Se‐Vacancy Engineering Enables Dual Electronic and Interfacial Regulation in SnSe ₂ Nanocatalysts for High‐Performance Lithium–Sulfur Batteries

Engineering chalcogen vacancies provides a versatile approach to concurrently modulate the electronic structure and adsorption behavior of metal chalcogenides, thereby enhancing their catalytic efficacy in lithium–sulfur (LiS) batteries. Here, precisely introduced Se vacancies in SnSe 2 convert Li‐polysulfide adsorption from a single‐site to a dual‐site mode, generating electron‐rich Sn edges and electron‐deficient Se centers. This dual‐regulation strengthens Li‐polysulfide anchoring, accelerates sulfur redox kinetics, and facilitates Li + transport by reducing the diffusion barrier. Comprehensive experimental characterization and density functional theory analyses reveal that Se vacancies reconstruct the band structure and expose new active sites, enabling fast charge transfer and reversible Li 2 S formation/decomposition. As a cathode catalyst, Se‐deficient SnSe 2 delivers an exceptional capacity of 776 mAh g −1 at 4 C and a high areal capacity of 5.52 mAh cm −2 at a sulfur loading of 5.2 mg cm −2 . This vacancy‐mediated dual‐regulation mechanism provides a general strategy for defect engineering of metal chalcogenides toward high‐performance and durable LiS batteries.