Preparation of binder-free CuO/Cu2O/Cu composites: a novel electrode material for supercapacitor applications

Abstract

Cuprous(I) oxide (Cu₂O) carries high theoretical specific capacitance (2247.6 F g⁻¹), however, the amount of research about the supercapacitive performance of Cu₂O is relatively small compared with other transition metal oxides. A composite of metal and metal oxide could improve the electrochemical performance efficiently. In this work, the results of XRD and XPS demonstrate that CuO/Cu₂O/Cu is prepared successfully via a facile, eco-friendly, one-step template-free growth process. SEM figures show that cubic CuO/Cu₂O/Cu uniformly and densely covers a skeleton of nickel foam. The binder-free CuO/Cu₂O/Cu electrode exhibits excellent supercapacitive performance with a high specific capacitance of 878 F g⁻¹ at a current density of 5 mA cm⁻² (1.67 A g⁻¹), when the current density is enlarged ten times (50 mA cm⁻² (16.7 A g⁻¹)), the specific capacitance still remains at 545 F g⁻¹. Furthermore, we have first successfully constructed a CuO/Cu₂O/Cu//AC asymmetric supercapacitor, which can achieve an energy density of 42 W h kg⁻¹ at a power density of 0.44 kW kg⁻¹. The good electrochemical performance and simple accessibility prove that the as-prepared CuO/Cu₂O/Cu/NF electrode has a potential application in electrochemical capacitors.