Nickel-Rich and Lithium-Rich Layered Oxide Cathodes: Progress and Perspectives

Ni-rich layered oxides and Li-rich layered oxides are topics of much research interest as cathodes for Li-ion batteries due to their low cost and higher discharge capacities compared to those of LiCoO2 and LiMn2O4. However, Ni-rich layered oxides have several pitfalls, including difficulty in synthesizing a well-ordered material with all Ni3+ ions, poor cyclability, moisture sensitivity, a thermal runaway reaction, and formation of a harmful surface layer caused by side reactions with the electrolyte. Recent efforts towards Ni-rich layered oxides have centered on optimizing the composition and processing conditions to obtain controlled bulk and surface compositions to overcome the capacity fade. Li-rich layered oxides also have negative aspects, including oxygen loss from the lattice during first charge, a large first cycle irreversible capacity loss, poor rate capability, side reactions with the electrolyte, low tap density, and voltage decay during extended cycling. Recent work on Li-rich layered oxides has focused on understanding the surface and bulk structures and eliminating the undesirable properties. Followed by a brief introduction, an account of recent developments on the understanding and performance gains of Ni-rich and Li-rich layered oxide cathodes is provided, along with future research directions.This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy under Contract No. DE-EE0006447. This work was supported by the Global Frontier R&D Program (2013M3A6B1078875) on Center for Hybrid Interface Materials (HIM) funded by the Ministry of Science, ICT & Future Planning, and by the Human Resources Development Program (No. 20124010203310) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korean government Ministry of Trade, Industry, and Energy