THE USE OF POLARIZED-LIGHT IN THE INFRARED REFLECTANCE SPECTROSCOPIC INVESTIGATION OF THE LITHIUM ORGANIC ELECTROLYTE INTERFACE

Surface films formed on lithium were investigated using in situ reflec tance infrared spectroscopy. Experiments were carried out using sophis ticated techniques like EMIRS (electro-modulated infrared reflectance spectroscopy) or SNIFTIRS (subtractively normalized interfacial Fourie r-transform infrared spectroscopy). Spectra were recorded with both p- and s-poiarized light to distinguish the surface species belonging to the passive layer from those in solution. The solutions used included LiAsF6 in mixtures of propylene carbonate, ethylene carbonate and dim ethoxyethane (1:1:3). The main components detected at the surface film s were lithium alkyl carbonates (ROCO(2)Li) and lithium carbonate (Li2 CO3), this in agreement with previous work by Aurbach and co-workers. Besides, spectra reveal the presence of other types of species whose n ature has been discussed.