Microarchitecture of polyvinylidene fluoride-bound self-standing microporous layer and its implication to water management in fuel cells

This study presents novel self-standing microporous layers (SSMPLs) for proton exchange membrane fuel cells (PEMFCs). SSMPLs with polyvinylidene fluoride (PVDF) as a binder were readily fabricated using the facile tape-casing and peeling-off method proposed in this study. The surface morphology, pore size distribution, and wettability of the SSMPLs with different carbon loadings and PVDF contents were investigated and compared with those of a commercially available polytetrafluoroethylene (PTFE)-bound gas diffusion layer. Experimental and theoretical studies using electrochemical impedance spectroscopy and the limiting current method were performed to elucidate the mechanism by which PVDF-bound SSMPL leads to higher PEMFC performance. The individual microstructures of PVDF-bound SSMPL and PTFE-bound MPL were visualized by using atomic force microscopy to distinguish the binder and carbon agglomerates and the water transport mechanism through each MPL was suggested.