Copper sulfides and their composites for high-performance rechargeable batteries

Copper sulfides (Cu_xS) are widely used as the promising electrode materials for secondary batteries because of the rich abundance, low cost, excellent capacity (～337/560 mA h/g for Cu₂S/CuS) as well as favorable electrical conductivity (10^?3 S/cm). Moreover, nanostructure designing and compounding with other conductive materials can enhance the electrochemical performance of Cu_xS. In this review, the up-to-date progress in the synthesis method as well as the application for secondary batteries (lithium-ion batteries, lithium-sulfur batteries, sodium-ion batteries, magnesium-ion batteries, and so on) of Cu_xS and their relevant composites have been discussed detailly. In the end, the challenges, feasible strategies, and application prospects for the Cu_xS are also summarized.