High-Potential Aqueous Asymmetric Supercapacitor Based on 2D Molybdenum Disulfide and Vanadium Pentoxide Electrodes

A wide-operating-voltage asymmetric supercapacitor (ASC) based on an aqueous electrolyte has great promise in the current energy storage technologies by providing better energy density, power density, safety, cost effectiveness, and long cycle life. Herein, the fabrication of an ASC using a 2D transition metal dichalcogenide (molybdenum disulfide (2D MoS2)) and a transition metal oxide (vanadium pentoxide, V2O5) as the negative and positive electrode, respectively, was demonstrated. The electrochemical and galvanostatic charge–discharge analysis of both positive (V2O5) and negative electrodes (2D MoS2) was carried out in a three-electrode setup. The results show stable operating potentials of −0.9 and 1.0 V for MoS2 and V2O5 electrodes, respectively. By combining these positive and negative electrodes in a 1 M sodium sulfate (Na2SO4) aqueous electrolyte, the developed ASC reveals a wide operating potential (2.0 V). The electrochemical analysis of the ASC in a stable operating potential of 1.4 V gives an areal capacitance and energy density of 30 mF/cm2 and 8.2 μWh/cm2, respectively, at a scan rate of 1 mV s–1. The performance of the ASC was analyzed for 5000 continuous charge–discharge cycles at a higher current of 3.5 mA. After 5000 cycles, the ASC exhibits more than 80% capacitance retention with a specific capacitance of 0.85 mF/cm2.