Heteroatoms Synergistic Anchoring Vacancies in Phosphorus-Doped CoSe2 Enable Ultrahigh Activity and Stability in Li–S Batteries

• A volcano-type relationship between catalytic activity and vacancy concentration is revealed, highlighting the trade-off between activity and stability. • A novel “heteroatoms synergistic anchoring vacancies” strategy is proposed, achieving P-doped CoSe2 with rich selenium vacancies (P-CS-Vo-0.5) that balances high activity and structural stability. • P doping lowers Se vacancy surface energy and effectively “pins” active sites, suppressing dynamic migration of vacancies and enhancing catalytic stability. • The optimized P-CS-Vo-0.5 separator enables ultrahigh capacity and stability in Li–S batteries, achieving 95.1% capacity retention after 80 cycles at high sulfur loading.