Delocalized Electrons of p-Block Selenium Single Atoms Achieve Synergistic Regulation of Conversion Kinetics and Lithium Deposition for Lithium–Sulfur Batteries

The practical applications of lithium–sulfur (Li─S) batteries are impeded by sluggish conversion kinetics of lithium polysulfides (LiPSs) and uncontrolled Li dendrite growth. While introducing single-atom catalysts (SACs) stands out as a promising strategy to overcome these issues, the p-block SACs exhibit great potential. However, the relationship between their synergistic regulation and atomic structure remains unclear. Here, by leveraging the p-electron delocalization induced by the p-π conjugated effect, p-block Se SACs were proposed to synergistically regulate the lithium/sulfur electrochemistry. The experimental and theoretical results demonstrate that the unique Se-C₂ coordination structure of Se SACs leads to activated p-electrons, which not only facilitates LiPSs conversion by p-p hybridization but also generates a uniform current distribution to guide Li plating and stripping behavior. Consequently, the Li─S batteries assembled with Se SACs demonstrate a low capacity decay rate of 0.056% per cycle over 1000 cycles at 1 C and achieve a high areal capacity of 5.58 mAh cm⁻² under a high sulfur loading of 6.41 mg cm⁻² and a low electrolyte/sulfur ratio of 8.3 µL mg⁻¹. This work elucidates the synergistic regulation of Se SACs from atomic orbital level and enlightens the application of p-block SACs in Li─S batteries.