R. Wycisk, J. Ballengee, J.W. Park, M. Brodt, P.N. Pintauro
Vanderbilt University, US
fuel cell, PEM, membrane, electrode, electrospinning, nanofiber
The focus of our research group has been on the use of electrospinning for the fabrication of nanofiber membranes and electrodes for PEM fuel cells. We have demonstrated dramatic improvement in fuel cell performance and durability with these unique nanostructures. Here we report on recent developments regarding low-Pt loading nanofiber electrodes and improved PEM nanofiber composite membranes. New results are presented on nanofiber electrode membrane-electrode-assemblies (MEAs) for hydrogen/air fuel cells. Both cathodes and anodes were fabricated by electrospinning a Pt/C catalyst powder suspension with a binder composed of Nafion® and poly(acrylic acid). Very high power density, 906 mW/cm2 at 80°C, was produced from MEAs with a Nafion 212 and a cathode electrospun from Johnson-Matthey (JM) HiSpec™ 4000 catalyst, at a Pt loading of only 0.055 mg/cm2 (2000 sccm humidified air, 2 atm backpressure). In a complimentary project, PEM films were fabricated utilizing a dual-fiber electrospinning concept. Composite membranes with polyphenylsulfone nanofibers reinforcing a perfluorosulfonic acid film of 3M 660 equivalent weight polymer were tested in a hydrogen/air fuel cell. The membranes composed of 72 vol% 3M660 exhibited very high conductivity, i.e. 93 mS/cm at 120oC and 50% RH with power output insensitive to feed gas humidity within 50-93% RH.