Rational screening-validation and mechanism analysis of ionic liquids for peeling cathode materials off aluminum foil from end-of-life lithium-ion batteries

Peeling off cathode materials from aluminum (Al) foil is a crucial prerequisite for recycling end-of-life lithium-ion batteries (LIBs). In this work, a systematic research framework is proposed to investigate ionic liquids (ILs) as solvents for realizing the mild and efficient recovery of cathode materials and Al foil by dissolving the polyvinylidene fluoride (PVDF) binder. The COSMO-RS prediction of critical thermodynamic property, the deep learning-aided estimation of key physicochemical properties, and the quantum chemical calculation of basicity are first integrated for rational IL screening. Four ILs identified thereafter are further evaluated from the interaction energy point of view to assess their application potential. Among them, one IL is experimentally synthesized by considering the difficulty and affordability, of which the peeling and recycling performances are thoroughly investigated. The separated cathode materials and Al foil are analyzed by SEM-EDS, XPS, and XRD for structure characterization. Finally, theoretical calculations and FT-IR characterization are combined to shed some insight into the dissolution and deactivation mechanism of PVDF in the IL. This work can provide valuable reference for the high-efficiency pretreatment of end-of-life LIBs.