Electrochemical characterization of commercial lithium manganese oxide powders

Five commercial Lithium manganese oxide powders have been studied. The XRD spectra showed all samples to exhibit the spinel structure. The composition and morphology were analyzed by Jaeger-Vetter titration and scanning elect ron microscopy. The Lithium intercalation/de-intercalation characteristics and the cycleability have been studied using state-of-the-art cells. The mo rphology of the particles and crystallites, as well as the defect structure of the spinel, were found to play an important role in the capacity retent ion during electrochemical cycling. The capacity corresponding to the 4.1 V phase transformation process faded faster than that of the 4.0 V single-ph ase transition during cycling, which enhanced lower plateau capacity fading and higher voltage polarization. The cycleability at the 3.0 V region has also been studied and indicated that the typical spinel lithium manganese o xide is not suitable to be cycled in the 3.0 V region. Therefore, it will b e deleterious to overdischarge the spinel materials. (C) 2000 Elsevier Scie nce B.V. All rights reserved.