Mg3(BH4)4(NH2)2as Inorganic Solid Electrolyte with High Mg2+Ionic Conductivity

Abstract

Mg3(BH4)4(NH2)2 compound was synthesized through the investigation of the Mg(BH4)2-Mg(NH2)2 phase diagram; its crystal structure was solved in a tetragonal unit cell with the space group I4¯. Interestingly, Mg3(BH4)4(NH2)2 has a high thermal stability with a decomposition temperature above 190 °C and exhibits a high Mg2+ ionic conductivity of 4.1 × 10-5 S·cm-1 at 100 °C with a low activation energy (0.84 eV). The reversible Mg deposition/stripping was demonstrated at 100 °C when using Mg3(BH4)4(NH2)2 as solid electrolyte. Thus, Mg3(BH4)4(NH2)2 is a compound that could help to develop rechargeable Mg-ion solid-state batteries.