Electrochemical Characterization of Stabilized Heteropolyacid / Ionomer Composite Membranes for High Temperature PEMFCs

摘要

From an applications point of view, several advantages result by operating a PEMFC at elevated temperatures (above 100°C) and low relative humidities. Therefore, a significant economic incentive exists to develop and commercialize PEMFCs that operate under these conditions. Nafion~direct R / heteropolyacid (HPA) composite membranes have been proposed for high temperature applications.However, heteropolyacids are soluble in water and leach out relatively easily from the host matrix. Stabilization of the HPA additive within the ionomeric matrix - which is essential for proper membrane processing and for good interfacial stability in membrane electrode assemblies (MEAs) - has been recently demonstrated in Nafion~direct R based systems. Studies aimed at investigating the water uptake and proton conductivities of the Nafion~direct R/ stabilized HPA composite membranes as a function of membrane processing conditions, operating temperatures and relative humidity were performed. Composite membranes prepared using hydrocarbon host matrixes other than Nafion~direct R were also evaluated to elucidate the role played by the inorganic additive in enhancing proton conductivity.