Ultra−Selective and Capacious Lithium Extraction from Geothermal Brines via β −Diketone Functionalized Brush−Shaped Polymer

Abstract The rapid rise of new energy vehicles and the energy storage industry drive a growing demand for direct and efficient lithium adsorption technologies to ensure sustainable lithium supply. Unfortunately, most reported lithium adsorption materials are ineffective for lithium extraction due to their unsatisfactory Li + adsorption capacity. In this work, a β −diketone functionalized brush−shaped polymer (Cell−g−pDK) is proposed as a readily recoverable adsorption material demonstrating high Li + adsorption performance (53.64 mg g −1 ), as well as exhibits excellent selectivity for Li + ( K d = 257.74 mL g −1 ) from complex and low−concentration brine. This performance is attributed to the unique brush topology, which features strong steric repulsion between the polymer chains, increasing persistence length and reducing chain entanglement compared to linear polymer. Remarkably, this brush−shaped polymer adsorption material achieves nearly 100% lithium extraction efficiency within 45 min from actual geothermal brine (≤100 mg L −1 , Li + ), alongside a 717.35−fold lithium enrichment and over ten reuses. The proposed functionalized polymer with special topological architecture will promote the development of selective adsorption materials for resource extraction.