Layer Stacking Structure Governed Transition-Metal Interlayer Migration for Reversible High-Voltage Oxygen Redox Plateau

Utilization of lattice oxygen redox electrochemistry is the holy grail for achieving high-capacity layered cathodes. However, prior to this, the large voltage hysteresis must be overcome. In this work, we uncover a novel scientific nature of layered stacking structure-governed interlayer transition‑metal migration that substantially modulates the reversibility of the high-voltage oxygen plateau. It is discovered that a kind of ribbon superlattice can facilitate the reversible high-voltage oxygen redox plateau in the P3-Na_0.6Li_0.2Mn_0.6Ti_0.2O₂ with the oxygen stacking series of "ABBCCA…", but plays no role in the P2-Na_0.6Li_0.2Mn_0.6Ti_0.2O₂ counterpart with the oxygen stacking series of "ABBA…". Combined with the experiments and theoretical calculations, it is unraveled that the P3 stacking framework can suppress O-type stacking faults and in turn elevates steric hindrance to the transition metal migration and the formation of molecular oxygen, thus enabling reversible high-voltage oxygen redox. In contrast, the P2 phase can transform into O2 phase at de-sodiated state, which accelerates severe interlayer transition metal migration, and triggers in-plane structural reconstruction and molecular oxygen, leading to loss of high-voltage plateau. This finding reveals how the layer stacking structure modulates the reversible oxygen redox plateau.