Reducing the PFAS‐Content in Fuel Cells: Novel Fluorine‐Free Gas Diffusion Layers for Hydrocarbon‐based Catalyst Coated Membranes

Abstract State‐of‐the‐art fuel cell components currently use per‐ and polyfluoroalkyl substances, such as polytetrafluoroethylene in gas diffusion layers (GDLs) and perfluorosulfonic acid (PFSA) ionomers in catalyst layers and membranes. In this study, a fluorine‐free gas diffusion layer including a microporous layer (MPL) is introduced, based on a silane‐hydrophobized GDL and a MPL consisting of various blends of vapor‐grown carbon fibers/carbon black and a fluorine‐free polymer binder. Immersion in highly oxidative hydrogen peroxide confirms sufficient chemical stability of the fluorine‐free binder material and the silane treatment. By using a state‐of‐the‐art hydrocarbon‐based catalyst‐coated membrane (CCM), the electrochemical performance is compared with a state‐of‐the‐art commercial GDL reference. A promising fuel cell performance of 2 A cm −2 at 0.67 V, 95 °C, and 80% relative humidity (RH) is achieved by pairing this novel cathode GDL/MPL with a thin, fluorine‐free, and self‐standing anode MPL. Further, the fluorine‐free GDLs enabled a more stable operation of the hydrocarbon‐based CCM, confirmed by a 10‐day constant current hold test at 2 A cm − 2 . The results emphasize the relevance of cell sub‐components like GDL/MPL to unlock the highest possible performance and stability with fully hydrocarbon‐based CCMs.