High temperature proton exchange membrane fuel cell using a sulfonated membrane obtained via H2SO4 treatment of PEEK-WC

Amethod for the sulfonation ofPEEK-WC, a glassy poly(ether ether ketone) with sulphuric acid is presented.Depending on the reaction time, polymers with ion exchange capacity (IEC) from 0.30 to 0:76 meqHþ=g are obtained, as determined by titration with NaOH solutions. The thermal properties of the polymerswere studied by differential scanning calorimetry, showing that the glass transition temperature increases with increasing degree of sulfonation, from 224 8C for pure PEEK-WC to 246 8C for the polymer having an IEC of 0:76 meqHþ=g. The sulfonated polymers were used to prepare proton exchange membranes for possible application in fuel cells. Dense membranes were prepared by solvent evaporation, usingDMAas the solvent. The transport properties of themembranes were determined in terms ofwater uptake and permeability for hydrogen and oxygen. Electrochemical characterization was performed by measuring cell voltage and power density curves as a function of current density at different working temperatures and the results were compared with those of a commercial Nafion membrane. A power density of 284 mW/cm2 was obtained for S-PEEK-WCmembrane at 120 8C inH2/air fuel cell, slightly above the corresponding value found for Nafion