Well-dispersed double carbon layers coated on Si nanoparticles and the enhanced electrochemical performance for lithium ion batteries

The amorphous carbon was coated on the surface of the nano-silicon with citric acid by a simple mechanical stirring in water bath method and high temperature pyrolysis method, and then the carbon-coated silicon composite material(Si@C) was coated with polyvinyl alcohol by the secondary mechanical stirring and high temperature pyrolysis to obtain double carbon layer-coated silicon composite material (Si@C@C). The microstructure and surface morphology of Si@C@C were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical properties of Si@C@C were investigated by constant current charge–discharge, cyclic voltammetry, and electrochemical impedance spectra techniques. The study found that the first reversible specific capacity of Si@C@C was 1669 mAh/g at the current density of 0.1 C. The specific capacity remained at 1300 mAh/g, while the capacity retention rate was 77.9% after 200 cycles. The cyclic stability of Si@C@C was higher than that of Si@C, which greatly improved the electrochemical performance of silicon-based materials as anode materials for lithium ion batteries.