Tailoring Na+ Solvation Environment and Electrode‐Electrolyte Interphases with Sn(OTf)2 Additive in Non‐flammable Phosphate Electrolytes towards Safe and Efficient Na‐S Batteries

Room-temperature sodium-sulfur (RT Na-S) batteries are promising for low-cost and large-scale energy storage applications. However, these batteries are plagued by safety concerns due to the highly flammable nature of conventional electrolytes. Although non-flammable electrolytes eliminate the risk of fire, they often result in compromised battery performance due to poor compatibility with sodium metal anode and sulfur cathode. Herein, we develop an additive of tin trifluoromethanesulfonate (Sn(OTf)