Development of proton-exchange polymer nanocomposite membranes for fuel cell applications
The design and development of proton conducting polymer electrolyte membranes from a linear constituent, sulfonated poly (ether ether ketone) (SPEEK), and inorganic additive, niobium oxide (NBO), have been achieved. The degree of sulfonation of SPEEK was measured by back titration method and found to be 57%. The physicochemical properties such as water uptake ability, ion-exchange capacity, swelling ratio, proton conductivity, and thermal stability of the prepared polymer nanocomposite membranes were studied in detail. The distribution of NBO throughout the polymer matrix has been examined by scanning electron microscopic and X-ray diffraction analyses and found to be uniform. The SP-NBO-10 composite membrane shows 38.4% of water uptake, whereas the pristine membrane limits to 27.1%. The prepared electrolyte membranes exhibit good proton conductivity at temperature varying from 30°C to 90°C and possess less activation energy for the transportation of proton by the incorporation of NBO filler. The thermal studies demonstrated that the stability of the composite membranes was significantly enhanced by the impregnation of NBO. The filler NBO shows excellent improvements on the polymer nanocomposite, making it a very promising additive for other polymers and offers new roads for energy applications.