Chitosan-derived large surface area porous carbon via microphase separation engineering of pore-regulation and nitrogen-doping coupling for high-performance supercapacitors

In the face of the contradiction between the shortage of fossil raw materials, global warming and growing energy demand, it is of great practical significance to apply biomass, which is widely available in nature, environmentally friendly and renewable, to energy storage. Based on the coupling mechanism of pore-regulation and N-doping, this study implements pre-carbonization through microphase separation engineering in the chitosan (CS) and aniline (AN) co-hydrothermal. Using hydrochar as the precursor, porous carbon with good electrochemical properties has been prepared by a multi-step process consisting of KOH activation, pyrolysis, pickling and water washing. The CS/AN co-doped porous carbons (1830.08-2576.53 m2/g) show an enhancement of 8.48%-52.73% in specific surface area compared to the CS porous carbon (1687.02 m2/g). The hierarchical network structure of the micro-mesoporous interconnects enables fast ion transport and the ultra-micropores further increase the specific capacitance of the electrodes. Theoretical calculation shows that N doping can effectively activate the chemically inert carbon structure and enhance the adsorption capacity of electrolyte ions, thus increasing the specific capacitance. Using 6 M KOH as the electrolyte, CS-AN60-220-800 exhibits a specific capacitance of 368.6 F/g (1.0 A/g) in the three-electrode system. In the two-electrode system, the supercapacitor device constructed with CS-AN60-220-800 demonstrates a capacitance retention of 95.32% (after 10,000 cycles) along with an energy density of 14.16 Wh/kg (with a power density of 125 W/kg), which is at a high level among similar biomass symmetric supercapacitors. The preparation strategy provides a valuable reference for the preparation of other biomass-based porous carbon, as well as for applications in energy storage.