Selective Lithium Adsorption of Silicon Oxide Coated Lithium Aluminum Layered Double Hydroxide Nanocrystals and Their Regeneration

Abstract Silicon oxide‐coated lithium aluminum layered double hydroxide (Li x Al 2 ‐LDH@SiO 2 ) nanocrystals (NCs) are investigated to selectively separate lithium cations in aqueous lithium resources. We directly synthesized Li x Al 2 ‐LDH NC arrays by oxidation of aluminum foil substrate under a urea and lithium solution. Various lithium salts, including Cl − , CO 3 2− , NO 3 − , and SO 4 2− , were applied in aqueous solution to confirm the anion effect on the captured and released lithium quantity of the Li x Al 2 ‐LDH NCs. In a 5% solution of sulfate ions mix with lithium chloride, the Li x Al 2 ‐LDH NCs separated a larger quantity of lithium than in other anion conditions. To enhance regeneration stability and lithium selectivity, thin layers of SiO 2 were coated onto the Li x Al 2 ‐LDH nanostructure arrays for inhibition of nanostructure destruction after desorption of lithium cations in hot water. The Li x Al 2 ‐LDH@SiO 2 nanostructures showed enhanced properties for lithium adsorption, including increase of stable regeneration cycles from three to five cycles, and they showed high lithium selectivity in the Mg 2+ , Na + , and K + cation mixed aqueous resource. Our nanostructured LDH lithium adsorbents would provide a facile and efficient application for cost‐efficient and large‐scale lithium production.