3D hierarchical CuS microflowers constructed on copper powders-filled nickel foam as advanced binder-free electrodes

Abstract A novel strategy, consisting of sonication-assisted filling step followed by a chemical-bath surface sulfidization process, was designed to fabricate 3D hierarchical CuS microflowers constructed on copper powders-filled nickel foam (Cu@CuS–NF) as advanced binder-free electrodes for high-performance supercapacitors. Scanning electron microscope, powder X-ray diffraction and X-ray photoelectron spectroscopy techniques were employed to confirm the microstructure and composition. Electrochemical measurements demonstrated that the Cu@CuS–NF electrode has highly improved capacitance with an ultra-high area capacitance of 11.4 F cm−2 at a high current density of 90 mA cm−2. Also, the Cu@CuS–NF electrode has superior cycling stability with more than 100% retention of the initial area capacitance after 3000 cycles at 180 mA cm−2. The excellent electrochemical performance can be mostly attributed to a combination of the ultra-large loading area and very good electroconductive network formed from copper powders filling inside nickel foam. Our work opens a new door to engineering ultra-high-performance nickel-foam-based electrodes for electrochemical devices including water splitting and energy storage/conversion.