A key component of batteries at the heart of electric vehicles and grid energy storage, lithium is the key to a clean energy future. But the production of a white metal like silver comes with significant environmental costs. These include the vast amount of land and time required to extract lithium from saltwater, with large operations operating over dozens of square miles and often requiring more than a year to begin production.
Now, researchers at Princeton have developed an extraction technique that reduces the amount of land and time needed to produce lithium. The researchers say their system could improve production at existing lithium facilities and unlock sources that were previously thought to be too small or profitable.
The core of the technique, described in nature water, a group of porous fibers woven into wires, has been engineered by the researchers to have a water-loving core and a water-repellent surface. When the ends are dipped in a salt-water solution, the water moves up the strands via capillary action—the same process that trees use to draw water from the roots to the leaves. The water rapidly evaporates from the surface of each wire, leaving behind salt ions such as sodium and lithium. As the water continues to evaporate, the salts become increasingly concentrated and eventually form sodium chloride and lithium chloride crystals on the wires, making them easier to cut.
In addition to concentrating the salts, the technique causes lithium and sodium to crystallize at different locations along the string due to their different physical properties. The low-solubility sodium crystallizes at the bottom of the string, while the highly soluble lithium salts crystallize near the top. The natural separation allowed the team to collect the lithium and sodium individually, a feat that would normally have required the use of additional chemicals.
“We aimed to take advantage of the fundamental processes of evaporation and capillary action to concentrate, separate and harvest lithium,” said Jed Jason Ren, professor of civil and environmental engineering and leader of the Andlinger Center for Energy and the Environment at Princeton. kept.” research team. “We don’t need to apply additional chemicals, as is the case with many other extraction technologies, and the process saves a lot of water compared to traditional evaporation approaches.”
The limited supply of lithium is a barrier to the transition to a low-carbon society, Ren said. “Our approach is cheap, easy to operate, and requires very little energy. It is an eco-friendly solution to a significant energy challenge.”
evaporation pond on a wire
Traditional brine extraction involves building a series of giant evaporation ponds to concentrate lithium from salt fields, brine lakes or groundwater aquifers. This process can take from several months to a few years. Operations are commercially viable in only a few places around the world that have sufficiently high initial lithium concentrations, an abundance of available land, and a dry climate to maximize evaporation. For example, there is only one active brine-based lithium extraction operation in the United States, which is located in Nevada and covers seven square miles.
String technology is far more compact and can start producing lithium much faster. Although the researchers caution that it will take additional work to scale up their technology from the lab to industrial scale, they estimate that it could cut the amount of land needed for current operations by more than 90 percent and the evaporation process. Can accelerate to more than 20. Compared to conventional evaporation ponds, it potentially produces an initial lithium harvest in less than a month.
Compact, low-cost and fast operations could expand access to new sources of lithium, such as untapped oil and gas wells and geothermal brines, that are currently too small or too dilute for lithium extraction. The quick evaporation rate could also allow operation in more humid climates, the researchers said. They are also investigating whether this technology would allow lithium to be extracted from seawater.
“Our process is like stringing an evaporation pond on a string, which allows us to achieve lithium harvests with a significantly smaller spatial footprint and more precise control of the process,” said Sunxiang (Sean) Zheng, co-author of the study and former Endlinger Center co-author on the study. allows.” Distinguished Postdoctoral Fellow. “If scaled up, we could open up new avenues for environmentally friendly lithium extraction.”
Because the materials for making the wire are inexpensive and the technology doesn’t require chemical treatment to operate, the researchers said that with additional enhancements, their approach would be a strong candidate for widespread adoption. In the paper, the researchers demonstrated the potential scalability of their approach by building an array of 100 lithium-extracting stars.
Ren’s team is already developing a second generation of the technique that will enable greater efficiency, higher throughput and greater control over the crystallization process. He credits the Princeton Catalysis Initiative for providing critical early support enabling creative research collaborations. Additionally, his team recently received an NSF Partnership for Innovation Award and an award from Princeton’s Intellectual Property (IP) Accelerator Fund to support the research and development process, including approaches to extracting important minerals other than lithium. Also included are ways to modify the . Along with Kelsey Hetzel, assistant professor of mechanical and aerospace engineering and the Andlinger Center for Energy and the Environment, Ren also received seed funding from the Princeton Center for Complex Materials to better understand the crystallization process.
Zheng is leading the launch of Purely Inc., a startup in the process of refining the technology and eventually bringing it to the wider market. Zheng was selected as one of four researchers in the inaugural Start Entrepreneurs group at Princeton, an academic fellowship and startup accelerator designed to foster inclusive entrepreneurship.
“As a researcher, you know firsthand that many new technologies are too expensive or difficult to scale up,” Zheng said. “But we’re very excited about it, and with some additional efficiency improvements, we think it has incredible potential to make a real impact on the world.”