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Traditional technologies for waste lithium-ion battery (LIB) recovery have the disadvantages of the use of corrosive acid and reductants, release of toxic gases, and a complex pretreatment procedure of aluminum foil exfoliation. In this study, a clean hydrometallurgical process is presented for the recovery of critical metals and aluminum foil from waste LIB cathode materials in a single step using an ethylene glycol (EG)–citric acid (CA) leaching system. The effects of reaction parameters, such as EG/CA molar ratio, temperature, time, and solid–liquid ratio on the leaching efficiencies of critical metals were carefully investigated. Here, 99.1% Li, 96.2% Co, 97.6% Ni, and 98.3% Mn were leached under optimized reaction conditions. Leaching kinetics show that the chemical reactions are the rate-controlling steps in the process. Characterization results confirm that the high leaching efficiency for critical metals is attributed to the condition of adding ethylene glycol as a reducing agent. Aluminum foil can be completely recycled because of the inhibiting effect of the newly generated citric ester in the EG–CA system. This process provides a novel alternative to conventional methods of recovery of metals from waste LIBs.
Zeng et al. (Thu,) studied this question.