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 conductor of electrons, the ultra-wideband semiconductor material Ga2O3 for its in-situ coating modification was adopted. 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+ migration 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 surface 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 center dot g(-1) in the first cycle of the charge-discharge at 0.1C (25 mA center dot g(-1)), and still maintained 127.4 mAh center dot g(-1) at 5C, which was better than 90.7 mAh center dot g(-1) of the unmodified material. G3-LRMO still had a capacity of 190.7 mAh center dot 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 impedance (R-ct) of the G3-LRMO material was 107.7 Omega after 100 cycles at 1C, which is much lower than that of the unmodified material (251.5 Omega), indicating that the Ga2O3 coating layer can improve the electron transfer rate of the material.