LAUSR

Abstract The preparation of functional separator has become an effective strategy to enhance the electrochemical performance of lithium-sulfur batteries (LSBs). Therefore, a functional separator suitable for LSBs has aroused great interest. In this work, we report a novel functional separator using LiVPO4F together with carbon nanotube (LVPF/CNT) as functional coating. The LVPF/CNT modified separator not only acts as a conductive layer to facilitate electron and lithium ion (Li+) transport, but also provides chemisorption for lithium polysulfides (LiPSs) and improves the electrochemical kinetics of LSBs. Thus, the cell with LVPF/CNT modified separator delivers an excellent cycle life with the capacity of 578.5 mAh g−1 after 1000 cycles at 1.5C. An ultra-long cycle life (551 mAh g−1 after 350 cycles at 0.5C) and a high areal capacity of 5.58 mAh cm−2 are obtained at a high sulfur loading of 7 mg cm−2. Moreover, the visualized transformation of the LiPSs in the tailor-made cell is also revealed by in situ XRD, while the density functional theory (DFT) simulated the principle of the interaction between the LVPF and LiPSs. This work provides a promising and insightful research to develop the progressive LSBs with functional separator.