Preparation of nitrogen-enriched porous carbon nanofibers and their electrochemical performance as electrode materials of supercapacitors

Nitrogen-enriched porous carbon nanofibers were prepared from a commercial polyimide resin by electrospinning, followed by carbonization. The products were characterized by scanning electron microscopy, nitrogen sorption and X-ray photoelectron spectroscopy. As-prepared carbon nanofibers were directly used as a supercapacitor electrode, and their electrochemical performance was investigated by cyclic voltammetry, charge-discharge tests and electrochemical impedance spectroscopy. The evolution of the porous structure and the surface nitrogen-containing functionality of the carbon nanofibers with carbonization temperature was also investigated. Results showed the carbon nanofibers with developed micropores and enriched with nitrogen were obtained by carbonization of polyimide nanofibers. Both the specific surface area and surface nitrogen content decreased gradually with the carbonization temperature. The carbon nanofibers obtained at 700 ℃ had the highest specific surface area of 447 m²/g, a fiber diameter of 234 nm and a nitrogen content of 4.1%. They also exhibited a specific capacity of 214 F/g or 0.57 F/m².