A fire-retarding electrolyte using triethyl phosphate as a solvent for sodium-ion batteries.

We introduce a fire-retarding phosphate-based electrolyte, 1 M NaBF 4 in triethyl phosphate with 3% vinylene carbonate as an SEI-forming additive, for sodium-ion batteries. With this electrolyte formulation, we achieved stable cycling performance with a capacity of 80.5 mA h g -1 and a retention of 77.8% after 200 cycles in the Na-ion full cell of Na 3.2 V 1.8 Zn 0.2 (PO 4 ) 3 vs. hard carbon.