Solid-state reaction synthesis of amorphous/nanostructured Si@SiOx-Cu3Si composites by mechanical milling for lithium-ion anodes

Abstract

In present study we developed an effective way to obtain amorphous/nanocrystalline Si in high-capacity Si-based composites for improving their cycle stability as lithium-ion anodes. Amorphous/nanostructured Si@SiOx-Cu3Si composites were synthesized via solid-state reactions using mechanical milling with bulk Si and CuO as starting materials. The microstructural characterization of Si@SiOx-Cu3Si composites demonstrated the phase transformation during the synthesis process of mechanical milling. The ratio and fine-scale distribution of amorphous Si in Si@SiOx-Cu3Si composites were quantitatively analyzed by confocal μ-Raman spectroscopy. The electrochemical properties indicated that Si@SiOx-Cu3Si composites exhibited enhanced cyclability due to containing a highly disordered amorphous Si. Calculated in a full-cell stack model, the lithium-ion cell using Si@SiOx-Cu3Si anodes could provide higher energy density over commercial graphite.