In situ Raman spectroscopic studies of electrochemical intercalation in LixMn2O4-based cathodes

Raman spectra of spinel LixMn2O4 (x = 1.0 and 1.1) were recorded in situ du ring electrochemical intercalation of lithium ions. We demonstrate that pha ses and structural modifications in these compounds can be identified using Raman spectroscopy. In stoichiometric LiMn2O4, Raman spectral results indi cated that a single-phase reaction is followed by a two-phase reaction and then by another single phase reaction when Lithium is deintercalated from t he spinel compound (0.1 < x < 1.0). In nonstoichiometric LixMn2O4 (x = 1.1) , Raman spectra clearly identify the presence of the lambda-MnO2 phase in t he cathode during charge and discharge. When spinel LiMn2O4 was intercalate d with lithium ions, the in situ Raman spectral changes were? consistent wi th a two-phase reaction between cubic LiMn2O4 and tetragonal Li2Mn2O4. (C) 1999 Elsevier Science S.A. All rights reserved.