Enhanced electrochemical performances of LiNi0.8Co0.1Mn0.1O2 by synergistic modification of sodium ion doping and silica coating

Abstract

LiNi0.8Co0.1Mn0.1O2 (LNCM811) is a promising cathode material for lithium ion batteries. However, it is difficult to commercialize on a large scale because of its unstable structure and fast capacity attenuation. To solve above problems, in this paper, the Na-doped LNCM811 material (LNCM811-Na) has been synthesized via hydrothermal method and high temperature solid phase method, and then it is coated with SiO2 (LNCM811-Na@SiO2) on the basis of Na doping. The structure, composition, morphology, and microstructure of LNCM811-Na@SiO2 are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. The results show that the specific capacity of the LNCM811–0.1Na@SiO2(3%) sample reaches 209 mAh g−1 at 0.5C (the LNCM811–0.1Na is 195 mAh g−1 and the LNCM811 is 178 mAh g−1). When the rate is increased to 10C, the specific capacity of the LNCM811–0.1Na@SiO2(3%) sample still reaches 115 mAh g−1 (the LNCM811–0.1Na is 95 mAh g−1 and the LNCM811 is 72 mAh g−1). The results of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) prove that Na doping and SiO2 coating can effectively reduce the polarization and the charge transfer impedance, further promote the improvement of electrochemical performance. Thus, the LNCM811–0.1Na@SiO2(3%) sample is a very promising material in power batteries.