Spent lithium-ion batteries (LIB) contain volatile and reactive chemicals possibly generating toxic and/or flammable gases during the related recycling. In this study, two types of spent LIB cells were subjected to combined mechanical and thermal treatments at the constant temperatures of 20 °C, 120 °C, 200 °C, and 400 °C under a nitrogen atmosphere. A total of 46 gaseous species, including electrolyte components, oxygenated hydrocarbons, hydrocarbons, and others, were qualitatively and quantitatively analyzed by mass spectrometry. At higher process temperatures, the concentration or volume of the formed gases increased accordingly. Additionally, at and below 120 °C, the formed gaseous species slightly differed depending on the cell type, whereas they were analogous at 400 °C. The formation of different gas species involved the activity of electrolyte volatilization, electrolyte degradation/decomposition, and pyrolysis of the organic separator and binder, followed by complex radical reactions among the species formed by the physicochemical reactions. Possible strategies to mitigate the risks that may arise associated with the gas formation during recycling are presented.
Keywords: Gas formation; Pre-treatment; Recycling; Spent LIB.
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