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Sliding Angle Characterization of Physicochemical and Roughness Changes of GDL Surfaces after Fuel Cell Operation

The effect of proton exchange membrane fuel cell (PEMFC) operation on physicochemical properties and roughness of gas diffusion layers (GDL) was evaluated in this work. In addition to static contact angle measurements commonly used for GDLs, sliding angle measurements were also performed on a membrane electrode assembly (MEA) both new and used in service within commercial PEMFC. These latter revealed significant changes after 4,000 h in service that were not detectable with the static counterparts. The main novelty of this study is to correlate the contact and sliding angle measurements and to combine them with various modeling approaches developed for modeled surfaces. After 4,000 h of aging, it was thus shown that the surface of the GDLs became more hydrophilic, contrary to the roughness, which remains unchanged.