Abstract

The accelerating demand for lithium is intensifying interest in direct lithium extraction (DLE) technologies that minimise the environmental footprint of conventional solar evaporation ponds. Among sorbent-based DLE concepts, aluminium based hydrotalcite like compounds (Al-HTlc), particularly lithium aluminium layered double hydroxide (LiAl-LDH), are considered the most mature sorbent options, offering facile lithium (Li+) recovery and high selectivity in highly saline chloride based solutions. Both properties arise from a distinct intercalation mechanism wherein Li+ and its counter-anions (e.g. Cl− or SO42−) are co-intercalated into the crystal structure upon brine exposure. Li+ selectivity arises partly from a steric match between Li+ (ionic radius ∼ 0.76 Å) and the ∼0.7–0.8 Å octahedral vacancies of Al(OH)3-derived layers. Intercalation of competing divalent ions (e.g. Mg2+) can be disfavoured by their substantially more negative hydration energies (−1830 vs −475 kJ mol−1 for Mg2+ and Li+, respectively), which hinder the necessary dehydration. Here, we present a crystallography-focused critical review that links water–ion interactions and dehydration barriers, crystal layer and interlayer structure, and sorption kinetics to explain performance trends and derive practical design principles. Controlled comparisons show sorption capacity rising with brine concentration, potentially attributable to partial dehydration of Li+, Lisingle bondCl ion-pair co-intercalation, or both at elevated ionic strength. We identify the main development barriers: sulfate poisoning, excessive Li+ desorption, and underutilised theoretical capacity; and evaluate defect engineering strategies including anion regulation, ion doping, stacking faults, and polymer intercalation, along with processing strategies, e.g. anion exchange, to address these gaps.

Keywords

aluminium-based hydrotalcite-like compounds (Al-HTlc), crystallography, ion separation, lithium–aluminium layered double hydroxides (LiAl-LDH), selectivity, structure–property

Document Type

Journal Article

Date of Publication

12-1-2026

Article Number

218383

ISSN

00108545

Volume

568

Publication Title

Coordination Chemistry Reviews

Publisher

Elsevier

School

Mineral Recovery Research Centre / School of Engineering / School of Science

RAS ID

100607

Funding Information

Amin Sarmadi appreciates the financial support from Edith Cowan University (ECU) through the ECU Higher Degree by Research Scholarship.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

Recommended Citation

Sarmadi, A., Boroumand, Y., Shirazi, M. M. A., Wajrak, M., Abrishami, S., Myers, M., Azhar, M. R., & Razmjou, A. (2026). Aluminium based hydrotalcite like compounds for direct lithium extraction: A critical review on crystallography and structure selectivity design. Coordination Chemistry Reviews, 568, 218383. https://doi.org/10.1016/j.ccr.2026.218383

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Link to publisher version (DOI)

10.1016/j.ccr.2026.218383