High Lithium Ion Conductivity LiF/GO Solid Electrolyte Interphase Inhibiting the Shuttle of Lithium Polysulfides in Long-Life Li–S Batteries

The “shuttle effect” that stems from the dissolution of polysulfides is the most fatal issue affecting the cycle life of lithium-sulfur (Li–S) batteries. In order to suppress the “shuttle effect,” a new strategy of using a highly lithium ion conductive lithium fluoride/graphene oxide (LiF/GO) solid electrolyte interphase (SEI) to mechanically prevent the lithium dendrite breakthrough is reported. When utilized in Li–S batteries, the LiF/GO SEI coated separator demonstrates significant feature in mitigating the polysulfide shuttling as observed by in situ UV–vis spectroscopy. Moreover, the restrained “shuttle effect” can also be confirmed by analysis of electrochemical impedance spectroscopy and characterization of lithium dendrites, which indicates that no insulating layer of solid Li 2 S 2 /Li 2 S is found on lithium anode surface. Furthermore, the LiF/GO SEI layer puts out good lithium ion conductivity as its lithium ion diffusion coefficient reaches a high value of 1.5 × 10 −7 cm 2 s −1 . These features enable a remarkable cyclic property of 0.043% of capacity decay per cycle during 400 cycles.