Electrochemical Performance Ni Doped Spinel LiMn<sub>2</sub>O<sub>4</sub> Cathode for Lithium Ion Batteries

LiNixMn2-xO4 (x=0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5) compounds with spinel crystal structure are synthesized by sol-gel method. The dependence of the physicochemical properties of these compounds has been extensively investigated by using X-ray diffraction (XRD), scanning electron microscope (SEM), cyclic voltammogram (CV) and charge-discharge test. It is found that as Mn is replaced by Ni, the initial capacity decreases, but the capacity retention is enhanced. Of all the LiNixMn2-xO4 (x=0, 0.05, 0.1, 0.2, 0.3, 0.4) compounds, the LiNi0.2Mn1.8O4 has best electrochemical performance, about 120mAhg-1 discharge capacity, its capacity retention rate of 96.6% after 100 cycles. However the LiNi0.5Mn1.5O4 sample shows excellent electrochemical performance at 4.7 V high potential, 150 mAhg-1 discharge capacity, above 110 mAhg-1 of capacity retention after 42 cycles of charge/discharge. The prepared LiNi0.5Mn1.5O4 powders sintered at 750 °C here has Fd3m space group.