Electrochemical behaviours of SiO2-coated LiNi0.8Co0.1Mn0.1O2 cathode materials by a novel modification method

Abstract

A novel SiO2-coating on cathode materials process is introduced to improve the electrochemical performance and storage property of LiNi0.8Co0.1Mn0.1O2. The continuous and uniform nanoscale layer of SiO2 is successfully coated onto the surface of LiNi0.8Co0.1Mn0.1O2 particles through carbonic acid neutralization method, which is demonstrated by X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). The nanostructured SiO2 coating film on the surface of particles working as protective layer can effectively weaken the host particles from HF corrosion and delay the increasing amount of the lithium impurities on the surface, improving the cycle performance and storage property of LiNi0.8Co0.1Mn0.1O2 significantly. This can be further demonstrated by the outcome of Cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) tests which show that the SiO2-modified layer can greatly reduce the polarization gap and significantly decrease the charge-transfer resistance during charge/discharge process. The results of charge–discharge tests also demonstrate that the cycle performance even at elevated cut-off voltage and high temperature (60 °C), as well as the rate capability of LiNi0.8Co0.1Mn0.1O2 sample are improved strikingly after SiO2 coating modification.