High-throughput screening of single-atom catalysts on defective graphene for advanced lithium-sulfur battery cathodes

Lithium‑sulfur (Li-S) batteries have emerged as promising candidates for next-generation energy storage, but challenges such as the shuttle effect and sluggish kinetics hinder their practical application. Defect engineering and the implementation of single-atom catalysts (SAC) can enhance lithium polysulfide (LiPS) adsorption and catalytic activity. Since high SAC loading remains a challenge, graphene defects provide ideal anchoring sites to increase loading and activate its inert surface. Herein, we used density functional theory (DFT) to propose a dual-engineering strategy by integrating intrinsic graphene defects- divacancy (DV) and Stone-Wales (SW)- with SAC (M-N₄, where M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn). Unlike previous studies on either defect engineering or single-atom catalysts, we perform a mechanism-guided screening of defect-SAC structures, revealing their potential synergistic effects for Li-S batteries. The local coordination environment strongly governs SAC performance, and defect sites induce charge redistribution that significantly enhances LiPS adsorption. Interestingly, our high-throughput DFT screening of 200 defect-SAC structures reveals that most configurations have negative formation energies, suggesting they are energetically favorable. More importantly, we identify an optimal adsorption energy window, showing that both weak and excessively strong adsorption are detrimental to catalytic efficiency. To further evaluate catalytic performance, we introduce Cumulative Conversion Energy (CCE), which captures key steps in LiPS transformation to compare the catalytic performance of different hosts. Overall, Fe- and V-based defect-SACs exhibit superior catalytic conversion and optimal adsorption energies, effectively mitigating the shuttle effect.