Researchers improve method to recycle and renew used cathodes from lithium-ion batteries

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http://jacobsschool.ucsd.edu/news/news_releases/release.sfe?id=2763

Researchers improve method to recycle and renew used cathodes from lithium-ion batteries

San Diego, Calif., Apr. 17, 2019 -- Researchers at the University of California San Diego have improved their recycling process that regenerates degraded cathodes from spent lithium-ion batteries. The new process is safer and uses less energy than their previous method in restoring cathodes to their original capacity and cycle performance.

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So the team developed a milder process to do the same job at ambient pressure (1 atmosphere). The key was using eutectic lithium salts—a mixture of two or more salts that melts at temperatures much lower than either of its components. This combination of solid lithium salts produces a solvent-free liquid that researchers can use to dissolve degraded cathode materials and restore lithium ions without adding any extra pressure in the reactors.

Illustration of the process to restore lithium ions to degraded NMC cathodes using eutectic molten salts at ambient pressure. Image courtesy of Advanced Energy Materials/Chen lab

The new recycling method involves collecting cathode particles from spent lithium ion batteries and then mixing them with a eutectic lithium salt solution. The mixture is then heat treated in two steps: it is first heated to 300 C, then it goes through a short annealing process in which it is heated to 850 C for several hours and then cooled naturally.

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“The goal is to make this a universal recycling process for all cathode materials,” Chen said. The team is also working on a process to recycle degraded anodes, such as graphite as well as other materials.

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