Influence of Particle Size on Rate Performance of Mesoporous Carbon Electric Double-Layer Capacitor (EDLC) Electrodes

Herein, mesoporous carbon materials with different particle sizes were prepared using the direct templating method. To control particle size, the concentration of surfactant/silicate dissolved in aqueous solution was varied. According to a decrease in the concentration, a larger surface area and a smaller particle size were observed, whereas pore size and connectivity remained invariant. From the investigation of electric double-layer capacitor performance, specific capacitance was proportional to surface area. From electrochemical impedance spectroscopy analysis, a resistance relevant to pseudocapacitive faradaic reaction on electrode surface became larger, but a decrease in the total electrolyte resistance in pores was observed as a function of particle size decrease. This contradictory behavior of two resistances resulted in an existence of optimal particle size for the minimum equivalent series resistance (1.40 Omega cm(2)), which was comparable with the ordered mesoporous carbon electrode from the MCM-48 template. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3490638] All rights reserved.