Preparation And Electrochemical Performance Study Of Rich Lithium Material Li_1.2Mn_0.54Ni_0.13Co_0.13O₂

Rich lithium material x Li2 Mn O3·（1-x）Li MO2 has so many advantages, such as high capacity and high working voltage, etc. These advantages make the rich lithium material become an ideal choice content to the demand of power battery used on cars. In this paper, Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ was prepared and optimized synthesis technology in order to obtain the optimum synthesis process. Rare earth elements La and Nd were doped though Li1.2Mn0.54-xNi0.13Co0.13MxO2 and Li1.2 [Mn0.54Ni0.13Co0.13]1-xMxO2 in order to obtain the impact on electrochemical performance. At last, switched to high pressure liquid electrolyte, and found out the impact on the performance of the material.In this paper, Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ was prepared by quaternary eutectic Li-N i-Co-Mn acetate process and characterized by testing measures such as XRD, SEM. The button cell electrochemical performance was researched testing measures such as cyclic voltammogram,charge and discharge technology and electrochemical impedance spectroscopy. According to experimental results, the best reaction condition was at 900℃ for 9h in flow air. In this condition,the material had a good layer structure and the particle size was uniform. In 2.0⁴.8V at 0.1C（1C=278m Ah/g） rate after 50 cycles, the discharge specific capacity could be maintained in 93.92%. Added citric acid in the preparation process of Li_1.2Mn_0.54Ni_0.13Co_0.13O₂, the results showed that the particle size was more uniform and the material had a better distribution. After switch to high pressure liquid electrolyte, the discharge capacity of material was increased.In order to improve the electrochemical performance of Li1.2 Mn0.54Ni0.13Co0.13O2,rare earth element La was doped by the way of Li1.2Mn0.54-xNi0.13Co0.13LaxO2 and Li1.2 [Mn0.54Ni0.13Co0.13]1-xLaxO2（x=0.01、0.03、0.05）. The layer structure of material was more completely, and cationic mixed degree was decline. It was good for lithium ion diffusion in the channel. However, the discharge specific capacity was reduced as La doped in the material. But cycle ability of Li1.2 [Mn0.54Ni0.13Co0.13]0.05La0.05O2 was improved.Nd was doped as the way as La and the layered structure was not been changed. When the x value of 0.03, compared with the material without doping, after 50 cycles Li1.2[Mn0.54Ni0.13Co0.13]0.97Nd0.03O2 showed better performance. The discharge specific capacity which retained 95.27%.In the other way of doping as Li1.2Mn0.54-xNi0.13Co0.13NdxO2, when the x value of 0.005, the initial discharge specific capacity was 207.96 m Ah/g and the coulombic efficiency was 74.85%. When the value of x was 0.01, Li1.2Mn0.53Ni0.13Co0.13Nd0.01O2 was charged and discharged 50 times. The discharge specific capacity which retained 94.29%.The results showed that, the cycle ability of the material doped with Nd was better.