Facile and scalable synthesis of SiOx materials for Li-ion negative electrodes
Amorphous SiO materials are considered to be alternative high-capacity anode materials for Li-ion batteries. However, the conventional preparation method is a high-temperature and energy-consuming vacuum process. In this study, a simple strategy to produce a SiOx material is proposed. Low-cost micron-sized Si and amorphous SiO2 powders are mechanochemically mixed using a high-energy mechanical milling process. As a result, SiOx materials are produced that have the potential to replace the current commercial SiO powders. The X-ray photoelectron spectra exhibit that the chemical bonding state of Si in the synthesized SiOx materials is similar to commercial SiO. The electron microscopic analyses demonstrate that the secondary particle sizes are reduced and Si crystallites with sizes of a few nanometers to a few tens of nanometers are embedded in the silicon oxide matrix. Due to the morphology and microstructure, the initial coulombic efficiency and cycling stability of the SiOx materials are greatly improved compared to the commercial SiO sample. To further enhance the electrochemical properties, carbon incorporations are carried out, which result in an excellent cycle performance being achieved for the Li-ion battery anodes. The ball-milled SiOx material has ample potential as an alternative to conventional SiO materials.