lab brine cooperates,

field brine doesn't

Problem statement

Direct lithium extraction (DLE) promises to recover lithium from brines without the 10–24 months of open-air evaporation that conventional processing requires, and a selection of DLE technologies has achieved Li+ recovery above 95% in testing. But each brine source has a distinct chemical composition — widely varying ratios of Mg, Ca, Na, K, and B to Li — so a process validated on one brine cannot be assumed to transfer to another. Only about 30% of DLE test experiments have been performed on real brines; most use synthetic solutions that omit the multivalent-ion interference and extreme Na+/Li+ concentration differences that cause selectivity failures in practice.

Why this matters

Lithium demand is projected to grow roughly fivefold between today and 2040 under stated policies, driven by EV batteries and grid storage. Conventional evaporation ponds are slow, water-intensive (over 90% of the brine's original water content is lost to evaporation), and workable only for the concentrated continental brines of a few regions — active brine operations are confined to a handful of salars in Chile, Argentina, China, and the United States. DLE could unlock lithium from geothermal brines, oilfield produced water, and more dilute salars worldwide — diversifying supply — but only if the technology generalizes across brine chemistries, and only if its own fresh-water demands, which may exceed those of evaporative practice, are controlled.

What’s been tried and why it hasn’t worked

The main DLE families are adsorption, ion exchange, solvent extraction, and membrane/electromembrane separation. Start-ups such as Lilac Solutions and EnergyX have run field pilots, and one full-scale ion-exchange DLE operation has been active at Salar del Hombre Muerto since 1996 — but even there, the eluted lithium solution is sent to evaporation ponds for final concentration. Multivalent ions compete with lithium during capture, yet many published studies start from solutions with Na+/Li+ molar ratios below 5, far from real brine compositions, and experiments omitting borates, Ca2+, and sulfate — species that can co-crystallize with lithium products — produce misleading purity values. Performance depends strongly on operating conditions: heating brine from 10°C to 80°C raised one manganese-oxide sorbent's lithium adsorption efficiency from 15% to 70%, an energy and chemical cost that becomes prohibitive at the roughly 21 million litres of brine per day a full-scale facility must process. Sorbent stability is an open problem — reported ion-exchange materials lose between 2.5% and 43% of capacity over tens of cycles, and dissolution rates suggest active materials would need replacement within months — and regeneration consumes chemicals, fresh water, and energy. Fresh-water consumption remains largely unquantified and may exceed that of evaporation ponds in arid brine regions.

What would unlock progress

DLE sorbents or membranes with validated selectivity across a representative range of real brine chemistries — realistic Mg2+/Li+ and Na+/Li+ ratios with full contaminant profiles, not simplified synthetic solutions. Standardized testing protocols using real or faithfully mimicked brines that capture the full range of interfering ions. Long-cycle stability data (the average number of cycles in published reports is fewer than 10). Closed-loop regeneration chemistries that minimize waste and fresh-water use across different brine compositions.

Entry points for student teams

A team could benchmark a commercial DLE sorbent across a panel of synthetic brines spanning the Mg:Li ratio range found in major global sources, mapping the selectivity cliff. Alternatively, a team could develop a synthetic brine standard recipe set that reproduces the interference patterns of 5–10 major brine sources for standardized testing. Chemistry, chemical engineering, and materials science skills apply.