Preparation and Lithium Storage Properties of Silicon/Reduced Graphene Oxide Nanocomposites

Silicon has attracted wide attention due to its high theoretical specific capacity. However, the huge volume change and poor reaction kinetics in the lithiation process lead to a serious deterioration of its structure, a continuous capacity attenuation and a poor magnification performance, thus restricting its practical application. To solve these problems, silicon/reduced graphene oxide (Si/rGO) nanocomposites with a three-dimensional cage-like conductive structure were designed by an in-situ electrostatic self-assembly and hydrothermal reduction method with commercial Si nano-particles with the size of 60 nm and natural flake graphite. The lithium ion storage performance and energy storage mechanism of Si/rGO nanocomposite were investigated. The results show that Si nano-particles are uniformly encapsulated into a three-dimensional cage-like conductive network structure of rGO, effectively limiting the volume expansion of nano-Si particles and providing the more ion transport channels in the process of lithium ion intercalation/detachment. The specific capacity of Si/rGO nanocomposites is 1246 mA·h/g at 0.1 A/g. The Coulomb efficiency is 98.2% and the capacity retention is 95.5% from fifth cycle, indicating that the nanocomposite has a fast stability behavior. The reversible capacity remains 852 mA·h/g, the Coulomb efficiency is 99.9%, and the capacity retention is 68.4% after 200 cycles.