Structural changes (degradation) of oxysulfide LiAl0.24Mn1.76O3.98S0.02 spinel on high-temperature cycling

The structural integrity of the oxysulfide material, LiAl0.24Mn1.76O3.98S0.02 before and after charge-discharge cycling at high temperature was studied by X-ray diffraction and high-resolution transmission electron microscopy. The rock salt phase Li2MnO3 which is associated with capacity loss has been detected at the surface of the oxysulfide particles in the electrode cycled in the 4 V region at 80 degreesC. The small structural degradation of the new oxysulfide material may be responsible for the excellent cyclability of the oxysulfide spinel at high temperature over the 4 V region. (C) 2001 The Electrochemical Society.