One-pot synthesis of transition metals-doped LiAl-LDHs to improve lithium adsorption performance and stability

Abstract

Transition metal doping of Li/Al-LDHs can alter the interlayer spacing and surface charge of LDHs, thereby enhancing adsorption performance and stability. To investigate the rules and mechanisms governing the enhancement of stability and adsorption capacity of Li/Al-LDHs through transition metal element doping, several transition metal elements (Co, Zn, Mn, Zr, and Ni) were selected, and the five types of transition metal-doped Li/Al-LDHs and one undoped Li/Al-LDHs were synthesized by a one-pot method. Compared to the original Li/Al-LDHs, the Co-doped Li/Al-LDHs exhibited higher adsorption capacity, lower dissolution loss, and greater stability. Additionally, after Co doping, the lattice constant of Li/Al-LDHs decreases, effectively reducing the intercalation energy and increasing lithium diffusion efficiency. When used for lithium adsorption, Co-Li/Al-LDHs exhibited a Li⁺ capacity of 12.6 mg/g and reached saturation adsorption within 90 min. Notably, Co-Li/Al-LDHs achieved a high Li⁺ adsorption capacity (6.46 mg/g) in East Taigener salt-lake brine. After 10 cycles, the adsorption capacity did not show any significant change, and after 336 h adsorption-desorption cycles (200 rmp, oscillation), the total Al dissolution loss was only about 0.035 ‰, demonstrating that Co doping can enhance the interlayer binding force of Li/Al-LDHs, thereby reducing the decomposition of the layered structure in solution, lowering aluminum dissolution loss, and improving structural stability. The results show that doping with transition metals can reduce the Al dissolution rate of LDHs, and Co-Li/Al-LDHs can be used as an efficient adsorbent for lithium extraction from salt lake and have higher stability.