Controllable synthesis of various kinds of copper sulfides (CuS, Cu7S4, Cu9S5) for high-performance supercapacitors

Abstract

Three types of copper sulfides including CuS, Cu₇S₄ and Cu₉S₅ were successfully synthesized at different concentrations of ethylenediamine in a liquid phase synthesis process. The whole shape evolution of Cu₇S₄ microstructures could be manipulated by adjusting the concentration of ethylenediamine. This study indicates that the coordination chemistry of ethylenediamine ligands and copper cations exerts vital effects on the formation of the dendritic structure. Furthermore, experimental conditions such as the reaction temperature and time are also observed to have an impact on the morphology of copper sulfides. The structures of Cu₇S₄ with snowflake-like morphology provided special paths for ion diffusion. Therefore, apart from the excellent discharge rate and good stability, Cu₇S₄ also exhibits a high specific capacitance of 1303.01 F g⁻¹ at a current density of 5 A g⁻¹.