SEM and FT-IR characterization of the passivation film on lithiated mesocarbon fibers

The passivation of graphitized mesocarbon fibers is studied by means of scanning electron microscopy (SEM) and FT-IR spectrometry. The passivation film was grown on the external surface by either a chemical decomposition of an ethylene carbonate (EC)—LiPF6 solution with pre-lithiated fibers or by electrochemical reduction under galvanostatic and potentiostatic regimes. These techniques led to different film morphologies and thicknesses. The film is heterogeneous in nature and behaves as a solvent-plasticized solid-state electrolyte.