Dual‐Anion Mutual‐Facilitation Effect Directs Surface Reconstruction for Reversible Anion Redox in Cobalt‐Free Li‐Rich Mn‐Based Cathodes

Li‐rich Mn‐based layered oxides (LLOs) offer high energy density through coupled cationic and anionic redox, but suffer from irreversible oxygen loss, voltage decay, and surface reconstruction. Here, we develop a mutual‐assisted F/S dual‐anion doping strategy to regulate anion incorporation and near‐surface evolution. Density functional theory calculations show that F alleviates S‐induced lattice strain, stabilizes the local charge environment, and lowers the barrier for S penetration. The resulting cathode features a depth‐dependent architecture with lattice‐incorporated F/S species, regulated oxygen vacancies, a spinel‐like reconstructed region and a sulfate/sulfite‐derived interphase, while retaining the layered bulk. Multiscale spectroscopy and operando analyses reveal enhanced Mn/Ni redox and reversible lattice‐oxygen activity, suppressing oxygen release, lattice breathing, electrolyte decomposition, and phase propagation. The optimized cathode retains 84.4% capacity after 200 cycles at 1 C with a voltage‐decay rate of 1.093 mV per cycle, and 88.63% after 1000 cycles at 5 C. Post‐cycling analyses and multiphysics simulations further link this durability to reduced transition‐metal dissolution, homogenized Li + transport, and mitigated stress localization. This work demonstrates dual‐anion doping as an effective route to coordinate defect chemistry, redox activity and interfacial reconstruction in high‐capacity cathodes.