Reconfigurable In-S Coordination in SPAN Cathodes: Unlocking High Sulfur Utilization and Fast Kinetics for Practical Li‒S Batteries.

Abstract

Sulfurized polyacrylonitrile (SPAN) has emerged as a promising cathode material for high-energy-density lithium‒sulfur (Li‒S) batteries due to its ability to confine sulfur and suppress polysulfide shuttling. However, conventional SPAN suffers from sluggish conversion kinetics and limited sulfur utilization, especially at high sulfur loadings. In this work, reconfigurable indium‒sulfur (In-S) coordination into SPAN to dynamically regulate sulfur bonding states is introduced. The non-crystalline In-S network reversibly anchors and releases sulfur during cycling, accelerating redox reactions while suppressing phase segregation. Structural analysis reveals atomically dispersed In-S coordination without crystalline inactive phases, achieving an active material content of 47.4 wt.% with only 1.18 wt.% indium addition (≈23% higher than conventional SPAN). Optimized In₅-SPAN cathodes deliver a high specific capacity of 1048 mAh·g^-1 at 0.5 A g^-1 under practical conditions of high SPAN mass loading (8.7 mg cm^-2) and lean electrolyte (E/SPAN = 4.1). This performance surpasses state-of-the-art SPAN-based cathodes under comparable lean-electrolyte and high-loading conditions. These findings illustrate a novel reconfigurable metal‒sulfur coordination strategy for next-generation Li‒S batteries with both high-energy-density and long cycle life.