X-RAY-ABSORPTION FINE-STRUCTURE STUDY ON LI-MN-O COMPOUNDS - LIMN2O4,LI4MN5O12 AND LI2MNO3

The lithium manganese oxide spinel LiMn2O4 obtained at different prepa ration temperatures shows different discharge characteristics. In orde r to study the difference between the discharge curves of HT-LiMn2O4 ( HT:high temperature) and LT-LiMn2O4 (LT:low temperature), we have anal yzed the XAFS (X-ray absorption fine structure) of synthesized LiMn2O4 and the products formed from an electrochemical oxidation-reduction p rocess. It was found that, on discharge, the energy shifts of the edge of the X-ray absorption near edge structure (XANES) spectra were diff erent between HT-LiMn2O4 and LT-LiMn2O4 and were not directly proporti onal to the discharge capacity. Moreover, the change in the Mn-Mn bond length of HT-LiMn2O4 with discharge was greater than that of LT-LiMn2 O4. (C) 1997 Published by Elsevier Science S.A.