Facile Synthesis of Rod-like Cu2−xSe and Insight into its Improved Lithium-Storage Property

A rod-like Cu 2− x Se is synthesized by a facile water evaporation process. The electrochemical reaction mechanism is investigated by ex situ X-ray diffraction (XRD). By adopting an ether-based electrolyte instead of a carbonate-based electrolyte, the electrochemical performance of Cu 2− x Se electrodes improved significantly. The Cu 2− x Se electrodes exhibit outstanding cycle performance: after 1000 cycles, 160 mA h g −1 can be maintained with a retention of 80.3 %. At current densities of 100, 200, 500, and 1000 mA g −1 , the capacity of a Cu 2− x Se/Li battery was 208, 202, 200, and 198 mA h g −1 , respectively, showing excellent rate capability. The 4-probe conductivity measurements along with electrochemical impendence spectroscopy (EIS) and cyclic voltammetry (CV) tests illustrate that the Cu 2− x Se electrodes display high specific conductivity and impressive lithium–ion diffusion rate, which makes the Cu 2− x Se a promising anode material for lithium–ion batteries. Graphical An ideal anode : A rod-like Cu 2− x Se is synthesized by water evaporation and its electrochemical properties in lithium–ion batteries using an ether-based electrolyte are studied and presented. Ex situ XRD is also used to investigate the electrochemical reaction mechanism.