A Self-Binding, Melt-Castable, Crystalline Organic Electrolyte for Sodium Ion Conduction.

The preparation and characterization of the cocrystalline solid-organic sodium ion electrolyte NaClO4 (DMF)3 (DMF=dimethylformamide) is described. The crystal structure of NaClO4 (DMF)3 reveals parallel channels of Na+ and ClO4- ions. Pressed pellets of microcrystalline NaClO4 (DMF)3 exhibit a conductivity of 3×10-4  S cm-1 at room temperature with a low activation barrier to conduction of 25 kJ mol-1 . SEM revealed thin liquid interfacial contacts between crystalline grains, which promote conductivity. The material melts gradually between 55-65 °C, but does not decompose, and upon cooling, it resolidifies as solid NaClO4 (DMF)3 , permitting melt casting of the electrolyte into thin films and the fabrication of cells in the liquid state and ensuring penetration of the electrolyte between the electrode active particles.