Synthesis of high power type LiMn1.5Ni0.5O4 by optimizing its preparation conditions

LiMn_1.5Ni_0.5O₄ has been synthesized by an ultrasonic-assisted sol-gel method. The precursor is heat treated at a series of temperatures from 650 °C to 1000 °C. The structure and physical-chemical properties of the as-prepared powder are investigated by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV) thermal gravimetric and galvanostatic charge-discharge tests in detail. As temperature goes up, the particle size increases, the reactivity of the material in 4 V region becomes more obvious, the structure of the samples become more stable and it behaves optimal electrochemical properties as the material is heat treated at 850 °C. When it is used as cathode active material in a lithium battery, it delivers high initial capacity of 134.5 mAh g⁻¹ (corresponding to 91.7% of the theoretical capacity), and high rate discharge capability, e.g., 133.4, 120.6, 111.4, 103.2 and 99.3 mAh g⁻¹ as discharged at 0.5, 1, 5, 10 and 15 C (1 C = 148 mA g⁻¹)-rates, respectively. It also shows satisfactory capacity retention even at high rate of 5 C, which is about 99.83% of the capacity retention per cycle.