Influence of oxidation on the electrochemical properties of silicon oxide-based carbon composites for anode materials of lithium-ion batteries

Abstract

A new type of silicon oxide-based carbon composite (SiOx@C) was developed to solve the prevalent challenges associated with conventional anode materials, such as pronounced volume fluctuations and inadequate electrical conductivity. The control of oxidation of SiOx was optimized to suppress the excessive formation of the solid electrolyte interphase (SEI) layer and eliminate the short circuits caused by volume variation. In addition, a uniform carbon layer could be formed on the surface of silicon oxide via the rotational chemical vapor deposition (r-CVD) method to improve electrical conductivity. The SiOx@C composites prevented the structural collapse caused by the volume variation of silicon with the buffering effect of the SEI layer produced by repeated charging and discharging. The discharge capacity was found to increase as the oxidation decreased. Particularly, the sample subjected to a reduction process at 700 °C for the SiOx-5h@C exhibited capacities ≥870 mAh g − 1 and excellent stability after 100 cycles at the current speed of 0.2 C.

Keywords

• Silicon oxide
• Magnesiothermic reduction
• Carbon layer
• Anode
• Lithium-ion batteries (LIBs)