Integrating LiF-rich solid electrolyte interphase and in-situ formed gel blocking layer for Li–S battery

Engineering stable interface protective films are imperative to enable lithium-sulfur (Li–S) batteries long-term cycling as they can suppress the growth of Li dendrites and shuttle effect of Li polysulfides, which have been recognized as two major challenges for plaguing the practical implementation of Li–S batteries. However, most of these efforts only pay attention to one side of Li metal anode or cathode. Herein, we report a facile yet effective strategy that simultaneously overcomes the aforementioned challenges by using Li hexafluorophosphate/fluoroethylene carbonate (LiPF 6 /FEC) solution immersed separator, resulting in a LiF-rich solid electrolyte interphase film at the surface of Li metal anode and an in-situ formed gel blocking layer on the separator-cathode interface. With joint theoretical calculations and characterization techniques, we confirm that the Li–S battery using the LiPF 6 /FEC soaked separator can achieve a better rate performance and cycling stability than that of using routine PE separator. This work provides a creative design for boosting the development of high-performance rechargeable batteries not limited Li–S battery. • LiPF 6 /FEC solution is first used to modify separator. • LiF-rich SEI film is integrated with in-situ formed gel blocking layer. • The mechanisms of LiPF 6 decomposition are elucidated in-depth. • DOL ring-opening polymerization mechanism induced by LiPF 6 is elucidated. • LiPF 6 /FEC solution immersed separator enhanced electrochemical performance.