Construction of oxygen vacancies enables a highly stable Li-rich layered oxides via nitrogen assisted roasting

The Li-rich oxides (LRMOs) are considered the most promising cathode materials due to their reversible anionic redox reaction and high reversible capacity. However, the irreversible release of surface oxygen gives rise to a range of issues, including significant first irreversible capacity loss, inferior rate performance, and serious capacity/voltage decay, which hinder their commercial applications. This study employs a nitrogen (N 2 ) assisted roasting technique to effectively construct oxygen vacancies (OVs) in Li 1.2 Mn 0.56 Ni 0.16 Co 0.08 O 2 (LLMO), aiming to mitigate the irreversible release of oxygen and alleviate voltage decay. X-ray photoelectron spectroscopy and electron paramagnetic resonance tests confirmed the successful introduction of OVs into the LLMO material, referred to as N-LLMO, during N 2 heat treatment. When used as a cathode in Li-ion batteries, N-LLMO exhibited a specific capacity of 258.3 mAh g −1 , an excellent capacity retention rate of 90.0 % after 200 cycles at 1.0 C, and a high-rate performance of 150.1 mAh g −1 at 5.0 C. These enhanced electrochemical performances can be attributed to the reduced irreversible release of O 2 through the OVs introduction, which facilitates the Li + diffusion dynamics and inhibits structural collapse during cycling. This study demonstrates that employing OVs strategy may pave the way for improving the overall electrochemical performance of LRMOs.