Synthesis of carbon-coated silicon nanoparticles by induction thermal plasma for lithium ion battery

Abstract

Synthesis of silicon nanoparticles with carbon coating by induction thermal plasma was investigated experimentally. Crystalline silicon was injected into plasma as raw material, and nanoparticles were produced through quenching process. Ethylene was chosen as carbon source for coating and injected into plasma downstream as a counter-flow with different gas flow rates to understand the effect on products. Synthesized silicon nanoparticles were successfully coated with carbon materials, and had an average diameter around 70 nm which was independent from ethylene flow rate. Obtained carbon coating was amorphous and consisted of sp2 carbons and sp3 carbons. Molar ratio of sp2 carbons to sp3 carbons, as well as the hydrogen content, decreased with higher ethylene gas flow rate. Increased concertation of hydrogen radicals was believed as the reason for those phenomenon due to etching effect on carbon coating. The above results are significant for the better performance of lithium ion batteries.