A universal multifunctional rare earth oxide coating strategy to stabilize high-nickel lithium layered oxide cathode

Abstract

LiNi0.8Co0.1Mn0.1O2 (NCM811) high-nickel lithium layered oxide material has gained recognition as a promising cathode material for lithium-ion batteries (LIBs) due to its relatively high output capacity. However, the presence of high nickel content leads to capacity fading resulting from surface residue lithium and cathode-electrolyte interfacial side reactions, posing a significant threat to the cycle life for battery. In this study, we have developed an ultrathin and uniform CeO2&LiCeO2 nanoscale rare earth composite functional coating in-situ for NCM811 cathode, utilizing residual lithium and rare earth oxide. Ex-situ scanning electron microscope (SEM), electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectrometer (XPS) analyses confirm the reduction in interfacial side reactions, leading to improved stability at the cathode-electrolyte interface. This improvement can be attributed to the removal of surface residual lithium and the formation of stable CeO2&LiCeO2 functional coatings. As a result, the NCM811 modified with the rare earth composite functional coating exhibits a higher capacity retention rate after 100 cycles (90.9% vs. 86.1%) and enhanced rate capacity (136 mAh g−1 vs. 117 mAh g−1) at 5 C than the NCM811. Even the designed full battery achieves an energy density as high as 253 Wh kg−1. This work presents an innovative approach to utilize residual lithium and rare earth oxide for in-situ functional coating formation, ultimately enhancing the lithium storage performance of high-nickel NCM811 cathodes.