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

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 92F/g in 0.5M 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.