Most lithium today comes from sprawling evaporation ponds that stretch across salt flats, taking over a year to concentrate the element and consuming vast quantities of water in regions already facing scarcity. A team at Rice University has developed a membrane that could make that process obsolete.
The membrane selectively extracts lithium from brines using an electrical current, achieving some of the highest selectivity rates reported while using considerably less energy than standard industrial methods. Published in Nature Communications, the research demonstrates how embedding nanoparticles of lithium titanium oxide into a thin polymer layer creates a material that allows lithium ions to pass through while blocking more abundant elements like sodium, calcium, and magnesium.
“The most widely used large-scale lithium extraction method today requires massive evaporation ponds and chemical precipitation. The process can take over a year to reach the target concentration and has fairly low lithium recovery rates.”
Qilin Li, the Karl F. Hasselman Professor of Civil and Environmental Engineering and co-director of Rice’s Nanotechnology Enabled Water Treatment Center, notes that conventional methods also produce considerable chemical waste. The new approach offers an alternative through electrodialysis, where an applied electrical current drives lithium ions through the membrane while other elements remain behind.
Engineering Selectivity at the Nanoscale
The challenge was compatibility. Lithium titanium oxide has a crystal structure perfectly sized for lithium ions to move through, but incorporating these inorganic particles into a polymer membrane typically creates defects that undermine performance. The Rice team solved this by grafting amine groups onto the lithium titanium oxide, allowing the particles to mix evenly into a plasticlike polyamide layer.
The resulting three-layer membrane proved remarkably selective. In tests, lithium ions passed through at more than three times the rate of sodium ions, despite sodium’s typically higher mobility in solution. The membrane achieved a lithium-to-sodium selectivity of 13.58 and a lithium-to-calcium selectivity of 173.90, among the highest values reported for similar membranes.
Computer simulations revealed the mechanism. The electrical field drives lithium ions to accumulate at the membrane surface, increasing their energy enough to shed their surrounding water molecules. Once dehydrated, lithium ions are small enough (about 0.95 angstroms in diameter) to hop through the crystal lattice. Sodium ions, even when dehydrated, remain too large at 1.90 to 2.32 angstroms.
From Laboratory to Industry
Jun Lou, the Karl F. Hasselmann Professor of Materials Science and Nanoengineering, emphasizes the membrane’s potential for large-scale production. The team tested its durability over two weeks of continuous use, finding no degradation in performance and no leaching of titanium from the crystal structure.
“Our goal was to develop a material that can extract lithium with minimum environmental impact. The smart design principles we used to develop the membrane architecture have ensured it can be adapted to help recover many other valuable resources from various waste streams.”
Each of the membrane’s three layers can be independently optimized, making it adaptable for extracting other valuable minerals like cobalt and nickel. The design plugs into existing industrial electrodialysis systems, which are typically used for desalination and wastewater treatment.
The research builds on a decade of work through Rice’s Nanotechnology Enabled Water Treatment Center, applying lessons learned about incorporating nanomaterials into membranes. Major contributors included Rice alumni Yuren Feng and Xiaochuan Huang, as well as postdoctoral researcher Yifan Zhu.
With global lithium demand surging for electric vehicle batteries and grid-scale energy storage, the technology arrives as the industry seeks faster, cleaner extraction methods. Most of the world’s lithium currently comes from saltwater deposits, but conventional extraction remains slow and environmentally intensive. The Rice membrane could accelerate production while reducing the environmental footprint of an element increasingly central to the energy transition.