Perfluoro-ethylene-1,2-bis-phosphonic acid fuel cell electrolyte

K. Kanamura, A. Tanaka, D. Gervasio, V. Kennedy, R. Adzic, E. B. Yeager, D. Burton, R. Guneratne

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11 Scopus citations

Abstract

Concentrated aqueous perfluoroethylene-1,2-bis-phosphonic acid, (OH)2OPCF2CF2PO(OH)2, has been investigated as an alternative to phosphoric acid as the electrolyte in the H2/O2 acid fuel cell. Phosphoric and bis-phosphonic acid solutions were equilibrated with pure O2 (P = 1 atm) and were used in (i) chronoamperometry experiments performed with a Pt microelectrode to estimate the O2 diffusion coefficient, D, and solubility, C, and (ii) O2 electroreduction polarization studies done with a gas-fed Teflon-bonded carbon electrode with a high surface area Pt catalyst in a microfuel cell. At 22°C in 85% bis-phosphonic acid, C was found to be 3.4 ± 0.3 × 10-4 mol/liter and D was 5.0 ± 0.5 × 10-7 cm2/s as compared with C = 2.8 ± 0.3 × 10-4 mol/liter and D = 1.2 ± 0.1 × 10-6 cm2/s in 85% phosphoric acid at T = 22°C. The over-potential for O2 reduction on the microfuel cell cathode was smaller in 85% bis-phosphonic acid than in 85% phosphoric acid for current densities up to 200 mA/cm2 at 100°C. This indicates that the oxygen electroreduction kinetics on Pt increased when phosphoric acid was replaced with the perfluorinated bis-phosphonic acid. At higher current densities (≥ 200 mA/cm2) where mass transport may influence cathode performance, the performance with bis-phosphonic acid was not as good as with phosphoric acid at 100°C, which is consistent with the higher viscosity and lower D found for bis-phosphonic acid relative to phosphoric acid at 22°C. As the temperature was raised from 100 to 200°C, the cathode performance improved with the bis-phosphonic acid electrolyte. The enhanced O2 reduction kinetics with the bis-phosphonic acid persisted in the fuel cell environment at temperatures up to 200°C for 500 h which demonstrated a major improvement in stability for a high performance perfluorinated fuel cell electrolyte used at higher temperatures such as 200°C.

Original languageEnglish (US)
Pages (from-to)2765-2770
Number of pages6
JournalJournal of the Electrochemical Society
Volume143
Issue number9
DOIs
StatePublished - Sep 1996

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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    Kanamura, K., Tanaka, A., Gervasio, D., Kennedy, V., Adzic, R., Yeager, E. B., Burton, D., & Guneratne, R. (1996). Perfluoro-ethylene-1,2-bis-phosphonic acid fuel cell electrolyte. Journal of the Electrochemical Society, 143(9), 2765-2770. https://doi.org/10.1149/1.1837104