Molecular O₂ Suppression by Relieving Magnetic Frustration for Sustainable Lithium-Rich Layered Oxides

The fundamental barrier to achieving a sustainable anionic redox reaction (ARR) in Li-rich layered oxides stems from the competing requirements of converting lattice oxygen into reversible oxygen dimer while rigorously preventing molecular O2 formation. Regrettably, this objective remains unattained for application-wise Li-rich layered oxides. We herein reveal that Li1.2Ni0.2Mn0.6O2 synthesized via conventional carbonate precursors introduces Li[NiMn5] and TM[Ni2Mn4] units, significantly exacerbating magnetic frustration and inducing molecular O2 formation. By contrast, hydroxide-synthesized Li1.2Ni0.2Mn0.6O2 (H-LNMO) effectively suppresses the formation of Li[NiMn5] and TM[Ni2Mn4] while it introduces slight chemical short-range disorder (CSRD), substantially relieving magnetic frustration. This magnetic-frustration-tuning strategy inhibits molecular O2 formation and oxidizes dimer (O2)n− to higher oxidation states (O2)m− (m < n). Resultantly, the capacity retention after 1000 cycles of H-LNMO can elevated from 29.5% to 84.6%, and a first-cycle capacity of 267 mAh/g can be achieved at 0.1C. In addition, this work statistically analyzed other types of layered Li-rich cathodes to prove the universal laws between magnetic frustration and degree of oxygen dimerization, proposing magnetic frustration engineering as an effective strategy to enhance ARR stability in Li-rich layered oxides.