Wang and his colleagues tested the recycled cathode powder in a number of cell types: coin, single-layer pouch, 1 Ah, and 11 Ah. They compared the performance of the different types to similar cells made with “fresh” cathode powder.
Cells using recycled cathodes were then put through an array of tests, where they performed almost identically to cells using fresh cathode materials. There was only one notable exception: The cells using recycled cathode materials lasted up to 53 percent longer.
The team tested batteries with recycled NMC111 cathodes, the most common flavor of cathode containing a third each of nickel, manganese, and cobalt. The cathodes were made using a patented recycling technique that Battery Resources, a startup Wang co-founded, is now commercializing. The recycled material showed a more porous microscopic structure that is better for lithium ions to slip in and out of. The result: batteries with an energy density similar to those made with commercial cathodes, but which also showed up to 53% longer cycle life.
While the recycled batteries weren’t tested in cars, tests were done at industrially relevant scales. The researchers made 11 Ampere-hour industry-standard pouch cells loaded with materials at the same density as EV batteries. Engineers at A123 Systems did most of the testing, Wang says, using a protocol devised by the USABC to meet commercial viability goals for plug-in hybrid electric vehicles. He says the results prove that recycled cathode materials are a viable alternative to pristine materials.