Preparation and Electrochemical Performance of Hollow Activated Carbon Fiber Self-Supported Electrode for Supercapacitor.

Hollow activated carbon fiber (HACF) with high specific surface area and high charge storage capability was prepared by pre-oxidation, carbonization and KOH-activation from polyacrylonitrile (PAN). HACF was used as self-supported working electrode directly without any binder and conductive agent. The effect of the activation time on specific surface area of HACF was studied intensively. The results show that the specific surface area of HACF increased with the increase of activation time from 0.5 h to 1.5 h, and then decreased with further increase of activation time. Highest specific surface area of 1873 m²g-1 and micropore volume of 0.61 cm³g-1 were obtained in HACF activated for 1.5 h. Electrochemical properties of HACF can be improved with increase of activation time, but excessive activation results in the decrease of specific surface area and increase of internal resistance of HACF. The self-supported electrode of HACF possesses a large specific capacitance of 323 F g-1 at 0.05 A g-1 and 216 F g-1 at 1 A g-1. Therefore, HACF can be a promising self-supported electrode for high performance supercapacitors.