impact of phase separation of polymeric proton exchange membranes on gas permeability for the fuel cell application

While high gas permeability is a requirement in some membrane industries, it is not considered advantageous in polymer electrolyte fuel cell (pefc) application# thus, proton exchange membranes are basically meant to be defect-free and dense# in this work, hydrogen cross-over rate and permeability values of state-of-the-art nafion®117 and sulfonated poly(ether ether ketone) (speek) membranes are measured by the volumetric method# in addition, surface characterization tests including field-emission scanning electron microscopy (fesem) and atomic force microscopy (afm) are performed in order to gain insight into their different gas permeation behavior# results show that approximately three times higher h2 permeability value for nafion membrane can be attributed to its well-defined phase separation# in other words, nafion exhibits more homogenous hydrophilic micro-structure which has made it more susceptible to gas leakage in comparison with speek membrane with randomly distributed phases#