Electrochemical Properties of Soluble CuCl·3TU Coordination Compound and Application in Electrolysis for Copper Foils

As the crucial current collector for lithium-ion batteries (LIBs), electrolytic copper foils are generally manufactured by electrodeposition in acidic copper sulfate solution. However, there are many disadvantages for traditional electrolytic copper foils, such as coarse grains, insufficient mechanical properties, and high energy consumption. In order to improve the performances of electrolytic copper foil, a novel cuprous electrodeposition system was developed in this study. A soluble cuprous coordination compound was synthesized. In addition, XPS, FT-IR spectrum, as well as single-crystal X-ray diffraction illustrated that thiourea coordinated with Cu(I) through S atom and therefore stabilized Cu(I) by the formation of CuCl·3TU. Importantly, the corresponding electrochemical behaviors were investigated. In aqueous solution, two distinct reduction processes were demonstrated by linear sweep voltammetry (LSV) at rather negative potentials, including the reduction of adsorbed state and non-adsorbed state. Moreover, the observed inductive loops in electrochemical impedance spectroscopy further confirmed the adsorption phenomenon. More significantly, the designed cuprous electrodeposition system could contribute to low energy consumptions during electrolysis. and produce ultrathin nanocrystalline copper foils with appropriate roughness. Consequently, the electrolysis method based on CuCl·3TU could provide an improved approach for copper foils manufacturing in advanced LIBs fabrication.