In our previous work, an amorphous Sn-Co alloy film prepared by electrocodeposition on Cu foil with rough surface was found to transform to a new phase structure during charge-discharge cycle to show more stable reaction with lithium. In this work, we prepared Sn-Co film on copper current collector which originally included the new phase structure, and examined its electrochemical and structural properties by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, extended X-ray absorption fine structure, and magnetic susceptibility measurement. Influence of the phase transformation on the cyclability is discussed in terms of adhesion between the film and current collector. (c) 2006 The Electrochemical Society.