Synthesis of Copper-Doped MnO2 Electrode Materials by One-Step Hydrothermal Method for High Performance

By adjusting the amount of Cu(NO3)2·3H2O, Cu2+-doped birnessite ?-MnO2 spherical substances were synthesized by a simple hydrothermal synthesis process without any templates and surfactants. The structure, morphology, and specific surface area were characterized by XRD, SEM, TEM and BET. Further study shows that the 0.25 mmol Cu-doped MnO2 sample is expected to provide higher specific capacitance (636.3 F g-1 at 1 A g-1 current density) compared with pure δ-MnO2 (335.6 F g-1 at the current density of 1 A g-1) and long-term cyclic stability (105.01 % capacitance retention after 1500 cycles at current density of 5 A g-1). Electrochemical impedance spectroscopy proved the low resistance characteristics of the prepared samples. All the results show that the copper-doped MnO2 material is not only low cost, but also of excellent electrochemical performance, thus possesses great potential in future energy development.