FUNCTIONALIZED SEPARATORS FOR LITHIUM-SULFUR BATTERIES: MECHANISMS, MATERIALS, AND PERFORMANCE OPTIMIZATION

Lithium-sulfur batteries, with ultrahigh energy density(2600 Wh kg -1 ) and cost efficiency, face critical challenges hindering commercialization: poor conductivity of S/Li 2 S, polysulfide shuttling, Li dendrite growth, and severe volume expansion. Functionalized separators emerge as a pivotal solution, integrating ion-sieving architectures, catalytic conversion, electrostatic repulsion, and chemisorption to suppress polysulfide migration while ensuring Li + transport. Advanced materials-carbon-based frameworks(graphene, CNTs), conductive polymers(PPy, PANI), porous MOFs/COFs, and inorganic compounds (transition metal oxides/sulfides)—synergistically enhance conductivity, anchor polysulfides, and accelerate redox kinetics. Heteroatom doping and heterostructure designs optimize adsorption and catalytic activity, achieving capacities >900 mAh g -1 and cyclability >1000 cycles. Flexible architectures demonstrate practical viability under mechanical stress. Future priorities include scalable fabrication of ultrathin separators, multifunctional integration (polysulfide suppression, dendrite inhibition), and compatibility with high-sulfur-loading cathodes. Bridging lab-scale innovations to industrial deployment requires harmonizing material design, electrolyte optimization, and advanced characterization to address interfacial instability and energy loss mechanisms.