Highly Selective Electrochemical Lithium Extraction from Diluted Lithium Sources Enabled by an Aqua-Stable Lithium Selective Ceramic Membrane─A Proof-of-Concept Study

The growing demand for lithium-ion batteries underscores the urgent need for developing sustainable methods capable of lithium extraction from diverse and diluted sources. Here, we introduce a modular and scalable electrochemical cell designed for lithium recovery from low-concentration aqueous solutions. The cell integrates three key components: a chlorine-evolution electrode, a lithium-capture electrode, and a novel water-stable ceramic lithium-selective membrane. To validate this cell concept, we systematically examined the effects of major operational parameters (voltage, lithium concentration, pH, stirring rate, and membrane surface treatment) on lithium extraction performance. Our results show that lithium recovery is predominantly limited by mass transport. In particular, stirring the solution at 750 rpm increases the lithium extraction current density by 78% compared with static conditions, largely due to the removal of microbubbles from the electrode surface. Additionally, applying an atomic-layer-deposited TiO2 coating to the ceramic membrane reduces interfacial resistance by 48%. Under the optimized conditions, the system achieves a lithium extraction rate of 430 g/day/m2 with a faradaic efficiency of 91% and nearly 100% Li selectivity from a 0.05M LiCl aqueous solution containing a large excess of Na+, Mg2+, and K+. These findings establish a promising proof-of-concept electrochemical platform for highly selective lithium extraction from dilute sources.