Extracting lithium from Australian mines, Chilean brine pools or clay deposits underneath Nevada, can be a painfully slow, expensive and environmentally damaging process. But batteries powering everything from smartphones to energy storage for wind farms and solar fields demand the metallic element.
UChicago Pritzker School of Molecular Engineering Asst. Prof. Chong Liu is developing better ways to not only supply high quantities of lithium, but to do so in an environmentally friendly way.
By researching the physical and chemical processes at solid-liquid interfaces for sustainable separation, Liu has created new ways to separate dilute ions from the water. This could be used to pull lithium, rare earth elements and other scarce materials directly from water – no mining or brine evaporation needed.
“The goal is a method that can be applied directly into the water source with minimum pretreatment,” Liu said. “We want to increase the selectivity of lithium to other elements so that you can fish out the lithium without disturbing the aqueous environment much.
The demand for lithium is poised to skyrocket as climate change demands more and better batteries to store wind and solar power.
The time to fight a global lithium shortage is now, before there is a shortage, Liu said.
"We all know that there will be a transition to renewable energy,” she said. “When you are looking at all those devices that need to be made, there will have to be a raw material that goes into manufacturing. There will be a supply issue.”
Working on water
While much of Liu’s research is spurred by the need to secure the supply chain, there is also a pressing environmental demand for a better way to obtain lithium, one that uses less energy, less water and less land than current practices.
The two major methods of lithium extraction are from mining and brine extraction, both of which create different environmental impacts. Mining lithium-containing spodumene is the method used in Australia and North Carolina.
“The harm with mining is that you have to use strong chemicals like acid to dissolve the elements to extract the lithium,” Liu said. “This consumes chemicals and produces waste, both of which harm the environment.”
Brine extraction, in which brine is pumped from lakes to evaporate on the surface before the lithium can be harvested, is also environmentally damaging, but additionally it is slow and costly, unlikely to be able to keep up with the expected spike in demand for lithium.
“The first step is always to take one year or two just for evaporation,” Liu said.
Brine extraction is the method used in South American lithium-producing nations like Chile, Argentina and Bolivia. This latter area – the “Lithium Triangle” – holds more than 75% of the world’s lithium supply.
The way the world gets its lithium creates socio-economic issues beyond just cost. Geography and geology benefit some countries over others at a climate moment when nations need to work together.
“It's not even. Some countries have more lithium, some countries have less,” Liu said. “The capability of production is also not even. Some countries have more advanced methods or technologies and some countries do not. But the demand for renewable technologies is a global issue.”
Other applications
While Liu said extracting lithium directly from the ocean is “the very end, the ultimate goal,” the extraction techniques she is pioneering show promise for different kinds of salt water, including surface seawater, geothermal brine water and the water that comes up as a byproduct of oil extraction.
This area has proven a jumping-off point for other areas of research. Liu and her team are also looking at applying these techniques to extracting rare earth elements. They are also researching sustainable manufacturing and possible new methods for fabricating membranes.
“One project can open up opportunities for others,” she said.
Her research also recently netted Liu a prestigious Sloan Fellowship, a yearly award recognizing early-career scientists and scholars “of outstanding promise.”
Liu joined PME in 2018, when it was still the Institute for Molecular Engineering. She said the caliber of “world-class scientists and engineers” hired from institutions around the world both initially attracted her and have kept it an intellectually stimulating place to work.
“You wouldn’t find another PME,” Liu said. “Everyone here is so energetic, you feel you can definitely learn from any one of them.”