Advances in capacitive deionization for selective lithium recovery from brines: Mechanisms, strategies, and future perspectives

The growing global demand for lithium, fueled by the expansion of electric vehicles and energy storage systems, calls for efficient and sustainable extraction technologies. Capacitive deionization (CDI) is emerging as a promising electrochemical method for lithium recovery from diverse aqueous sources, including low-grade brines, geothermal waters, and industrial effluents. By applying a low-voltage electric field, CDI captures lithium ions either through electrosorption onto porous electrodes or via intercalation into redox-active materials. Compared to conventional separation technologies, CDI offers distinct advantages such as low energy consumption, mild operating conditions, rapid adsorption kinetics, and scalable modular design. This review systematically summarizes recent advancements in CDI-based lithium extraction with a focus on research methodology. Key research strategies are categorized into four domains: structural engineering of electrodes, surface and interface modification, advanced material integration, and machine learning and simulation. Applications across various source solutions are discussed, and standard performance metrics such as adsorption capacity, selectivity, energy consumption, and cycling stability are outlined. The review concludes by identifying critical challenges and proposing future research directions that emphasize multifunctional electrode design, scalable fabrication, and data-driven material discovery. This work offers comprehensive guidance for advancing CDI technologies toward practical and sustainable lithium recovery.