Rectangular microscale carbon tubes with protuberant wall for high-rate electrochemical capacitors

Abstract: A series of novel rectangular microscale carbon tubes with protuberant wall are prepared by polyaniline with hollow carbon nanospheres (HCNSs) as templates. By changing mass ratio of ammonium persulfate to HCNSs, the morphology and the tube dimension of those samples can be controlled. Chemical activation with KOH at 1123K results in a large specific surface area (SSA), ranging from 1680 to 2415m2 g−1, and big pore volumes, ranging from 1.274 to 1.550cm3 g−1. Electrochemical tests show that the special morphology effectively increases charge–discharge rate. The maximum capacitance reaches 230Fg−1 at a potential scan rate of 50mVs−1, and 50% of which even can be remained at a scan rate of 1000mVs−1. The electrochemical impedance tests show that the frequency exceeds 10Hz and even reaches up to 15Hz for the optimum sample corresponding to the 50% of the maximum capacitance, which is intensely higher than 1Hz for common porous carbon. [Copyright &y& Elsevier]