Pioneering MOF-303 in Lithium–Sulfur Batteries: Coordination Defect Engineering Enables Accelerated Sulfur Redox and Dendrite-Free Plating

Abstract Lithium–sulfur (Li–S) batteries are severely hindered by the shuttle effect of lithium polysulfides (LiPSs) and uncontrolled lithium dendrite growth. Herein, a defect-engineered MOF-303 (D-MOF-303) modified separator is developed via a ball-milling strategy to simultaneously mitigate both issues, marking the first application of MOF-303 in the Li–S battery field. The intentional introduction of ligand defects and oxygen vacancies reduces particle size, establishes a hierarchical porous structure, and amplifies local Lewis acidity. Consequently, the D-MOF-303 coating layer provides exceptional chemisorption and accelerated electrocatalytic conversion kinetics for LiPSs, while concurrently homogenizing lithium-ion flux to achieve long-term dendrite-free lithium plating. Benefiting from these synergistic merits, the resulting Li–S full cells exhibit high capacity retention over 500 cycles at 0.5 C, enhanced rate capability up to 3 C, and notable environmental resilience under high-humidity aging conditions. This work demonstrates the potential of coordination defect engineering in metal–organic frameworks for advancing high-energy-density and commercially viable energy storage technologies.