The Mechanism of SEI Formation on a Single Crystal Si(100) Electrode

A fundamental study of interfacial phenomena on a Si(100) single crystal electrode in organic carbonate-based electrolytes was carried out. The SEI formation on the Si(100) single crystal electrode was investigated as a function of the electrolyte composition, electrode potential and Li x Si lithiation degree. Fourier transform infrared spectroscopy (FTIR) and X-ray photon spectroscopy (XPS) studies of the SEI layer during early stages of SEI formation indicate a strong dependence of the SEI composition on the electrolyte composition. However, the influence of the electrolyte composition becomes negligible at low potentials, when lithium alloys with Si and forms amorphous Li x Si. The effect of vinylene carbonate (VC) and fluoroethylene carbonate (FEC) electrolyte additives on the composition of the SEI layer was evaluated.