CONSTRUCTION AND DESTRUCTION OF PASSIVATING LAYER ON LIXC6 IN ORGANICELECTROLYTES - AN IMPEDANCE STUDY

The microstructure and thermal stability of the passivating layer form ed on LixC6 during electrochemical intercalation reaction investigated by using electrochemical impedance spectroscopy. A porous structure i s inferred from the destruction of the passivating film built in 1 M L iClO4 ethylene carbonate after transferring to 1 M LiClO4/propylene ca rbonate. The film is shown to be thermally stable, while the electrode suffers from self-discharge. The formation process involves three rea ctions: gas evolution, film formation and intercalation. In ethylene c arbonate-based electrolytes, the resistance of the surface layer is hi gher in absence of ester co-solvents. The relative importance of the t hree reactions is used to explain the results.