Effect of SiOx-coating crystallinity on electrochemical performance of Si@SiOx anode materials in lithium-ion batteries

Abstract

In this work, SiOx coatings with different crystallinity are successfully prepared on the surface of the silicon (Si) particles by dry oxidation and wet oxidation. The SiOx coatings formed by low-temperature dry oxidation are not only continuous and uniform, but also have the low crystallinity. Theoretically, the continuous, uniform and low-crystallinity SiOx coating is more advantageous for lithium-ion transport and structural stability during the alloying/de-alloying. As a result, the 550 °C sample shows the best electrochemical performance. For example, the 550 °C sample has the highest specific discharge capacity at 2C than other samples. As the rate is restored to 0.1 C, the 550 °C sample also exhibits faster recovery of capacity. Besides, the discharge specific capacity of the 550 °C sample is up to 1108 mAh g−1 after 100 cycles at 0.5 C, showing the best cycle stability.