Lithium, widely recognized as the “energy metal of the 21st century,” is essential for the transition to sustainable energy systems and the expansion of electromobility. With annual consumption increasing by nearly 30% and global demand expected to outpace accessible reserves by 2030, the development of efficient, scalable, and environmentally responsible lithium extraction technologies has become an urgent industrial priority.
Direct Lithium Extraction (DLE) has gained attention as a sustainable alternative to evaporation ponds and mining, particularly for underutilized resources such as lithium-enriched associated waters from oil and gas condensate fields. These waters, often considered industrial waste, represent a promising source of lithium when processed through advanced membrane technologies. Unlike traditional approaches, DLE provides high recovery rates, reduced environmental footprint, and product purity compatible with battery-grade requirements.
This work focuses on the design of composite polymer membranes modified with crown ethers, specifically amino-benzo-15-crown-5 ether (AB15C5). Crown ethers are macrocyclic ligands that selectively bind alkali metal cations depending on the size of their central cavity. AB15C5 exhibits a strong affinity for Li⁺ due to the close match between its coordination cavity (1.7–2.2 Å) and the ionic radius of lithium. This guest–host complexation mechanism allows for preferential lithium transport, even in the presence of competing ions such as Na⁺, Mg²⁺, and Ca²⁺, which are typically abundant in oilfield brines. Structural characterization confirmed the uniform distribution of the ligand, and electrochemical testing demonstrated a marked increase in lithium selectivity. Pilot-scale experiments with East Siberian formation waters yielded lithium carbonate with 98.5% purity, underscoring the practical viability of this approach.
By integrating selective crown ether chemistry with scalable membrane engineering, this technology transforms a challenging industrial byproduct into a valuable resource. The results highlight the potential of crown ether-modified membranes as a competitive DLE solution, enabling sustainable lithium recovery and supporting the global shift toward clean energy.
