Single‐Crystal NCM‐Enabled Multifunctional Separator Design for High‐Performance Lithium‐SPAN Batteries

ABSTRACT High‐energy and sustainable batteries are key to a low‐carbon future, and lithium‐sulfur (Li‐S) systems stand out for their high energy density, abundance, and low cost. Organo‐polymer cathodes such as sulfurized polyacrylonitrile (SPAN) cathodes offer solid‐state conversion and suppress polysulfide shuttling, yet their sluggish redox kinetics and limited active material utilization hinder practical performance. Herein, we introduce a multifunctional trilayer mixed‐conduction separator that synergistically integrates ionic selectivity, kinetic facilitation, and interfacial stabilization. The separator, composed of single‐crystal NCM811 (SC‐NCM), BP2000 carbon, and Li‐Nafion binder sandwiched between two polypropylene separators (PP|SC‐NCM|PP), forms Li + ‐ion transport channels, interfacial charge redistribution, and promotes stable solid‐state redox reactions (S to Li 2 S) within the SPAN cathode. This architecture enhances Li + transference number (0.60), ionic conductivity (1.82 × 10 −3 S·cm −1 ), and electrolyte uptake (68%), while suppressing thermal shrinkage and self‐discharge. As a result, the cells deliver an initial discharge capacity of 1779 mAh·g −1 at 0.1C, retains 80% capacity after 500 cycles (1C), and sustain 771 mAh·g −1 at 10C (high‐rate capability). This scalable, recyclable, and multifunctional separator offers a sustainable route to high‐performance Li‐S batteries and sets a precedent for mixed‐conduction membrane designs in next‐generation energy‐storage technologies.