Over the years, our reliance on lithium-ion batteries to power everyday devices has increased dramatically. For a long time, researchers have warned us about two things: one is that there is only so much lithium -- and other metals used in electronics -- on the planet and the other is that when a rechargeable battery reaches the end of its life, if not disposed of properly, those materials will become a threat to human health and the environment.
Those issues have led to scientists to look for solutions. Many breakthroughs have been made in extending the life of rechargeable batteries, which helps reduce the amount of metals that need to be mined and the frequency with which they get thrown away. Now, there just needs to be a better way to recycle the batteries at the end of their life that protects people and the environment and recovers those precious metals so that they can be reused.
Researchers at the University of South Florida have created a process for extracting lithium and cobalt from lithium-ion batteries that is straight from nature. The researchers found that fungi can safely and simply extract the metals from used batteries, keeping the materials out of landfills and ready to be reused in new batteries.The batteries are first taken apart and the cathodes are pulverized. Then three different strains of fungus -- Aspergillus niger, Penicillium simplicissimum and Penicillium chrysogenum -- take over.
"Fungi naturally generate organic acids, and the acids work to leach out the metals," explained Jeffrey A. Cunningham, Ph.D., the project's team leader, to the American Chemical Society. "Through the interaction of the fungus, acid and pulverized cathode, we can extract the valuable cobalt and lithium. We are aiming to recover nearly all of the original material."
Processes used to recycle batteries and other electronics can require high temperatures and harsh chemicals and can be unsafe. The fungi are able to recover the valuable metals safely and, as a bonus, it's very inexpensive.
"Fungi are a very cheap source of labor," Cunningham said.
Cheap and effective. Tests have shown that the acids from the fungi are able to extract up to 85 percent of the lithium and up to 48 percent of the cobalt from old batteries. Once extracted, the metals remain in a liquid acid mixture, so the next step is to figure out how to remove the metals from that liquid.
The researchers are also working on testing different strains of fungus and the acids they produce to see which are best at extracting different metals so that this process could be used on a variety of electronics.