Catalyst-Free Synthesis of Si-SiO_<i>x</i> Core-Shell Nanowire Anodes for High-Rate and High-Capacity Lithium-Ion Batteries

Si-SiO_<i>x</i> core-shell nanowires (NWs) ranging from 10 to 30 nm in diameter are prepared by a simple evaporation of silicon monoxide and control of substrate temperatures without any catalyst. The Si-SiO_<i>x</i> NWs grown at 735 and 955 °C are strongly anchored to the Cu current collector by forming copper silicide at the interface between Si and Cu, and subsequently used as anodes in lithium-ion batteries, in which no binder or conducting materials are used. The Si-SiO_<i>x</i> NWs anodes show excellent electrochemical performances in terms of capacity retention and rate capability. In particular, the Si-SiO_<i>x</i> NW anode grown at 955 °C shows a reversible capacity of ∼1000 mAh g^–1 even at a high-rate of 50 C. This catalyst-free synthetic route of Si-SiO_<i>x</i> NWs that are strongly anchored to the Cu current collector opens up an effective process for fabricating other high-capacity anodes in lithium-ion batteries (LIBs)