Electrospun Nafion Nanofiber for Proton Exchange Membrane Fuel Cell Application

Abstract

Proton exchange membrane fuel cells (PEMFCs) are attractive power plants for use in many applications, including portable power sources, electric vehicles, and on-site combined power/heat plants, due to the inherently high efficiency and low emission. The membrane electrode assembly (MEA) is the key component of a PEMFC. A standard five layer MEA consists of a proton exchange membrane, two catalyst layers, and two gas diffusion layers. The most commonly used electrolyte material is proton conductive perfluorinated sulfonic acid membrane, such as Nafion. Hydrogen is oxidized at the anode/electrolyte interface, the so-called triple-phase-boundary (TPB) active sites. TPB region must be a good electron conductor, a good ion conductor, and a porous structure for fuel/air diffusion. Typical PEMFC TPB is a porous structure made with Nafion and catalyst particle mixture. In this paper, electrospinning is used to synthesize polymer/Nafion nanofibers. Electrospinning is a straightforward method that has been successfully used to prepare fibers or fiber mats from a broad range of organic polymers. In the electrospinning process, a polymer solution held by its surface tension at the end of a capillary tube is subjected to an electric field, and as the electric field strength increases, a solid fiber is generated as the electrified jet is continuously stretched because of the electrostatic repulsions between the surface charges and the evaporation of solvent. Uniform one-dimensional Nafion nanofibers have been fabricated using Nafion solution and solutions containing polyvinyl pyrrolidone, polyethylene oxide, and polyvinyl alcohol. The morphologies of polymer/Nafion nanofibers, fabricated under different electrospinning conditions and different polymer compositions, are presented.