In-situ mechanochemical synthesis of sub-micro Si/Sn@SiOx-C composite as high-rate anode material for lithium-ion batteries

•Fabrication of sub-micro Si/Sn@SiOx-C composite by a facile milling and annealing process without any by-products.•Nano-SnO2 was in-situ reduced to metallic Sn via ball-milling with micrometer Si.•The prepared composite delivers excellent rate capability and cyclability.•The superior performance is derived from introduction of sn with high electronic conductivity, dual-buffering of inner SiOx matrix and surface carbon layer. Micrometer silicon (MSi) particles are prospective anode material for high energy-density lithium-ion batteries. Aiming at the scale-up production and the improvement in rate capability, a novel sub-micro Si/Sn@SiOx-C (SSSC) composite via a facile two-step process of milling and annealing is designed and synthesized. With the structural uniqueness including in-situ introduction of metallic tin (Sn) originated from mechano-reduction of nano tin dioxide (nano-SnO2) with MSi, dual-buffering of inner SiOx matrix and uniform surface carbon layer, SSSC electrodes exhibit impressive rate capability and stable cyclability. The optimum architecture of SSSC-73 (i.e. weight ratio of precursor MSi-to-SnO2 is 7:3) delivers stable cycling with 1102 mAh g−1 (at 0.5 A g−1) over 100 cycles and exceptional rate performance with a high capacity retention of 95% over 500 cycles at 2 A g−1. Particularly, this facile and cost-effective preparation of SSSC composites has no by-products, making it competitive in practical application. A sub-micro Si/Sn@SiOx-C composite was in-situ mechanochemically synthesized by a combinational milling and annealing method and exhibit excellent high-rate performance. [Display omitted]