Nanosized Amorphous SnO₂ Particles Anchored in the Wheat Straw Carbon Substrate as the Stabilized Anode Material of Lithium-Ion Batteries

Nanosized SnO2 particles anchored on wheat straw (WS) carbon (SnO2/C) as an anode candidate of lithium-ion batteries is obtained based on a space-confined and self-absorptive synthetic strategy. The unique one-dimensional porous structure of WS provides a perfect space-confined dual-function substrate for the growth of SnO2 with particle size below the critical size, and the reversed free expansion of SnO2/C during the charge–discharge process of lithium ions is utilized to stabilize the electrochemical properties. The as-synthesized SnO2/C composite with amorphous dominant SnO2 nanoparticles (a-SnO2/C) exhibits an initial capacity of 517.6 mAh g–1 and a capacity ratio of 52.9% in the potential range 0–1.0 V to that in 0–3.0 V at 0.05 C (80 mA g–1) after 100 cycles. In particular, compared with pure SnO2 and graphene-coated SnO2 synthesized by a spray-drying and calcining process, the capacity retention of a-SnO2/C is enhanced from less than 15% to 84.1% after 300 cycles, indicating that this space-confined structure can provide a robust connection between a-SnO2 and carbon substrate and then improve the electrochemical performance and stability of a-SnO2/C anode material. The as-proposed synthetic strategy not only provides a new scalable application for WS as a self-sacrificing precursor to construct sustainable anodes but also solves the serious structural collapse problem of metal oxide anodes.