Covalent organic frameworks (COFs) with features of light elements, tailored functional groups, and designable structures are regarded as promising candidates for future potassium ion batteries (PIBs), while the low electronic conductivity and intricate reaction mechanism restrict their practical application. Herein, a needle-like COF material, marked as CPT, was synthesized by an acid-catalyzed condensation reaction between cyclohexanehexone and 2,3,7,8-phenazine tetramine. It was constructed by interconnected phenazine with π-conjugated structures, displaying the advantages of rich electron delocalization, thin sheet thickness, and low dissolution in electrolytes. When applied as the anode of PIBs, the CPT anode delivered a high reversible capacity of 305 mAh g−1 at 0.1 A g−1 over 200 cycles. Besides, it also exhibited promising potential for “high-temperature” application potential by retaining a capacity of 400 mAh g−1 at 0.1 A g−1 after 100 cycles at 45 °C. Full cells with CPT anode and potassiathed organic cathode displayed good cycling and rate performances. Furthermore, the step-wise K-storage mechanism was jointly determined by in-situ characterization techniques and theoretical calculations. This study not only presents a molecular engineering approach for designing organic materials but also provides novel insights into the underlying mechanism governing potassium storage.
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