Powering the Future Without PFAS

Per- and polyfluoroalkyl substances (PFAS) are a diverse class of >10 000 anthropogenic chemicals containing at least one -CF2- or -CF3 moiety (with a few exceptions).[1] Structures range from high molecular weight fluoropolymers such as polytetrafluoroethylene (PTFE) to relatively low molecular weight, water-soluble acids such as trifluoroacetic acid (TFA). Despite their diversity, all PFAS are either highly persistent or break down to persistent end products.[2] Although some have been linked to adverse health effects, hazard data are lacking for most PFAS. Due to their unique properties and structural diversity, PFAS have found widespread use in society. One example is their uses in lithium-ion batteries (LIBs). Our recent review of PFAS uses in LIBs found that they are prevalent in electrodes and binder, electrolyte (and additives), and separator, see Figure 1.[3] In the cathode, for example, polyvinylidene fluoride (PVDF) is considered the gold standard binder today due to its excellent electrochemical stability and processing properties, among others. However, potential formation and/or emission of PFAS to the environment is of risk during LIB recycling, in addition to the risks of human exposure during LIB manufacturing. With increased activity in hydrometallurgical recycling processes because of its ability to recover Li, the use of PFAS in LIBs will lead to emissions of PFAS. Our work highlighted the need to 1) assess the emissions of PFAS from LIB recycling and 2) development of new materials based on a design-for-recycling concept. In the present works, we assessed the currently available PFAS alternatives that could be used in LIBs.[4] We also adopt the concept of essential use when assessing the uses of PFAS in batteries, as well as apply the functional substitution framework to look beyond drop-in substitution as an alternative.[5][6] Preliminary results indicate that powering the future without PFAS can be achieved. However, the timeframe of substitution in individual components remains highly uncertain. In addition, within a wholistic sustainability assessment, it needs to be demonstrated that PFAS replacement will not lead to burden shifting. The need for innovation enabled by eminent researchers in academia and industry alike is crucial, both in providing advancements with novel materials as well as designing batteries for various uses with differing requirements. REFERENCES [1] OECD (2021), OECD Series on Risk Management, No. 61, OECD Publishing, Paris. [2] I. T. Cousins, J. C. DeWitt, J. Glüge, G. Goldenman, D. Herzke, R. Lohmann, C. A. Ng, M. Scheringer and Z. Wang, Environ. Sci.: Processes Impacts, 2020, 22, 2307–2312. [3] A. Rensmo, E. K. Savvidou, I. T. Cousins, X. Hu, S. Schellenberger and J. P. Benskin, Environ Sci Process Impacts, 2023, 25, 1015–1030. [4] E. K. Savvidou, A. Rensmo, J. P. Benskin, S. Schellenberger, X. Hu, M. Weil and I. T. Cousins, Environ. Sci. Technol., 2024, 58, 21908–21917. [5] I. T. Cousins, G. Goldenman, D. Herzke, R. Lohmann, M. Miller, C. A. Ng, S. Patton, M. Scheringer, X. Trier, L. Vierke, Z. Wang and J. C. DeWitt, Environ. Sci.: Process Impacts, 2019, 21, 1803–1815. [6] J. A. Tickner, J. N. Schifano, A. Blake, C. Rudisill and M. J. Mulvihill, Environ. Sci. Technol., 2015, 49, 742–749.