Chemical Reduction Synthesis and Electrochemistry of Si-Sn Nanocomposites as High-Capacity Anodes for Li-Ion Batteries.

Pure Sn and Si-Sn phases are successfully synthesized by a facile and scalable chemical reduction method. The as-produced Si-Sn nanocomposites exhibit excellent cycling stability, as evidenced by a reversible capacity of 700 mAh/g over 200 cycles, due to the exceptional conductivity and ductility of Sn as well as its buffering effect. More specifically, homogeneous mixing between Si and Sn during the liquid phase reaction helps reduce the maximal stress evolved upon electrochemical cycling by confining the expansion of the electrochemically active metal component. Additionally, the chemical reduction method produces small and uniform particles in the final product that are more favorable to Li+ diffusion and tolerant of mechanical stress and strain. Our work demonstrates that the chemical reduction method, free of ultrahigh vacuum and/or temperature, presents a new approach for the development of intermetallic metal anodes through the incorporation of various metal precursors.