Selective Adsorption and Recovery for Low-Quality Lithium-Containing Resources: Materials, Mechanism, and Outlook

With the rapid expansion of the global lithium-battery industry, efficient and sustainable lithium recovery from low-grade lithium resources, such as lithium precipitation mother liquor characterized by a high sodium-to-lithium ratio, has become a critical research challenge. Among the emerging technologies, the adsorption method, recognized for its operational simplicity, high selectivity, and process flexibility, has garnered significant attention. This review systematically summarizes recent advancements in two primary categories of adsorbents for selective lithium recovery: organic adsorbents (crown ether-based materials) and inorganic adsorbents (aluminum-based layered double hydroxides (LiAl-LDHs), titanium-based ion sieves (H2TiO3, H4Ti5O12), and manganese-based ion sieves (HMn2O4, H1.6Mn1.6O4, H4Mn5O12). For each class, the synthesis methods, adsorption mechanisms, performance (capacity, selectivity, kinetics, and cycling stability), and key influencing factors are thoroughly discussed and compared. Titanium-based sieves demonstrate high capacity and stability, manganese-based materials show excellent kinetics, aluminum-based adsorbents offer industrial scalability, and crown ether-based materials exhibit superior ion size selectivity. The review also identifies limitations, such as the slow kinetics of H2TiO3, manganese dissolution in manganese-based ion sieves, and the cost of functionalized organics. Finally, future research directions are proposed, focusing on enhancing adsorption kinetics and stability via material design (e.g., morphology control, doping, hybridization), developing scalable and cost-effective synthesis routes, and exploring the integration of adsorption with other separation technologies to create efficient hybrid processes for the sustainable exploitation of low-grade lithium.