The use of 7Li, 19F and 31P MAS NMR, made quantitative through the implementation of empirical calibration, is combined with transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) to probe the elements involved in surface species and to unravel the inhomogenous architecture of the interphase. At room temperature, contact with the electrolyte leads to a covering of the oxide surface first by LiF and lithiated organic species are found on the outer part of the interphase. At 55 掳C, not only the interphase proceeds in further covering of the surface but also thickens resulting in an increase of 240%of lithiated species and the presence of -POF2 fluorophosphates. The composition gradient within the interphase depth is also strongly affected by the temperature.
In agreement with the electrochemical performance, quantitative NMR surface analyses show that the use of LiBOB-modified electrolyte results in a Li-enriched interphase, intrinsically less resistive than the standard LiPF6-based interphase, comprised of a mixture of resistive LiF with non lithiated species.