Electrochemical properties of mechanochemically synthesized CoSn₂-C nanocomposite-type anode material for Li-ion batteries

CoSn₂-C nanocomposites with Sn₃₀Co₁₅C₅₅ average formula, consisting of CoSn₂ nanocrystals dispersed in a disordered carbon matrix were obtained by a mechanochemical method from CoSn₃, Co and graphite, and for comparison, by a typical mechanical milling. Crystal structure and microstructure of the materials were characterized by XRD, SEM and TEM methods, while electrochemical performance, electrochemical impedance spectra and cyclic voltammetry were tested in lithium cells. Both nanocomposites showed a high initial coulombic efficiency (79%), quite stable cycling performance and excellent rate capability, however, the mechanochemically prepared CoSn₂-C exhibited significantly higher reversible capacity (600 mAh·g^{- 1}). The obtained results proved that the mechanochemical method is a simple and effective way of manufacturing anode materials from Sn-Co-C system for application in high-energy-density lithium ion batteries.