Improved elevated temperature performance of spinel LiMn2O4 via surface-modified by Li-rich Li1.2Ni0.2Mn0.6O2 for lithium-ion batteries

In order to improve the electrochemical performance of LiMn 2 O 4 at elevated temperatures, a series of Li 1.2 Ni 0.2 Mn 0.6 O 2 -modified LiMn 2 O 4 samples have been synthesized by a facile sol-gel method. The structure and morphology of pristine and modified LiMn 2 O 4 are investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The Li 1.2 Ni 0.2 Mn 0.6 O 2 coating layer is identified by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), which plays an important role in reducing the dissolution of manganese, thereby improving the cycle performance and rate capability of the material. The 2 wt% Li 1.2 Ni 0.2 Mn 0.6 O 2 -modified LiMn 2 O 4 sample exhibits a higher capacity retention of 95.88% than that of the pristine one (81.2%) after 200 cycles at 1C and 25 °C. Furthermore, a capacity retention of 89.74% is obtained for the 2 wt%-modified LiMn 2 O 4 sample after 200 cycles at 1C and 55 °C, compared to 66.34% for the pristine one. Surface modification with a Li-rich Li 1.2 Ni 0.2 Mn 0.6 O 2 material is a good way to improve the elevated temperature performance of LiMn 2 O 4 .