Evolution of the Si electrode/electrolyte interface in lithium batteries characterized by XPS and AFM techniques: The influence of vinylene carbonate additive

The effect of vinylene carbonate (VC) as electrolyte additive on the properties of the silicon electrode / liquid electrolyte interface was studied in this paper. Galvanostatic cycling, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to investigate the SEI layer properties and the morphology at different stages of the cycling of thin film electrodes. The electrochemical performances were drastically improved by the introduction of a few per cent of VC additive. It was found that the SEI layer formed in VC-containing electrolyte has a different chemical composition and better resists to the stress caused by large volume variations associated with lithiation and delithiation reactions. The chemical and topographic modifications of the electrode surface at various stages of cycling are discussed in correlation with the evolution of the reversible capacity over cycling with and without VC. This study highlights the importance of the SEI which governs the electrochemical performances of Si thin film model electrodes.