Doping engineering of lithium-aluminum layered double hydroxides for high-efficiency lithium extraction from salt lake brines
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abstract
Lithium-aluminum layered double hydroxides (LiAl-LDH) have been be successfully applied in commercial-scale for lithium extraction from salt lake brine, however, further advancement of their applications is hampered by suboptimal Li adsorption performance and ambiguous extraction process. Herein, a doping engineering strategy was developed to fabricate novel Zn2 -doped LiAl-LDH (LiZnAl-LDH) with remarkable higher Li adsorption capacity (13.4 mg/g) and selectivity (separation factors of 213, 834, 171 for Li /K , Li /Na , Li /Mg2 , respectively), as well as lossless reusability in Luobupo brine compared to the pristine LiAl-LDH. Further, combining experiments and simulation calculations, it was revealed that the specific surface area, hydrophilic, and surface attraction for Li of LiZnAl-LDH were significantly improved, reducing the adsorption energy (Ead) and Gibbs free energy (ΔG), thus facilitating the transfer of Li from brine into interface followed by insertion into voids. Importantly, the intrinsic oxygen vacancies derived from Zn-doping depressed the diffusion energy barrier of Li , which accelerated the diffusion process of Li in the internal bulk of LiZnAl-LDH. This work provides a general strategy to overcome the existing limitations of Li recovery and deepens the understanding of Li extraction on LiAl-LDH.
