Abstract
The microstructures and electrochemical properties of rapidly-solidified silicon alloys mixed with various forms of carbon have been investigated. Rapidly-solidified Si70Ni15Ti15 (at%) alloy (SNT1515) ribbons were prepared by arc-melting, followed by melt spinning process in vacuum. The obtained ribbons were fragmented by ball milling to produce a fine powder of -500mesh. The alloy powder was mixed with various types of carbon: multi-walled carbon nanotubes, hard carbon, soft carbon, and graphite. Each was added by 2wt% by ball milling for 2 hours. The microstructure of the melt-spun ribbon showed a fine silicon primary phase surrounded by Si7Ni4Ti4 and TiSi2 intermetallic compounds. The additions of carbon to the SNT1515 alloy remarkably improved its cyclic performance. Soft carbon was identified to be the most effective in improving the cycle capacity because of its fine particles and uniform distribution.
Keywords: Carbon nanotubes, electrochemical property, hard carbon, melt-spun ribbon, silicon-based alloy anode, soft carbon.