Synthesis of SiO₂@carbon-graphene hybrids as anode materials of lithium-ion batteries

SiO₂@carbon-graphene (SiO₂@C-G) hybrids with excellent electrochemical performance were prepared by the self-assembly of colloidal silica, sucrose and graphene oxide followed by ultrasonic-assisted hydrothermal and heat treatments. The mass ratio of silica to sucrose is crucial to the electrochemical performance of the resulting hybrids. A hybrid with a mass ratio of silica to sucrose of 0.15 shows the best reversible lithium storage performance, delivering an initial discharge capacity of 906 mAh·g^-1 and a capacity of 542 mAh·g^-1 at the 216^th cycle at a current density of 100 mA·g^-1. The excellent cycling ability and high reversible capacity are attributed to a synergetic effect of the good conductivity of the SiO₂@C-G hybrids, the small SiO₂ particle size and the good dispersion of SiO₂ nanoparticles in the hybrids. This methodology may provide a simple, scalable and eco-friendly strategy to prepare superior electrode materials from cheap and low electrical conductivity metal oxides.