By Will Cushman
With ever more electric vehicles on the road, regulators and automakers are considering what can be done with the millions of batteries that power EVs after they’re spent. Even when their useful life is over, EV batteries contain valuable lithium that could be recycled and used in new batteries, but coming up with a cost-effective way to do so is critical. Now, a group of University of Wisconsin–Madison chemists is hopeful they’ve found a solution, and they’re already filing patents and courting global carmakers.
The work has been led by Kyoung-Shin Choi, a UW–Madison chemistry professor who specializes in developing electrochemical processes for various ends. Choi and her colleagues have come up with a proof of concept for using electrochemistry to extract lithium from spent lithium-iron-phosphate (LFP) batteries, which have been widely adopted by major EV manufacturers like Tesla and China’s BYD.
Lithium-based EV batteries come in a few flavors, and while LFP batteries have lower energy densities than batteries that are based on elements like nickel, manganese, and cobalt, they’re significantly cheaper to produce and safer to operate. On the flip side, iron and phosphate aren’t worth much compared to nickel or cobalt, making LFP batteries less attractive from a recycling perspective. “At this point, there’s no economically compelling method to recover lithium from spent LFP batteries even though the market is shifting to them,” says Choi.
“Access to natural lithium resources is also limited,” Choi says. “We need an innovative method that makes lithium recovery from spent LFP batteries commercially viable to support a circular and competitive battery economy.” The problem has become all the more pressing for global carmakers since the European Union has new regulations aimed at reducing the environmental impact of batteries.
Current methods for recovering lithium from spent batteries depend on energy-intensive heat or an extensive series of steps that consume a lot of chemicals and generate significant waste, Choi says.
Instead, Choi developed a two‐step electrochemical process that doesn’t require special conditions and minimizes chemical inputs and waste. The first step sees lithium ions leached out from spent LFP batteries and selectively extracted by a lithium-ion storage electrode. In the second step, the extracted lithium ions are released in a separate solution to recover them as high-purity lithium chemicals.
Choi and her colleagues have demonstrated the process’s viability using both a commercial LFP battery and black mass, which is an industrially mass-produced substance from spent LFP batteries. They recently detailed the process in the journal ACS Energy Letters and have filed a patent for it through the Wisconsin Alumni Research Foundation.
The work has begun to catch the attention of battery makers and automakers who are seeking new ways to bolster the resilience of the battery market. Choi’s team is now developing a prototype of the technology to answer outstanding questions about how to commercialize the process, and she’s forming a startup company.
“The technology works, but it is important to scale it up in the most cost-effective manner,” Choi says, adding that it will be crucial for successful commercialization to streamline the technology with other steps in the overall recycling process, such as the production and use of black mass.