High Coulomb Efficiency Sn-Co Alloy/rGO Composite Anode Material for Li-ion Battery with Long Cycle-Life

The low cycle performance and low Coulomb efficiency of tin-based materials confine their large-scale commercial application for lithium-ion batteries. To overcome the shortage of volume expansion of pristine tin, Sn-Co alloy/rGO composites have been successfully synthesized by chemical reduction and sintering methods. The effects of sintering temperature on the composition, structure and electrochemical properties of Sn-Co alloy/rGO composites were investigated by experimental study and first-principles calculation. The results show that Sn-Co alloys are composed of a large number of CoSn and trace CoSn₂ intermetallics, which are uniformly anchored on graphene nanosheets. The sintering treatment effectively improves the electrochemical performance, especially for the first Coulomb efficiency. The first charge capacity of Sn-Co alloy/rGO composites sintered at 450 °C is 675 mAh·g^-1, and the corresponding Coulomb efficiency reaches 80.4%. This strategy provides a convenient approach to synthesizing tin-based materials for high-performance lithium-ion batteries.