Decoding Symmetry-Breaking Band Structures in Nanocatalysts for Kinetically Favorable Li-S Batteries

Abstract The conventional d-band center theory represents catalyst electronic structures using an averaged energy and may therefore overlook higher-order information contained in the complex and asymmetric density of states of alloy catalysts (ACs). Here, combining quantum chemistry with interpretable machine learning, we identify the transformed d-band peak position (Epp) as an alternative electronic descriptor for alloy–polysulfide interactions in lithium-sulfur batteries. Epp integrates information related to the d-band position, bandwidth, and band shape, and correlates with the electron occupation of S3p–Md (M = metal) antibonding states and the calculated polysulfide adsorption strength. A series of bimetallic ACs recovered from spent lithium-ion batteries was employed to experimentally evaluate the descriptor. Within this series, CoFe shows favorable electrochemical performance, enabling an ampere-hour-level pouch cell with an energy density of 426 Wh kg–1 under a sulfur loading of 12.5 mg cm–2 and an electrolyte-to-sulfur ratio of 3.6 mL g–1.