In Situ Raman Spectroscopy of Single Microparticle Li +-Intercalation Electrodes

Modifications in the vibrational properties of a single microparticle of LiMn₂O₄ induced by extraction and subsequent injection of Li⁺ into the lattice have been monitored in situ via simultaneous acquisition of Raman scattering spectra and cyclic voltammetry data in 1 M LiClO₄ solutions in ethylene carbonate (EC):diethyl carbonate (DEC) mixtures (1:1 by volume). Statistical analyses of the spectra in the range 15 < SOD < 45%, where SOD represents the state of discharge (in percent) of the nominally fully charged material, i.e., λ-MnO₂, were found to be consistent with the coexistence of two distinct phases of lithiated metal oxide in agreement with information derived from in situ X-ray diffraction (XRD) measurements involving more conventional battery-type electrodes.