Research on the separation process of positive electrode active material and aluminum foil

Abstract

Separating the cathode active material and aluminum foil is an important step in the recovery of materials from used lithium-ion batteries. It is difficult to separate aluminum foil and positive active material because of the strong bonding of polyvinylidene fluoride (PVDF). During the conventional stripping technology, using corrosive acids/alkalis, toxic reagents and releasing toxic gases such as dioxins and HF, which are harmful to human health and the environment. In the study, a low-toxic, efficient and low-cost solvent consisting of “propylene glycol and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][BF6]) ionic liquid” was used to solve these questions. The experimental results showed that the separation rate of the positive active material from the aluminum foil was more than 99 % when the anodes were stirred in propylene glycol and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][BF6]) ionic liquid (the volume ratio of 5:1) at 140 ℃ for 30 min. This work would provide an insight into the environmentally friendly, simple and effective solution to separate of cathode material and aluminum foil in waste lithium-ion batteries.