Nanoparticles with a core-shell structure of Si@SiO2 with an average size of about 50nm were obtained by plasma chemical synthesis through the decomposition of monosilane. Electrochemical impedance spectroscopy (EIS) was used to study the behavior of anodes based on the composite Si@SiO2 during the cyclic charge/discharge. Based on the results of Si@SiO2 anodes studies by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) in conjunction with thermodynamic modeling (TM), assumptions were made about chemical and electrochemical processes occurring during prolonged cycling in the electrolyte 1M LiPF6 in ethylene carbonate/diethyl carbonate (1:1v/v).