The Cu-Sn alloy electrode was prepared by a one-step electrodepositing method using rough Cu foil as the substrate, and was determined as the intermetallic composite of Cu6Sn5 using an X-ray diffraction (XRD) method. The electrode surface morphology was analyzed by scanning electron microscopy (SEM) which displayed “small islands” structure with many nano-particles on it. The first discharge and charge capacities were determined as 461 and 405 mAh•g－1, respectively. Electrochemical impedance spectra (EIS) indicated that there appeared three arcs in the Nyquist plots respectively representing the impedance of solid electrolyte interphase film, charge transfer and phase transformation in the first lithiation, and their evolutive principles were also investigated.

Key words: lithium ion battery, anode, Cu6Sn5 alloy, electrochemical impedance spectroscopy, phase transformation