Hybrid membranes for fuel cells based on nanometer YSZ and polyacrylonitrile matrix

Abstract

A great deal of effort is required to design polymer electrolyte fuel cells (PEFCs) using new polymers and hybrid organic/inorganic compounds that can work at higher temperatures. These materials must have lasting thermal stability as well as improved ionic conductivity. Operation at elevated temperatures is desirable for PEFCs systems since they draw high power density in fast electrode kinetics and also for improvement of CO-tolerance, etc. In the higher range of temperatures (150–200 °C), new materials such as solid acids with phase transition to superprotonic conduction or strong solid acids supported on metal oxide systems seem to be an appropriate alternative to polybenzimidazoles (PBI) and other composite membranes. In this context, we evaluate a new hybrid matrix resistant at high temperatures, made of pyridine polymer obtained from polyacrylonitrile (PAN) and nanometric oxides (e.g., zirconium(IV) oxide-yttria stabilized, YSZ) by thermo-oxidative process in a centrifugal field. These hybrid matrixes aim further developments either to embed solid acids nanoparticles or to design strong solid acids on nanooxides, making them appropriate for proton exchange membranes. SEM, TEM, XRD and Raman spectroscopy were used to establish the structure and morphology and to characterize the composite membranes. The dependence of the electrical conductivity on temperature, water uptake, and methanol permeability are evaluated.