Preparation of mesoporous carbon microsphere/activated carbon composite for electric double-layer capacitors

Mesoporous carbon microspheres(MCMs) with specific surface area and diameter of 1 850 m2/g and 1 μm,respectively,were synthesized using the solvothermal method.When mass fraction 20% of these were added to a high surface area-activated carbon(HSAC: 3 200 m2/g) its interfacial resistance and ion diffusion resistance decreased significantly.The specific capacitance of the composite electrode is 230 F/g in 6 mol/L KOH electrolyte,whereas those of pure HSAC and MCMs are only 190 and 148 F/g,respectively,at a high current density of 12 A/g.The improvement in electrochemical performance of the HSAC electrode at high current densities is attributed to the small particle diameter,mesoporous structure and high specific surface area of the added MCMs.