Spatially Decoupled Polysulfide Trapping and Catalytic Conversion in Pyridine‐Rich Covalent Organic Framework for Li‐S Batteries
Jun‐Hyeong Lee, Dae‐Hui Jeong, Yong Hui Kim, Jae Hun Seol, Jae‐Hoon Shin, Tae‐Hyeop Kim, Jaewoo Lee, Sang Uck Lee, Jong‐Ho KimABSTRACT
The lithium polysulfide (LiPS) shuttle and sluggish redox kinetics remain major challenges for rechargeable Li‐S batteries. Herein, a Lewis‐basic pyridine‐rich covalent organic framework (PCOF) is developed as a dual‐functional host that enables effective LiPS trapping and catalytic conversion. Elemental sulfur‐loaded PCOF (S@PCOF) and atomically Co‐coordinated PCOF‐derived framework (Co@PCOF) are synthesized and integrated to construct a Li‐S cathode with spatially separated active sites. PCOF exhibits stronger binding affinity and faster binding kinetics for LiPS than pyridine‐free COF (BCOF) with an identical imine content, highlighting the role of pyridine groups in LiPS trapping. Moreover, density functional theory (DFT) calculations reveal a lower energy barrier for the potential‐determining step (Li 2 S 2 → Li 2 S) on PCOF than on BCOF, originating from its higher p ‐band center. The Co@PCOF‐integrated PCOF cathode delivers the highest Li 2 S nucleation and dissolution capacities with accelerated kinetics, enabling highly reversible sulfur redox reactions. Full cells employing the S@PCOF+Co@PCOF cathode exhibit a high discharge capacity (952 mAh g −1 ), superior Coulombic efficiency (98%), excellent long‐term cycling stability, and robust rate performance across various C‐rates. This work provides a rational design strategy for spatially separating LiPS trapping and catalytic sites in pyridine‐rich COF cathodes, offering new insights into the development of high‐performance Li‐S batteries.