Simple Synthesis and Characterization of Ball Milled SiOx for Use as a Negative Electrode Material

Abstract

SiO x is an attractive anode material given its high specific capacity and its increased lifetime due to its supporting matrix of lithium silicates irreversibly formed during its first lithiation. While SiO x is normally created by simultaneous evaporation and vapor deposition of Si and SiO 2 powders, this can be very difficult and energy consuming method. It is shown here that SiO x with controlled oxygen content can be made by ball milling crystalline silicon powder in an oxidizing medium using two different milling techniques. To characterize the SiO x powders, oxygen content is quantified using a KOH-based method and BET surface area is measured. Electrochemical testing using coin cells is completed and the results are compared to commercially available SiO samples. The results show that SiO x with competitive properties can be made by ball milling. Further work is required to reduce the specific surface area of the material made by ball milling.