On the actual cathode mixed potential in direct methanol fuel cells

M. Zago, A. Bisello, A. Baricci, C. Rabissi, E. Brightman, G. Hinds, A. Casalegno

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Methanol crossover is one of the most critical issues hindering commercialization of direct methanol fuel cells since it leads to waste of fuel and significantly affects cathode potential, forming a so-called mixed potential. Unfortunately, due to the sluggish anode kinetics, it is not possible to obtain a reliable estimation of cathode potential by simply measuring the cell voltage. In this work we address this limitation, quantifying the mixed potential by means of innovative open circuit voltage (OCV) tests with a methanol-hydrogen mixture fed to the anode. Over a wide range of operating conditions, the resulting cathode overpotential is between 250 and 430 mV and is strongly influenced by methanol crossover. We show using combined experimental and modelling analysis of cathode impedance that the methanol oxidation at the cathode mainly follows an electrochemical pathway. Finally, reference electrode measurements at both cathode inlet and outlet provide a local measurement of cathode potential, confirming the reliability of the innovative OCV tests and permitting the evaluation of cathode potential up to typical operating current. At 0.25 A cm−2 the operating cathode potential is around 0.85 V and the Ohmic drop through the catalyst layer is almost 50 mV, which is comparable to that in the membrane.

LanguageEnglish
Pages714-722
Number of pages9
JournalJournal of Power Sources
Volume325
Early online date28 Jun 2016
DOIs
Publication statusPublished - 1 Sep 2016

Fingerprint

Direct methanol fuel cells (DMFC)
fuel cells
Cathodes
methyl alcohol
cathodes
Methanol
Open circuit voltage
open circuit voltage
crossovers
Anodes
anodes
commercialization
outlets
Hydrogen
impedance
membranes
Membranes
catalysts
Oxidation
oxidation

Keywords

  • cathode
  • DMFC
  • impedance
  • mixed potential
  • reference electrode

Cite this

Zago, M. ; Bisello, A. ; Baricci, A. ; Rabissi, C. ; Brightman, E. ; Hinds, G. ; Casalegno, A. / On the actual cathode mixed potential in direct methanol fuel cells. In: Journal of Power Sources. 2016 ; Vol. 325. pp. 714-722.
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On the actual cathode mixed potential in direct methanol fuel cells. / Zago, M.; Bisello, A.; Baricci, A.; Rabissi, C.; Brightman, E.; Hinds, G.; Casalegno, A.

In: Journal of Power Sources, Vol. 325, 01.09.2016, p. 714-722.

Research output: Contribution to journalArticle

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AU - Bisello, A.

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AU - Hinds, G.

AU - Casalegno, A.

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