0 K including zero point energy (ZPE) corrections.