Relaxation Phase Analysis of Li Inserted Li-Mn-O Cathode for Secondary Li Ion Batteries

We electrochemically inserted various amounts of lithium into LiMn2O4 and investigated the relaxation structure after termination of lithium insertion by using X-ray diffraction measurement and Rietveld analysis. The mole fraction of the Li-lean phase decreased and that of the Li-rich phase increased with the relaxation time after lithium insertion. It is considered that the Li-lean phase containing excess lithium formed during the lithium insertion process separated into two phases, the Li-lean phase without excess lithium and the Li-rich phase, during the relaxation process after termination of lithium insertion. (c) 2012 The Electrochemical Society. All rights reserved.