Organic Crystalline Solid Electrolytes with High Mg-Ion Conductivity Composed of Nonflammable Ionic Liquid Analogs and Mg(TFSA).

The development of solid electrolytes with Mg-ion conductivity at room temperature is an important issue to achieve all-solid magnesium batteries. We focus on organic ionic crystals with Mg-ion conduction paths in addition to nonflammable and nonvolatile features as an innovative candidate of solid electrolytes with Mg-ion conductivity. Herein, we show the development of novel organic ionic crystals, [N(CH)(CHCH)][Mg{N(SOCF)}] ( = 0 or 2), using analogs of ionic liquids, [N(CH)][N(SOCF)] (NTFSA) and [N(CH)(CHCH)][N(SOCF)] (NTFSA), and magnesium salt, Mg{N(SOCF)} (Mg(TFSA)). We also report the crystal structures of the obtained crystals and the high Mg-ion conductivity of 10 S cm under mild conditions of 80 °C in the solid state. These results indicate that organic ionic crystals with ion conduction paths have significant potential as safe solid electrolytes and provide insights into developing innovative Mg-ion conductors.