Comparison of different soft chemical routes synthesis of submicro-LiMn2O4 and their influence on its electrochemical properties

A comparative study of submicro-crystalline spinel LiMn2O4 powders prepared by two different soft chemical routes such as hydrothermal and sol-gel methods is made. The dependence of the physicochemical properties of the spinel LiMn2O4 powder has been extensively investigated by using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope, cyclic voltammogram, charge-discharge test, and electrochemical impedance spectroscopy (EIS). The results show that the electrochemical performances of spinel LiMn2O4 depend strongly upon the synthesis method. The LiMn2O4 powder prepared by hydrothermal route has higher specific capacity and better cycling performance than the one synthesized from sol-gel method. The former has the max discharge capacity of 114.36 and 99.78 mAh g(-1) at the 100th cycle, while the latter has the max discharge capacity of 98.67 and 60.25 mAh g(-1) at the 100th cycle. The selected equivalent circuit can fit well the EIS results of synthesized LiMn2O4. For spinel LiMn2O4 from sol-gel method and hydrothermal route in the first charge process R (SEI) remain almost invariable, R (e) and R (ct) first decreasing and then increasing with the increase of polarization potential.