Preparation and characterization of tin-graphite composite material with carbothermal reduction

Tin-graphite composite material was prepared by carbothermal reduction method from SnO₂ and graphite in Ar atmosphere. The material was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Electrochemical lithium insertion-extraction character of the material was determined by constant current charge-discharge, slow scanning cyclic voltammetry (CV), and electrochemical impedance spectrometry (EIS) methods. The results of XRD and SEM show that spherical metallic Sn particles reduced from SnO₂ are separated in graphite. The initial lithium insertion-extraction special capacities of the material can reach to 887 and 615 mA·h/g respectively, and initial Coulombic efficiency 69%. Even after 15 cycles, tin-graphite composite material still shows high extraction special capacities as 387 mA·h/g, the high capacity retention at the 15th cycle as 63% and an excellent cycle performance with only 2.5% capacity loss per cycle.