Conductivity Of Ionomers Research Articles

Highly Conductive Aromatic Ionomers with Perfluorosulfonic Acid Side Chains for Elevated Temperature Fuel Cells

A versatile and facile synthetic approach to a new class of ionomers with rigid aromatic backbone and pendant perfluorinated sulfonic acid groups is described. Characterization of the prepared polymers has been carefully carried out by 1H and 19F NMR, elemental analysis, intrinsic viscosity, TGA and DSC. It is shown that the perfluorosulfonic acids greatly enhance the proton conductivity of ionomers under high temperature and low humidity conditions. The aromatic ionomers exhibit comparable proton conductivity to Nafion over a wide humidity range at elevated temperatures, while maintaining other outstanding properties of aromatic polymers, e.g. low gas permeability, excellent thermal and chemical stability and good mechanical properties. It is also demonstrated that the maximum power density and current density of the aromatic ionomers are 30% and 43% higher, respectively, than those of Nafion in initial fuel cell tests at 120 °C.

固体高分子形燃料電池(PEFC)の氷点下起動繰り返しによる性能劣化の特性(熱工学,内燃機関,動力など)

This study investigates the characteristics of performance degradation caused by repeated cold starts of an MEA below freezing point in PEFC. It was made clear by this study that significant decay of performance was caused by repeated sequence of 50 cycles of freeze, cold start, operation and thaw under constant environmental temperature of -30deg. C. By applying Tafel analysis, it was made clear that performance degradation is expressed mainly by the increase in activation overpotential and concentration overpotential and the increases are in proportion to repeated cycle number. It was also found that performance decay appeared mainly in the cathode as measured by cyclic voltammetery (CV) and AC impedance spectroscopy (ACIS). New Diagnostic measurement that is application of Transmission Line Model as equivalent circuit revealed that increase of impedance in proton conductivity of ionomer in cathode catalyst layer was dominant.

Test system rapidly analyses ionomers and membranes

US-based Scribner Associates Inc has launched the Model 740 membrane test system (MTS) which, it claims, is the first commercial instrument designed specifically for easy, rapid and accurate measurement of the through-thickness resistance and conductivity of ionomer and polymer electrolyte membranes.

Synthesis and characterization of polydioxolane polyurethane ionomer

A series of novel sodium salts of sulfonated polyurethane ionomers with polydioxolane as soft segment was successfully synthesized and their properties were characterized by means of Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and complex impedance analysis. As the ionization level increased, the compatibility of the hard segments and soft segments was improved and the glass transition region of soft segment became broader. The effects of ionization level, temperature, chemical components of soft segment on ionic conductivity of ionomers were investigated in detail. Adjusting the ionization level and incorporating PEG soft segment into the PDXL-PU ionomers, a new type of solid polymer electrolyte material with good mechanical properties and high ionic conductivity could be obtained.