Princeton researchers have developed a new approach for concentrating, separating, and harvesting lithium salts. Credit: Bumper DeJesus
Key points:
- Researchers have developed a green string-based technique for lithium production.
- If the technology can be successfully scaled to industry, it can cut land use by over 90 percent and accelerate the evaporation process by more than 20 times.
- The team is already developing a second generation of the technique that will enable greater efficiency.
Researchers at Princeton have developed an extraction technique that slashes the amount of land and time needed for lithium production. The team says their system can improve production at existing lithium facilities and unlock sources previously seen as too small or diluted to be worthwhile.
Lithium is a vital component of electric vehicle batteries and grid energy storage, but it comes with significant environmental costs. Among them is the vast amount of land and time needed to extract lithium from briny water, with large operations running into the dozens of square miles and often requiring over a year to begin production.
Conventional brine extraction involves building a series of huge evaporation ponds to concentrate lithium from salt flats, salty lakes or groundwater aquifers. The process can take anywhere from several months to a few years, and is only commercially viable in a handful of locations around the world that have sufficiently high starting lithium concentrations, an abundance of available land, and an arid climate to maximize evaporation. For example, there is only one active brine-based lithium extraction operation in the United States, located in Nevada and covering over 7 square miles.
Now, researchers at Princton have developed a string-based technique. The method, described in Nature Water, is a set of porous fibers twisted into strings, which the researchers engineered to have a water-loving core and a water-repelling surface. When the ends are dipped in a salt-water solution, the water travels up the strings through capillary action. The water quickly evaporates from each string’s surface, leaving behind salt ions such as sodium and lithium. As water continues to evaporate, the salts become increasingly concentrated and eventually form sodium chloride and lithium chloride crystals on the strings, allowing for easy harvesting.
In addition to concentrating the salts, the technique causes the lithium and sodium to crystallize at distinct locations along the string due to their different physical properties. Sodium, with low solubility, crystallizes on the lower part of the string, while the highly soluble lithium salts crystallize near the top. The natural separation allowed the team to collect lithium and sodium individually, a feat that typically requires the use of additional chemicals.
Although the researchers caution that it will take additional work to scale their technology from the lab to an industrial scale, they estimate it can cut the amount of land needed by more than 90 percent of current operations and can accelerate the evaporation process by more than 20 times.
The team is already developing a second generation of the technique that will enable greater efficiency, higher throughput, and more control over the crystallization process.