New technology enables lithium to be extracted from brines economically and sustainably

A new technology can extract lithium from brines at an estimated cost of less than 40% of the current dominant extraction method and just a quarter of the current market price of lithium. The new technology would also be much more reliable and sustainable in its use of water, chemicals and land than current technology, according to a study published in Matter by researchers at Stanford University.

Global demand for lithium has exploded in recent years, fueled by the rise of electric vehicles and renewable energy storage. The primary source of lithium extraction today relies on evaporating brines in huge pools exposed to the sun for a year or more, leaving behind a lithium-rich solution, after which a massive use of potentially toxic chemicals finishes the job. Water with high concentrations of salts, including lithium, occurs naturally in some lakes, hot springs and aquifers, and is a byproduct of oil and gas operations and seawater desalination.

Many scientists are looking for cheaper, more efficient, more reliable and more environmentally friendly methods of extracting lithium. This typically involves direct lithium extraction that bypasses large evaporation ponds. The new study presents the results of a new method using an approach known as “redox-coupled electrodialysis” (RCE), along with cost estimates.

“The efficiency and cost advantages inherent in our approach make it a promising alternative to current extraction techniques and a potential game-changer for the lithium supply chain,” said Yi Cui, lead author of the study and professor of materials science and engineering in the School of Engineering.

The research team estimates that its approach costs between $3,500 and $4,400 per tonne of high-purity lithium hydroxide, which can be converted more cheaply into battery-grade lithium carbonate, compared with about $9,100 per tonne for the dominant lithium-from-brine technology. The current market price for battery-grade lithium carbonate is nearly $15,000 per tonne, but a shortage in late 2022 pushed the volatile lithium market price to $80,000.

Meeting growing demand

Lithium has so far played a critical role in the global transition to sustainable energy. According to a report by McKinsey & Co, lithium demand is expected to grow from about half a million tonnes in 2021 to around 3 to 4 million tonnes by 2030. This surge is mainly driven by the rapid adoption of electric vehicles and renewable energy storage systems, both of which rely heavily on batteries.

Traditionally, lithium has been extracted from mined rocks, a method that is even more expensive, energy-intensive, and uses toxic chemicals than brine extraction. As a result, the dominant method of lithium extraction today is the evaporation of brines from salt lakes, although this remains at high financial and environmental cost. This method also relies heavily on specific climatic conditions that limit the number of commercially viable salt lakes, casting doubt on the lithium industry’s ability to meet growing demand.

Cui and his team’s new method uses electricity to move lithium through a solid-state electrolyte membrane, from low-lithium water to a more concentrated, high-purity solution. Each in a series of cells increases the lithium concentration to a solution from which final chemical isolation is relatively easy. This approach uses less than 10% of the electricity required by current brine extraction technology and has a lithium selectivity of nearly 100%, making it very efficient.

“The advantages of our approach over conventional lithium extraction techniques strengthen its feasibility for environmentally friendly and cost-effective lithium production,” said Rong Xu, co-senior author of the study, a former postdoctoral researcher in Cui’s lab and now a faculty member at Xi’an Jiaotong University in China. “Ultimately, we hope our method will significantly advance electric transportation and renewable energy storage capacity.”

Environmental costs and benefits

The study includes a brief techno-economic analysis comparing the costs of current lithium extraction with those of the RCE approach. The new method is expected to be relatively inexpensive, mainly due to lower capital costs. It eliminates the need for large-scale solar evaporation ponds, which are expensive to build and maintain. The new method uses significantly less electricity, water and chemicals, in addition to the sustainability benefits, further reducing costs.

By avoiding the extensive land use and water consumption of traditional methods, the RCE approach also reduces the ecological footprint of lithium production.

The RCE method works with a variety of saline waters, including those with varying concentrations of lithium, sodium and potassium. Experiments in one study showed that the new technology could extract lithium, for example, from wastewater resulting from oil production. It could potentially be used to extract lithium from seawater, which has lower concentrations of lithium than brines. Extracting lithium from seawater using conventional methods is not commercially viable today.

“Direct lithium extraction techniques like ours have been under development for some time. The main competing technologies to date have major drawbacks, such as the inability to operate continuously, high energy costs, or relatively low efficiency,” said Ge Zhang, a postdoctoral researcher at Stanford and co-author of the study. “Our method does not appear to have any of these drawbacks. Its continuous operation could contribute to a more reliable lithium supply and calm the volatile lithium market.”

Looking to the future

The scalability of the RCE method is also promising. In experiments where the device scale was increased fourfold, the RCE method continued to perform well, with energy efficiency and lithium selectivity remaining very high.

“This suggests that the method could be applied on an industrial scale, making it a viable alternative to current extraction technologies,” Cui said.

Still, the study highlights some areas for further research and development. The researchers experimented with two versions of their method. One extracts lithium faster and uses more electricity. The other is slower and uses less electricity. The slower extraction results in lower costs and a more stable membrane for extracting lithium continuously and for a long time, compared to the faster extraction. Under high current densities and faster water flow, the membranes degrade, leading to reduced efficiency over time.

Although this was not demonstrated in the slower extraction experiment, the researchers are interested in optimizing the design of their device for potentially faster extraction. They are already testing other promising materials for the membrane.

Additionally, the researchers did not demonstrate the extraction of lithium from seawater in this study.

“In principle, our method is also applicable to seawater, but there might be problems with membrane stability in seawater,” Zhang said.

Despite everything, the team remains rather optimistic.

“As our research continues, we believe our method could soon move from the laboratory to large-scale industrial applications,” Xu said.