Electrochemical reactions of lithium with transition metal stannides

High-quality crystalline MSn2 (M = Cr and Co) thin films have been successfully fabricated by reactive pulsed laser deposition. The physical and electrochemical properties of the as-deposited thin films have been investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), galvanostatic cycling and cyclic voltammetry (CV). XRD measurement indicates that the as-deposited thin films prepared at 400 °C consisted mainly of MSn2 (M = Cr and Co) with a small quantity of metal tin. The specific reversible capacities of CrSn2 and CoSn2 thin film electrodes are found to be 467 mA h/g and 465 mA h/g, respectively. A mechanism involving an irreversible decomposition of MSn2 (M = Cr and Co) and a classical alloying process of Sn is proposed. MSn2 (M = Cr and Co) as the starting anode materials for conversion to the Li–Sn alloy can improve its electrochemical performance with high reversible capacity and good stable cycle.