Si-Cu/carbon composites with a core-shell structure for Li-ion secondary battery
SiCu/carbon composites with a carbon core and a SiCu 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 SiCu composite and carbon was the structural advantage of SiCu/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 SiCu/carbon composite was greatly improved compared to Si. A phase-controlled shell (SiCu composite) acted as another advantage for this SiCu/carbon composite, as it rendered not only good ductility for accommodating the volume expansion, but also enhanced kinetics.