A new method to extract valuable metals from lithium-ion batteries promises to cut the energy and environmental costs of known battery recycling techniques.
It requires a liquid solvent made of easily available substances derived from urine and acetic acid, the main ingredient in vinegar. And it recovers over 97 percent of cobalt in a battery, according to a study published in the journal ACS Omega.
The growing market for electric vehicles as well as consumer electronics has driven a dramatic rise in demand for rechargeable lithium-ion batteries. But the environmental benefit of batteries is shadowed by the impact of the critical metals that go into them.
Cobalt is one of the main metals in batteries. Much of it comes from Democratic Republic of Congo, where mining practices are beset with human-rights and environmental abuses. Then there’s the enormous used battery waste to contend with. Most discarded batteries end up in landfills, posing a threat to the environment.
Battery makers are trying to reduce the use of cobalt in lithium-ion chemistries. And there is a growing call for more battery recycling to reuse cobalt and other metals. Recycling metals in batteries today involves pulverizing them and then either heating them at temperatures over 500°C using lots of energy, or dissolving them in harsh chemicals such as acids, which creates harmful byproducts.
The new method developed by a team from Linnaeus University in Sweden and the Indian Institute of Technology Madras in India promises to use harmless chemicals and much less energy.
It relies on a solvent that is a combination two chemicals. One chemical is derived from urea, which occurs naturally in urine, while the other is made from acetic acid. The researchers first reported these solvents in 2019.
They have now used it to dissolve lithium cobalt oxide, the compound used in most laptop and cellphone batteries. The reaction is most efficient at a relatively mild 180°C. After two days in the heated solvent, the researchers could separate more than 97 percent of the cobalt, which they reused to make new fully functional batteries.
“The combination of readily available and relatively harmless substances and high energy efficacy gives our method potential to work for large scale extraction,” said Ian Nicholls, professor of chemistry at Linnaeus University, in a press release. “With more efficient and environmentally friendly methods, we can reuse a very significant portion of the cobalt that is already in use, instead of mining.”
Source: Subramanian Suriyanarayanan et al. Highly Efficient Recovery and Recycling of Cobalt from Spent Lithium-Ion Batteries Using an N-Methylurea–Acetamide Nonionic Deep Eutectic Solvent. ACS Omega, 2023.
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