Developmental Progress of Electrodialysis Technologies and Membrane Materials for Extraction of Lithium from Salt Lake Brines

Salt lake brines have become the main source of lithium owing to their abundant reserves and low extraction costs. The low absolute concentration of Li+ and the complexity of accompanying ions in the brines are crucial issues, thereby inspiring the development of a variety of lithium extraction technologies. Among them, electrodialysis (ED) enables acceptable separation performance, reduced energy consumption, and near-zero pollution toward salt lake brines with a high Mg2+/Li+ mass ratio. Most recently, the rapid advancement of integrated ED technologies and emerging strategies for membrane material fabrications are conducive to facilitating the implementation of this technology. The newly proposed processes can achieve higher energy utilization and enhance the concentration of lithium salt products. For membrane materials, the superior permselectivity between lithium and magnesium is still the current pursuit. The key metrics for developing membranes involve tuning the materials' hydrophilicity, pore size, and charge. Among them, due to the rise of lithium-specific recognition materials, it is believed that coupling them with ED technology to achieve efficient and precise extraction of lithium will be the future development direction.