A study on the effect of lithium insertion–extraction on the local structure of lithium manganese oxides using X-ray absorption spectroscopy

Electronic and structural aspects of LixMn2O4 electrodes obtained from electrochemical oxidation–reduction process have been investigated by Mn K-edge X-ray absorption fine spectroscopy (XAFS). Charging of LixMn2O4 gave rise to an increase in the intensity of the peak at ca. 6543 eV and a shift of the overall peak positions towards higher energies in normalized X-ray absorption near-edge structure (XANES) spectra. Mean Mn–O bond length was at minimum in the charged state and it increased progressively with lithium insertion. Moreover, the extended X-ray absorption fine structure (EXAFS) spectrum of a second-charged LixMn2O4 electrode was somewhat different from that of the first one partly due to some disorder rendering different site energy.