High-performance Ti-doped V2O5 coating on the Ni-rich layered cathode: Construction and theoretical calculation

Abstract

Surface coating had been widely acknowledged as an effective method to improve the electrochemical performance of the cathodes for lithium-ion batteries (LiBs). In this study, a high-conductivity Ti0.05V1.96O5 (TVO) coating was successfully deposited on the surface of Li(Ni0.8Co0.1Mn0.1)O2 (NCM811) particles. The crystal structure, micro morphology and element composition of the resulted NCM811 @TVO samples were evaluated using X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) analysis. Subsequently, the electrochemical performance of NCM811 @TVO cathodes were evaluated by galvanostatic charge/discharge tests (GCDT) and electrochemical impedance spectroscopy (EIS). The experimental results suggested that incorporating a TVO coating on the NCM811 cathode effectively enhanced both the rate capability and the cycling stability. Furthermore, first-principles calculation based on the density functional theory (DFT) were performed to elucidate the distinct electronic structure and Li ion migration behavior of V2O5 and TVO. The DFT calculation demonstrated that the introduction of Ti ions into the V2O5 leaded to the formation of small polarons and excessive free electrons, while significantly reduced the energy barrier for Li+ migration along [100] direction.