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MnO 2 @PCs (porous carbons) exhibiting high energy and power density are utilized as supercapacitor electrodes and prepared by impregnating porous carbons (PCs) derived from coal tar pitch (CTP) with KMnO 4 as the manganese source. This study systematically investigates the impact of MnO 2 loading on the microstructure and electrochemical performance in sample. It is found that the specific surface areas (SSA) of all MnO 2 @PCs significantly reduced compared to that of the PCs 2789 m 2 g −1 . The suggested mechanism might be a combination of the energy storage mechanism of dual layer capacitors with pseudo‐capacitance due to redox reactions of MnO 2 . Notably, MnO 2 @PCs‐0.0075 exhibits a maximum SSA of 1454.62 m 2 g −1 . Its specific capacitance reached 561 F g −1 at 0.5 A g −1 , while the capacitance of the PCs increased by 81.5% to 309 F g −1 . Remarkably, the Coulombic efficiency remained at 100%. The power density and energy density are determined in a two‐electrode test system to be 0.5 kW kg −1 and 58.01 Wh kg −1 , respectively, at 0.5 A g −1 . Concluding from these results and related literature, the MnO 2 content significantly influences the electrochemical performance, suggesting that MnO2@PCs‐0.0075 could be a promising supercapacitor (SC) electrode material, provided its capacitance retention is enhanced.
Cao et al. (Sun,) studied this question.