A new test system for the study of corrosion during the startup and shutdown of PEMFCs

Christos Kalyvas, Anthony R. Kucernak, Daniel J.L. Brett (Advisor), Gareth Hinds (Advisor)

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Abstract

Degradation of proton exchange membrane fuel cells (PEMFCs) is generally observed as slow, irreversible decay in the performance followed by sudden failure. The gradual performance loss is mainly linked to changes in the electrodes and membrane. The degradation of the electrodes is usually caused by catalyst degradation and carbon support corrosion. One of the distinct degradation modes is caused by the shutdown/startup cycling of the cell. During the startup or shutdown of fuel cells, when a change in gas on the anode side of the fuel cell often takes place, an air/fuel front can be formed. This causes the interfacial potential of the membrane to drop in the hydrogen starved region of the anode, resulting in high potentials (>1.4V) on the cathode side. Under such high potentials, carbon oxidation, water electrolysis or platinum dissolution can occur at the cathode (Eq.1-3), giving rise to a performance degradation [1-2].

C + 2H2O --> CO2 + 4H+ + 4e- (1)
2H2O --> O2 + 4H+ + 4e- (2)
Pt + xH2O --> PtOx + 2xH+ + 2xe- (3)

A new fuel cell test system has been developed for the study of the carbon corrosion phenomena in PEMFCs. By using printed circuit board (PCB) technology, a PCB-fuel cell assembly is constructed. This contains a segmented PCB with a single flow channel routed on each segment and holes in each channel for gas entry and exit. The anode electrode is segmented and bonded onto the PCB substrate with the membrane and the cathode hot pressed on it.

Various parameters of the experimental design are investigated in order to test the robustness of the method. Profiles of the lateral and total currents are presented demonstrating the capability of the technique to detect and measure them. The concentration of carbon dioxide produced by the carbon support oxidation (reaction 1) is measured in the cathode exhaust. The carbon loss is quantified and the severity of the cathode catalyst layer corrosion is discussed.

References:
[1] H. Tang, et al., Journal of Power Sources, 158, 1306-1312, 2006.
[2] S. Maass, et al., Journal of Power Sources, 176, 444-451, 2008.
Original languageEnglish
Pages1-28
Number of pages28
Publication statusPublished - 21 Sept 2011
Event2nd International Workshop on Degradation Issues on Fuel Cells - Capsis Hotel, Thessaloniki, Greece, Thessaloniki, Greece
Duration: 21 Sept 201123 Sept 2011
Conference number: 2

Workshop

Workshop2nd International Workshop on Degradation Issues on Fuel Cells
Country/TerritoryGreece
CityThessaloniki
Period21/09/1123/09/11
OtherThe workshop will be comprised of plenary and parallel sessions with oral presentations, which will include state of the art reviews on degradation issues on PEFC, SOFC and MCFC.

Keywords

  • PEM Fuel cells, Carbon corrosion, Start-up and shutdown of PEM fuel cells

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