Phosphorus‐Pinned Sulfur Vacancies Stabilize Heterointerfaces for High‐Performance Li‑S Batteries

Heterojunction electrocatalysts have emerged as promising candidates for advancing lithium‐sulfur battery cathodes due to their tunable electronic structures and abundant active sites, yet their performance is often compromised by the thermodynamic instability arising from excessive defect sites at the interface. We report a phosphorus doping strategy to stabilize pre‐engineered sulfur vacancies in a carbon‐coated CoS 2 ‐FeS 2 heterojunction (P‐V S ‐CFS@C). Partial occupancy of V s by P 3− not only passivates the vacancy structure and suppresses interfacial trap effects, but also strengthens lithium polysulfide (LiPSs) adsorption. Density functional theory calculations reveal that phosphorus incorporation modulates the local charge redistribution, generating spin‐polarized states near the Fermi level and lowering the energy barrier for the critical Li 2 S 2 ‐to‐Li 2 S conversion. The resulting P‐V S ‐CFS@C/S cathode delivers a high‐rate capacity of 784.1 mAh g −1 at 5 C and exceptional long‐term cycling stability with 963.6 mAh g −1 retained after 1000 cycles at 1 C. This work presents a rational anion‑doping approach for stabilizing heterointerface defects and offers new insights into interface engineering for durable electrocatalysis in energy‑storage systems.