Regulating lithium extraction based on intercalated SO in Li/Al-LDHs.

Reasonable construction of Li/Al-LDHs with interlayer anions is essential to improve the adsorption performance, especially for intercalating SO anions and blocking Li desorption. Hence, anion exchange between Cl and SO in the interlayer of Li/Al-LDHs was designed and prepared to demonstrate the strong exchangeability of SO for Cl intercalated in the Li/Al-LDH interlayer. Intercalated SO enlarged the interlayer spacing and significantly transformed the stacking structure of Li/Al-LDHs, resulting in fluctuating adsorption performance with changes in the intercalated SO content at different ionic strengths. What is more, SO repelled the intercalation of other anions, thus inhibiting Li adsorption, as verified by the negative correlation between adsorption performance and intercalated SO content in high-ionic-concentration brines. Desorption experiments further revealed that enhanced electrostatic attraction between SO and the Li/Al-LDH laminates hindered Li desorption. Additional Li in the laminates was essential for preserving the structural stability of Li/Al-LDHs with higher SO contents. This work provides a new insight into the development of functional Li/Al-LDHs in ion adsorption and energy conversion applications.