Tailoring Phase‐Transition Pathways Through Low‐Temperature Topotactic Lithiation to Suppress Structural Defects of Ni‐Rich Co‐Free Cathodes

ABSTRACT Layered oxide cathodes remain one of the most promising cathode materials for lithium‐ion batteries. Replacing Co with Ni raises specific capacity and lowers cost, but Ni‐rich Co‐free materials often suffer from structural instability and compromised electrochemical performance. Herein, a “low‐temperature lithiation–high‐temperature crystallization (LL–HC)” strategy is proposed to improve the layered structure of Ni‐rich Co‐free cathode materials via low‐temperature topotactic lithiation. This tailored reaction pathway effectively suppresses structural defects, enhances phase‐transition reversibility, and mitigates variations in lattice parameters during charge/discharge. As a result, a Ni‐rich Co‐free cathode material with high capacity, high initial Coulombic efficiency, and excellent rate performance is achieved, thereby reducing the reliance on Co in Ni‐rich cathodes. This work offers valuable insights into synthesis‐pathway regulation and defect control for Ni‐rich Co‐free and other layered oxide cathode materials.