Improvement of cycle performance for silicon/carbon composite used as anode for lithium ion batteries

The silicon/carbon composite was prepared by mixing the silicon, graphite and pitch in the tetra-hydrofuran solution followed by pyrolyzing the blends after the evaporation of solvent. The electrochemical performance of the silicon/carbon anode for lithium ion batteries was improved by the treatment of composite powders with KCl aqueous solutions. Scanning electron microscope (SEM) observation and electrochemical impedance spectroscopy (EIS) results showed that the morphology stability of the composite electrodes can be kept during the electrochemical charge/discharge process. The composite electrode of silicon/carbon composite showed an initial reversible capacity of 575 mAh g^-1 and still maintained a high reversible capacity of 506 mAh g^-1 after 40 cycles with the capacity loss of ∼0.3% per cycle.