Electrochemistry and Thermal Behavior of SiOx Made by Reactive Gas Milling

SiO x with various oxygen contents were synthesized from Si powder by a simple room-temperature ball milling method by controlling the air exposure time during milling. The resulting SiO x consists of nano and amorphous Si dispersed in an amorphous silicon oxide matrix. The oxygen saturated composition of SiO 0.37 is thermally stable up to 800 °C and has improved cycling performance after annealing. The 1st irreversible capacity is reduced by high temperature annealing due to defect healing, while the high reversible capacity (1500–2000 mAh g −1 or 1600–1800 Ah l −1 ) is well maintained. This work demonstrates the thermal properties of SiO x made by reactive gas milling and how internal defects directly influence its electrochemistry.