Phase Transitions in Li2MnO3 Electrodes at Various States-of-Charge

We studied the structural transformations from the layered-type to spinel-type ordering upon galvanostatic charging (Li+ extraction) of Li2MnO3 electrodes. We have determined by X-ray, electron diffraction techniques and Raman spectroscopy analyses that these transformations partially occurred even at the initial states-of-charge, at potentials of 4.3-4.5 V, and in fully charged (4.7V) and discharged (2.0V) states as well. The above transformations are evident also from the analysis of the intrinsic magnetic properties of Li2MnO3 electrodes that indicate short-range spin correlations typical for the Li2Mn2O4 and LiMn2O4 spinel-type structures, depending on the state of charge and the C-rates used for the cycling. (C) 2014 Elsevier Ltd. All rights reserved.