Extraction Technologies for Lithium Resources from Salt Lake Brines: Research Progress, Challenges and Future Prospects

Lithium has emerged as a critical energy metal due to its indispensable role in batteries, aerospace applications, new energy vehicles, and large-scale energy storage systems. The accelerated growth of electric mobility and renewable energy storage has led to a substantial increase in lithium demand, thereby exacerbating the prevailing global supply–demand imbalance. To address this challenge, it is imperative to diversify lithium resources and to advance extraction technologies that are both efficient and sustainable. In comparison with conventional hard-rock deposits, liquid resources such as salt lake brines, oilfield brines, and deep-well brines are gaining attention owing to their broad distribution, abundant reserves, and advantages of reduced land use, lower water consumption, and lower carbon emissions. This work presents a critical review of current lithium recovery strategies from brines, including precipitation, solvent extraction, adsorption, nanofiltration/electrodialysis, and electrochemical methods. Each approach is critically evaluated in terms of Li/Mg selectivity, extraction efficiency, operational stability, and environmental compatibility. Precipitation processes offer simplicity but suffer from low Li recovery and high chemical consumption; solvent extraction achieves high selectivity but faces phase and reagent loss; adsorption using Mn-based sieves yields high capacity with good regeneration stability, whereas membrane and electrochemical systems enable continuous lithium recovery with reduced energy input. Distinct advantages and existing gaps are systematically summarized to provide quantitative insights into performance trade-offs among these pathways. Key findings highlight that organophosphorus–FeCl3 systems and Mn-based lithium-ion sieves show the best trade-off between selectivity and regeneration stability, whereas emerging membrane–electrochemical hybrids demonstrate promise for low-energy, continuous lithium recovery. The prospects for future development highlight highly selective functional materials, integrated multi-technology processes, and greener, low-energy extraction pathways.