Optimization of Al^(3+) Doping on the Microstructure and Electrochemical Performance of Spinel LiMn_(2)O_(4)

A series of spinel Li Al_(x)Mn_(2-x)O_(4) (x≤0.1) cathode materials was synthesized by controlled crystallization and solid state route with micro-spherical Mn_(3)O_(4) as 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 Al^(3+)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 Al^(3+)doping would slightly reduce the discharge capacity,but it could effectively improve the cyclic stability of the material.The initial capacity of Li Al_(0.04)Mn_(1.96)O_(4) is 121.6 m Ah/g.After 100 cycles at a rate of 1 C (1 C=148 m A/g),the capacity can still reach 112.9 m Ah/g,and the capacity retention rate is 96.4%.Electrochemical impedance spectroscopy (EIS) suggests that Al^(3+)doping can effectively enhance the diffusion capacity of lithium ions in the material.