Novel silicon/carbon nano-branches synthesized by reacting silicon with methyl chloride: A high performing anode material in lithium ion battery

Abstract

To overcome the existing technical barriers of pulverization and fast capacity fading of Si/C composite anodes in lithium ion batteries and to low their production cost, we have developed a facile method for preparing Si/C nano-branches (Si/C NBs) by reacting commercial Si microparticles directly with CH3Cl gas over Cu-based catalyst particles followed by a simple post treatment. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and Raman spectroscopy. It was found that the diameter and the length of Si/C NBs were ∼70 nm and ∼6 μm, respectively. When used as the anode materials for lithium ion batteries, they displayed excellent electrochemical properties with an average specific capacity of 849 mA h g−1 at a current density of 50 mA g−1. The much improved electrochemical performance is attributed to the unique branched nanostructure and the coated carbon layer on the surface, which can effectively increase the electrical conductivity and buffer the volume change. This work provides a simple and low-cost route to prepare Si/C anode materials with novel branched nanostructure for lithium ion batteries.