Graphene/Fe₂O₃/SnO₂ ternary nanocomposites as a high-performance anode for lithium ion batteries

We report an rGO/Fe₂O₃/SnO₂ ternary nanocomposite synthesized via homogeneous precipitation of Fe₂O ₃ nanoparticles onto graphene oxide (GO) followed by reduction of GO with SnCl₂. The reduction mechanism of GO with SnCl₂ and the effects of reduction temperature and time were examined. Accompanying the reduction of GO, particles of SnO₂ were deposited on the GO surface. In the graphene nanocomposite, Fe₂O₃ nanoparticles with a size of ∼20 nm were uniformly dispersed surrounded by SnO₂ nanoparticles, as demonstrated by transmission electron microscopy analysis. Due to the different lithium insertion/extraction potentials, the major role of SnO₂ nanoparticles is to prevent aggregation of Fe₂O ₃ during the cycling. Graphene can serve as a matrix for Li ⁺ and electron transport and is capable of relieving the stress that would otherwise accumulate in the Fe₂O₃ nanoparticles during Li uptake/release. In turn, the dispersion of nanoparticles on graphene can mitigate the restacking of graphene sheets. As a result, the electrochemical performance of rGO/Fe₂O₃/SnO₂ ternary nanocomposite as an anode in Li ion batteries is significantly improved, showing high initial discharge and charge capacities of 1179 and 746 mAhg^-1, respectively. Importantly, nearly 100% discharge-charge efficiency is maintained during the subsequent 100 cycles with a specific capacity above 700 mAhg^-1.