Preparation of SiC-Coated Silicon Nanofiber/Graphite Composites as Anode Material for Li-Ion Batteries by the Chemical Vapor Deposition Method

Abstract

Si material has huge lithium storage capacity, but its huge volume changes during charging and discharging making it difficult to use. However, by using nano-sizing Si material and building a coating structure can effectively reduce the capacity reduction caused by the expansion of the Si material. In our experiment, dichlorodimethylsilane was used as the silicon source and carbon source for the deposition of silicon nanofibers and SiC-coated on a spherical graphite substrate, and then the SiC cladding was deposited without changing the temperature and silicon source, and only the C to H ratio in the atmosphere was controlled to build the cladding layer. In our experiment, silicon nanofibers were deposited on graphite surfaces using dichlorodimethylsilane as the silicon source, followed by SiC cladding on the surface of the Si/G composites using dichlorodimethylsilane as the silicon source and carbon source. The end product was controlled by controlling only the C to H ratio in the atmosphere at the same temperature. The preparation of SiC@Si/G composites with silicon nanofibers and cladding structures by a single CVD process and single raw materials. The material has a silicon nanofiber structure and SiC coating structure. The presence of silicon is effective in providing very high capacity and the presence of the SiC layer is effective in improving the capacity retention of the composite material for increasing the Coulomb efficiency of the material. At a current density of 100 mA h g−1, the material has a reversible capacity of 647.3 mA h g−1 at the first cycle. After 100 cycles, it has a 76.2% retention rate. The electrodes can be extremely stable after cycling without significant swelling.