Effect of the elevated temperature on the local structure of lithium manganese oxide studied by in situ XAFS analysis

Effect of the elevated temperature and that of the lithium deintercalation on the structure of stoichiometric material LiMn2O4 and lithium excess mate rial Li(Mn1.85Li0.15)O-4 were investigated by in situ XAFS technique. The s toichiometric material showed capacity loss after charge-discharge cycles a t 60 degrees C and gave deformed XAFS spectra, while the lithium excess mat erial showed resistance to the high-temperature cycling and gave a similar XAFS spectra to the non-heated material. The XAFS analysis suggests that hi gh-temperature cycles caused structural disorder of LiMn2O4, but not that o f Li(Mn1.85Li0.15)O-4. Since the lithium excess material has good structura l stability against the cycling at the elevated temperature, this material will be suitable for the cathode material of the commercial batteries. (C) 1999 Elsevier Science S.A. All rights reserved.