Discovering Synthetic Molecular Receptors for Sustainable Separation of Lithium

Lithium is a critical component of batteries that power everything from smartphones to electric vehicles. Current methods for extracting lithium are often inefficient, costly, and harmful to the environment. This project will design new molecular binders that selectively capture lithium ions from natural sources such as salt lakes and geothermal brines. It will result in materials that capture and release lithium more efficiently and sustainably. This work will strengthen the U.S. supply chain for critical materials, promote energy security, and reduce environmental impact. In addition to its scientific contributions, the project will train students in advanced chemical research, support workforce development in science and technology, and inspire the next generation of STEM leaders through educational activities and outreach initiatives. The key challenge in this field is how to selectively extract lithium ions from an aqueous solution containing many other ions. Existing processes often use crown ethers and other macrocyclic receptors with cavities that trap lithium, but exclude larger metal ions. These receptors typically show weak lithium binding, low selectivity over competing ions, and costly syntheses. This project introduces a new approach to designing acyclic molecular receptors that exploit strong noncovalent forces, particularly ion-dipole and electrostatic interactions, to achieve selective lithium binding. The project team will design and synthesize a series of acyclic molecular receptors and systematically evaluate their lithium binding in solution. Promising candidates will then be immobilized onto solid supports, and their separation performance will be assessed under conditions typical of industrial practice. The results will advance fundamental understanding of how noncovalent interactions can be exploited for selective ion binding. Overall, the project will establish the molecular-level principles needed to develop sorbents with improved efficiency, selectivity, and sustainability for lithium extraction. This project will promote national self-reliance for critical minerals. Additional benefits will derive from extensive outreach activities at pre-college level, and incorporating virtual reality experiences for chemistry education. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.