Gradient Mo Doping via Fick's Law for Stabilizing Lattice Oxygen in Lithium‐Rich Manganese‐Based Cathodes

ABSTRACT Lithium‐rich manganese‐based (LR) cathodes can deliver high capacity through oxygen redox, but irreversible oxygen release often causes structural degradation, voltage decay, and poor cycling stability. Herein, we propose a Fick's law–guided gradient molybdenum (Mo) doping strategy to simultaneously stabilize bulk lattice oxygen and protect surface interfaces. Gradient‐distributed Mo forms strong Mo–O bonds that suppress oxygen loss, while high‐valent Mo induces an in situ Li ₂ MoO ₄ coating and a partial spinel structure, mitigating electrolyte erosion and facilitating Li ⁺ diffusion. The optimized LR@S‐Mo cathode delivers a reversible capacity of 195.1 mAh·g ⁻¹ with 88.6% retention after 300 cycles at 1C. Theoretical calculations support that Mo doping reduces the Li ⁺ diffusion barrier and enhances oxygen stability. This work provides a unified surface‐to‐bulk modification route for high‐energy‐density LR cathodes. In this work, a surface‐enriched, depth‐dependent Mo distribution is constructed based on a diffusion‐guided design, accompanied by an in situ Li ₂ MoO ₄ /spinel surface layer, which correlates with improved electrochemical stability of lithium‐rich Mn‐based cathodes.