Direct lithium extraction with hygroscopic salts could lower costs
Building a reliable lithium supply chain remains a major challenge. Although the material is relatively abundant in the Earth’s crust, with significant deposits in Bolivia, Argentina, the United States, Chile, Australia, and China, extracting it in a way that is both economically viable and environmentally sustainable is far from simple.
That is why new research on direct lithium extraction driven by humidity has drawn such strong interest. The study was carried out by researchers at Princeton University and Princeton Critical Minerals in the United States, who developed a modular room-temperature process that could make lithium recovery significantly more affordable.
Lithium extraction methods, how today’s technologies compare
Today, lithium supply relies mainly on two extraction routes, each tied to the type of deposit involved. One is hard-rock mining, primarily from spodumene, which requires significant energy for blasting, crushing, and chemical processing.
The other is brine extraction, using highly saline fluids found beneath salt flats or generated as byproducts from oilfield wastewater and geothermal plants. Brines are estimated to hold about 78% of global lithium resources, but recovering the metal efficiently becomes viable only when lithium concentrations are high.
Dissolved organic compounds and other impurities can further complicate the process, often requiring multiple technologies or advanced pre-treatment steps. That is especially true in the broader field of direct lithium extraction with hygroscopic salts and related technologies, which can include adsorption, ion exchange, solvent extraction, and membrane-based processes, all of which still face scaling challenges.
In other cases, such as solar evaporation, extraction can take a very long time and come with a poor water footprint.
It is within this context that the Princeton University engineering team’s work stands out. The researchers developed a spontaneous direct lithium extraction method driven by hygroscopicity, the ability of a substance to absorb moisture from the air.
Selective deliquescence delivers 96% lithium recovery
The system relies on the behavior of lithium chloride hydrate, a hygroscopic salt. When added to brine tailings from mining operations under controlled relative humidity of 12% to 30%, the material absorbs water and forms a concentrated lithium solution, while leaving other minerals and impurities in solid form.
This process, known as selective phase deliquescence, enables rapid solid-liquid separation without the need for added water, chemical reagents, or thermal energy.
“By optimizing humidity and moisture flux, we achieve rapid lithium recovery up to 96% with concentrations reaching 97,000 ppm, greatly surpassing industrial-grade requirements,” the researchers wrote in the paper published in Nature Communications.
They also said the method proved robust in binary and multicomponent mixtures, as well as in real tailings samples under extraction conditions. According to the team, the results show competitive performance across a broad range of feed ratios and seasonal variations, while cutting extraction times to just hours or minutes, compared with the months often required by conventional methods.
Toward modular lithium production
According to reporting by Sanjukta Mondal for Phys.org, the team also built a modular pilot model for direct lithium extraction with hygroscopic salts, showing how the technology could work at industrial scale.
The researchers estimate that the system could process between 3.65 and 8.01 kilograms of waste per day for every meter of module height, a level of efficiency that appears to outperform many emerging lithium extraction technologies.
The study, Hygroscopicity-driven spontaneous sustainable direct lithium extraction, was published in Nature Communications in 2026, but the work is still under review.