Coordination-mediated Molecular Sieve Membranes for Sustainable Lithium Extraction

Nanochannel membranes with sub-1-nm channels provide an energy-efficient and sustainable way of ion separations for direct lithium extraction from salt-lake brines. Channel modifications by binding ion exchange groups are a widely adopted strategy to improve membrane selectivity, this valence-dependent strategy poorly discriminates among monovalent cations and often compromises membrane durability, as fixed negative charges promote swelling in aqueous brines. In contrast to previous designs, this project will develop nanochannel membranes that present neutral, hard oxygen donor ligands in well-defined porous networks. By leveraging coordination-specific functionality, the membranes are designed to accelerate lithium transport while suppressing competing ions, thereby increasing ion perm-selectivity without introducing fixed charge. We will demonstrate and verify the concept in three steps: (1) fabricate prototype membranes by grafting oxygen donor groups into a layered COF backbone to exploit strong ion-functional groups coordination; (2) evaluate ion-separation performance (e.g., Li+/Na+) across membranes with systematically varied coordination environments and against pristine controls; and (3) elucidate how metal-oxygen coordination governs transport and separation by integrating experiments, targeted characterisation, and computational modelling. This project will push the state-of-the-art in practice, concept, and mechanism terms by fabricating a high-performance ion-separation membrane that exceeds current upper bounds. It will also define a coordination-mediated transport mechanism as a new framework for interpreting mass transport in next-generation nanochannel membranes.