Fluorination of SiOx as an effective strategy to enhance the cycling stability of lithium-ion batteries

Herein, fluorinate silicon monoxide (SiO-F) is prepared by heat treatment of SiO with ammonium bifluoride (NH4HF2) at low temperatures to improve the cycling stability of SiO. The fluorination of SiO is confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier-Transform infrared spectroscopy (FT-IR). The SiO-F exhibits higher initial discharge capacity, rate capability, and cycling stability than untreated SiO (pristine SiO). The superior electrochemical performances of the SiO-F are attributed to the formation of a LiF-rich solid electrolyte interphase (SEI) layer formed by the reaction between Li-ion and F-groups on the surface of SiO during the charge and discharge cycle.