Optimization of Al3+Doping on the Microstructure and Electrochemical Performance of Spinel LiMn2O4①

A series of spinel LiAl xMn2- xO4(x≤ 0.1) cathode materials was synthesized by controlled crystallization and solid state route with micro-spherical Mn3O4as the precursor. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the crystal structure of the synthetic material and the microscopic morphology of the particles. It was found that Al3+doping did not change the spinel structure of the synthesized materials, and the particles had better crystallinity In the charge and discharge test of the synthesized materials, we found that Al3+doping would slightly reduce the discharge capacity, but it could effectively improve the cyclic stability of the material. The initial capacity of LiAl0.04Mn196O4is 121.6 mAh/g. After 100 cycles at a rate of 1 C (1 C = 148 mA/g), the capacity can still reach 112.9 mAh/g, and the capacity retention rate is 96.4%. Electrochemical impedance spectroscopy (EIS) suggests that Al3+doping can effectively enhance the diffusion capacity of lithium ions in the material.