Bio-Inspired and Synergistic Ion Transport: Advancing the Frontiers of Lithium Extraction From Complex Aqueous...

The global demand for lithium has driven the pursuit of efficient extraction from complex sources like salt lake brine and seawater. Conventional membranes face a "permeability-selectivity trade-off," especially under high salinity and competitive conditions. This review examines advances in lithium-selective membranes, from basic size-sieving and charge regulation to biomimetic channels using molecular recognition and asymmetric gating. Beyond these conventional approaches, we emphasize a pivotal and necessary paradigm shift in ion transport strategy to address the limitations of traditional "forward-flow" separation. Specifically, we highlight our recent research into the design of artificial cation-chloride cotransporters, which bypasses the constraints of salt-induced Debye screening by facilitating electroneutral ion pair migration, thereby enabling resilient lithium extraction from concentrated brines. Furthermore, we discuss the "reverse lithium extraction" paradigm, a strategic reassessment of separation strategy that prioritizes the selective retention of Li⁺ within the membrane matrix. By allowing competing cations to permeate freely while trapping the target species, this "reverse sieving" strategy effectively sidesteps the overwhelming competitive pressure characteristic of seawater mining. By analyzing the interplay between nanoconfinement chemistry and ion transport kinetics, this review provides a strategic roadmap for the development of the next generation of resilient separation materials for global lithium resource harvesting.