Insights into the challenges and potential solutions of Li- and Mn-rich layered cathode materials

Abstract

Li- and Mn-rich layered oxides (LMRs) are a type of ideal cathode material for the next-generation high-energy Li-ion batteries due to their ultrahigh reversible capacity over 250 mAh g⁻¹. Their extraordinary capacity originates from the unique coherent nanodomains of hexagonal LiTMO₂ and monoclinic Li₂MnO₃, which promotes LMRs to have hybrid redox chemistry of anions and cations. However, oxygen anion redox process will induce a decrease in the diffusion coefficient and the irreversible oxygen release, and the resulting oxygen vacancies may accelerate the migration of transition metals. Therefore, the LMR cathodes always suffer from four challenges: poor rate capability, low initial Coulombic efficiency (ICE), substantial capacity degradation and voltage decay, which seriously restrict the large-scale application. Herein, this work will combine with the literature reports and the research results of our team over the past ten years, briefly present the viewpoints on solving the above problems of LMRs.