Revealing the Atomic‐Scale Evolution of Ni‐Ions and NiO6 Octahedrons for Regenerating Spent Ni‐Rich Cathodes

Abstract

As a promising recycling strategy, the thermal solid‐state regeneration method captures enormous attention, due to its low cost and great structural stability for recovering Ni‐rich cathodes. Note that the fundamental structural traits of bulk‐phase always serve as important roles in their electrochemical properties, but the regeneration of Ni‐rich materials still suffers from an unclear understanding of physical‐chemical evolution, especially about the variation of fundamental units and vital elements. Herein, in this work, the crystalline and structural evolution is systematically investigated at the atomic level. Especially Ni‐ions valence state and NiO6 octahedral symmetry, their orderliness and valence state transformation are further illustrated, which bring about the control of local lattice structure, internal strain, and interfacial ordering. Supported by the detailed tailoring of NiO6 octahedral ordering and Ni‐ions chemical properties, the as‐regenerated Ni‐rich cathodes deliver considerable cycling durability and structural stability at different voltage regions. Supported by the kinetic analysis, the acceleration of reaction kinetics is further confirmed, along with the decreased interfacial side reactions. Given this, the work is expected to shed light on the in‐depth understanding for the regeneration process of degraded Ni‐rich cathodes, and provide a path for high‐efficiency reconstruction of high‐performance cathodes.