Chitosan-based layered carbon materials prepared via ionic-liquid-assisted hydrothermal carbonization and their performance study

Layered porous carbon (NCSIL-900) with a graphitization-like layered structure possessing developed oxygen- and nitrogen-containing groups were prepared via hydrothermal carbonization of chitosan in the presence of an ionic liquid (IL; 1-butyl-3-methylimidazolium chloride). The IL served as a dispersant, structure-directing agent and nitrogen source during the reaction, and facilitated the formation of a layered and mesoporous structure. Thus, NCSIL-900 exhibited developed micro/mesoporous characteristics in layered structures. When evaluated as an electrode material for supercapacitors, NCSIL-900 exhibited specific capacitance of 355 F/g at 0.2 A/g in (1 M H2SO4 electrolyte) and 275 F/g at 0.2 A/g in (6 M KOH electrolyte) in a three-electrode system. The values were 157.5 F/g at 0.5 A/g in (1 M H2SO4 electrolyte) and 120.8 F/g at 0.5 A/g in (6 M KOH electrolyte) in a two-electrode system. The layered porous structure and nitrogen-containing groups of NCSIL-900 contributed to its high specific capacitance. In this work, layered carbon materials that are promising candidates for electrode materials were prepared via a “green” route using “green” solvent and raw materials.