Nitrogen‐Doped Carbon Membrane Derived from Polyimide as Free‐Standing Electrodes for Flexible Supercapacitors

Abstract

Nitrogen‐doped carbon materials have attracted great interest in the energy storage due to the better electrochemical performances than the pristine carbon materials. In this work, a heterocyclic polyimide containing benzopyrrole and benzimidazole rings is carbonized to fabricate the free‐standing and flexible carbon membrane (Carbon PI ) with a high packing density (0.89 cm −3 ), in which the location of nitrogen atoms in the doped configurations is easily controlled. XPS analysis indicates that quaternary nitrogen is the predominant nitrogen‐doped configurations. The high content of nitrogen effectively improves the wettability of the electrode materials. The Carbon PI membrane exhibits excellent volumetric capacitance (159.3 F cm −3 at 1 A g −1 ), high rate capability (127.5 F cm −3 at 7 A g −1 ), and long cycle life. TEM images reveal the very slight change of the microstructure of graphitic nanosheet of Carbon PI during the long charge/discharge cycles.