Y2o3 Functional Coating to Enhance the Lithium Storage Performance of High-Voltage Medium-Nickel Low-Cobalt Layered Oxide Cathode

Abstract

The layered oxide cathode materials with high nickel and low cobalt content in high voltage are considered as promising candidates for lithium-ion batteries due to their high capacity, low cost and high safety. However, increasing the charging cut-off voltage and reducing the cobalt content will lead to the deterioration of the electrode-electrolyte interface environment and other phase-structured problems, which will seriously affect the service life of the battery. In this study, we successfully coated Y2O3 on the surface of the cathode material by liquid-phase mixing and solid-phase calcination technology, and synthesized Y2O3-coated modified LiNi0.65Co0.05Mn0.30O2 cathode material (NCM-Y). At a high voltage of 4.5 V, the cathode material modified by Y2O3 coating showed significantly improved cycling stability compared with the unmodified material. The capacity retention rate after 200 cycles increased from 74.2% to 94%. Additionally, the graphite-type high voltage full cell prepared in this study demonstrated a capacity retention rate of 88.2% after 150 cycles, with an energy density reaching up to 228 Wh kg−1. These improvements can be attributed to the protective effect of the Y2O3 coating, which reduces side reactions between the electrode material and the electrolyte, thereby enhancing both the phase stability of the material and the stability of the electrode-electrolyte interface. This work provides valuable insights into the application of high voltage, high-nickel, low-cobalt cathode materials.

Keywords: Lithium-ion batteries, High-voltage medium-nickel low-cobalt cathode, Yttrium oxide coating, Electrochemical performance