PORE CHARACTERISTICS AND ELECTROCHEMICAL PERFORMANCE OF ACTIVATED CARBON FIBERS FOR ELECTRIC DOUBLE-LAYER CAPACITORS

摘要

A series of pitch-based activated carbon fibers (ACFs), including micro- (from OG5A to OG20A) and mesoporous (MP60 and MP90) ACFs, were used as electrode materials in 1.0M Et_4NBF_4/PC electrolyte for electric double layer capacitors (EDLC). The relationship between the capacitances of carbon electrodes and their pore characteristics was demonstrated in detail. The results showed that the gravimetric capacitance C_g increased with the increase of surface area in general for all the samples investigated. However, the capacitance not only depended on the surface area, but also on the pore size distribution. The capacitance of samples (OG5A and OG7A) with small pore size was very low for the ion-sieving effect, and the surface capacitance for all the samples increased with the increase of mesopore fraction.