Electrochemical and calorimetric approach to spinel lithium manganese oxide

A simultaneous electrochemical and calorimetric measurement was conducted o n a spinel lithium manganese oxide (LiMn2O4)-cathode, carbon-anode prismati c lithium ion cell. From the comparison of thermal behavior at room tempera ture (25 degrees C) and at an elevated temperature (40 degrees C), a pronou nced exothermic thermal behavior was observed during charging in the high v oltage region (0.2 < x < 0.5 in LixMn2O4) at elevated temperatures. The deg raded cell that was operated at 40 degrees C indicated that the capacity fa ding occurred mainly in the same high voltage region in advance of lower re gion. The irreversible thermal behavior observed by calorimetry clearly ind icates the degradation of LiMn2O4 at elevated temperatures. (C) 1999 Elsevi er Science S.A. All rights reserved.