Structural Stabilization of 4.6 V LiCoO₂ Through Tri‐Site Co‐Doping with Al‐Mg‐F

Abstract Uplifting the charging voltage of LiCoO₂ is crucial for surpassing current energy density thresholds in Li‐ion batteries. However, the structural and chemical instability of LiCoO₂ in the deeply delithiated state is a major obstacle to the practical implementation of high‐voltage LiCoO₂. This study proposes a multi‐element co‐doped LiCoO₂ that exhibits enhanced electrochemical performances at 4.6 V (vs Li/Li⁺). Al, Mg, and F are doped at three distinct lattice sites, and the contributions of each dopant are investigated using advanced synchrotron X‐ray analyses and electron microscopies. Al and Mg delay the detrimental transition to the H1‐3 phase and facilitate a smoother phase transition, thereby preserving particle robustness. The electronegative anion dopant F mitigates oxygen oxidation and ensures a wider range of transition metal redox reactions. These enhancements enable the particles to withstand numerous cycles without severe cracking or surface degradation, thereby significantly improving cyclability. Consequently, the tri‐site doping strategy effectively minimizes capacity sacrifice and bolsters battery performance, with every dopant functioning synergistically.