Silicon alloys composed of silicon nanoparticles embedded in inert Cu-Al-Fe matrix phases were synthesized and encapsulated with reduced graphene oxide (rGO) nanosheets. Successful synthesis of the silicon alloys and their encapsulation with rGO were confirmed by X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopic analyses. The silicon alloy encapsulated with an optimal amount of rGO delivered an initial discharge capacity of 1140.7mAhg−1 with good capacity retention and exhibited excellent rate capability. This superior performance could be attributed to the unique structure of silicon alloy encapsulated by rGO, which could effectively accommodate the large volume change during cycling and provide continuous electronic conduction pathway in the electrode.