Effects of acid concentration, temperature, and time on recycling of post-vehicle-application lithium-ion batteries of varying chemistries

Abstract

The purpose of this project was to develop and validate a common process for separating the active materials from the copper and aluminum foils of post-vehicle-application lithium-ion batteries. Batteries from two different manufacturers were disassembled, and anode and cathode samples were used for recycling testing. The materials tested from a third manufacturer were scraps of coated foils from the manufacturing process that had never been assembled into cells. The cathodes from each manufacturer were aluminum foils with coatings of differing chemistries. The anode foils from each manufacturer were copper with a carbon coating. The process developed used acid baths to separate the active materials from the foils. To allow for separation of the differing active materials (depending on supplier and battery chemistry) from the foils, the acids were selected to react with the aluminum and copper foils. The processes were stopped once sufficient reaction had occurred so that the coatings no longer adhered to the foils. The optimum recycling condition was identified as the lowest acid concentration, the lowest temperature, and the shortest time required for full separation of the coatings from the foils for all cell chemistries (manufacturers). Full separation of the graphite coating from the copper foils of the anodes was achieved within 35 s by using 0.5 mol/L of H2SO4 (sulfuric acid) at 40 °C. Full separation of the active materials from the aluminum foils of the cathodes was achieved within 83 s by using 2.0 mol/L of HNO3 (nitric acid) at 70 °C.