Electrochemical characterization of micro-sized Sb/SnSb composite anode

Micro-sized Sb/SnSb composite synthesized by carbothermal reduction shows a high-specific capacity (ca. 650 mAh/g), a low initial irreversible capacity loss (∼14%) and a good cycling stability, which are ascribed to the lower specific surface area and the polycrystalline feature of the synthesized Sb/SnSb particles. The large amount of grain-boundaries inside the Sb/SnSb particles can relieve the mechanical stress, originated from the big volume changes upon lithiation and delithiation, by grain-boundary slipping, and thus maintain the structure stability of electrode. The electrode reaction process was characterized by cycling voltammetry and AC impedance techniques. The results indicate that some local cracking of the SEI film may occur due to the large volume changes of active materials and the new film formation takes place. This will not only consume some lithium and thus produce the irreversible capacity loss during cycling process, but also result in decreased SEI film resistance and charge transfer resistance.