Exploring the influence of oxygen distribution on the performance of SiOx anode materials

Adjusting the O distribution in the silicon suboxide (SiO x ) is a potentially feasible strategy to obtain high specific capacity and cycling stability simultaneously, but it has not been thoroughly studied. In this article, we find that controlling the Mg content and heating rates can result in significant differences in the O distribution of the prepared SiO x by magnesiothermic reduction. Astonishingly, the electrochemical performance of SiO x is closely related to the O distribution. When the ratio of surface O to core O is close to 2:1, this appropriate O distribution is beneficial for the overall performance of SiO x . As a result, the optimized s SiO x -0.95–10 °C electrode provides a high discharging capacity of 1470.2 mAh·g −1  at 0.1C and can maintain a capacity of 501.7 mAh·g −1  at 5 C. More importantly, a high-capacity retention of 622.5 mAh·g −1 can be obtained after 200 cycles for the optimized SiO x -0.95–10 °C electrode. Because increasing the surface O content can generate more Li 2 O during the lithiation process and alleviate the volume expansion of SiO x , while excessive surface O can reduce the electronic conductivity of the SiO x , affecting its cycling performance. This article provides new ideas and methods for obtaining SiO x anode with excellent comprehensive performance.