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

• CoSn2-C nanocomposite (Sn30Co15C55) was prepared by a simple mechanochemical route.
• CoSn2 nanocrystals dispersed in carbon matrix ensure good cycleability.
• Capacity of CoSn2-C prepared by mechanical alloying is higher than the milled one.
• Apparent lithium diffusion coefficient in CoSn2-C is of the order of 10− 11 cm2·s− 1.

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.