Fishnet‐Like, Nitrogen‐Doped Carbon Films Directly Anchored on Carbon Cloths as Binder‐Free Electrodes for High‐Performance Supercapacitor

The low specific capacitance and energy density of carbon electrode has extremely limited the wide application of supercapacitors. For developing a high‐performance carbon electrode using a simple and effective method, a fishnet‐like, N‐doped porous carbon (FNPC) film is prepared by calcining the KOH‐activated polyindole precoated on carbon cloths. The FNPC film is tightly anchored on carbon cloths without any binder. The FNPC film with 3.8 at% N content exhibits a fairly high specific capacitance of 416 F g−1 at 1.0 A g−1. Moreover, the assembled button‐type cell with two FNPC film electrodes shows a high energy density of 16.4 Wh kg−1, a high power density of 67.4 kW kg−1, and long‐term cyclic stability of 92% of the initial capacitance after 10 000 cycles at 10 A g−1. The high performances mainly came from the integration of pseudocapacitance and electrical double‐layer capacitance behavior, wettability, fishnet‐like nanostructure, as well as the low interfacial resistivity. This strategy provides a practical, uncomplicated, and low‐cost design of binder‐free flexible carbon materials electrode for high‐performance supercapacitors.