In situ mapping of potential transients during start-up and shut-down of a polymer electrolyte membrane fuel cell

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Abstract

Progression of a fuel/air front through the anode flow-field during start-up or shut-down of a polymer electrolyte membrane fuel cell is known to generate elevated cathode potentials, leading to corrosion of the carbon catalyst support. Here we present spatially resolved measurements of such potential transients in an operating fuel cell, using an innovative reference electrode array combined with quantification of carbon corrosion by measurement of CO2 in the cathode outlet. A systematic study of the effect of relative humidity on start-up/shut-down potential transients and carbon corrosion rates was carried out at open circuit and with the application of a small external load. The results are discussed in the context of a schematic framework for the reverse current decay mechanism expressed in terms of local electrode potential. In all cases carbon corrosion was more severe during start-up than during shut-down, with the highest cathode potentials measured opposite the anode outlet during start-up and opposite the anode inlet during shut-down. The carbon corrosion rate was least severe under the driest conditions, which was attributed to the increased membrane resistivity. This new technique provides a powerful diagnostic tool for evaluation of start-up/shut-down tolerant catalyst layers and optimisation of fuel cell hardware design.

LanguageEnglish
Pages160-170
Number of pages11
JournalJournal of Power Sources
Volume267
DOIs
Publication statusPublished - 1 Dec 2014

Fingerprint

Proton exchange membrane fuel cells (PEMFC)
fuel cells
corrosion
Carbon
electrolytes
membranes
carbon
polymers
Anodes
Cathodes
anodes
cathodes
Corrosion
outlets
Corrosion rate
Fuel cells
catalysts
Electrodes
electrodes
circuit diagrams

Keywords

  • carbon corrosion
  • polymer electrolyte membrane fuel cell
  • reference electrode
  • start-up/shut-down
  • elevated cathode potentials

Cite this

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abstract = "Progression of a fuel/air front through the anode flow-field during start-up or shut-down of a polymer electrolyte membrane fuel cell is known to generate elevated cathode potentials, leading to corrosion of the carbon catalyst support. Here we present spatially resolved measurements of such potential transients in an operating fuel cell, using an innovative reference electrode array combined with quantification of carbon corrosion by measurement of CO2 in the cathode outlet. A systematic study of the effect of relative humidity on start-up/shut-down potential transients and carbon corrosion rates was carried out at open circuit and with the application of a small external load. The results are discussed in the context of a schematic framework for the reverse current decay mechanism expressed in terms of local electrode potential. In all cases carbon corrosion was more severe during start-up than during shut-down, with the highest cathode potentials measured opposite the anode outlet during start-up and opposite the anode inlet during shut-down. The carbon corrosion rate was least severe under the driest conditions, which was attributed to the increased membrane resistivity. This new technique provides a powerful diagnostic tool for evaluation of start-up/shut-down tolerant catalyst layers and optimisation of fuel cell hardware design.",
keywords = "carbon corrosion, polymer electrolyte membrane fuel cell, reference electrode, start-up/shut-down, elevated cathode potentials",
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AU - Hinds, G.

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N2 - Progression of a fuel/air front through the anode flow-field during start-up or shut-down of a polymer electrolyte membrane fuel cell is known to generate elevated cathode potentials, leading to corrosion of the carbon catalyst support. Here we present spatially resolved measurements of such potential transients in an operating fuel cell, using an innovative reference electrode array combined with quantification of carbon corrosion by measurement of CO2 in the cathode outlet. A systematic study of the effect of relative humidity on start-up/shut-down potential transients and carbon corrosion rates was carried out at open circuit and with the application of a small external load. The results are discussed in the context of a schematic framework for the reverse current decay mechanism expressed in terms of local electrode potential. In all cases carbon corrosion was more severe during start-up than during shut-down, with the highest cathode potentials measured opposite the anode outlet during start-up and opposite the anode inlet during shut-down. The carbon corrosion rate was least severe under the driest conditions, which was attributed to the increased membrane resistivity. This new technique provides a powerful diagnostic tool for evaluation of start-up/shut-down tolerant catalyst layers and optimisation of fuel cell hardware design.

AB - Progression of a fuel/air front through the anode flow-field during start-up or shut-down of a polymer electrolyte membrane fuel cell is known to generate elevated cathode potentials, leading to corrosion of the carbon catalyst support. Here we present spatially resolved measurements of such potential transients in an operating fuel cell, using an innovative reference electrode array combined with quantification of carbon corrosion by measurement of CO2 in the cathode outlet. A systematic study of the effect of relative humidity on start-up/shut-down potential transients and carbon corrosion rates was carried out at open circuit and with the application of a small external load. The results are discussed in the context of a schematic framework for the reverse current decay mechanism expressed in terms of local electrode potential. In all cases carbon corrosion was more severe during start-up than during shut-down, with the highest cathode potentials measured opposite the anode outlet during start-up and opposite the anode inlet during shut-down. The carbon corrosion rate was least severe under the driest conditions, which was attributed to the increased membrane resistivity. This new technique provides a powerful diagnostic tool for evaluation of start-up/shut-down tolerant catalyst layers and optimisation of fuel cell hardware design.

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