Structure and Electrochemical Properties of Li-rich Li2+4xMn0.6+2xNi0.6-6xCr0.8O4 Spinel Prepared by Hydrothermal Method

A series of cathode materials, Li2+4xMn0.6+2xNi0.6-6xCr0.8O4 (x = 1/30, 1/20, 1/15, 1/12), was prepared via hydrothermal method, and their composition, structure and electrochemical properties were investigated using X-ray diffraction(XRD), inductively coupled plasma-atomic emission spectrometry (ICP-AES), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometry (FTIR), Raman spectrometry and charge-discharge tests: XRD measurements combining with ICP results reveal that the obtained samples are Li-rich type spinel structure. Moreover, XPS results suggest that the valence for Cr is +3 for x=1/15 and 1/12 and no Cr6+ exist. As to their electrochemical properties, it is found that these materials have a high-voltage plateau near 4.7 V and a low-voltage near 2.7 V. With the increase of x value, both charge and discharge capacities of the samples increase. The sample with x = 1/12 shows a good cyclic performance as well as good rate capability.