Tin Based Alloys For Lithium Ion Batteries

The electrochemical behaviour of a standard electrodeposited equiatomic nickel-tin alloy has been tested. Such a material can be an interesting candidate to make thin film anodes for lithium ion batteries since it is deposited by a simple electroplating technique. Using standard deposition conditions, 3 mu m thick films of NiSn alloy were deposited onto copper current collectors. The electrochemical behavior of the electrodes suggests that the decomposition of the NiSn alloy occurs during the lithium insertion leading to the formation of nickel particles, followed by the formation of Li-Sn alloys. It is believed that the extraction of lithium during the discharge leads to the decomposition of the Li-Sn alloys. However, according to the structural characterizations performed on the samples, there is no clear evidence to support these reactions. Despite an interesting theoretical capacity of 682 mAh/g, the maximum capacity observed in the NiSn thin films was 77 mAh/g. This low value of the capacity is related to a very slow diffusion of lithium throughout the electrode.