Single-phase Cu-Sn intermetallics were used to investigate their phase transformations during lithiation/delithiation, together with their negative-electrode properties. The stoichiometric Cu-Sn samples were prepared as thermodynamically warranted phases using a reduction-diffusion method with controlled potentials. Potentiostatic lithiation tests suggested that Cu3Sn directly changes into LixSn, while Cu6Sn5 becomes Li2CuSn before LixSn forms. We also revealed that separation from Li2CuSn into Cu and LixSn occurs at +0.11 to +0.10 V vs. Li. Additionally, charging/discharging tests with cutoff potentials of +1.5 V to +0.11 V showed better cycling performance than that with +1.5 V to +0.00 V. probably due to the suppression of LixSn formation. Such a tendency can be expected in other Cu6Sn5 electrode materials. (C) 2013 Elsevier Ltd. All rights reserved.