Breaking Electronic Symmetry Via Axial Asymmetric Coordination at Co Site in Dual-Channel Catalyst Boosts High-Performance Li-S Batteries.

Abstract

Lithium-sulfur (Li-S) batteries face challenges from polysulfide shuttling and sluggish redox kinetics. Single-atom Co-N-C catalysts are promising but require precise coordination modulation to optimize the activity. Herein, an axial Co-O asymmetric configuration integrated into oxygen-doped dual-channel mesoporous carbon (CoN₄-O₂@CMK-5) is engineered via a theoretical-guided design. The axial Co-O coordination creates an asymmetric electronic environment, enhancing d-p hybridization to optimize LiPSs adsorption and bidirectional conversion. The resulting Li-S battery delivers a high capacity of 811 mAh g^-1 at 1C after 200 cycles and exceptional durability (no decay over 500 cycles at 5C). Even with a high sulfur loading and low electrolyte, the cathode maintains a superior areal capacity of 6.77 mAh cm^-2 without attenuation. Combined experimental and theoretical calculation analyses reveal that axial oxygen coordination regulates the Co 3d-orbital electronic structure, enhancing adsorption capacity and lowering conversion barriers. This work highlights the critical role of asymmetric coordination engineering in advancing high-performance Li-S batteries.