Synthesis of copper sulfide nanowire arrays for high-performance supercapacitors

A copper sulfide (CuS) nanowire (NW) array with a hierarchical nanoarchitecture is directly fabricated on copper foil using a simple and cost-effective liquid-solid reaction. The morphology and microstructure of CuS NW arrays are systematically investigated by scanning electron microscopy, X-ray diffraction spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Electrochemical results obtained at various polarization cut-offs and scan rates reveal that the CuS NW array shows highly reversible features and favorable rate abilities. Most importantly, the excellent specific capacitance that is achieved in CuS NW nanoelectrodes is as high as 305 F g−1, which is one of the high value reported CuS-based pseudocapacitors. An energy density of 70.8 Wh kg−1 is obtained at a current density of 2 mA cm−2. The CuS NW nanoelectrode has superior cycling stability with 87% retention of initial specific capacitance after 5000 cycles.