Li-rich layered cathode materials Li-1.2[M0.4Mn0.4]O-2 (M = Ni, Co, Ni1/2Mn1/2 and Fe) are synthesized under various temperatures (800-1000 degrees C). WhenM= Ni, higher sintering temperature may cause the formation of Li[Li-x(Ni0.5Mn0.5)(1-x)]O-2 + (0.1-0.5x)Li2O (0 <= x < 0.2, Ni = +2 and +3), which is certified by XRD patterns, XPS spectra and Ni K-edge X-Ray absorption spectrum. For M = Co and Ni1/2Mn1/2 samples, single phase with layered structure can be obtained in the investigated temperature range and higher sintering temperature contributes to improving their crystallinity. Besides, when M = Fe, the mixture of cubic alpha-LiFeO2 and layered Li2MnO3 are always observed simultaneously. Comparative electrochemical studies of Li-1.2[M0.4Mn0.4]O-2 (M = Ni, Co, and Ni1/2Mn1/2) exhibit different charge-discharge mechanisms. The results indicate that the reactivity of the redox couples in the M = Co sample are higher than that of the other two samples. By contrast, the redox couples in the M = Ni sample shows the lowest reactivity among the three samples. Local phase transition from layered structure to spinel-like phase during cycling can be detected from the charge/discharge curves and XRD patterns for M = Co sample, while the layered structure can be maintained very well during cycling in the M = Ni and Ni1/2Mn1/2 samples. (c) 2017 The Electrochemical Society. All rights reserved.