Facile Synthesis of Rod-like Cu2-x Se and Insight into its Improved Lithium-Storage Property.

A rod-like Cu2-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 Cu2-x Se electrodes improved significantly. The Cu2-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 Cu2-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 Cu2-x Se electrodes display high specific conductivity and impressive lithium-ion diffusion rate, which makes the Cu2-x Se a promising anode material for lithium-ion batteries.