Structural degradation mechanism of oxysulfide spinel LiAl0.24Mn1.76O3.98S0.02 cathode materials on high temperature cycling

Structural degradation of oxysulfide spinel, LiAl0.24Mn1.76O3.98S0.02 electrode in the 4 V region (4.3-3.0 V) cycled at high temperature has been investigated by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The capacity loss during cycling is noticeably increased in the cell operation temperature from 50 degreesC to 80 degreesC. HRTEM study shows that the rock salt phase Li2MnO3 has been detected at the particle surface of discharged spinel electrode cycled at 80 degreesC. The capacity loss of the spinel electrode at high temperature is ascribed to the MnO dissolution from the formed Li2Mn2O4 at the particle surface. (C) 2001 Published by Elsevier Science B.V.