Mg<sub>3</sub>(BH<sub>4</sub>)<sub>4</sub>(NH<sub>2</sub>)<sub>2</sub> as Inorganic Solid Electrolyte with High Mg<sup>2+</sup> Ionic Conductivity
Ronan Le Ruyet, Benoît Fleutot, Romain Berthelot, Yasmine Benabed, Geoffroy Hautier, Yaroslav Filinchuk, Raphaël Janot
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 I4̅. 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.