Aqueous/Nonaqueous Hybrid Electrolyte for Sodium-Ion Batteries

Here, we report an aqueous/nonaqueous hybrid electrolyte based on sodium trifluoromethanesulfonate with an expanded electrochemical window up to 2.8 V and high conductivity (∼25 mS cm –1 at 20 °C). The hybrid electrolyte inherits the safety characteristic of aqueous electrolytes and the electrochemical stability of nonaqueous systems, enabling stable and reversible operation of the Na 3 V 2 (PO 4 ) 3 /NaTi 2 (PO 4 ) 3 sodium-ion battery.