Engineering Crystalline Frameworks into Porous Liquids to Fabricate Graphene Oxide/Porous Liquid Membranes for Efficient Li+/Mg2+ Separation

The quest for sustainable energy transition has intensified the demand for lithium extraction from salt-lake brines, necessitating advanced membranes for high-efficiency Li+/Mg2+ separation. Integrating porous frameworks and two-dimensional (2D) scaffolds has shown promise for fabricating ion-permselective membranes, but is hampered by poor processability. Here we transform crystalline frameworks into porous liquids (PLs), and embed them within graphene oxide (GO) laminates to engineer an ultrathin and defect-free GO/PLs membrane. Discrete porous guests are uniformly confined within 2D nanofluidic channels mediated by a sterically hindered solvent. The GO/PLs membrane exhibits ultrahigh Li+ permeance (0.75 mol m−2 h−1) and exceptional Li+/Mg2+ selectivity (154.4) by regulating ion dehydration and ion-to-channel interactions. Efficient lithium extraction from simulated brine is demonstrated, reversing the Mg/Li ratio of 40 to achieve a Li/Mg ratio of 4.6. This work reports the manufacturing strategy of hybrid membranes based on porous frameworks and 2D materials for precise ion separation. The authors transform crystalline frameworks into porous liquids to fabricate graphene oxide/porous liquid membranes. This strategy overcomes crystal agglomerations and interfacial defects, shedding light on the engineering of hybrid membranes.