Structural degradation mechanism of oxysulfide spinel LiAl 0.24Mn1.76O3.98S0.02 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°C to 80°C. HRTEM study shows that the rock salt phase Li2MnO3 has been detected at the particle surface of discharged spinel electrode cycled at 80°C. The capacity loss of the spinel electrode at high temperature is ascribed to the MnO dissolution from the formed Li2Mn2O4 at the particle surface.