Effect of manganese dioxide on supercapacitive behaviors of petroleum pitch-based carbons

•Porous carbon was obtained by KOH activation at the temperature of 850 °C.•Nano-MnO2 was loaded on the surface of petroleum pitch by chemical reaction.•MnO2 enhanced the electrochemical performance of petroleum pitch-based carbon.

Petroleum pitch is activated with KOH, and different concentrations of MnO2 nanoparticles are impregnated on petroleum pitch-based activated carbons with a simple chemical reaction. Fiber-like MnO2 is successfully grown on the surface of the activated carbons. The specific capacitance of A-PP-0.02 is 92 F/g in 0.5 M Na2SO4. This increase is due to the appropriate combination of the pore structure and MnO2 that allows electrolyte ions to easily reach the electrode. The results indicate that MnO2 is a promising metal oxide for increasing the specific capacitance of petroleum pitch-based activated carbons and can overcome the low energy density.