LiNi0.5Mn1.45Zn0.05O4 with Excellent Electrochemical Performance for Lithium Ion Batteries

Pure LiNi0.5Mn1.45Zn0.05O4 with a mixture of ordered and disordered phase has been successfully synthesized by a low temperature solution combustion synthesis method at 700°C. The phase structure and micro morphologies are investigated by X-ray powder diffraction(XRD), infrared spectroscopy(FT-IR) and scanning electron microscopy(SEM). The electrochemical properties are studied by cyclic voltammetry(CV), electrochemical impedance spectroscopy(EIS) and galvanostatic charge-discharge testing. The results indicate that the substitution of Zn on Mn site in the LiNi0.5Mn1.5O4 can improve the cycling stability both at room temperature and even at elevated temperature 55°C and the rate capability significantly. The initial specific capacity at 1C rate of LiNi0.5Mn1.45Zn0.05O4 is 140.4mAh/g, and can remain 95% after 400 cycles at room temperature and 92.9% after 100 cycles at 55°C. The specific capacity of LiNi0.5Mn1.45Zn0.05O4 is high to 125.3mAh/g at 10C, and the capacity retention is still 95.4% after 100 cycles at 10C compared with the first cycle at 10C. The excellent performance of LiNi0.5Mn1.45Zn0.05O4 is ascribed to its better crystallinity, higher conductivity and higher lithium diffusion coefficient(DLi).