Electrochemical lithiation reactions of Cu6Sn5 and their reaction products

Electrochemical lithiation reactions of a thin-film Cu6Sn5 alloy electrode were studied in an organic carbonate electrolyte containing LiPF6 salt using conventional charge-discharge techniques and analysing the reaction products by transmission electron microscopy (TEM). A partially lithiated phase, LixCu6Sn5, (where x < 3), that appears to be a solid solution of Li in the basic crystal structure of Cu6Sn5 was identified by TEM in a Cu6Sn5-alloy electrode discharged at 0.5 V. At a further cathodic potential of 0.3 V the formation of Li2CuSn was observed in agreement with earlier reports. At the potential close to that of the Li-metal plating (similar to0.01 V discharge cut-off) Li7Sn2 phase was identified as the main composition without observation of a further lithiated phase beyond Li7Sn2. (C) 2004 Elsevier B.V. All rights reserved.