Resorcinol-formaldehyde based porous carbon as an electrode material for supercapacitors Original Research Article

Porous carbon materials were prepared using resorcinol and formaldehyde catalyzed by KOH in a sol–gel process followed by carbonization, during which the KOH serves as an activating agent and generates pores mainly located in the micropore range. With an increase of mass ratio of KOH to resorcinol from 1 to 4, both the specific surface area and the pore volume of the carbons increased, from 522 to 2760 m2/g and 0.304 to 1.347 cm3/g, respectively, but the average pore diameter decreased from 4.4 to 2.5 nm. Samples were investigated as electrode materials in supercapacitors and the relevant electrochemical behavior was characterized by cyclic voltammetry, electrochemical impedance spectroscopy and constant current charge–discharge experiments using 30% KOH aqueous solution as electrolyte. The highest specific capacitance of up to 294 F/g was obtained at a current density 1 mA/cm2 for the sample with mass ratio of KOH to resorcinol of 2. Only a slight decrease in capacitance for the same sample, from 294 to 242 F/g, was observed when the current density increased from 1 to 30 mA/cm2. The specific capacitance only decayed 3% at a current density 30 mA/cm2 after 1000 cycles, which indicates that the sample possesses excellent power property and cycle durability.