Bis(2,2,2-trifluoroethyl) Ether As an Electrolyte Co-solvent for Mitigating Self-Discharge in Lithium–Sulfur Batteries

Lithium–sulfur batteries suffer from severe self-discharge because of polysulfide dissolution and side reaction. In this work, a novel electrolyte containing bis­(2,2,2-trifluoroethyl) ether (BTFE) was used to mitigate self-discharge of Li–S cells having both low- and high-sulfur-loading sulfur cathodes. This electrolyte meaningfully decreased self-discharge at elevated temperature, though differences in behavior of cells with high- and low-sulfur-loading were also noted. Further investigation showed that this effect likely stems from the formation of a more robust protective film on the anode surface.