In situ Raman spectroscopic study of LixCoO2 electrodes in propylene carbonate solvent systems

Simultaneous measurements of in situ Raman spectroscopy and cyclic voltammetry have been carried out for thin film electrodes of LixCoO2 in propylene carbonate containing 1 M LiClO4. The Raman lines of 485 and 587 cm−1 observed at LixCoO2 electrodes were attributed to the A1g and Eg modes of the LiCoO2, respectively. The Raman intensity of two lines changed drastically during the insertion/extraction of lithium ions. This effect can be explained by the reduction of the optical skin depth due to the conductivity change of LixCoO2. Phase transition from Raman-active phase to Raman-inactive phase is also conceivable.