<p>The realization of high-energy rechargeable lithium-sulfur (Li-S) batteries is obscured by the necessity to operate under stringent parameters, including a high areal sulfur mass loading, a high sulfur fraction, and a lean electrolyte. However, under such regimes, precipitation of lithium polysulfides (LiPSs), sluggish conversion kinetics, and exacerbated polysulfide ‘shuttle effect’ emerge as paramount challenges. Here, we show that by decorating a conventional battery separator with a layer of FeS₂ nanoclusters anchored in an oxygen-rich porous carbon scaffold (FeS₂-PCNS), the as-prepared functional separator synergistically couples strong LiPSs adsorption with superior electrocatalytic activity. In this way, the dual-functional separator helps to immobilize soluble LiPSs at the cathode-electrolyte interface while simultaneously accelerating the conversion kinetics. Li-S batteries employing the new separator exhibit reduced voltage polarization, improved rate capability, and superior cycling stability. Under rigorous conditions of a high areal sulfur mass loading (6.5 mg cm⁻²) and a lean electrolyte-to-sulfur (E/S) ratio (4.5 µL mg_S⁻¹), the S cathode delivers a high specific capacity of 1197 mA h g⁻¹ (7.8 mA h cm⁻²), and maintains ∼100% of its initial capacity after 100 cycles. The battery also shows much improved rate capabilities at 2000 mA g⁻¹, 3 mg cm⁻². This work offers new insights into the rational design of highperformance Li-S batteries with practicality.</p>