Novel approach to preparation of LiMn2O4 core/LiNixMn2−xO4 shell composite

Combining two methods, coating and doping, to modify spinel LiMn2O4, is a novel approach we used to synthesize active material. First we coated the LiMn2O4 particles with the nickel oxide particles by means of homogenous precipitation, and then the nickel oxide-coated LiMn2O4 was calcined at 750 °C to form a LiNixMn2−xO4 shell on the surface of spinel LiMn2O4 particles. Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), cyclic voltammetry (CV) and charge-discharge test were performed to characterize the spinel LiMn2O4 before and after modification. The experimental results indicated that a spinel LiMn2O4 core is surrounded by a LiNixMn2−xO4 shell. The resulting composite showed excellent electrochemical cycling performance with an average fading rate of 0.014% per cycle. This improved cycle stability is greatly attributed to the suppression of Jahn-Teller distortion on the surface of spinel LiMn2O4 particles during cycling.