Pitaya-like Sn@C nanocomposites as high-rate and long-life anode for lithium-ion batteries.

In this article, we report on the preparation of the pitaya-like Sn@C nanocomposite with an aerosol spray pyrolysis and its application as a high-rate and long-life anode material for lithium-ion batteries. The structure and morphology analysis of the as-prepared Sn@C nanocomposite shows that Sn nanoparticles with a size of about 8 nm are homogeneously dispersed in the spherical carbon matrix (denoted as Sn8@C). The Sn8@C nanocomposite exhibits an initial discharge capacity of 1007.1 mA h g(-1) and maintains a reversible capacity of 910 mA h g(-1) after 180 cycles at 200 mA g(-1) (0.305 C). A capacity of 410 mA h g(-1) was obtained after 1000 cycles at 4000 mA g(-1) (6.1 C). Furthermore, the Sn8@C nanocomposite displays a charge-discharge capacity of 205.3 mA h g(-1) at 16 000 mA g(-1) (24.4 C). This high-rate performance is owing to the fact that the ultrasmall tin nanoparticles can effectively alleviate the absolute stress/strain during the lithiation/delithiation process and that the uniformly embedded nanoparticles in the stable carbon framework can accommodate the large volume change with a buffering effect to prevent Sn nanoparticles from aggregating.