Ion‐Induced Symmetry Breaking in 2D FePS 3 Enables Rational‐Polarized Sulfur Sites for Accelerated Li‐O 2 Batteries Kinetics

ABSTRACT Condensed materials featuring strongly polarized sulfur sites are widely explored for electrochemically driven oxygen catalysis. However, excessive polarization often leads to overly strong adsorption of reaction intermediates and consequent site passivation. Herein, an ion‐exchange strategy is developed to construct Li + ‐doped FePS 3 with rationally regulated sulfur polarization. Compared with pristine FePS 3 , Li + ‐doped FePS 3 exhibits a moderately shifted S p‐band center, thereby optimizing the adsorption of LiO 2 and Li 2 O 2 intermediates. When employed as an electrocatalyst for Li‐O 2 batteries, Li + ‐doped FePS 3 delivers a reduced overpotential of 1.53 V, a high specific capacity of 11287 mAh g −1 , and stable cycling with suppressed polarization at 500 mA g −1 . In situ x‐ray absorption spectroscopy reveals reversible valence evolution of Fe sites during battery operation. Further electronic‐structure analysis demonstrates that Li + ‐induced electronic reconstruction synergistically regulates the Fe 3d states and S p orbitals, enabling balanced interactions with LiO x intermediates and accelerating oxygen electrochemistry. This work establishes ion‐mediated symmetry breaking as an effective strategy for regulating anion‐site reactivity and promoting efficient Li‐O 2 chemistry.