Composite SiO/C anodes for lithium-ion batteries (LIB) obtained by carbonization of silicon monoxide with fluorocarbon were investigated. Preliminary modification of the initial silicon monoxide was carried out by disproportionation and subsequent treatment in hydrofluoric acid. The study of the elemental composition of modified SiO and the electrochemical performance of composite anodes made from it showed that the oxygen content in the oxide matrix played a decisive role in changing their behavior. Depletion of its oxygen as a result of treatment in HF had a beneficial effect, leading to higher stability of the electrodes during cycling, an increase in their capacity, coulombic efficiency and rate capability.