Composite electrodes of WO3 coating on mesocarbon microbeads of a supercapacitor

In this study, a composite electrode of a supercapacitor was fabricated by coating tungsten oxide (WO₃) onto mesocarbon microbeads with a high-specific surface area (2685 m² g⁻¹). Composite carbon was prepared through composite solution filtration and heat treatment. To determine the optimal processing parameters of the composite electrode, the effects of the temperature of the heat treatment and the concentration of carbon black (CB) on the capacitance properties of supercapacitors were investigated. The structural characteristics of composite carbon and electrodes were observed through composition analyses such as X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The capacitive performance of composite electrodes was evaluated using cyclic voltammetry (CV) in 1 M LiClO₄ electrolytic solution. The results revealed that the optimal composite electrode can be obtained using 1 M H₂O₄W, a heat-treatment temperature of 100 °C, and an addition of 25 wt% CB. The specific capacitance of the composite electrode was 194.8 F g⁻¹. The supercapacitor achieved an energy density and power density of 243.5 Wh kg⁻¹ and 69.0 kW kg⁻¹ (@0.15 A g⁻¹), respectively. In addition, the supercapacitor exhibited an excellent charge/discharge efficiency of 97.8%.