Combined In Situ Raman and IR Microscopy at the Interface of a Single Graphite Particle with Ethylene Carbonate/Dimethyl Carbonate

Abstract

A combined in situ Raman- and external reflectance Fourier transform infrared (FTIR)-microscopic approach aimed at exploiting the complementary nature of these two powerful spectroscopic methods is presented and applied to the same spot on a graphite electrode. Polished single graphite particles were selected because they offer a suitable compromise between acceptable lithium intercalation properties and sufficiently high IR reflectivity. This study constitutes the first application of combined in situ Raman and IR spectroscopy to a material of practical relevance to lithium-ion batteries. In preliminary experiments, scanning electron microscopy (SEM) and attenuated total reflectance (ATR) were employed to characterize the electrodes. In situ Raman microscopy was shown to be particularly sensitive to structural changes in the electrode material whereas in situ IR microscopy provided an efficient way of investigating the interface with the organic electrolyte. The Raman spectra showed clear evidence of lithium intercalation while the IR spectra were dominated by solvation effects determined by the interactions between ethylene carbonate and dimethyl carbonate and Li+.