Enhanced Polysulfide Redox Reaction of Co/Fe Dual-Atom Catalysts Embedded in Metal-Organic Framework-Derived...

Lithium-sulfur (Li-S) batteries have attracted significant interest owing to their high theoretical energy densities and cost-effectiveness. However, their practical application is hindered by sluggish lithium polysulfide (LiPS) redox kinetics and the shuttle effect, which result in rapid capacity decay and poor rate performance. Herein, a Co-Fe dual-atom catalyst embedded in nitrogen-doped microporous carbon (CoFeDA-CN) is rationally designed to address these limitations. In CoFeDA-CN, the spatially adjacent Co and Fe atomic centers are stabilized by nitrogen coordination within the MOF-derived porous carbon matrix, providing a strong chemical affinity for LiPSs and promoting efficient redox conversion. The dual-metal synergy effectively modulates the electronic structure at the active sites, thereby facilitating reversible conversion between long-chain polysulfides and Li₂S, while effectively suppressing polysulfide dissolution. As a result, the CoFeDA-CN@S cathode exhibits a high initial discharge capacity of 1361 mAh g^-1 at 0.1C and retains 922 mAh g^-1 at 1C. Even at a high sulfur loading of 5.3 mg cm^-2, a practical areal capacity of 5.60 mAh cm^-2 is achieved at 0.1C. Notably, it delivers outstanding cycling stability and maintains its performance over 500 cycles at 4C with a low decay rate of 0.065% per cycle. This study establishes a robust and scalable dual-atom catalytic platform for achieving durable and high-performance Li-S batteries.