Electrical double layer capacitors with activated sucrose-derived carbon electrodes

Electrical double layer capacitors (EDLCs) with activated sucrose-derived carbons (ASCs) as electrodes are reported. The carbons were prepared by the pyrolysis of sucrose followed by the activation with CO2 gas for 1–5 h at 900 °C to tune the pore size distribution and the specific surface area (SSA). The porosity of the ASCs has been characterized using N2 and CO2 adsorption measurements. The activation increased the SSA from ∼200 to 3000 m2 g−1 and produced pores mostly in the 0.4–2 nm range. The pyrolysis of sucrose without CO2 activation produces a carbon with specific capacitance as low as 4 F g−1, whereas selected ASCs exhibit specific capacitance in excess of 160 F g−1 and excellent frequency response in a two-electrode EDLC cell with 1 M H2SO4 electrolyte. The activation time of 4 h resulted in the most promising electrochemical performance. Excellent ASC stability was confirmed by extensive electrochemical characterization after 10,000 charge–discharge cycles.