Improved Li–S batteries obtained by using multifunctional separators modified with vapor grown carbon Fiber/MoS2 composites

Abstract Li–S battery is considered as one of the most competitive energy storage devices mainly due to the high theoretical specific capacity and high specific energy. However, when facing with the practical application, some issues, especially poor electro-conductivity of element sulfur and severe polysulfides (LiPSs) migration, are still needed to solve to further improve the performance of the Li–S batteries. Aiming at the above two disadvantages, in this work, multifunctional separators are designed as efficient LiPSs absorber via coating vapor grown carbon fiber/MoS2 (VGCF/MoS2) composites on the polypropylene separator (PP) near the cathode side. For the as-prepared VGCF/MoS2 coated polypropylene separator (VM/PP), MoS2 could provide strong chemical adsorption for the LiPSs, while the VGCF framework could act as an electronic transmission channel for the conversion of LiPSs, and also provide physical adsorption for LiPSs at the same time. Benefit from these characteristics, the batteries with VM/PP exhibits a high initial capacity of 1208.7 mAh g−1 at 0.2C and maintains at 862.4 mAh g−1 after 200 cycles. Impressively, the VM/PP shows the high specific capacity of 904.3 mAh g−1 and long-lasting cycling stability with 0.03% capacity attenuation per cycle over 600 cycles at 1.0C, demonstrating excellent electrochemical performance.