Electric-field assisted contra-diffusion synthesis of lithium ion-selective ZIF-8 membranes

Developed an electro-assisted diffusion strategy for ZIF-8 membrane fabrication. • Electric-field-guided growth enabled defect-free and thickness-controlled ZIF-8 layers. • Secondary crystallization improved membrane integrity and lithium-ion selectivity. • ZIF-EaD membranes achieved selective Li + separation from Co 2+ and Ni 2+ ions. The rapid proliferation of lithium-ion batteries has led to a growing accumulation of end-of-life battery waste, posing serious environmental risks while intensifying demand for the recovery of critical materials such as lithium. This study proposes an electro-assisted diffusion (EaD) method for fabricating defect-free ZIF-8 (ZIF-EaD) membranes on a nylon substrate for lithium extraction from spent battery leachate. Guided by an applied electric field, the method promotes directed migration and collision of metal ions with organic ligands, resulting in a dense separation membrane with controllable thickness. The ZIF-EaD membranes fabricated under an electric field of 1.5 V exhibited a Li + flux of 1.59 × 10 −6  mmol cm −2  s −1 , with separation factors of 5.13 and 3.69 for Li + /Co 2+ and Li + /Ni 2+ , respectively. These results demonstrate an efficient and controllable strategy for preparing lithium-ion-selective membranes, offering a new technical pathway for the development of high-performance ion-selective separation membranes.