Y2O3 modification on nickel-rich LiNi0.8Co0.1Mn0.1O2 with improved electrochemical performance in lithium-ion batteries

Abstract

Doping and coating are frequently employed for the improvement of the properties of Ni-rich NCM materials. In this work, we prepared stable LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) materials modified with Y₂O₃ via a wet chemical method. In order to investigate the action mechanism of Y₂O₃ on NCM811, we analyzed the microstructures using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Also, to study the electrochemical performances, we conducted a charge/discharge test and cyclic voltammetry. Our results show that Y₂O₃ modified NCM811 materials have good thermal stability, and proper content of Y₂O₃ can effectively prevent the materials from damaging and significantly improve the electrochemical properties of the materials. Particularly, 1% Y₂O₃ modified NCM811 material show much better cycling performance than other samples. During cycling at 1.0C, the 1% Y₂O₃ modified NCM811 shows capacity retention of 90.1% after 100 cycles, which is higher than 69.4% for pristine NMC811. We examined the microstructures of the materials before and after circulation. Using the SEM results, we conclude that structural changes are among the key factors that lead to the degradation of the electrochemical properties of materials.