Study of the Electrode/Electrolyte Interface on Cycling of a Conversion Type Electrode Material in Li Batteries.

Previous work demonstrated that TiSnSb is a promising negative electrode material with high electrochemical performance due to the benefit of conversion type reaction vs Li. At low potentials, the volumetric change upon cycling entails electrolyte degradation which remains the main factor limiting the cycling life of TiSnSb based electrodes. To further improve the understanding of the formation of a solid electrolyte interphase (SET) in the presence of alkyl carbonate based electrolytes and of its evolution upon cycling, powerful surface characterization techniques are combined for studying the electrode/electrolyte interface of TiSnSb composite electrodes. Electrochemical impedance spectroscopy is used for monitoring in situ the resistivity of the SET, while XPS and solid state NMR spectroscopy can provide useful information on :the SET chemical composition and its evolution during cycling.