ABSTRACT Lithium‐sulfur batteries (LSBs) face sluggish sulfur reduction reaction kinetics and severe polysulfide shuttling issues, which significantly limit their performance. In this work, a multifunctional separator with a 3D porous framework featuring confined pore structures and selective adsorption capability is constructed to address these challenges. Within this separator, Lewis acid–base interactions between Ce‐MOF‐808 and lignosulfonate (SL) effectively regulate the Ce 4+ catalytic activity, thereby lowering the kinetic barrier and accelerating the conversion of short‐chain polysulfides into insoluble Li 2 S during the liquid‐solid transformation. Furthermore, SL prevents the accumulation of long‐chain polysulfides near the Ce 4+ sites through localized electrostatic repulsion, avoiding catalyst poisoning and thereby maintaining continuous catalytic availability. These synergistic effects collectively enable long‐lasting catalytic activity toward polysulfide conversion in LSBs, resulting in a fivefold enhancement in capacity and an impressively low capacity decay rate of just 0.033% per cycle over 500 cycles at 1C. This work underscores the transformative potential of Lewis acid–base interactions for enhancing sulfur redox kinetics and introduces a versatile methodology for designing advanced separators for LSBs.
Zhang et al. (2026) studied this question.