Development of self-humidifying nano-composite membrane for polymer electrolyte membrane fuel cell

Çaçan, Umut Baki
Low humidity self-humidifying nano-composite membrane electrode assemblies (MEA) were developed for Polymer Electrolyte Membrane Fuel Cell (PEMFC) working at elevated temperatures. The nano-composite membranes were prepared by adding nano-sized silica particles (SiO2) or inorganic fillers with a size of approximately 20 nm to a polymeric material which is commercially named as Nafion (Perfluoro Sulfonic Acid/PFSA). The particle content of the nano-composite membranes were between 2.5 – 10 wt. %. In this manner, highly specific interaction surfaces were obtained between the polymer and added SiO2 particles, so that dehydration in the assemblies can be prevented at elevated temperatures due to the chemically available water in the polymeric membrane. The composite membranes were prepared using both an ultrasonic probe and an ultrasonic bath, and the prepared composite membranes were characterized using thermal gravimetric analysis (TGA), x-ray diffraction technique (XRD), scanning electron microscopy (SEM), proton conductivity, water uptake, and mechanical testing measurements. Pluronic L64® and PEG were used as the surface compatibility (dispersing) agents, and they were incorporated into the polymer matrix containing 3 wt. % SiO2 to prevent uneven distribution of the nanosized SiO2 particles. Additionally, the same inorganic filler (SiO2 – 0.3 wt. % of catalyst solution) was also applied into the anode side catalyst layer, which was combined with the SiO2 based composite membranes, and five layers MEAs were attained. Performances of the PEMFC composite membranes having 5 cm2 active electrode areas were determined using a single PEMFC test station using pure hydrogen gas and compressed dry air in order to determine the influence of working temperatures ranging from 65 to 80oC. The polarization curves of the membranes showed that the performance of the self-humidifying composite membranes containing SiO2 at the anode side catalyst layer was better.
Citation Formats
U. B. Çaçan, “Development of self-humidifying nano-composite membrane for polymer electrolyte membrane fuel cell,” M.S. - Master of Science, Middle East Technical University, 2015.