A new technology can extract lithium from brines at an estimated cost of less than 40% of today’s dominant extraction method and at only a quarter of the current market price of lithium. According to a study published today in Object by researchers at Stanford University.

Global demand for lithium has soared in recent years, driven by the increasing adoption of electric vehicles and renewable energy storage. The dominant method of lithium extraction today relies on evaporating brines in huge ponds under the sun for a year or more, leaving behind a lithium-rich solution, and then finishing the process with massive use of potentially toxic chemicals. Water with high concentrations of salts, including lithium, occurs naturally in some lakes, hot springs and aquifers, and is a byproduct of oil and natural gas extraction and seawater desalination.

Many scientists are looking for cheaper, more efficient, more reliable and more environmentally friendly methods of lithium extraction. This usually involves direct lithium extraction, bypassing large evaporation ponds. The new study reports the results of a new method that uses an approach called “redox pair electrodialysis” (RCE) and provides cost estimates.

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

The research team estimates that their approach costs $3,500 to $4,400 per tonne of high-purity lithium hydroxide, which can be inexpensively converted into battery-grade lithium carbonate. By comparison, the prevailing technology for extracting lithium from brine costs about $9,100 per tonne. The current market price for battery-grade lithium carbonate is nearly $15,000 per tonne, but a shortage in late 2022 drove the volatile lithium market price to $80,000.

Meeting the increasing demand

Lithium has played a crucial role in the global energy transition so far. According to a report by McKinsey & Co., demand for lithium is expected to grow from about half a million tons in 2021 to an estimated 3 to 4 million tons by 2030. This sharp increase is largely due to 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 rock, a method that is even more expensive, energy-intensive and requires toxic chemicals than brine extraction. As a result, lithium is now mainly extracted by evaporating brine from salt lakes, but this still comes with high financial and environmental costs. This method is also highly dependent on certain climatic conditions that limit the number of commercially viable salt lakes, raising doubts about the lithium industry’s ability to meet increasing demand.

Cui and his team’s new method uses electricity to transport lithium through a solid-state electrolyte membrane from water with a low lithium concentration into a more concentrated, high-purity solution. Each cell in a series of cells increases the lithium concentration up 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 almost 100%, making it very efficient.

“The advantages of our approach over conventional lithium extraction techniques increase its feasibility for environmentally friendly and low-cost lithium production,” said study co-leader Rong Xu, a former postdoctoral fellow in Cui’s lab who is now a faculty member at Xi’an Jiaotong University in China. “Ultimately, we hope our method will significantly advance electrified transportation and the ability to store renewable energy.”

Cost and environmental 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 cost-effective, mainly due to lower capital costs. It eliminates the need for large solar evaporation ponds, which are expensive to build and maintain. The significantly lower consumption of electricity, water and chemicals in the new method – apart from the sustainability benefits – also reduces costs.

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

The RCE method works with a wide variety of brines, including those with varying concentrations of lithium, sodium and potassium. Study experiments showed that the new technology could extract lithium from wastewater generated during oil production, for example. It could potentially be used to extract lithium from seawater, which has lower lithium concentrations than brines. Lithium extraction from seawater using conventional methods is currently not commercially viable.

“Direct lithium extraction techniques like ours have been in development for some time. The main competing technologies to date have significant drawbacks, such as the inability to operate continuously, high energy costs or relatively low efficiency,” said Ge Zhang, a postdoctoral fellow 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.”

A look into the future

The scalability of the RCE method is also promising. In experiments where the scale of the device was quadrupled, the RCE method continued to show good results, with both 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,” said Cui.

Still, the study highlights some areas where more research and development is still needed. The researchers experimented with two versions of their method. One extracted the lithium faster and used more electricity. The other was slower and used less electricity. The slower extraction resulted in lower costs and a more stable membrane for continuous and long extraction of the lithium compared to the faster extraction. At high current densities and faster water flow, the membranes degraded, resulting in reduced efficiency over time. Although this was not observed in the slower extraction experiment, the researchers want to optimize the design of their device for potentially faster extraction. They are already testing other promising materials for the membrane.

Furthermore, the researchers could not detect lithium extraction from seawater in this study.

“In principle, our method is also applicable to seawater, but there could be stability problems with the membrane,” says Zhang.

Nevertheless, the team remains quite optimistic.

“We believe that as our research progresses, our method could soon move from the laboratory to large-scale industrial application,” said Xu.