Synthesis And Modification Of LiNi Co _0.1 Mn _{O 2 For Lithium Ion Batteries}

Li0.8Co0.1Mn0.1O2inherits the high specific capacity of LiNiO2, at the same time,the problems of its serious Li+/Ni2+cation mixing and difficult synthesis improve significantly because of the addition of Co and Mn, but for better application of commercialization, its cycle stability, storage performance and rate performance need to be improved.How to make LiNi0.8Co0.1Mn0.1O2not only have high specific capacity, but also have a better cycle stability,storage performance and rate performance become the research hotspot of most researchers.This paper mainly introduces about using the co-precipitation method synthesis of spherical-like811cathode materials, and discussed the impact of synthesis process conditions on the performance of811cathode materials, such as types of precipitation agent, aging time, sintering time.On this basis, the influence of Li+-doping, Mg2+-doping, Al3+-doping and Li-Al co-doping on the811performance by experiment were discussed, on the other hand, the influence of AlPO4-coated and LiCoPO4-coated on the811performance were also discussed. SEM, laser particle size, tap density, XRD, XPS, ICP-AES, EIS, differential capacity curves, electrochemical performance tests were used for characterize the performance of the materials.Test results show that different precipitants, different aging time, different sintering time, different ions doping and different coated can all obtained materials with α-NaFeO2layered structure.Mg2+-doping have an effect of stable P-Ni(OH)2phase and inhibiting α-Ni(OH)2phase in precursors, and Al3+-doping have an effect of stable α-Ni(OH)2phase in precursors.Precursors obtained by Na2CO3precipitation method is amorphous and811obtained by Na2CO3precipitation method has a high cation mixing degree,its electrochemical performance is bad.By controlling the aging time of precursors,extended the sintering time, Li+-doping, Mg2+-doping,Al3+-doping and Li-Al co-doped can all inhibit Li+/Ni2+cation mixing in materials, improve the orderliness of materials layered structure, improve the reversible capacity and cycling performance of the materials.Mg2+-doping and Al3+-doping can inhibit Li+out from the interior of cathode materials and reduce the formation of Li2CO3on the surface of cathode materials.Li2CO3will increase RSEI of materials and impact on the electrochemical properties of materials. Li+-doping, Mg2+-doping and Al3+-doping material can inhibit the phase change from H2to H3during charge/discharge, and reduce the irreversible capacity caused by phase change. Charge and discharge test results show, with the synergy of Li+-doping and Al3+-doping, Li-Al co-doped get a good electrochemical performance, its initial discharge capacity of0.2C is159.7mA-h/g, with a initial activation charge/discharge efficiency of76.4%,152.1mA-h/g remains after20cycles, capacity retention rate of95.2%.There is a small amount of Li3PO4on the material surface after the AlPO4-coated and LiCoPO4-coated, and the amount of Li3PO4phase is relatively small in LiCoPO4-coated materials, also it was found that some of Al3+into the crystal lattice of AlPO4-coated cathode material particles, while some of Co2+into the crystal lattice of LiCoPO4-coated cathode material particles. EIS tests showed that AlPO4-coated and LiCoPO4-coated can effectively reduce the RSEI and Rct of materials, and the effect of AlPO4-coated is better than LiCoPO4-coated.AlPO4-coated can not only improve the electrochemical properties of the materials at low rate, but also improve the electrochemical properties of materials at high rate.LiCoPO4-coated did not effectively improve the performance of materials at low rate, but the electrochemical properties improved of materials at high magnification.