Synthesis and Electrochemical Properties of Copper Oxides/Co-Mn Hydroxides Composite Nanowire Arrays on Copper Foam

In recent years, design and fabrication of advanced electrode materials to improve the energy density and power density of supercapacitors (SCs) have been the focus of energy storage fields. Rational constructing core-shell nanostructures on conductive substrate holds a promising approach for developing high-performance SCs. In this work, the hierarchical copper oxides/Co-Mn layered double hydroxides (Cu_xO/Co-Mn LDH) composite nanowire arrays grown on copper foam were fabricated by a simple thermal oxidation with potentiostatic electrodeposition. The composites with different electrodeposition time were obtained. The structure and morphology of composites were investigated via field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of composites were investigated with cycle voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectrum (EIS). The results showed that thin layer of interdigitated Co-Mn LDH was deposited uniformly on the surface of Cu_xO nanowires with the deposition of 18 min. The length of the composite nanowires was 5~10 μm and the diameter was around 50 nm. Interlaced Co-Mn LDH nanosheets deposited on Cu_xO nanowires could effectively provide large electroactive area for fast and reversible reaction to enhance the capacitance, while Cu_xO nanowires improved the mechanical robustness of the active materials on Cu foam to ensure their structural stability during redox reaction. Meanwhile, the composite structures on Cu foam could be directly used as electrode materials without addition of polymer binder or additive and thus decrease internal resistance. Consequently, the composite electrode material exhibited a specific capacitance of 305.0 F/g at 1 A/g and the capacitance retention was 70.7% at 10 A/g and good cycling stability (80.4% capacitance retention after 2 000 cycles at 1 A/g). These attractive results demonstrated that core-shell Cu_xO/Co-Mn LDH with hierarchical architecture could be promising electrode materials for high-performance supercapacitors.