Multiscale Hierarchically Engineered Carbon Nanosheets Derived from Covalent Organic Framework for Potassium‐Ion Batteries

Abstract Previous research on potassium‐ion batteries (PIBs) indicates that promising carbon anode materials should have several carefully crafted features across different length scales including uniform heteroatom doping at atomic scale, proper carbon interspacing at sub‐nanoscale, and hierarchical pore system with pore size spanning from nano‐ to macro‐scale. However, it remains a grand challenge to construct a carbon material that possesses all the features. Here, this paper reports an attractive strategy of converting ordered mesoporous covalent organic framework (COF) via guest dopant inclusions and high‐temperature COF–guest interactions into carbon nanosheets with multilevel hierarchy. The as‐prepared carbon material exhibits homogeneous co‐doping of nitrogen and phosphorus, a large carbon layer interspacing of ≈0.4 nm, and rich micro/meso/macro‐pores. The assembled PIB anode delivers a high reversible potassium capacity of 404 mAh g −1 at 100 mA g −1 , as well as excellent long‐term stability by maintaining a capacity of 179 mAh g −1 at 1000 mA g −1 over 2000 cycles, placing it in the rank of best‐performing carbon anodes for PIBs. This work demonstrates the intriguing power of COF–guest chemistry in hierarchically engineering carbon structures.