Interlayer Dual‐Sieving Engineering of Al‐Intercalated MoS 2 for Ultrafast and Selective Lithium Recovery from High‐Sodium Lithium‐Bearing Brine

ABSTRACT The growing demand for lithium necessitates sustainable selective extraction from high‐sodium lithium‐bearing brine. 2D MoS 2 , though noted for its high capacity and fast kinetics, suffers from poor Li + /Na + selectivity, as its excessive interlayer spacing fails to differentiate between ions with similar radii. Here, we propose an electrochemical dual‐sieving strategy via Al 3+ intercalation into 1T‐MoS 2 , which simultaneously constructs geometric sieving channels through sub‐Ångström S–S constrictions (2.20, 1.51, and 1.40 Å) that exclude Na + while permitting Li + , and creates Al‐centered polarized microdomains that establish a gradient electron channel for electronic sieving. The engineered Al‐1T‐MoS 2 cathode delivers ultrafast Li + extraction kinetics (1577.07 mg·g −1 ·day −1 , 4.3‐fold enhancement), a high specific capacity (1869.62 mAh·g −1 ), and an excellent Li + /Na + separation factor of 41.6 (11.2‐fold improvement). Structural and mechanistic analyses reveal that Al intercalation reduces the Mo–Mo interlayer spacing from 7.46 to 5.06 Å, while the S–S constrictions create the actual geometric barrier. The intercalated Al 3+ also induces an electron gradient that forms polarized adsorption sites. Density functional theory calculations demonstrate that this dual‐confinement structure lowers the Li + migration barrier by over 90% while significantly increasing barriers for competing ions (Na + , K + , Ca 2+ , and Mg 2+ ). This work establishes a generalizable intercalation‐engineering paradigm for designing ion‐selective materials.