Robust design framework for high efficiency lithium extraction via flow-through electrosorption in complex water systems

Abstract

Addressing the growing global demand for lithium, this study introduces a next-generation flow-through electrosorption system designed for the selectively recovering lithium ions from seawater and various brine sources. Specifically, we designed and comparatively evaluated three types of cathode electrocatalysts, Lanthanum@Ti<inf>4</inf>O<inf>7</inf>@Titanium Carbide (TiC), Ti<inf>4</inf>O<inf>7</inf>@TiC, and TiC, each engineered to enhance lithium selectivity in the presence of competing ions such as Na+, K+, and Mg2+. The results demonstrated that the system comprising carbon cloth as the anode and La@Ti<inf>4</inf>O<inf>7</inf>@TiC as the cathode achieved the highest lithium recovery rate, demonstrating outstanding selectivity and adsorption performance. Under an optimized charging/discharging voltage of 1.3/−1.3 V, the La@Ti<inf>4</inf>O<inf>7</inf>@TiC cathode achieved a lithium recovery capacity of 29.85 μmol g−1 with low specific energy consumption, while exhibiting high selectivity with Li/Na, Li/K, and Li/Mg ratios of approximately 3.5, 4.5, and 4.4, respectively. The underlying lithium-selective adsorption mechanism was systematically elucidated through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), as well as density functional theory (DFT) calculations for each electrocatalyst. In addition, the system's operational stability and electrode durability were validated through multiple charge/discharge cycling tests. This study provides the first demonstration of lithium recovery via a flow-through electrosorption system, in which a lanthanum-modified Magnéli phase Ti<inf>4</inf>O<inf>7</inf>@TiC cathode achieves superior lithium selectivity by synergistically regulating electronic structure and ion transport. These findings provide important foundational insights for the strategic design of electrocatalysts and the process optimization of electrosorption-based separation systems for resource recovery.