Toxicity Identification and Evolution Mechanism of Thermolysis-Driven Gas Emissions from Cathodes of Spent Lithium-Ion Batteries

Spent lithium-ion batteries (LIBs) typically contain a combination of both strategic materials and toxic chemicals that cannot be easily disposed. Nowadays, that are many different methods used to treat spent LIBs with the primary aim of critical metals recovery; nevertheless, as a result of the toxic chemicals within the battery waste, the chemical composition and potential danger of the off-gases generated during recycling process have become a serious concern. In an attempt to further understand the characteristics of the off-gases that are emitted from spent LIBs cathodes during thermolysis process, a system of thermogravimetry-differential thermal analysis coupled with mass spectrometry equipped with skimmer-type interface and with electron ionization (TG-DSC-EI-MS) has been employed to qualitatively analyze the generated off-gases. Based on the obtained observations, it was confirmed that inorganic gases of H-2, H2O, CO2, gaseous hydrocarbons, and fluoride-containing gases were generated. Moreover, the off-gas species and relative yield of the individual gases formed were found to be significantly affected by the thermolysis temperature under different atmospheric conditions. From the combined results from TG-DSC-EI-MS, thermogravimetric differential scanning calorimetry analysis (TG-DSC), chemical analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM), the correlation between the evolution characteristics of the gas emissions and thermolysis behavior of the cathodes from spent LIBs has been established. The availability of this type of quantitative data is useful when undertaking environmental assessments and for the design of off-gas management systems for spent LIBs recycling processes.