One-step electrosynthesis of LiAl-Cl LDHs for lithium recovery: Process optimization and performance evaluation

Lithium aluminum layered double hydroxides (LiAl-Cl LDHs) are considered promising materials for low-quality brines owing to their excellent ion selectivity. However, conventional hydrothermal and co-precipitation methods generally suffer from high energy consumption, long processing times, and heavy reliance on acid/base regulation, which limits their sustainable large-scale application. Herein, we developed an electrolysis method that employed graphite electrodes and used AlCl 3 ·6H 2 O as the aluminum source, thereby eliminating the need for sacrificial anodes and the continuous addition of acid or base. The effects of NaCl amount, Al/Li molar ratio, temperature, aging time, and pH on the formation of LiAl-Cl LDHs were systematically investigated. Under the optimal conditions (0.4 mol NaCl, Al/Li = 2:1, 80 °C, aging for 30 min, pH = 6), well-crystallized LiAl-Cl LDHs with a flower-like morphology, a specific surface area of 66.948 m 2 /g, and a maximum adsorption capacity of 11.418 mg/g were obtained. The adsorption process followed a pseudo-second-order kinetic model, and the equilibrium data fitted the Sips isotherm well, indicating heterogeneous Li + adsorption on structurally available Li-associated sites. The material retained approximately 77% of its initial Li + adsorption capacity after 10 cycles and exhibited high Li + selectivity. Furthermore, benchmarking against representative LiAl-Cl LDHs adsorbents indicates competitive Li + adsorption performance, while the principal advantage of the present route lies in its simplified electrosynthesis process. This study provides a simplified electrochemical route for the synthesis of aluminum-based lithium adsorbents.