Interlayer Dual-Sieving Engineering of Al-Intercalated MoS₂ for Ultrafast and Selective Lithium Recovery from...

The growing demand for lithium necessitates sustainable selective extraction from high-sodium lithium-bearing brine. 2D MoS₂, 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 Al³⁺ intercalation into 1T-MoS₂, 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-MoS₂ 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 Al³⁺ 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⁺, Ca²⁺, and Mg²⁺). This work establishes a generalizable intercalation-engineering paradigm for designing ion-selective materials.