Enhancing Catalysis and Sieving Polysulfides by Oxygen Vacancy‐Rich Separator Modifier for High‐Performance Li‐S Batteries

Lithium-sulfur (Li-S) batteries have been hindered by the low active material utilization, sluggish kinetics and Li anode corrosion caused by the dissolution of Li polysulfides (LiPSs) intermediates. To solve these problems simultaneously, Fe-doped H2TiO3 anchored on the reduced graphene oxide (rGO/H2TiO3-x-Fe) is designed via dopant selection and doping content optimization as a novel separator modifier. Tunable Fe-doping induces the controllable generation of oxygen vacancies (OVs), endowing rGO/H2TiO3-x-Fe with suitable Lewis acid character, which causes a sieving effect via the differentiated adsorption between OVs and various LiPSs. All the long-chain LiPSs are blocked, while partial Li2S4 passes over the separator to react with the Li anode for forming robust SEI, which could ease the Li corrosion from LiPSs and suppress Li dendrite. Furthermore, the optimized electronic structure and the enhanced electronic conductivity from Fe-doping promote the catalytic effect for the LiPSs redox to accelerate the conversion of the blocked LiPSs. Consequently, with the synergistic effect between sieving effect and enhanced catalysis, rGO/H2TiO3-x-Fe modified separator provides Li-S battery remarkable cycling (fading rate: 0.035%@5 C during 1000 cycles), power, and shelving performances. This strategy, based on rational dopant selection and OVs regulation, offers a universal separator design for high-performance Li-S batteries toward industrialization.