An Ultra‐Long‐Life Lithium‐Rich Li_1.2Mn_0.6Ni_0.2O₂ Cathode by Three‐in‐One Surface Modification for Lithium‐Ion Batteries

Abstract

Voltage decay and capacity fading are the main challenges for the commercialization of Li-rich Mn-based layered oxides (LLOs). Now, a three-in-one surface treatment is designed via the pyrolysis of urea to improve the voltage and capacity stability of Li_1.2 Mn_0.6 Ni_0.2 O₂ (LMNO), by which oxygen vacancies, spinel phase integration, and N-doped carbon nanolayers are synchronously built on the surface of LMNO microspheres. Oxygen vacancies and spinel phase integration suppress irreversible O₂ release and help lithium ion diffusion, while N-doped carbon nanolayer mitigates the corrosion of electrolyte with excellent conductivity. The electrochemical performance of LMNO after the treatment improves significantly; the capacity retention rate after 500 cycles at 1 C is still as high as 89.9 % with a very small voltage fading rate of 1.09 mV cycle^-1 . This three-in-one surface treatment strategy can suppress the voltage decay and capacity fading of LLOs.