Study of ash-removed porous carbon loaded manganese dioxide and its electrochemical properties

Heteroatom participation is considered to be the most effective method to improve the electrochemical performance of supercapacitors. In this study, MnO₂/AR-PC was prepared by one-step activation method using KOH as activator and KMnO₄ as manganese source, and the pore structure was characterized, which showed that the specific surface area (SSA) of AR-PC was 1710.309 m²g⁻¹, while that of MnO₂/AR-PC was 936.487 m² g⁻¹. The specific surface area calculated using BET N₂ adsorption–desorption isotherm. Furthermore, in the three-electrode system with 6 M KOH solution as electrolyte, the specific capacitance of the samples was as high as 658 F g⁻¹ at a current density of 0.5 A g⁻¹, which was 72% higher than that of AR-PC. In the two-electrode system, the specific capacitance of MnO₂/AR-PC at 0.5 A g⁻¹ was 323 F g⁻¹ with a power density of 500 W kg⁻¹ and an energy density of 44.87 Wh kg⁻¹. Even at a high power density of 20 KW kg⁻¹, the energy density was still 21.67 Wh kg⁻¹. It is concluded from these results and related literature that the MnO₂ content has a great influence on the electrochemical performance, which suggests that MnO₂/PCs may be a promising electrode material for supercapacitors (SCs) if the capacitance retention can be improved.