Synthesis and Application of an Aromatic Sulfonate Sodium Salt for Aqueous Sodium‐Ion Battery Electrolytes

The two-step synthesis of sodium (2,3,5,6-tetrafluorophenoxy) diethane sulfonate (Na-TFP) is reported, starting from 2,3,5,6-tetrafluorohydroquinone as the precursor. Compared with conventional aqueous electrolytes such 0.5 m NaClO4 and Na2SO4, solution Na-TFP provides higher ionic conductivity over a wide range temperature (e.g., >60 mS cm−1 at 20 °C >70 30 °C) wider electrochemical stability window. Electrochemical cells Na2VTi(PO4)3 positive electrode active material carbon-based negative provide stable capacity for more than 450 cycles in Na-TFP. Additionally, symmetric are studied. employing exhibit good cycling high dis-/charge rate 5C 50 cycles, which superior to performance solutions Na2SO4 electrolyte. design this bifunctional salt may trigger new ideas development water-based sodium-ion battery electrolytes.