MnO2 Films deposited on CuO nanomaterials as electrode materials for supercapacitors

In this paper, CuO/MnO2 composites with different morphology were successfully fabricated by simple and economical electrodeposition and successive ionic layer adsorption and reaction (SILAR) method as electrode materials for supercapacitors (SCs). The spherical and wheat-shaped CuO/MnO2 composites were obtained by changing the deposition voltage. The wheat-shaped CuO/MnO2 composite electrodes exhibited better electrochemical performance than the spherical. Its areal capacitance is up to 261.4 mF/cm2 at a current density of 1 mA/cm2 in 1 M Na2SO4 electrolyte and the capacitance retention reaches 90% after 1000 charge-discharge cycles. The symmetric aqueous SCs was then assembled with wheat-shaped CuO/MnO2 as positive and negative electrode materials respectively. The SCs exhibited not only outstanding specific capacitance of 152.7 mF/cm2 at 1 mA/cm2, but also good cycling stability of 74.2% after 500 charge-discharge cycles. Furthermore, its operating voltage window reaches 1.6 V, which results in an outstanding energy density of 54.3 μWh/cm2 and a power density of 5040 μW/cm2. This strategy of changing the morphology of materials by changing the deposition voltage provides an ideal scheme for improving the properties.