Silicon–carbon nanocomposites produced by reduction of carbon monofluoride by silicon

Abstract

It is suggested to form porous silicon-carbon nanocomposites via thermal reduction of carbon monofluoride by silicon. For this purpose a mixture of powders of nanocrystalline silicon and fluorocarbon is subjected to cold compaction and the resulting pellets are annealed in an inert atmosphere at T = 800 °C. The density, porosity, structure, composition, and electrical resistivity of thus produced Si–C materials have been studied in detail in relation to the content of the monofluoride in the starting mixture. It was shown that the materials obtained have a hierarchical porous structure constituted by silicon nanoparticles in a shell of finely dispersed carbon. The shells contacting with each other form a carbon matrix providing a high electrical conductivity of the material. The composite was used to fabricate negative electrodes of lithium-ion batteries with increased storage capacity. The electrochemical characteristics of Si–C nanocomposite anodes of varied composition were analyzed and those with high carbon content demonstrated the best performance.