Pulsed Charging‐Induced Interfacial Stabilization Enables Highly Stable Iron Phosphate Electrode for Ultrafast Electrochemical Lithium Extraction

ABSTRACT Amid the soaring global demand for lithium, electrochemical lithium extraction using iron phosphate (FePO 4 ) electrodes is promising, yet its practical application in salt lake brines is severely constrained by high Mg 2+ /Li + ratios. Herein, we unravel the intrinsic degradation mechanism by demonstrating that Mg 2+ intercalation weakens the Fe─O bonds in FePO 4 , triggering Fe 2+ dissolution, and inducing the formation of Fe 2 O 3 surface species that deteriorate electrode performance. To tackle this critical challenge, we propose a novel pulsed charging protocol where reverse potentials not only efficiently flush out surface‐intercalated Mg 2+ but also enrich Cl − on the electrode surface, thereby modulating the electronic structure and lowering the Mg 2+ deintercalation barrier. The FePO 4 ||Ag cell integrated with this protocol exhibits superior Li + extraction kinetics (∼20 mg g −1 h −1 ), high LiCl product purity (99.95%), and exceptional cycling stability (800 h operation with ∼80% performance retention) in real salt lake brines. This work establishes a theoretical basis for electrode protection and provides a robust strategy to advance high‐efficiency electrochemical lithium extraction.