Fluorinated polyoxadiazole for high-temperature polymer electrolyte membrane fuel cells

Dominique Gomes, Suzana Nunes*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

For the first time a fluorinated polyoxadiazole doped with phosphoric acid as a proton-conducting membrane for operation at temperatures above 100 °C and low humidities for fuel cells has been reported. Fluorinated polyoxadiazole with remarkable chemical stability was synthesized. No changes in the molecular weight (about 200,000 g mol-1) can be observed when the polymer is exposed for 19 days to mixtures of sulfuric acid and oleum. Protonated membranes with low doping level (0.34 mol of phosphoric acid per polyoxadiazole unit, 11.6 wt.% H3PO4) had proton conductivity at 120 °C and RH = 100% in the order of magnitude of 10-2 S cm-1. When experiments are conducted at lower external humidity, proton conductivity values drop an order of magnitude. However still a high value of proton conductivity (6 × 10-3 S cm-1) was obtained at 150 °C and with relative humidity of 1%. In an effort to increase polymer doping, nanocomposite with sulfonated silica containing oligomeric fluorinated-based oxadiazole segments has also been prepared. With the addition of functionalized silica not only doping level but also water uptake increased. For the nanocomposite membranes prepared with the functionalized silica higher proton conductivity in all range of temperature up to 120 °C and RH = 100% (in the order of magnitude of 10-3 S cm-1) was observed when compared to the plain membrane (in the order of magnitude of 10-5 S cm-1).

Original languageEnglish (US)
Pages (from-to)114-122
Number of pages9
JournalJournal of Membrane Science
Volume321
Issue number1
DOIs
StatePublished - Aug 1 2008

Keywords

  • Fuel cell
  • Nanocomposite
  • PEMFC
  • Polyoxadiazole
  • Proton conductivity
  • Sulfonated silica

ASJC Scopus subject areas

  • Filtration and Separation
  • Polymers and Plastics

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