Adhesion of Nafion for advanced proton exchange membrane fuel cell architectures under low fabrication temperature

Nafion has been used as one of the essential materials for proton exchange membrane fuel cells. The ability to laminate Nafion to itself and other materials, to form hermetic seals, leads to novel architectures, including a device designed by our group. In this work, understanding of cohesion/adhesion is essential because the sealing relies on interfacial properties of the materials. Since the ionic character of Nafion is known to be sensitive to processing temperature, it is essential to understand what regimes of processing conditions lead to a good device operation while providing robust sealing. To characterize cohesion/adhesion strength and understand the correlation with fabrication, the T-peel test was applied. Results show that the bonding strengths of Nafion-Nafion increase sharply with processing temperature. More dramatically, the presence of an interposed aluminum layer further increases the strength by up to a factor of 100 for processing temperatures below 140 degrees C. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to characterize the resulting surfaces and to evaluate the surface chemistry of the delaminated Nafion-Al joints. The bonding across the interface was enhanced by formation of Al-F and O-F-x bonds as a result of the introduction of Al. Adhesion strength increases as the preponderance of the two types changes with the bonding temperature.

Automated summary

Nafion has been used as a critical material for proton exchange membrane fuel cells, with the ability to form hermetic seals by laminating Nafion to itself and other materials. Understanding cohesion/adhesion is essential for sealing technology, as bonding strength increases dramatically with processing temperature and the presence of an aluminum layer. Characterization techniques like T-peel test, scanning electron microscopy, and X-ray photoelectron spectroscopy were used to evaluate the surface chemistry and bonding mechanisms.