Preparation and lithium storage performance of a carbon-coated Si/graphene nanocomposite

A carbon-coated Si/graphene (Si@C/G) nanocomposite was prepared by dispersing a mixture containing graphene, citric acid, and Si nanoparticles in ethanol, followed by drying and carbonization at 800 °C for 1 h. Transmission electron microscopy revealed that a carbon layer with a uniform thickness of ca. 2 nm was formed on the surface of the Si nanoparticles. The Si@C nanoparticles were supported by graphene sheets with a strong interaction between them. However, the carbon layer on the Si@C nanoparticles without the graphene addition was not uniform. This can be ascribed to the high thermal conductivity of graphene that ensures a uniform temperature distribution on the surface of the Si nanoparticles. As an anode material for lithium ion batteries, the Si@C/G electrode exhibits a high initial coulombic efficiency of 82.7% and an excellent cycling stability with a capacity of 1431 mAh g−1 after 100 cycles at a current density of 500 mA g−1. Such excellent electrochemical performance is attributed to the high electrical conductivity and superior flexibility of graphene. arbon Materials 2014, 29(4): 295–300]