Si–Cu/carbon composites with a core–shell structure for Li-ion secondary battery

Si–Cu/carbon composites with a carbon core and a Si–Cu composite shell have been synthesized by two-step mechanical fusion process. Large amount of pores around composite particles as well as the bridging disordered carbon layer between Si–Cu composite and carbon was the structural advantage of Si–Cu/carbon composite, which could prevent the electrochemical degradation induced by enormous volume changes during Li+ insertion or extraction. With these structural characteristics, the cyclic property of Si–Cu/carbon composite was greatly improved compared to Si. A phase-controlled shell (Si–Cu composite) acted as another advantage for this Si–Cu/carbon composite, as it rendered not only good ductility for accommodating the volume expansion, but also enhanced kinetics.