A Unified Cation–Anion Electronic-Structure Descriptor for Compound Catalysts in Li-S batteries

Lithium–sulfur batteries (LSBs) remain limited by sluggish sulfur redox kinetics and the dissolution/shuttling of lithium polysulfides (LiPSs), motivating catalysts that accelerate conversion without overbinding intermediates. While d-band concepts and ligand field theory are often used to interpret activity trends, they typically emphasize TM-centered interactions and underrepresent the role of chalcogen anions and interfacial charge transfer. Here, we propose a unified electronic-structure framework that integrates cation (d-orbital) and anion (p-orbital) contributions and introduces a quantitative orbital-hybridization degree (OHD) metric to elucidate chalcogenide catalysis in LSBs. As a proof of concept, we synthesize hollow-sphere CoSe 2 co-doped with metal (Cu/Ni) and non-metal (P) elements. We couple a bucket-effect concept to identify the limiting sulfur intermediate with two descriptors, d–p OHD (TM d ↔ LiPS sulfur p) and s–p OHD (Li s ↔ lattice chalcogen p). DFT and charge analysis show that Cu-Ni-CoSe 2 -P exhibits the highest OHD values and strongest interfacial charge transfer, consistent with optimized LiPS binding, reduced sulfur redox barriers, and suppressed polysulfide shuttle. Accordingly, an S/Cu-Ni-CoSe 2 -P cathode delivers an initial discharge capacity of 1241 mAh g –1 at 0.2C and retains 571 mAh g –1 after 200 cycles at 0.5C with Coulombic efficiency above 96%. This work establishes an integrated bucket-effect/OHD descriptor approach that links electronic structure to sulfur redox kinetics and guides the design of high-performance chalcogenide catalysts beyond TM-only descriptors.