Formation of nitrogen-doped holey carbon nanosheets via self-generated template assisted carbonization of polyimide nanoflowers for supercapacitor

Holey carbon nanosheets provide unique in-plane pores and abundant interlayer channels, which facilitates the penetration and transmission of ions and significant application in the energy storage. However, rational design and fabrication of holey carbon nanosheets with optimized morphology and porosity remains a challenge. Herein, the nitrogen-doped holey carbon nanosheets (N-HCNs) have been prepared via one-step activation and self-generated template assisted carbonization route using "bottom-up" self-assembled polyimide (PI) nanoflowers as carbon precursor and ethylenediaminetetraacetic acid disodium zinc salt hydrate (EDTA-Na2Zn) as activating agent and self-generated template. The N-HCNs demonstrates an integral nanoflowers structure with intertwined and holey carbon nanosheets, which would benefit for the transport of ions and electrons, resulting in a satisfactory specific capacitance of 205 F g 1 at a current density of 0.5 A g 1. More important, a symmetric aqueous supercapacitor assembled based on N-HCNs electrodes carries a wide operating voltage of 2.0 V, possesses high energy density of 17.92 Wh kg 1 at a power density of 500 W kg 1, along with outstanding cycling stability. The present work proposes an affordable strategy to design novel porous carbon materials with controlled morphology for advanced energy storage and conversion.