Degradation mechanism of spinel LiAl0.2Mn1.8O4 cathode materials on high temperature cycling

The structural degradation of the Al-doped spinel material, LiAl0.2Mn1.8O4, before and after charge-discharge cycling in the 4 V region at elevated te mperature has been studied by X-ray diffraction and high-resolution transmi ssion electron microscopy. The capacity loss during cycling was noticeably increased with cell operation temperature from 50 to 80 degreesC. The forma tion of tetragonal Li(2)Mn2O(4) and the rocksalt phase Li2MnO3 in the spine l electrode cycled at elevated temperature could be responsible for the mai n cause of the capacity loss.