Nano-Si Filled Graphite Anode Particles by Mechanofusion

Abstract

Silicon-graphite composite anode materials for Li-ion cells were synthesized by embedding nano-Si into voids within natural graphite by mechanofusion, followed by carbon coating by chemical vapor deposition. In the resulting structure, voids within the natural graphite were completely filled with silicon nanoparticles encapsulated in carbon. This resulted in the silicon being protected from reaction with the electrolyte. The as-prepared silicon-graphite composites were shown to cycle well in electrodes with no special binders (PVDF) and in conventional electrolytes without any additives (i.e. no fluoroethylene carbonate). Furthermore, nearly all the Si within the voids were fully active. This provides a promising and simple strategy for silicon-graphite composites that can be used as a drop-in replacement for graphite to increase Li-ion cell capacity.