Enhanced electrochemical performance of LiNi${}_{0.8}$Co${}_{0.1}$Mn${}_{0.1}$O${}_2$ cathode via wet-chemical coating of MgO

LiNi${}_{0.8}$Co${}_{0.1}$Mn${}_{0.1}$O${}_2$ (NCM811) has a high potential for using as the cathode material for lithium-ion batteries (LIBs) for electric vehicles owing to its high energy density and low cost. However, its poor rate capability and cycling performance have significantly hindered its application. In this study, we successfully design a uniform magnesium oxide (MgO) coating on NCM811 via a wet-chemical coating followed by heat treatment using magnesium ethoxide [Mg (OEt)${}_2$] dissolved in ethanol as the Mg source. The effects of MgO coating on the surface states, crystal structure, and electrochemical performances of NCM811 cathode material are studied in detail. After 100 cycles, the capacity retention of MgO-coated NCM811 is 90.1% at room temperature at 1 C, whereas the pristine NCM811 is only 74.5%. Besides, the MgO-coated NCM811 delivers a better rate property than pristine NCM811. Prominent improvements in electrochemical performances are attributed to the fact that the formation of MgO coating layer helps to suppress deleterious side reactions, lower the overpotential on the surface, and facilitate lithium-ion diffusion.