The effect of the microstructure of mesophase-pitch-based activated carbons on their electrochemical performance for electric double layer capacitors

Activated carbons(ACs) prepared from mesophase pitch and carbonized mesophase pitch by KOH activation were used to fabricate electrodes for electric double layer capacitors.Nitrogen adsorption at 77 K was used to characterize the specific surface area and pore structure of the ACs,which showed a bimodal pore size distribution.The performance of the ACs in an organic electrolyte(1 mol/L of Et4NBF4 in propylene carbonate) was investigated with voltage sweep cyclic voltammetry and constant current charge-discharge cycling.Results show that the capacitance of the ACs not only depends on the surface area and pore size distribution,but also on carbonization treatment.SEM images show that the AC particles from carbonized pitch are formed by stacking of layered slices,which favors an infiltration of solvent into the inner surface of the carbon and improves the capacitance per unit area of micropores.