Effect of aqueous electrolytes on the electrochemical behaviors of ordered mesoporous carbon composites after KOH activation as supercapacitors electrodes

Abstract

The electrochemical behaviors of ordered mesoporous carbon composites after KOH activation as supercapacitors electrodes in various electrolytes, such as acidic, alkaline, neutral aqueous solutions, are thoroughly investigated by cyclic voltammetry, galvanostatic charge/discharge, cyclic life, rate ability, leakage current and electrochemical impedance spectroscopy. These results demonstrate that the structures of ordered mesoporous carbon composites, as well as hydrated ionic radius, conductivity and ionic mobility of electrolytes are relevant to their electrochemical performances. The electrochemical performances of ordered mesoporous carbon/graphene composites (OMC/G) in different electrolytes are in deeply comparison with those of ordered mesoporous carbon composites (OMC) without graphene. It is found that ordered mesoporous carbon composites attain better specific capacitance and rate ability in acidic and alkaline electrolytes than those in neutral electrolytes. However, when the operating voltage increases up to 1.7 v, OMC/G composites in neutral aqueous electrolytes can achieve the best energy density and power density up to 27.23 Wh kg−1 and 7528.5 W kg−1, respectively.