Evaluation of Fluorochemical Leaching from Lithium-Ion Batteries Under Simulated Solid Waste Landfill Conditions

Lithium-ion batteries (LiBs) are widely used in electronic devices and renewable energy systems. Fluorochemicals are essential components of LiBs, as a component of electrolytes, electrodes, and coatings. However, there are concerns about the environmental release of fluorochemicals, especially within landfills after disposal, due to the fact that landfill leachate is typically treated in facilities not designed to attenuate fluorochemicals. We have evaluated the occurrence of fluorochemical compounds in commercial LiBs and fluoropolymer binders and the release of LiB-derived fluorochemicals in simulated municipal solid waste (MSW) leaching experiments. Our survey of 19 LiBs found per- and polyfluoroalkyl substances (PFAS) including bis(perfluoroalkyl)sulfonimide (bis-FASI, up to 36 mg) and inorganic fluorochemicals such as hexafluorophosphate (PF₆^-, up to 1.4 g) and bis(fluorosulfinyl)imide (bis-FSI, up to 250 mg). PFAS were also measured in fluoropolymer binders in the range of 2-2000 ng/g. Nontargeted analysis resulted in detection of diverse fluorinated sulfonimides and organic phosphofluoridates in batteries as well as 6 novel PFAS in fluoropolymer binders. Analysis of MSW landfill leachates indicated the presence of LiB-derived fluorochemicals up to 76 μg/L. Simulated MSW leaching experiments showed that LiBs released PFAS (up to 100 mg/L) and inorganic fluorochemicals (up to 1.4 g/L) into the landfill leachate over a period of 220 days. Furthermore, PF₆^- and bis-FSI transformed in landfill leachate to form organic phosphofluoridates and novel amino sulfonyl fluorosulfanomides. This is the first report of PFAS and fluorochemical release from LiBs and transformation under landfill leaching conditions.