To address the huge volume changes and unstable solid-electrolyte interface (SEI) layer during lithiation/delithiation of silicon, this paper proposes a novel ‘silicon alloy’ concept that is achieved by proposing the synthesis of Si/WSi2 via a magnesiothermic co-reduction. The WSi2 is formed by absorbing the heat generated from magnesiothermic co-reduction, which increases the conductivity and acts as the mechanical backbone to buffer the volume change. Thereby, Si/WSi2 displays a superior specific charge capacity of 2678 mAh g−1 at the current density of 100 mA g−1 as an anode material, with the capacity retention of 84% after 40 cycles. Moreover, it shows excellent rate capability of 997 mAh g−1 at the current density of 10 A g−1 and excellent cycling performance up to 100 cycles at the current density of 1 A g−1.