Polyvinyl Chloride-Derived Organosulfur Cathodes for Durable Li-S Battery

The properties of sulfur host materials are critical for mitigating the lithium polysulfide (LiPS) shuttle effect and prolonging the Li-S battery lifetime. Herein, we have developed a unique polyvinyl chloride (PVC)-derived polymeric host material (named as XC); results show that XC host is capable of achieving strong chemical/physical confinement to the encapsulated sulfur and lithium polysulfide (LiPS) intermediates, thus significantly reducing the shuttling effect and improving the battery cycle life to above 500 cycles with only 9.3% capacity loss (74.4% after 1000 cycles). While with increased S loading of 6.2 mg-S/cm² and electrolyte-to-sulfur ratio of 6 μL/mg-S, the XC/S28 composite comprising 20% XC and 80% S maintains 67.5% of its capacity at the 200^th cycle. Apart from the chemical immobilization of short-chain S_x (x = 2-4) in micropores or organic skeletons, the use of XC as a polymeric encapsulant still maintains the solid-liquid-solid conversion in highly solvating electrolytes, guaranteeing high discharge voltage and energy while significantly extending cycle life.