Fabricating a Flow-Through Hybrid Capacitive Deionization Cell for Selective Recovery of Lithium Ions

The demand for lithium-ion batteries in electric vehicles and portable electronics is rapidly growing, which will likely overshoot the available global lithium resources in the near future. Developing effective strategies that ensure the long-term sustainability of lithium supply and minimize environmental impact has aroused increasing interest. Here, an “all-in-one” electrochemical system with easy operation, which simultaneously integrated the flow-through system and the hybrid capacitive deionization device, has been demonstrated for selective recovery of lithium ions from aqueous solutions and simulated brine. The electrochemical flow-through HCDI cell comprises a battery-type electrode of λ-MnO2 nanorods and an electric double layer capacitive electrode of activated carbon. Lithium ions are captured based on Faradaic redox reactions in the λ-MnO2 electrode, whereas anions are adsorbed on the surface of porous carbon. The as-fabricated HCDI cell exhibits a high lithium-uptake capacity of 18.1 mg g–1 and satisfactory stability. Moreover, the λ-MnO2 electrode shows excellent selectivity for lithium ions when simulated brine containing multiple cations (e.g., Li+, Na+, K+, Mg2+, and Ca2+) was used as a feed solution. The present method is low-cost and avoids the use of harmful acids or organic solvents. Thus, this flow-through HCDI cell with high selectivity and stability is promising for recovering lithium ions from lithium-containing solutions.