Multifunctional Ho2O3 Coating with Oxygen Vacancies Enables High-Performance Lithium-Rich Layered Oxide Cathodes

Li-rich materials with exceptionally high specific capacity have great potential for the commercialization of cathode materials in the future. However, irreversible oxygen loss, transition metal (TM) dissolution, and structural degradation during cycling make the commercialization of Li-rich cathode materials difficult. Here, a uniform Ho2O3 coating was formed on the surface of Li-rich layered oxide (LLO) cathodes due to the good electrical conductivity and abundant oxygen vacancies of Ho2O3. The high conductivity of the material improves the kinetic performance. The modification layer effectively stabilizes the evolution of CEI during the long cycling process and inhibits the occurrence of irreversible side reactions. More importantly, the abundant oxygen vacancies effectively inhibited oxygen precipitation and enhanced the reversibility of anion redox. The charging and discharging processes of the material and the modification mechanism are deeply analyzed through a series of characterizations. The results show that the modification method effectively improves the electrochemical performance of the materials. The capacity loss of the Ho2O3-coated material is less than that of LLO after long cycling at 1C and 0.5C, and the discharge-specific capacity of the modified material can be increased to 158.1 mAh g(-1) at 5C. This paper provides a new guiding path for the design of future high-voltage LLO materials.