Hollow Li/Al-LDH architecture engineering to accelerate mass transfer for high-efficiency low-grade lithium extraction

Hollow Li/Al-LDHs were rationally designed to overcome diffusion limitations of granular adsorbents. • Hydrophilic binder and spinning-parameter regulation optimized hollow Li/Al-LDHs. • Finite element analysis revealed the mass-transfer enhancement of hollow structures. • Optimized hollow Li/Al-LDHs showed fast Li + kinetics and efficient dynamic cycling. Adsorption has become a central approach for industrial salt lake lithium extraction. A structural engineering strategy is developed to rationally fabricate hollow fiber-structured Li/Al layered double hydroxide granules (HF-LDHs) with enhanced mass transfer to overcome the extraction efficiency limitation from conventional granulation methods. The hollow architecture provides shortened diffusion pathways through a favorable pore microstructure and dual accessible surfaces for Li + directional migration with markedly accelerating intraparticle transport. HF-LDHs are characterized by good hydrophilicity and structural integrity with a compressive of 4.99 MPa, and the optimized granules can reach adsorption equilibrium within 60 min, which is shortened by over half to that of these traditional lithium adsorbent granules. Fixed-bed dynamic evaluation further demonstrates a rapid 2 h saturation and high effluent quality with a Mg 2+ /Li + ratio below 2. Moreover, HF-LDHs maintain a stable working capacity of about 7.20 mg/g over 20 cycles, with a high Li + extraction rate of 2.70 (mg/(g·h)), highlighting their potential for low-grade lithium recovery. Download: Download high-res image (240KB) Download: Download full-size image