Charles Standridge, PhD, Professor and Assistant Dean
GVSU News – Professor Lindsay Corneal and Master of Science in Engineering student Eric Li of the School of Engineering of Grand Valley State University (GVSU) have been working on recycling processes for lithium-ion batteries that have reached the end of useful life in a vehicle. This work is in keeping with the GVSU core value of sustainability – meeting current needs without compromising the needs and resources of future generations. It has been performed as part of our partnership with Sybesma’s Electronics in Holland MI.
Thus the purpose of recycling lithium-ion batteries is to extract and collect as much valuable material from the spent cells as possible, in an economical and environmentally friendly way. Recycling process development focused on lithium iron phosphate (LiFePO4) batteries for which no previous studies have been reported.
Acid leaching method proved successful
The particular LiFePO4 cell that interests the researchers consists of a graphite-coated copper foil (anode), LiFePO4-coated aluminum foil (cathode), two separator layers, liquid electrolyte, plastic components, and aluminum shells. At issue is how to efficiently separate the coating from the foil and to extract the raw material. Dismantling and alternative material extraction procedures were developed and tested. The latter involve using either acid leaching, N-Methyl-2-pyrrolidone (NMP) separation, or acidic gas to separate the materials on both electrodes of the battery.
Results showed that the acid leaching method is effective in separating components of both electrodes in a short time at an elevated temperature. The graphite coating completely detached from the copper foil in 0.5 mol/L sulfuric acid (H2SO4) solution in one minute at 40°C (104°F), and 95% of the LiFePO4 coating detached from the aluminum foil in 0.5 mol/L nitric acid (HNO3) solution in one minute at 50°C (122°F).
Researchers will continue testing
N-Methyl-2-pyrrolidone (NMP) was also used on the attempt to separate the materials in electrodes, but the results were unsuccessful. The researchers studied copper-graphite self-separation by acidic gas, and the application with NO2 was proven successful. However, more precise measurement on the effective gas concentration is recommended for practical applications in the future.
The research team will continue developing and refining the recycling process throughout the fall of 2013.