Multiple Accessible Redox-Active Sites in a Robust Covalent Organic Framework for High-Performance Potassium Storage

• Published in: Journal of the American Chemical Society 2023-03, Vol.145 (9), p.5105-5113
• Main Authors: Chen, Xue-Ling, Xie, Mo, Zheng, Ze-Lin, Luo, Xiao, Jin, Hongchang, Chen, Yan-Fei, Yang, Guo-Zhan, Bin, De-Shan, Li, Dan
• Format: Article
• Language: English
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.2c11264

Covalent organic framework (COF) materials with porous character and robust structure have significant applied implications for K-ion battery (KIB) anodes, but they are limited by the low reversible capacity and inferior rate capability. Here, based on theoretical calculations, we identified that a porous bulk COF featuring numerous pyrazines and carbonyls in the π-conjugated periodic skeleton could provide multiple accessible redox-active sites for high-performance potassium storage. Its porous structure with a surface-dominated storage mechanism enabled the fast and stable storage of K-ions. Its insolubility in organic electrolytes and small volumetric change after potassiation ensured a robust electrode for stable cycling. As a KIB anode, this bulk COF demonstrated an unprecedentedly outstanding combination of reversible capacity (423 mAh g–1 at 0.1 C), rate capability (185 mAh g–1 at 10 C), and cyclability. The theoretical simulation and comprehensive characterizations confirmed the active sites are contributed by CO, CN, and the cation−π effect.