High-Performance Supercapacitor Electrode Materials from Chitosan via Hydrothermal Carbonization and Potassium Hydroxide Activation

Nitrogen-rich porous carbonaceous materials suitable for supercapacitor applications can be synthesized directly from chitosan using a hydrothermal treatment (250 degrees C, 14h) that is followed by chemical activation of the carbonized solids with KOH (ca. 800 degrees C, 2h). The synthesized chitosan-derived carbonaceous materials (CDCMs) had high specific surface area (ca. 2200m(2)g(-1)), large pore volume (ca. 1.36cm(3)g(-1)), and high nitrogen content (ca. 6.3%). When a current density of 0.5Ag(-1) was applied to CDCM-800 obtained at an activation temperature of 800 degrees C, specific capacitances of 231 and 305Fg(-1) were achieved for 0.5m K2SO4 and 6m KOH aqueous electrolytes, respectively. Capacitances of 154 and 198Fg(-1) were retained for the respective electrolytes at 20Ag(-1). CDCM-800 had an energy density of 8.5Whkg(-1) corresponding to a specific power of 1kWkg(-1) at 20Ag(-1) in 6m KOH aqueous electrolytes. The prepared carbonaceous materials retained 99% of their properties for over 3000cycles at 1Ag(-1) in 0.5m K2SO4. The nitrogen-rich nanoporous carbonaceous materials have wide application in energy, electrical, chemical, analytic, separation, and catalysis.