The consumption of electrical energy grows alongside the development of global industry. Generating energy storage has become the primary focus of current research, examining supercapacitors with high power density. The primary raw material used in supercapacitor electrodes is activated carbon (AC). To improve the performance of activated carbon, we used manganese dioxide (MnO2), which has a theoretical capacitance of up to 1370 Fg−1. The composite-based activated carbon with a different mass of 0–20% MnO2 was successfully introduced as the positive electrode. The asymmetric cell supercapacitors based on activated carbon as the anode delivered an excellent gravimetric capacitance, energy density, and power density of 84.28 Fg−1, 14.88 Wh.kg−1, and 96.68 W.kg−1, respectively, at 1 M Et4NBF4, maintaining 88.88% after 1000 test cycles.
