Tailoring the physicochemical properties of chitosan-derived N-doped carbon by controlling hydrothermal carbonization time for high-performance supercapacitor application.

Although a few methods have been employed to fabricate N-doped porous carbons from various N-containing biomass resources, it is still a big challenge to obtain porous carbons with high supercapacitance performances. Herein, we demonstrate that aN-doped porous carbon with superior supercapacitance can be prepared from chitosan by properly controlling hydrothermal carbonization (HC). The physicochemical and supercapacitance properties of the HC-derived carbon are highly time-dependent and can be readily tailored. As compared with traditional direct pyrolysis, the proper control of HC time plays a very important role in promoting the supercapacitance performances of the N-doped carbon by increasing turbostratic structure, doped N content and active N species, specific surface area, and especially balancing micro- and mesoporosity. These synergistic effects produce a N-doped carbon with an ultrahigh specific capacitance of 406 ± 36 F g-1 in a three-electrode system, outstanding rate capability, and ultrahigh energy density (23.6 ± 3.1 W h kg-1).