Highly mesoporous carbonaceous material of activated carbon beads for electric double layer capacitor

The activated carbon beads (ACB) are prepared by a new preparation method, which is proposed by mixing the coal tar pitch and fumed silica powder at a certain weight ratio and activation by KOH at different weight ratios and different temperatures. The BET surface area, pore volume and average pore size are obtained based on the nitrogen adsorption isotherms at 77 K by using ASAP 2010 apparatus The results show that our samples have much high specific surface area (SSA) of 3537 m(2) g(-1) and high pore volume value of 305 cm(3) g(-1). The percentage of mesopore volume increases with the weight ratio of KOH/ACB ranging from 4% to 72% The electrochemical double layer capacitors (EDLCs) are assembled with resultant carbon electrode and electrolyte of 1 mol L-1 Et4NBF4/PC. The specific capacitance of the ACB sample could be as high as 191 7 F g(-1) by constant current charge/discharge technique, indicating that the ACB presents good characteristics prepared by the method proposed in this work. The investigation of influence of carbon porosity structure on capacitance indicates that the SSA plays an important role on the capacitance and all the pore sizes of less than 1 mu. from 1 to 2 nm and larger than 2 nm contribute to the capacitance Mesopore structure is beneficial for the performance at high current density. (C) 2010 Elsevier Ltd All rights reserved