Tuning the ratio of Al2O3 to LiAlO2 in the composite coating layer for high performance LiNi0.5Mn1.5O4 materials

A series of Al compound-coated LiNi0.5Mn1.5O4 materials is synthesized by a facile calcination process under different temperatures. The effect of calcination temperature on physicochemical properties and electrochemical performance of Al-coated LiNi0.5Mn1.5O4 materials are investigated by using the X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of as-prepared materials showed that the C-500 sample (calcined at 500 degrees C) has excellent cycling performance and rate capability. Meanwhile, even at high operation temperature (55 degrees C), the capacity retention is 88% after 50 cycles at a rate of 0.5 C. Moreover, the crystal structure and surface morphology of C-500 sample after 200 cycles are also studied. All the results indicated that the composite coating layer with Al2O3 and LiAlO2 can not only reduce the side reactions at the electrode and electrolyte interface, but also provide an effective channel for the diffusion of Li+ in the charge/discharge process.