Preparation and characterization of core-shell structure Si/C composite with multiple carbon phases as anode materials for lithium ion batteries

Modified spherical graphite/silicon/flake graphite/disordered carbon (SG/Si/C) composite is successfully synthesized by using nano-silicon, flake graphite (FG), modified spherical graphite (SG) and citric acid as raw materials via liquid solidification and subsequent pyrolysis. The material is characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscope and electrochemical measurement. The morphology observation shows a core-shell structure with silicon/carbon material as the shell and SG particles as the core. SG/Si/C composites display a good cycle performance with capacity retention of 86% after 50 cycles under a current density of 100 mA g(-1), and also exhibit an excellent cycling performance at higher current densities of 200 mA g(-1) and 300 mA g(-1). The available raw materials availability and simple synthesis process promote the as-prepared SG/Si/C materials a promising anode for commercial use. (C) 2015 Elsevier B.V. All rights reserved.