Boosting the Capacitor Performance of the Metal Organic Frameworks Derived V₂O₅ Nanoflower by Cu Doping

Due to its ultrahigh theoretical capacitance, vanadium pentoxide (V₂O₅) is considered to be a valid candidate for advanced supercapacitors. However, because of the low electron/electrolyte transfer rate, the capacitive performance still remains to be improved. In this report, Cu doping is adopted to improve the capacitive performance by a two-steps strategy consisting of microwave-assisted solvothermal and postannealing treatments. The electrochemical results indicate that the Cu doping was beneficial for improving the specific capacitance, extending the potential window, and improving the rate ability and long-term stability of V₂O₅. Furthermore, the mechanism for the performance improvement is explained in detail by combining theoretical calculation and experiments. The results indicated that, compared with that of undoped V₂O₅, the larger interplanar spacing, better electrical conductivity, a larger proportion of V³⁺/V⁴⁺, and more abundant oxygen vacancies result in an improved capacitive performance. Our proposed Cu-doped V₂O₅ (Cu-V₂O₅) can be used as both a positive electrode and a negative electrode for the assembly of the symmetric supercapacitor, which can be used as an energy storage device for light emitting diode lamps.