Comparison of magnetic properties in LixCoO2 and its decomposition products LiCo2O4 and Co3O4
Abstract Thermal stability of cathode material in the charged state is an important aspect for the safety of rechargeable batteries. It is well known that layered Li x CoO 2 decomposes to a mixture of LiCoO 2 and Co 3 O 4 at elevated temperatures. However, not many experimental evidences exist on intermediate phases those may form during the decomposition. Using magnetic measurements we show that it is possible to distinguish between the spinels LiCo 2 O 4 and Co 3 O 4 and thereby follow the decomposition of Li x CoO 2 . We characterize the magnetic behavior of thermally aged Li x CoO 2 (x = 0.98, 0.76, 0.55) with increasing annealing time. Our results reveal the appearance of magnetic ordering in the thermally degraded products. The detailed analysis illustrates that the formation of Co 3 O 4 is preceded by the formation of a meta stable LiCo 2 O 4 phase.