Electrochemical performance of supercapacitors with KOH activated mesophase carbon microbead electrodes

In this study mesophase pitch carbon microbeads (MCMB) were activated by KOH with various mass ratios (4:1, 6:1, and 8:1) and activation temperatures (600, 700, and 800 °C). The activated MCMB was used as the electrode materials for supercapacitors. The effects of the KOH/MCMB ratios and the activation temperatures on the surface characterization and electrochemical properties were investigated. A carbon dioxide adsorption instrument (Autosorb-1) was used to measure the specific surface area and micropore volume of the activated MCMB. The surface structure of carbon materials was observed by scanning electron microscopy (SEM). The chemical composition of the activated MCMB was determined by X-ray photoelectron spectroscopy (XPS). The electrochemical properties of the electric double layer capacitor were determined by cyclic voltammetry (CV) and galvanostatic charge/discharge cycling methods using 6 M KOH aqueous solution as the electrolyte. The activated MCMB K4-800 has the largest specific surface area (3115 m2/g) and micropore volume (1.063 cm3/g). The results indicate that the K4-800 shows the largest specific capacitance (279 F/g) at 2 mV/s.

► MCMBs were activated by KOH with various mass ratios and activation temperatures.
► The activated MCMB was used as the electrode materials for supercapacitors.
► The K4-800 activated MCMB has the largest specific surface area and micropore volume.
► The K4-800 activated MCMB shows the largest specific capacitance (279 F/g) at 2 mV/s.