A cheap Si powder byproduct from solar cell production was applied as a negative electrode for lithium-ion batteries. To improve the cycle and rate performances, the as-obtained Si powder was composited with tungsten oxide and coated with carbon, in sequence. After preparing the composite material, its electrochemical performance is evaluated, which exhibits a high reversible capacity of 975 mA h g^− 1 with improved cycleability. Especially, the rate capability is significantly improved to 390 mA h g^− 1 under 1000 mA g^− 1 applied current. This advanced electrochemical performance is attributed to the matrix effect of the formed Li₂O and W metal with carbon coating, as identified using ex-situ X-ray diffraction experiments, and associated with the low polarization resistance observed in the galvanostatic charge intermittent technique.​