N,O-Doped Hierarchical Meso/Microporous Carbon Frameworks Enable Efficient Carbon-Based Supercapacitor

•A series of covalent organic framework are synthesized via facile polycondensation and cyclopolymerization reaction.•Dual-heteroatoms doped hierarchical porous carbon framework is rationally designed via high-temperature pyrolysis.•The heteroatoms doped hierarchical porous carbon nanosheets not only shorten electrolyte ions transport, but also accelerate the kinetics.•The assembled symmetric supercapacitor device reveals an high energy density of 15.28 Wh kg−1 at power density of 352.5 W kg−1.