Cu-based materials as high-performance electrodes toward electrochemical energy storage

Cu-based materials, including metal Cu and semiconductors of Cu2O and CuO, are promising and important candidates toward practical electrochemical energy storage devices due to their abundant, low cost, easy synthesis and environmentally friendly merits. This review presents an overview of the applications of Cu-based materials in the state-of-art electrochemical energy storage, including both lithium-ion batteries and supercapacitors. The synthesis chemistry, structures and the corresponding electrochemical performances of these materials are summarized and compared. During chemical synthesis and electroactive performance measurement of Cu-based materials, we found that Cu-Cu2O-CuO sequence governs all related transformations. Novel water-soluble CuCl2 supercapacitors with ultrahigh capacitance were also reviewed which can advance the understanding of intrinsic mechanism of inorganic pseudocapacitors. The major goal of this review is to highlight some recent progresses in using Cu-based materials for electrochemical energy storage.