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

Abstract

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.