Growing demand for lithium-ion batteries places pressure on global supplies of cobalt and other material components, prompting greater emphasis on reuse and recycling. Many manufacturers contend that impurities in recycled materials may undermine battery performance, a concern that should be alleviated by researchers from Worcester Polytechnic Institute in Massachusetts after demonstrating that batteries with recycled cathodes can outperform those incorporating virgin materials.

After spent lithium-ion batteries were cut up, shredded and sieved, the cases, wires, plastics and circuit boards are removed for recycling, leaving a black mass that contains graphite, the cathode materials and some other metal residues. Leaching and filtering recovers about 90% cobalt, manganese and nickel are recovered and processed to form a recycled cathode powder for use in new battery cells.

Testing confirmed that cells equipped with recycled cathodes performed almost identically to those assembled with fresh cathode materials. There was only one notable exception: the devices using recycled cathode materials lasted up to 53% longer.

During charge/discharge tests, control cells degraded to 80% of their original capacity after 3,150 cycles and to 70% capacity after 7,600 cycles. Cells incorporating recycled materials the recycled material cells required 4,200 cycles before degraded to only 80% state of charge and were put through 11,600 cycles before the 70% capacity mark was reached,

This performance boost is attributed to the larger pores in the center of recycled cathode powder particles relative to control materials, as observed by scanning electron microscopy.

Researchers from A123 Systems Advanced and Applied Research Center (Massachusetts), Battery Resourcers (Massachusetts), U.S. Argonne National Laboratory, U.S. Brookhaven National Laboratory, Rice University and the United States Advanced Battery Consortium (Michigan) also contributed to this study, which is published in Joule.

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