In-situ construction of ZIF-embedded hydrogel electro-driven membranes for lithium selectivity

Electro-driven membranes with monovalent ion selectivity represent a promising technology for sustainable lithium (Li) recovery from spent lithium-ion battery (LIB) leachate. However, existing membranes suffer from limited Li + selectivity and low ion permeation rates. In this study, a zeolitic imidazolate framework (ZIF)-embedded hydrogel electro-driven membrane was developed for selective Li + extraction via electrodialysis (ED). A poly(dimethyl diallyl ammonium chloride) (PDDA) network-threaded ZIF (QZIF) layer was in-situ constructed within the hydrogel matrix of Kevlar aramid nanofibers (KANFs), forming a stable composite layer on a sulfonated polysulfone (SPSF) substrate. Benefiting from the synergistic effects of size sieving and electrostatic repulsion, the resulting QZIF@KANF#SPSF membrane exhibited rapid Li + transport while effectively rejecting larger divalent ions (Ni 2+ , Co 2+ , and Mn 2+ ). During ED at 5 mA cm −2 , the QZIF@KANF#SPSF membrane achieved a Li + permeation rate of 0.45 mol m −2  h −1 in a 25 mM Li + , Ni 2+ , Co 2+ , and Mn 2+ mixed solution, with high permselectivities of 13.8, 12.2, and 10.5 for Li + /Ni 2+ , Li + /Co 2+ , and Li + /Mn 2+ , respectively. This strategy of embedding charged ZIFs within a hydrogel matrix provides a robust and scalable pathway for enhancing Li + selectivity and transport efficiency in advanced separation processes for spent LIB recycling.