Textural and electrochemical characterization of porous carbon nanofibers as electrodes for supercapacitors

Porous carbon nanofibers (CNFs) enriched with the graphitic structure were synthesized by thermal decomposition from a mixture containing polyethylene glycol and nickel chloride (catalyst). The textural and electrochemical properties of porous CNFs were systematically compared with those of commercially available multi-walled carbon nanotubes (MWCNTs). The high ratio of mesopores and large amount of open edges of porous CNFs with a higher specific surface area, very different from that of MWCNTs, are favorable for the penetration of electrolytes meanwhile the graphene layers of porous CNFs serve as a good electronic conductive medium of electrons. The electrochemical properties of porous CNFs and MWCNTs were characterized for the application of supercapacitors using cyclic voltammetry, galvanostatic charge-discharge method, and electrochemical impedance spectroscopic analyses. The porous CNFs show better capacitive performances (C-s = 98.4 F g(-1) at 25 mV s(-1) and an onset frequency of behaving as a capacitor at 1.31 kHz) than that of MWCNTs (C-s = 17.8 F g(-1) and an onset frequency at 1.01 kHz). This work demonstrates the promising capacitive properties of porous CNFs for the application of electrochemical supercapacitors. (C) 2007 Elsevier B.V. All rights reserved.