(355d) Enhancement of the Interfacial Bonding Strength of Nafion for a Novel PEM Fuel Cell Architecture

Fuel cells produce power with little pollution and are consequently an attractive approach for clean energy; the proton exchange membrane fuel cell (PEMFC) is one of the most widely implemented. Nafion, a perfluorinated polytetrafluoroethylene (PTFE) based proton exchange membrane, has been used as one of the essential and important materials for PEMFC. Further, the ability to hermetically seal the Nafion to itself and other materials can lead to higher voltage and performance. Therefore, we examined the cohesion and adhesion strength of Nafion and other key materials in a novel architecture of PEMFC designed by our group (the double-side air breathing thin flexible fuel cell or TFFC). The structure of the TFFC lacks outside packaging, and instead relies on the material’s thermoplastic properties for bonding and sealing.

Vital characteristics of the bulk Nafion membrane (thermal properties and mechanical properties) were determined by several tests: Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), small amplitude oscillation testing, and uniaxial tensile testing. Then, to determine the correlation between cohesion/adhesion strength and the fabrication methods, the T-peel test was applied. Afterwards, Scanning Electron Microscope (SEM) was used to characterize and evaluate the surface morphology of the overlap areas’ surface after peeling off the other layer.

The results show that under a given fabrication pressure, increasing fabrication temperature leads to a linear increase in bonding strength when the processing is done in a Nanoimprint Lithography system. However, the bonding strengths of the samples bonded by a conventional parallel-plate press increase sharply with temperature. SEM micrographs after peeling demonstrate that the samples bonded in the parallel-plate press at high temperature (160°C and 180°C) and elevated pressure form strong bonds at the interface of two Nafion layers.