Hydrometallurgical recovery of spent cobalt-based lithium-ion battery cathodes using ethanol as the reducing agent.

Abstract

A reducing agent can reduce Co3+ to Co2+ in LiCoO2, thus increasing the leaching efficiency and extraction rate of Co-based cathode materials from spent lithium-ion batteries (LIBs). Herein, ethanol was employed as the reducing agent to leach LiCoO2 obtained from LIBs in a sulfuric acid solution. The effects of operating temperatures (50-90\u202f°C), dosage of ethanol (0-20\u202fvol%), concentration of sulfuric acid (2-6\u202fmol/L), and solid/liquid ratio (10-40\u202f\u202fg/L) on the leaching efficiency of LiCoO2 were investigated. By adding 5\u202fvol% ethanol in a 6\u202fmol/L sulfuric acid solution at 90\u202f°C, the extraction efficiency of Co and Li are both over 99%, meaning that ethanol can reduce Co3+ to Co2+ while the ethanol was oxidized to acetic acid. The dissolution of LiCoO2 obeys the residue layer diffusion control model. Although ethanol is a promising reducing agent, future efforts should pay to the management of the secondary wastewater. Overall, the ethanol can be used as a reducing agent to assist the leaching of cathode materials from spent LIBs.