A high-performance pseudocapacitive electrode based on CuO-MnO.sub.2 composite in redox-mediated electrolyte

In the present work, a simple and cost-effective precipitation approach was carried out to fabricate CuO nano-needle, and its electrochemical performance was evaluated in a redox-mediated electrolyte (2 M KOH and 0.3 M K.sub.3Fe(CN).sub.6). A high specific capacitance of 2519 F/g was recorded at a specific current of 8 A/g. However, the electrode suffered from poor rate capability as the specific capacitance was rapidly decreased to 100 and 1 F/g when the specific current was increased to 30 and 50 A/g, respectively. The CuO nanoparticles were further modified with MnO.sub.2 by a hydrothermal method, and the resulting CuO-MnO.sub.2 (CMO6) electrode delivered a high specific capacitance of 539 F/g even at very high specific current of 50 A/g. The as-synthesized electrode materials were structurally and morphologically characterized using X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The electrochemical performances of the CuO and MnO.sub.2-CuO composites have been examined in detail.