Cu–Si1−xGex core–shell nanowire arrays as three-dimensional electrodes for high-rate capability lithium-ion batteries

► SiGe layer was deposited on the Cu nanowire arrays via a co-sputtering method. ► The Cu–SiGe 3D electrodes show improved performance as anode for Li-ion battery. ► Improved performance was attributed to the advantages of the electrodes’ structure. We demonstrate the synthesis of new Cu–Si1−xGex core–shell nanowire array electrodes by directly depositing Si1−xGex layer on the surface of pre-synthesized Cu nanowire arrays via co-sputtering method. When used as anodes of lithium-ion batteries, the Cu–Si1−xGex (x=0.4) nanowire array electrodes show excellent electrochemical performance in terms of cycle stability and rate capability, which is much better than that of planar electrodes. The improved performance can be attributed to the good strain accommodation, fast electron transport and good electrical contact of the nanowire array electrodes. The effect of Ge content and the thickness of alloy film on the electrochemical performance of the three-dimensional electrodes have also been investigated.