Fabricating\na Flow-Through Hybrid Capacitive Deionization\nCell for Selective Recovery of Lithium Ions

Abstract

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