Monitoring of PFAS in lithium-ion battery parts and recycling residues via LC-MS/MS analysis
Source: BAM
Lithium-ion batteries (LIBs) are among the most efficient energy storage systems at the present time. This is achieved thanks to the finely tuned chemistry of the cells, relying on rare raw materials such as nickel, cobalt or lithium as well as electrolytes, binders or membranes with high chemical stability. As the number of used batteries continues to rise, their recycling is becoming increasingly important for the recovery of raw materials. Meanwhile, waste management is challenged by the complex composition of LIBs and the employment of environmentally harmful ingredients.
Our study contributes to the assessment of potential hazardous substance emissions during LIB recycling by examining EOL-LIBs and (intermediate) products of their recycling for per- and polyfluoroalkyl substances (PFAS). PFAS, known as “forever chemicals”, are subject to environmental and political discussions because of their high persistence and their toxic effects on human health.
The analytical procedure of this study therefore targets some common and legacy PFAS (perfluoro carbonic and sulfonic acids, respectively C2-C14 and C1-C10) on the one hand and PFAS linked to a use in LIBs on the other hand. The analytical set-up combines liquid chromatography tandem mass spectrometry (LC-MS/MS), a tailored sample preparation procedure for the LIB recycling materials and an isotope dilution assay, allowing the reliable and sensitive quantification of the target analytes.
The application of the analytical procedure to the LIB recycling materials confirms – for the first time in this manner – the presence of PFAS as trifluoro acetic acid (TFA), perfluoro butane sulfonic acid and bis(trifluoromethanesulfonyl)imide as well as the structurally similar, non-PFAS analogue bis(fluorosulfonyl)imide. These findings indicate that LIB recycling activities may lead to the emission of PFAS, particularly TFA. This serves as a point of departure for risk assessments and recycling procedure optimizations in this field. Nevertheless, the analytical results also suggest that other substance groups with environmentally harmful properties may play a more important role compared to PFAS. This underlines the need for more systematic studies to achieve a better understanding of complex battery chemistry and to take this knowledge into account for the recycling process flow.
...