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

Silicon oxide‐coated lithium aluminum layered double hydroxide (LixAl2‐LDH@SiO2) nanocrystals (NCs) are investigated to selectively separate lithium cations in aqueous lithium resources. We directly synthesized LixAl2‐LDH NC arrays by oxidation of aluminum foil substrate under a urea and lithium solution. Various lithium salts, including Cl−, CO32−, NO3−, and SO42−, were applied in aqueous solution to confirm the anion effect on the captured and released lithium quantity of the LixAl2‐LDH NCs. In a 5% solution of sulfate ions mix with lithium chloride, the LixAl2‐LDH NCs separated a larger quantity of lithium than in other anion conditions. To enhance regeneration stability and lithium selectivity, thin layers of SiO2 were coated onto the LixAl2‐LDH nanostructure arrays for inhibition of nanostructure destruction after desorption of lithium cations in hot water. The LixAl2‐LDH@SiO2 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 Mg2+, 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. Recyclable lithium adsorbent: Silicon oxide‐coated lithium aluminum layered double hydroxide (LixAl2‐LDH@SiO2) was developed as lithium adsorbent via a direct growth on an aluminum metal substrate to simplify the multistep process of lithium recovery such as separation, dispersion, and washing steps in powder form.