Solvothermal synthesis of CuSe nanoplates for sodium storage

Sodium-ion batteries have emerged as a promising candidate for energy storage devices, due to abundant reserves. Transitional metal selenides have attracted wide attention due to their easy preparation and good electric conductivity. Here, a simple and facile solvothermal method was used to prepare hexagonal CuSe nanoplates without using expensive reagents and complicated processes. The electrochemical performances and underlying reactions of CuSe nanoplates as the anode material for sodium-ion batteries were investigated in detail. CuSe nanoplates are capable of fast Na storage. They deliver a reversible capacity of 183.5 mAh g−1 at a current density of 5 A g−1 and the capacity retention is ~97.4% after 800 cycles at 2 A g−1. Ex-situ X-ray diffraction (XRD) and selected area electron diffraction (SAED) show that CuSe underwent a conversion reaction, leading to Cu2−xSe in the first-charging process that then worked as the active material in the following cycles.