Fluoroalkyl ether electrolyte with sulfur-wetting and shuttling-inhibition functionalities for high-rate lithium sulfur batteries

Lithium-sulfur (Li–S) batteries have been acknowledged as one of the most fascinating energy storage devices due to their remarkable theoretical energy density. However, low conductivity and polysulfide shuttling are notorious challenges for their commercial applications. Here, by directly introducing fluoroalkyl ether 2,2,2-trifluoroethyl-1,1,2,3,3,3-hexafluoropropyl ether (THE) into commercial ether electrolytes, we design a fluoroalkyl ether electrolyte to improve high-rate cyclic performance of Li–S battery. As confirmed by density functional theory calculations, in-situ Raman, and electron density maps, the THE electrolyte, with abundant high-polarity CF₃ and CF₂ groups, fully wets the sulfur cathode and inhibits the polysulfide shuttling, owing to the intense repulsive interaction (1.97 eV) with polysulfide ions and the robust absorption interaction (−2.42 eV) with sulfur cathode. With the THE electrolyte, the Li–S battery cycling 500 times at 5 C (10.5 mA cm⁻²) delivers a capacity retention of 53.3%, holding promise for developing high-rate, long-period Li–S batteries.