A Universal Graphene‐Selenide Heterostructured Reservoir with Elevated Polysulfide Evolution Efficiency for Pragmatic Lithium–Sulfur Battery

Abstract The practical application of lithium–sulfur (Li–S) batteries has been handicapped by the notorious polysulfide shuttling and sluggish sulfur conversion kinetics. Although the functional modification of separator is readily proposed as an effective strategy to optimize the Li–S redox reactions, the excessive material dosage and invalid structural design still result in inferior electrocatalyst utilization. Herein, generic graphene‐metal selenide heterostructures (Gr‐M_xSe_y, M = Mo, W, Mn, Cu and Zn) are controllably grown on commercial glass fiber (GF) separator employing a sequential low‐temperature chemical vapor deposition procedure. Such a tailored reservoir can not only render ample active sites but also realize the synergy of polar and catalytic framework, which maximizes the electrochemical functions in alleviating shuttle effect and guiding Li₂S nucleation/decomposition. The thus‐derived Gr‐M_xSe_y/GF separator affording favorable heatproof feature endows the Li–S battery with an outstanding cycling stability (100% capacity retention over 100 cycles at 0.2 C). Furthermore, the flexible Li–S pouch cell based on this new separator delivers good device performance (with a capacity decay of 0.25% per cycle over 100 cycles). This study offers comprehensive insight into the reliable separator design toward working Li–S batteries.