Electrochemistry and Thermal Behavior of SiOx Made by Reactive Gas Milling

Abstract

SiOx 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 SiOx consists of nano and amorphous Si dispersed in an amorphous silicon oxide matrix. The oxygen saturated composition of SiO0.37 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 SiOx made by reactive gas milling and how internal defects directly influence its electrochemistry.