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. (c) 2007 Elsevier Ltd. All rights reserved.