STUDIES ON ELECTROCHEMICAL OXIDATION OF NONAQUEOUS ELECTROLYTE ON THELICOO2 THIN-FILM ELECTRODE

In this study, we demonstrated an in situ FTIR measurement for an elec trochemical oxidation of propylene carbonate with 1.0 mol dm(-3) LiClO 4 on LiCoO2 cathode active material used in rechargeable lithium batte ries. A thin film electrode of LiCoO2 was prepared by an r.f. sputteri ng method. The prepared LiCoO2 film had high quality as an electrode f or the in situ FTIR measurement as well as a cathode material. The FTI R spectra were obtained at various electrode potentials ranging from 4 .1 to 4.8 V vs. Li/Li+. Peaks corresponding to decomposition products of propylene carbonate show that the electrochemical oxidation of prop ylene carbonate was assigned to some compounds having carboxylic group s and carboxylic acid anhydrides. Several peaks attributed to propylen e carbonate were also observed, indicating that propylene carbonate wa s adsorbed on the LiCoO2 thin film electrode surface before the anodic polarization.