Effect of Mn Source on 5 V LiNi0.5Mn1.5O4 Positive Electrode Materials Prepared by Combustion Method

Sub-micrometric LiNi0.5Mn1.5O4 cathode materials were prepared by sucrose combustion method with two different Mn sources. The effect of manganese acetate and manganese nitrate on the crystal structure, morphology, particle size and electrical performance of the prepared samples was evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), particle size analysis, cyclic voltammetry (CV),galvanostatic charge-discharge test and electrochemical impedance spectroscopy (EIS). XRD analysis shows that the structure of both samples is a typical cubic spinel with Fd3m space group. The particle size and the distribution of the LiNi0.5Mn1.5O4 powder are strongly influenced by Mn source. The materials prepared by manganese acetate have smaller particle size and narrower particle size distribution, which can facilitate Li ions extraction and insertion. Furthermore, the sample LiNi0.5Mn1.5O4 prepared by manganese acetate has better electrochemical performances. An initial specific capacity of 144.5 mAh.g(-1) at 1C in the voltage range of 3.6 similar to 5.2 V, 96% of the initial capacity after 100 cycles is maintained, and capacities of 136.3, 132.0, 124.7 and 96.6 mAh.g(-1) are achieved at the rate of 3C, 5C, 10C and 20C, respectively.