Controlled Synthesis of Metal‐Organic Frameworks (MOFs) at Co ₉ S ₈ Composite for High‐Performance Lithium–Sulfur Batteries

ABSTRACT This study develops a novel MOF‐235@Co 9 S 8 composite via hydrothermal synthesis to overcome the limitations of MOF‐235 as a sulfur host in lithium‐sulfur batteries, such as poor conductivity and weak polysulfide adsorption. Serving as a multifunctional matrix, Co 9 S 8 promotes MOF‐235 nucleation, resulting in smaller particles and increasing the specific surface area by 76.7% (reaching 147.6 m 2 g −1 ) compared to pure MOF‐235. The optimized MOF‐235@5%Co 9 S 8 /S cathode delivers a high initial discharge capacity of 859.3 mAh g −1 at 0.5 C and maintains 556.4 mAh g −1 after 500 cycles, achieving a capacity retention of 64.7% and substantially outperforming the unmodified MOF‐235/S. These enhancements arise from the synergistic effects of Co 9 S 8 , which improves electrical conductivity and lithium‐ion diffusion, chemically anchors polysulfides through polar Co─S bonds, and catalytically accelerates polysulfide conversion, effectively suppressing the detrimental shuttle effect. This composite demonstrates excellent potential for high‐performance, long‐cycle‐life lithium‐sulfur batteries.