Click-polymerized polyenamine membranes for efficient lithium extraction

The clean energy transition drives burgeoning global demand for lithium, highlighting the critical role of nanofiltration (NF) and reverse osmosis (RO) membranes for selective lithium extraction. However, conventional polyamide NF membranes, typically fabricated from hydrolysis-susceptible acyl chlorides, exhibit limited Li+/Mg2+ separation efficiency. Here, we report the fabrication of polyenamine membranes via amino-yne Michael addition reaction by substituting hydrolysis-susceptible acyl chlorides with activated alkyne monomers. The resulting NF membranes feature a positively charged surface, narrow pore size distribution, and exceptional chemical stability, achieving a high Li+/Mg2+ selectivity of 309. Similarly, by employing amine monomers that generate reduced intrinsic cavity, the same chemistry also affords RO membranes with NaCl rejection > 97%. Module-scale evaluations validated the potential of coupling click-polymerized NF and RO membranes for battery-grade Li2CO3 (> 99.9%) production from salt-lake brines and spent lithium-ion batteries. This versatile click-chemistry platform provides an alternative to conventional polyamides for sustainable critical resource recovery. There is a burgeoning global demand for lithium, though it is challenging for some membranes to discriminate between Li+ and Mg2+ ions. Here the authors design a charged polyenamine membranes to optimize Li+ /Mg2+ selectivity.