Synthesis of Sn-Sb-Cu-C and Sn-Co-C and investigation of them using as anode material for lithium ion batteries

Sn based metal alloy compounds are shown as alternative instead of graphite anode materials for lithium ion batteries. This thesis investigates the synthesis and characterization of Sn-based lithium-ion battery anodes. SnSbCu-C nanocomposite alloy have been synthesized for the first time on by a mechanochemical process involving high-energy mechanical milling. Characterization of the nanocomposite by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive x-ray spectroscopy (EDS) reveals that this alloy is composed of crystalline nanoparticles of SnSbCu dispersed in a matrix of carbon. Also cyclic voltammetry, chronopotensiometry and impedance tests are applied for electrochemical characterization of materials. The XRD analysis confirmed that the Sn-Sb-Cu-C is composed of Sn, SnSb alloy, Cu and C. As the anode materials, Sn45Sb16Cu4C35 composite shows a high reversible capacity of 527.3 mA h g-1 with capacity retention of 70% after 200 cycles at a current density of 50 mA g-1, which is much better than those of the commercial Sn-Co-C composite (with same Sn and C amounts to the former composite; reversible capacity of 350.7 mA h g-1 with capacity retention of 46% after 200 cycles at the same current density). This superior performance of the Sn45Sb16Cu4C35 composite for LIBs is attributed to the Cu content to guarantee the high electronic conductivity. Furthermore, SnSb alloy content in the composite can relieve volume changes and improve the mechanical stability of the anode due to its stepwise lithium insertion mechanism. The results indicate that Sn45Sb16Cu4C35 is a promising candidate for the anode of LIBs.