Raman diagnostics of LiCoO2 electrodes for lithium-ion batteries

LiCoO2 based electrode materials were characterized in detail using visible Raman spectroscopy. The studied materials comprise the active LiCoO2 material itself as well as electrochemically relevant composites of LiCoO2 with binder and conductive additives. Spatially resolved analysis, i.e. mapping of LiCoO2 composite electrodes reveals a significant variation of chemical composition across the electrode surface. Based on wavelength-dependent studies we demonstrate the presence of a resonance enhancement for LiCoO2 materials for green laser excitation allowing for in situ studies on the LiCoO2-based electrodes during lithium de-intercalation. During in situ experiments no significant structural changes occur consistent with the fact that visible Raman spectroscopy probes mainly the surface region of the LiCoO2 composite electrode. Our results demonstrate the potential of Raman spectroscopy for spatially resolved and in situ analysis of lithium-ion batteries.