A modified carbothermal reduction method for preparation of high-performance nano-scale core/shell Cu6Sn5 alloy anodes in Li-ion batteries

Core–shell structured, carbon-coated, nano-scale Cu6Sn5 has been prepared by a modified carbothermal reduction method using polymer coated mixed oxides of CuO and SnO2 as precursors. On heat treatment, the mixture oxides were converted into Cu6Sn5 alloy by carbothermal reduction. Simultaneously, the remnants carbon was coated on the surface of the Cu6Sn5 particles to form a core–shell structure. Transmission electron microscope (TEM) images demonstrate that the well-coated carbon layer effectively prevents the encapsulated, low melting point alloy from out flowing in a high-temperature treatment process. Core–shell structured, carbon coated Cu6Sn5 delivers a reversible capacity of 420 mAh g−1 with capacity retention of 80% after 50 cycles. The improvement in the cycling ability can be attributed to the fact that the carbon-shell prevents aggregation and pulverization of nano-sized tin-based alloy particles during charge/discharge cycling.

Research highlights▶ A modified carbothermal method was used to prepare nano core–shell Cu6Sn5/C. ▶ Hydrophobic nano-CuO and SnO2 as precursors. ▶ Cu6Sn5/C showed improved electrochemistry performance. ▶ TEM images demonstrated well-coated carbon layer on Cu6Sn5 particles.