Gas diffusion electrodes containing sulfonated poly (arylene ether) ionomer for PEFCs. Part 1. Effect of humidity on the cathode performance

Takeshi Yoda, Takuya Shimura, Byungchan Bae, Kenji Miyatake, Makoto Uchida, Hiroyuki Uchida, Masahiro Watanabe

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

Gas diffusion electrodes (GDEs) containing Pt/C catalyst and sulfonated poly (arylene ether) (SPAE) ionomer as a proton conducting binder (SPAE-GDE) were prepared. The cathode performances were evaluated in a PEFC at 80 °C and relative humidities (RH) from 60 to 100%. The value of the electrochemical active surface area (ECA) of 65 m2 g-1 for the SPAE-GDE, which was measured by cyclic voltammetry at 100%-RH and 40 °C, was nearly the same as that for a Nafion-GDE. In contrast, the RH-dependencies of the performance indices (such as mass activity at 0.9 V, Tafel slope, or current density at 0.7 V) at the SPAE-GDE were very large and distinct from those for the conventional Nafion-GDE. With decreasing RH, the mass activity at the Nafion-GDE decreased monotonically, whereas that at the SPAE-GDE reached a maximum at 88%-RH and decreased steeply below 78%-RH, predominantly due to a strong adsorption of functional groups, probably sulfonate groups, in the SPAE on the Pt catalyst surface. However, at 88-100%-RH, the concentration polarization became significant for current densities j > 0.1 A cm-2 due to excessive swelling of the SPAE ionomer. Strategies to improve the performance of SPAE-GDEs have been elucidated.

Original languageEnglish
Pages (from-to)4328-4333
Number of pages6
JournalElectrochimica Acta
Volume54
Issue number18
DOIs
Publication statusPublished - 2009 Jul 15
Externally publishedYes

Keywords

  • Catalyst layer
  • Gas diffusion electrode
  • Ionomer
  • PEFC
  • Sulfonated polyether

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Electrochemistry

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