Characteristic comparison of leaching valuable metals from spent power Li-ion batteries for vehicles using the inorganic and organic acid system

This work presents a new insight: the leaching rules of various batteries and leaching agents were explored. In this study, LiNi0.5Co0.2Mn0.3O2 (NCM) and composite material batteries (CMB) were treated by environmentally friendly acid (phosphoric acid, citric acid, and acetic acid). The properties and composition of NCM and CMB were characterized and analyzed, and the optimal leaching conditions were investigated. For NCM, the leaching efficiencies of Li, Ni, Co, and Mn by phosphoric acid were 95.4%, 99.8%, 99.5%, and 98.0%, respectively, while those by citric acid were 91.0%, 85.7%, 99.9%, and 93.6%, respectively. For CMB, the optimal leaching efficiencies of phosphoric acid were Li 92.9%, Ni 93.3%, Co 94.8%, Mn 94.3%, while citric acid were Li 88.2%, Ni 72.5%, Co 94.0%, Mn 90.5%. Comparing the leaching behavior revealed that NCM was more easily leached than CMB, that may be correlated with the structure and composition of the active components. Three acids were evaluated for their efficacy and availability: phosphoric acid > citric acid > acetic acid. And kinetics and leaching mechanisms suggested that the kinetic behaviors of NCM and CMB in the three leaching systems were all following the Avrami model.