Fine‐Tuning 2D Heterogeneous Channels for Charge‐Lock Enhanced Lithium Separation from Brine

The extraction of lithium (Li) from complex brines presents significant challenges due to the interference of competing ions, particularly magnesium (Mg²⁺), which complicates the selective separation process. Herein, a strategy is introduced employing charge-lock enhanced 2D heterogeneous channels for the rapid and selective uptake of Li⁺. This approach integrates porous ZnFe₂O₄/ZnO nanosheets into Ag⁺-modulated sub-nanometer interlayer channels, forming channels optimized for Li⁺ extraction. The novelty lies in the charge-lock mechanism, which selectively captures Mg²⁺ ions, thereby facilitating the effective separation of Li from Mg. This mechanism is driven by a charge transfer during the formation of ZnFe₂O₄/ZnO, rendering O atoms in Fe-O bonds more negatively charged. These negative charges strongly interact with the high charge density of Mg²⁺ ions, enabling the charge-locking mechanism and the targeted capture of Mg²⁺. Optimization with Ag⁺ further improves interlayer spacing, increasing ion transport rates and addressing the swelling issue typical of 2D membranes. The resultant membrane showcases high water flux (44.37 L m⁻² h⁻¹ bar⁻¹) and an impressive 99.8% rejection of Mg²⁺ in real brine conditions, achieving a Li⁺/Mg²⁺ selectivity of 59.3, surpassing existing brine separation membranes. Additionally, this membrane demonstrates superior cyclic stability, highlighting its high potential for industrial applications.