Preparation and characterization of sPEEK/ORMOSIL hybrid membrane for fuel cell

Abstract

Fuel cell is the conversion system from the chemical energy of fuel to electric energy. Owing to its high efficiency and low emission of pollutants they have been investigated as a promising alternative energy source. Direct Methanol Fuel Cell operates at low temperature and uses methanol, perfluorinated membranes as fuel and electrolyte, respectively. They have outstanding chemical and mechanical stability and show excellent performance. However perfluorinated membranes are highly conductive, they have a few weak point which include high price, methanol crossover and manufactures emitting pollutants. Those demerits of these membranes motivate a research for the alternative membranes. In this study, novel polymer electrolyte membrane for Direct Methanol Fuel Cell was synthesized and its characteristics were investigated. PEEK(poly(ether ether)ketone) was used as a primary polymer matrix. Sulfonated PEEK polymer is a kind of hydrocarbon and has the thermal stability due to aromatic ring in the backbone. In spite of low methanol permeability, it is low proton conducting polymer. In order to improve the proton conductivity sPEEK polymer was modified with organic silanes. We used the impregnant solution including TEOS and Isocyanate for stable silica network and phosphotungstic acid for high acidity. These ingredients diffused into sPEEK polymer were hydrolyzed and condensed under acid condition by sol-gel reaction. As the results high proton conductive membrane were synthesized. The characteristic of the hybrid membrane was analyzed by ThermoGravimetric Analysis(TGA), Scanning Electron Microscope(SEM), Energy Distribution Spectrometer(EDS) and Frequency Analyzer(FRA). Methanol permeability and water uptake were measured as well. In order to improve the properties of hybrid membrane as well as proton conductivity we investigated the effect of concentration of additives in the impregnant solution and confirmed the influence of each component on proton conductivity a...