From conventional to smart adsorbents: Advanced adsorption strategies for lithium harvesting from aqueous systems

The growing implementation of renewable and green energy systems has seen a significant surge in the utilization of lithium (Li) in lithium-ion rechargeable batteries. Meeting this increasing demand requires the development of effective lithium recovery techniques from different water-based sources. Conventional lithium extraction technologies have faced several difficulties, including slow reaction rates, high energy requirements, and environmental issues, particularly related to extensive freshwater consumption. However, lithium extraction via ion exchange and adsorption has been proven to be effective at scale. This review examines the efficiency of various adsorbents for lithium extraction from aqueous solutions, using key performance indicators and comparing them with current literature benchmarks. Special attention will be paid to new types of lithium adsorbents – smart adsorbents, including ion-imprinted polymers, functional MOFs and COFs, and hybrid materials. The latest advances in smart adsorbents provide the benefits of engineered active centres, selective properties, and controlled lithium adsorption mechanisms, enabling lithium trapping despite competition with other ions. Additionally, this review assesses the ability of adsorbents to facilitate large-scale manufacturing of lithium compounds, such as Li 2 CO 3 and LiOH, highlighting their benefits and drawbacks under different operational conditions. It further highlights the importance of standardised adsorbents, whether organic or inorganic, and agreed-upon performance indicators, enabling fair comparisons and quicker improvement of lithium recovery technologies.