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.