International audienceThe formation of a passivation film (solid electrolyte interphase, SEI) at the surface of the negative electrode of full LiCoO2/graphite lithium-ion cells using LiPF6 (1M) in carbonate solvents as electrolyte was investigated by means of x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The analyses were carried out at different potentials of the first and the fifth cycles, showing the potentialdependent character of the surface-film species formation. These species were mainly identified as Li2CO3 up to 3.8 V and LiF up to 4.2 V. This study shows the formation of the SEI during charging and its partial dissolution during discharge. Copyright © 2005 John Wiley & Sons, Ltd

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X-ray photoelectron valence spectra of lithium salts LiBF4, LiPF6, LiTFSI, and LiBETI have been recorded and analyzed by means of density functional theory (DFT) calculations, with good agreement between experimental and calculated spectra. The results of this study are used to characterize electrode/electrolyte interfaces of graphite negative electrodes in Li-ion batteries using organic carbonate electrolytes containing LiTFSI or LiBETI salts. By a combined X-ray photoelectron spectroscopy (XPS) core peaks/valence analysis, we identify the main constituents of the interface. Differences in the surface layers' composition can be evidenced, depending on whether LiTFSI or LiBETI is used as the lithium salt.