Effective enhancement of electrochemical performance for spherical spinel LiMn2O4 via Li ion conductive Li2ZrO3 coating

In order to enhance the electrochemical performance of spherical spinel LiMn2O4, an in situ coating technique with Li2ZrO3 is successfully developed. The structure and morphology of the Li2ZrO3 coated LiMn2O4 are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), energy dispersive spectrometer (EDS) and selected area electron diffraction (SAED). The results reveal that the Li2ZrO3 coating uniformly deposited on the surface of the spherical spinel LiMn2O4 with a thickness of 3 nm. In addition, the electrochemical performances of the Li2ZrO3 coated LiMn2O4 and no-coating LiMn2O4 samples are characterized by electrochemical impedance spectroscopy (EIS) and charge-discharge tests. It has been found that the electrochemical performance of spherical spinel LiMn2O4 is obviously enhanced. Particularly, the 3 wt.% Li2ZrO3 coated LiMn2O4 sample exhibits excellent cycling performance with 99.0% and 90.2% capacity retention after 100 cycles at 1 C at 25 °C and 55 °C, which are apparently higher than 89.9% and 58.0% of no-coating spinel LiMn2O4. Therefore, it can be considered that a thin Li2ZrO3 coating layer is an effective way to improve the electrochemical performance of LiMn2O4, especially the elevated temperature performance.