Air Instability of Ni-Rich Layered Oxides–A Roadblock to Large Scale Application

摘要

Benefiting from the excellent lithium ions diffusion kinetics and considerabledischarge specific capacity, Ni-rich layered oxides have become the preferredselection cathode active materials (CAMs) for high energy density Li-ionbatteries. However, due to the distinctive electronic structure of nickel ions(Ni~(2+/3+/4+)) and the strict criteria for sintering conditions, the Ni-rich CAMsinherently suffer from notorious deterioration when in contact with theambient air. This review provides a comprehensive and critical overview ofair instability for Ni-rich CAMs, a neglected but critical issue for large-scaleapplication. The fundamental understanding of derivation of air instabilityand characterizations is first given, followed by a discussion of evolutionbehaviors and the corresponding negative influence on fabricating propertiesof electrodes and electrochemical/safety performance of batteries. Afterward,various material modification strategies for improving air storage stabilityincluding pre-treatment by doping and coating and post-treatment by gas,wash, and heat are overviewed. Finally, some perspectives for further explorationto address the air instability issue and pave ways toward Ni-rich CAMs’practical applications are also proposed.