The Polymer Society of Korea

Abstract

The rising demand for lithium-ion batteries necessitates selective lithium recovery from aqueous sources such as seawater, geothermal brine, and spent electrolytes. Herein, we report an electrospun nanofiber membrane comprising 12-crown-4 (a Li⁺-selective ligand) and graphene nanosheets embedded in a polyethersulfone matrix. Graphene enabled homogeneous dispersion and immobilization of the ligand, while improving membrane stability, porosity, and hydrophilicity. DFT calculations confirmed the higher binding affinity of 12-crown-4 for Li⁺ over Na⁺ and K⁺. Noncovalent interactions between graphene and the ligand suppressed leaching. In a flow system, the membrane achieved a maximum Li⁺ adsorption capacity of 86.3 mg g⁻¹ and retained over 93% performance after 10 regeneration cycles. This work demonstrates a scalable, regenerable membrane for lithium-selective separation based on molecular recognition and nanostructural design.