Dual-phase anion engineering for boosting lithium capture by Li/Al-LDHs

Lithium aluminum layered double hydroxides (Li/Al-LDHs), the most widely industrialized lithium adsorbents dependent on the unique acid-free desorption, while exhibited limited capacity in low-salinity systems. Herein, an anion regulation strategy was developed to enhance Li + extraction by introducing and controlling multivalent anions. Experiments confirmed Li + adsorption capacity of Li/Al-LDHs could increase from 0.40 mg/g to 5.83 mg/g by introducing SO 4 2− in a chloride solution containing 2 g/L Mg 2+ . It was well explained by density functional theory (DFT) calculations that the highly charged anions in solution would induce higher ionic strength and adsorption energy to enhance Li + extraction of Li/Al-LDHs. Furthermore, an interlayer repair method effectively replaced accumulated divalent anions within the interlayers using easily elutable Cl − ions, facilitating Li + release from the laminates and ensuring cycling stability. Besides, multiple cycles remaining stable enhanced capacities further confirmed the sustained effectiveness of this strategy for boosting Li + capture from low-salinity systems.