Lithium-based Lithium-based Base Layer Li [Li _X Ni _0.13 Co _{0.13 0.54 < Synthesis And Modification Of Cathode Materials}

This thesis mainly summarizes the characteristics and research development of cath-ode materials for Li-ion batteries and systematically carries out the synthesis and electrical performance optimization of layered Li-rich manganese-based Li[LixNi0.13Co0.13Mn0.54]O2cathode materials.By using sulphate and LiOH-H2O as its main raw materials, the precursor has been prepared by co-precipitation method. The particle size and morphology of the precursor and the electrical performance of the Li[Li0.2Ni0.13Co0.13Mn0.54]O2has been influenced by fac-tors such as the sintering temperature, reactant concentration, pH, co-precipitation temper-ature. With the increase of the concentration of reactants, the particle size of precursor be-comes larger, and the number of nanoparticles attached to a large particles increase, which gets the first discharge capacity of246.0mAh/g at1mol/L and the first efficiency of77.3%at2mol/L. With the increase of pH, the particle size of precursor and Li[Li0.2Ni0.13Co0.13Mn0.54]O2material becomes smaller. When pH is11.5, the first discharge capacity of the material is256.6mAh/g and its first efficiency can be up to78.6%. The particle size of precursor becomes larger as the co-precipitation temperature increases. When the reaction temperature is40℃, The first discharge capacity is up to253.7mAh/g and the first efficiency reaches77.4%. Meanwhile, this paper analyses the effect of particle size on the electrical performance of materials. As Li+diffusion path shorten and Li+port increase, the smaller the particles, the better electrical performance. The data indicates that the Li[Lio.2Ni0.13Co0.13Mno.54]O2material prepared at950℃for10h achieves a good elec-trical performance. The first discharge capacity reaches258.9mAh/g, meanwhile, the first efficiency reaches75.6%.Li[LixNi0.13Co0.13Mn0.54]02(x=0.09,0.12,0.16,0.22,0.24,0.29,0.33,0.37) is synthe-sized by solid state method by using Ni0.13Co0.13Mno.54(OH1.6and Li2CO3as its raw mate-rials. Ni0.13Co0.13Mn0.54(OH)1.6is provided by Gold Sky Energy Materials Co. Ltd. By the optimization of lithium content, Li1.22Ni0.133Co0.131Mn0.54O2achieves the best electrochem-ical performance. By testing the electrical performance between2-4.8V at12.5mA/g, the discharge capacity is up to253.7mAh/g and the first efficiency is68.4%. For both precur-sors that the small and dispersive particle materials can improve the layered Li-rich man-ganese-based cathode materials for the first efficiency.