Preparation and electrochemical performance of Li-rich layered cathode material, Li[Ni0.2Li0.2Mn0.6]O-2, for lithium-ion batteries

The Li-rich layered cathode material, Li [Ni0.2Li0.2Mn0.6]O-2, was synthesized via a mixed oxalate method, and its structural and electrochemical propertieswere compared with the same material synthesized by the sol-gel method. X-ray diffraction (XRD) shows that the synthesized powders have a layered O-3-LiCoO2-type structure with the R-3m symmetry. X-ray photoelectron spectroscopy (XPS) indicates that in the above material, Ni and Mn exist in the oxidation states of +2 and +4, respectively. The layered material exhibits an excellent electrochemical performance. Its discharge capacity increases gradually from the initial value of 228 mA hg(-1) to a stable capacity of over 260 mA hg(-1) after the 10th cycle. It delivers a larger capacity of 258 mA hg(-1) at the 30th cycle. The dQ/dV curves suggest that the increasing capacity results from the redox-reaction of Mn4+/Mn3+.