High-Flux Selective Lithium Sieving Membranes via Amorphous Ni(OH)₂ Nanosheet Intercalation on Graphene Oxide

A tailored asymmetric membrane, denoted AM-a-Ni(OH)₂ NS@GO, was fabricated by integrating amorphous Ni(OH)₂ nanosheets into graphene oxide (GO) layers. The architecture enables the simultaneous enhancement of Li⁺ selectivity and transmembrane flux via precise regulation of interlayer spacing and surface charge. The asymmetric design comprises a compact sieving layer for ion discrimination coupled with a hybrid adsorption layer to facilitate efficient mass transfer. The amorphous Ni(OH)₂ nanosheets introduce abundant oxygen vacancies, thereby selectively trapping divalent cations while ensuring stable interlayer spacing. During electrodialysis testing using simulated brine, AM-a-Ni(OH)₂ NS@GO demonstrates a Li⁺ flux of 90 mmol·m⁻² h⁻¹ and a Li⁺/Mg²⁺ selectivity ratio of 37, significantly surpassing the performance of commercial Nafion membranes and pristine GO counterparts. This study establishes a promising strategy for sustainable lithium extraction from complex aqueous resources.