Complex Impedance Studies of Electrosprayed and Extruded Nafion Membranes
Abstract
Fuel cells and other alternate forms of power and power generation have recently become a focal point of increased technological interest. One promising type of fuel cell is based on the Proton Exchange Membrane (PEM). Nafion 117 is one of the current benchmark membranes being used in these fuel cells. The aim of this study was to conduct fundamental scientific research into the proton transport properties of Nafion polymer membranes produced using various deposition techniques. The main focus was a comparison between electrosprayed and traditional extruded films. In addition, a study of the orientation effects in extruded Nafion membranes was conducted. Although the deposition technique of electrospraying has been used for nearly a century, it has only recently been applied to PEM fuel cell membranes. In this application, the method of deposition is designed to reduce the fabrication costs of fuel cells. Tests including measurements of conductivity, swelling effects, and activation volumes in relation to changing environmental pressures and relative humidities were performed on samples formed by the two deposition techniques. Conductivity is a measurement of the ease of passing charge carriers, while activation volume is a parameter that is helpful in determining proton transport mechanisms. Activation volumes in certain regimes are indicative of either polymer side chain deformation, Grotthuss transport, or vehicular transport of protons. These studies found a close correlation in the results comparing bulk conductivities for the two deposition techniques. The activation volumes found for the electrosprayed and extruded membranes followed the same response to changing water contents.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 05, 2004
- Accession Number
- ADA425009
Entities
People
- Joshua M Mueller
Organizations
- United States Naval Academy