a critical element used in rechargeable batteries and susceptible to supply chain disruption - can be recovered from battery waste using an electrochemically driven recovery process. The method has been tested on commonly used types of lithium-containing batteries and demonstrates economic viability with the potential to simplify operations, minimize costs and increase the sustainability and attractiveness of the recovery process for commercial use.
The study, led by University of Illinois Urbana-Champaign chemical and biomolecular engineering professor Xiao Su, describes a process that leaches metals from batteries into an organic solvent, then uses an electrochemical cell in which a polymer-coated electrode is used to capture lithium.
"The main challenge is the presence of other metals in lithium recovery streams, particularly in organic leachates, which is a common way to dissolve spent batteries for recycling," Su said. "To overcome these challenges, we've introduced a copolymer that captures lithium selectively directly from organic solvents and that can be electrochemically regenerated."
The study findings are published in the journal ACS Energy Letters and were co-led by former graduate student Nayeong Kim, with contributions from postdoctoral researchers Johannes Elbert and Hee-Eun Kim and undergraduate student Chengxian Wu.
In the lab, Su's research team dismantles batteries and leaches out metals into an organic solvent, creating a mixture containing lithium and other metals. They then moved the solvent into an electrochemical cell with an electrode coated with a specially designed copolymer that specifically captures lithium ions from the mixture, much like a sponge.
"The lithium-filled electrode is then put into a new solution, and a voltage is applied," Su said. "That triggers the polymer to release the captured lithium ions, which are collected, while leaving other metals behind in the original leachate. This electrochemical regeneration allows for repeated cycles of selective, efficient lithium recovery from waste batteries."
Su's research in resource recovery typically includes an economic viability analysis, and this study follows with that hallmark.
"We found that, using a three-stage approach, the recovered lithium could be produced at a cost that is economically favorable compared to current lithium market prices," he said.
This means the new method could be significantly less expensive or at least cost-competitive with existing methods of lithium production. Su said that while the proof-of-concept results are very promising, there is still room for more work in scaling up the system as well as process modeling to validate their findings further.
"These results help highlight the broad applicability of electrochemical separations for metal recycling, not only in water, but also from organic solvents that are commonly used to leach waste batteries. We envision this work helping establish a more circular, sustainable supply chain for lithium, enhancing supply security and potentially reducing the environmental impacts associated with other forms of lithium extraction, such as mining."
The U.S. Department of Energy supported this research through the Basic Energy Sciences program, grant #DE-SC0025636. Su also is affiliated with civil and environmental engineering, chemistry and the Beckman Institute for Advanced Science and Technology at the U. of I.
