Innovative Approach to Recycle Lithium‐Ion Battery Electrolytes via Sequential Chemical Processes

A chemical separation method is developed to recycle and purify nonaqueous electrolytes from spent lithium-ion batteries. The new process consists of a sequence of precipitation in tandem with each distillation and solvent-assisted vacuum extraction to obtain high-quality electrolyte precursors. The reformulated electrolytes exhibit excellent electrochemical performance in lithium-ion battery. The significance of this process undoubtedly extends to other battery systems beyond lithium.

Abstract

The rapid growth of electric vehicles (EV) has driven the widespread use of lithium-ion batteries (LIBs). This will result in a large amount of spent batteries that if not properly disposed will pose significant environmental damage, especially from the electrolyte. The electrolyte contains lithium hexafluorophosphate (LiPF₆), which when treated by either incineration or water washing can generate harmful F- and P-containing substances such as hydrofluoric acid (HF). In this study, an innovative two-step process is presented to separate and purify both the solvents and lithium salts from the spent electrolyte. Antisolvent assisted precipitation is used to selectively isolate LiPF₆ salt in the form of a complex with ethylene carbonate. Subsequent distillation then separates the volatile electrolyte solvents and antisolvent from each other effectively. In addition, a new process to further purify LiPF₆ from its ethylene carbonate (EC) complex is also presented. This electrolyte recycling method not only enables the recovery of the high-value LiPF₆ salt and the electrolyte solvents, but also paves the way for environmentally responsible and circular LIB recycling.