Ga2O3 coated modification and electrochemical performance of Li1.2Mn0.54Ni0.13Co0.13O2 cathode material
To solve the bottleneck problem of lattice oxygen precipitation during the cycling process of lithium-rich manganese-based anode materials and the poor cycling performance due to the lithium-rich phase of the poor con-ductor of electrons,the ultra-wideband semiconductor material Ga2O3 for its in-situ coating modification was adopt-ed.The purpose of the surface modification is to improve its electronic conductivity to increase the multiplicity of performance,and at the same time,the C2/m space group of the Ga2O3 coating layer can both improve the Li+migra-tion rate and inhibit the Li+migration rate.It can also inhibit the lattice oxygen precipitation of Li-rich manganese-based materials.A pristine sample of Li-rich manganese-based cathode materials Li1.2Mn0.54Ni0.13Co0.13O2(P-LRMO)was prepared by co-precipitation method,and in-situ coated with different contents of Ga2O3 by simple wet-chemical method as well as low-temperature calcination method.The results of transmission electron microscopy(TEM)and X-ray photoelectron spectroscopy(XPS)showed that the Ga2O3 coating layer was successfully synthesized on the sur-face of the pristine sample.The results of electrochemical tests showed that the modified material G3-LRMO with mass fraction of 3％Ga2O3 had the best electrochemical performance,which could reach 270.1 mAh·g-1 in the first cycle of the charge-discharge at 0.1 C(25 mA·g-1),and still maintained 127.4 mAh·g-1at 5C,which was better than 90.7 mAh·g-1 of the unmodified material.G3-LRMO still had a capacity of 190.7 mAh·g-1 after 200 cycles at 1C,and the capacity retention rate increased from 72.9％to 85.6％,which proves that the modification of Ga2O3 coating can improve the cycling stability of lithium-rich manganese-based materials.Moreover,the charge transfer imped-ance(Rct)of the G3-LRMO material was 107.7 Ω after 100 cycles at 1C,which is much lower than that of the unmodified material(251.5 Ω),indicating that the Ga2O3 coating layer can improve the electron transfer rate of the material.
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