New insights into axially asymmetric mechanism for enhanced anchoring and catalytic performance in lithium-sulfur batteries.

Lithium‑sulfur batteries (LSBs) are extensively considered as a leading candidate for future-oriented energy storage and conversion systems, facing significant challenges in commercial application caused by the shuttle effect and the slow pace of redox kinetics. To address these challenges, the design of cathode materials with superior performance is essential. In this study, a systematic screening of axially asymmetric N-coordinated graphene-supported transition metal single-atom catalysts (SACs) is conducted using Density Functional Theory (DFT) for analyzing their anchoring and catalytic properties in lithium‑sulfur batteries. The research reveals that the axially asymmetric coordination structure breaks the limitations of traditional d-p orbital hybridization theory. Despite the presence of antibonding state occupation in the d-orbitals of Fe/Co, their unique "transfer-convergence" charge transfer mechanism and the synergistic catalytic effect of TM-N work together to regulate the d-orbitals, enabling the Fe-NC and Co-NC system to exhibit appropriate anchoring capability, efficient catalytic performance, and lower LiS decomposition barriers. Further analysis combined with machine learning (ML), identifies the d-band center (ε), electronegativity (χ), and charge transfer amount (ΔQ) as key features affecting anchoring and catalytic performance. The SISSO algorithm is used to construct descriptors for adsorption energy (E) and Gibbs free energy (ΔG), providing a feasible strategy for rapid screening and prediction of reasonable SACs. This method also provides novel perspectives for developing cathode materials in lithium‑sulfur batteries.