Electric‐Field‐Triggered Sulfonate Interfacial Regulation Enables High‐Selectivity Electrochemical Direct Lithium Extraction via Dynamic Ion Sieving

ABSTRACT Electrochemical direct lithium extraction emerges as a promising route toward sustainable lithium supply, yet pervasive interference from Na + and Mg 2+ incurs formidable kinetic barriers. Herein, we construct field‐responsive H 1.6 Mn 1.6 O 4 @poly (3,4‐ethylenedioxythiophene)‐polystyrenesulfonate (HMO@PEDOT:PSS) sulfonate interfaces and establish a dynamic ion sieving mechanism for selective lithium recovery. Synergistically integrated conductive PEDOT framework and sulfonate functional moieties endow the heterointerfaces with instantaneous electric field‐triggered responsiveness. The field‐sensitive‐sulfonate sites dynamically regulate interfacial cation affinity, enabling prominent selective separation of Li + against Na + and Mg 2+ in harsh brine media. Profiting from real‐time interfacial modulation, the as‐fabricated electrode achieves superior lithium extraction performance and drastically enhanced magnesium rejection, having an exceptional separation factor of 458.9 while preserving a high of 1069.4. Alternating electric field actuates reversible conformational evolution of sulfonate groups, alleviating impurity ion entrapment and reviving blocked Li + migration pathways. Theoretical calculations unveil field‐induced thermodynamic inversion, converting strong Mg 2+ adsorption into electrostatic repulsion to facilitate impurity expulsion. In situ spectroscopic characterizations further corroborate dynamically tunable sulfonate‐cation coordination behavior. This work sheds light on triggered sulfonate‐cation interfacial engineering to boost high‐performance electrochemical lithium extraction via dynamic ion sieving.