Enhancement of the electrochemical properties of vanadium dioxide via nitrogen-doped reduced graphene oxide for high-performance supercapacitor applications

A one-step solvothermal approach was used to integrate nitrogen-doped reduced graphene oxide into vanadium dioxide (VO2) to prepare a V@XN-G (where X = 24, 48 and 96 and is the mass of urea as the nitrogen (N) source) nanocomposite material. After optimization, V@48N-G showed better performance with a specific capacitance of 197.4 F g(-1) at 0.5 A g(-1) in a wide working potential window of 0.0-0.8 V vs. silver/silver chloride and was adopted as a positive electrode. Thus, cocoa waste-based activated carbon (ACC) was investigated and considered a negative electrode in assembling an asymmetric full-cell V@48N-G//ACC. The device exhibited good specific energy and power of 28.8 W h kg(-1) and 425.1 W kg(-1), respectively, at a voltage window and specific current of 1.7 V and 0.5 A g(-1), respectively. Its cycling stability resulted in a Coulombic efficiency (CE) and capacitance retention (CR) of 99.8% and 73%, respectively, over 10 000 galvanostatic charge/discharge cycles at 10 A g(-1). Therefore, the V@48N-G//ACC device shows excellent electrochemical performance and is suitable for energy storage application technology.