A sodium bis(perfluoropinacol) borate-based electrolyte for stable, high-performance room temperature sodium-sulfur batteries based on sulfurized poly(acrylonitrile)

Abstract

Sodium bis(perfluoropinacol)borate, NaB[O2C2(CF3)4]2 (Na-PPB), as part of the electrolyte is introduced to room temperature (RT) sodium-sulfur batteries based on a sulfurized poly(acrylonitrile) (Na-SPAN) cathode. Na-PPB was stable under atmospheric conditions for 20 days and showed no sign of degradation. Na-SPAN full cells based on a Na-PPB electrolyte demonstrated excellent oxidation stability against various current collectors and delivers a high discharge capacity of >950 mAh/gsulfur with 100 % coulombic efficiency over 500 cycles.

Keywords

• Sodium-sulfur batteries
• Sulfur-polyacrylonitrile cathode
• Bidentate ligands
• Weakly coordinating anion
• Hydrolysis
• Potential energy barrier