Polarization study of a PEMFC with four reference electrodes at hydrogen starvation conditions

Baumgartner, Wolfgang Richard; Parz, Peter; Fraser, Simon D.; Wallnöfer, Eva; Hacker, Viktor

doi:10.1016/j.jpowsour.2008.01.001

Cited by 153 publications

(82 citation statements)

References 17 publications

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“…By using a dual cell configuration, a cathode potential as high as 1.75 V was measured, which was different from the calculated value reported by Reiser et al [47]. Baumgartner et al [50] obtained a cathode electrode potential of up to 1.5 V with four reference electrodes under hydrogen starvation conditions, which also resulted in a H 2 /air boundary in the anode. Shen et al [56] measured the cathode, anode, and membrane potentials versus a hydrogen reference electrode using a special electrode design, as shown in Fig.…”

Section: Reverse Currentcontrasting

confidence: 61%

“…• Reference electrode method: Since it is not possible to distinguish between the anode and cathode half-cell reactions with a segmented fuel cell assembly, the reference electrode method has been developed and employed by several research groups [50][51][52][53][54][55]. Measurement of the cathode potential was achieved by introducing a constant potential into the test cell, utilizing a reference electrode, and then the anode and cathode potentials could be determined relative to this constant potential.…”

Section: Reverse Currentmentioning

confidence: 99%

“…Measurement of the cathode potential was achieved by introducing a constant potential into the test cell, utilizing a reference electrode, and then the anode and cathode potentials could be determined relative to this constant potential. In this method, a small strip of membrane in the MEA was soaked in sulfuric acid with a mercury sulfate reference electrode [50] or a hydrogen reference electrode [56]. Both the anode side and the cathode side of the MEA were considered the working electrode.…”

Section: Reverse Currentmentioning

confidence: 99%

“…Some researchers have investigated the current distribution of PEMFCs during local fuel starvation [50,[77][78][79][80][81][82][83], and Yousfi-Steiner et al [48] provided an excellent review of the causes and consequences of starvation issues. So in this review, we will turn from performance degradation due to local fuel starvation arising from a hydrogen/air interface, and focus in Section 4 on materials improvement and system strategies to mitigate catalyst decay during the startup and shutdown processes.…”

Section: Fuel Starvationmentioning

confidence: 99%

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A review on performance degradation of proton exchange membrane fuel cells during startup and shutdown processes: Causes, consequences, and mitigation strategies

Wang

et al. 2012

Journal of Power Sources

272

150

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a b s t r a c tPerformance degradation during startup and shutdown is considered an important issue affecting the durability and lifetime of proton exchange membrane fuel cells (PEMFCs). Due to the high potentials experienced by the cathode during startup and shutdown, the conventional carbon support for the cathode catalyst is prone to oxidation by reacting with oxygen or water. This paper presents an overview of the causes and consequences of performance degradation after frequent startup-shutdown cycles. Mitigation strategies are also summarized, including the use of novel catalyst supports and the application of system strategies to prevent performance degradation in PEMFCs. It is found from the literature review that improvements in catalyst supports to prevent oxidation come at the expense of high cost, and the novel supports developed to date are not sufficient to completely prevent carbon oxidation in fuel cell engines. System strategies, including potential control and reaction gas control, have been developed and applied in fuel cell engines to alleviate or even avoid performance decay. This review aims to provide a clear understanding of the mechanisms related to degradation behaviors during the startup and shutdown processes, thereby helping fuel cell material or system developers in their efforts to prevent performance degradation and prolong the lifetime of PEMFCs.Crown

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Section: Reverse Currentcontrasting

confidence: 61%

Section: Reverse Currentmentioning

confidence: 99%

Section: Reverse Currentmentioning

confidence: 99%

Section: Fuel Starvationmentioning

confidence: 99%

See 2 more Smart Citations

A review on performance degradation of proton exchange membrane fuel cells during startup and shutdown processes: Causes, consequences, and mitigation strategies

Wang

et al. 2012

Journal of Power Sources

272

150

View full text Add to dashboard Cite

show abstract

“…The underlying mechanism seem to be different for 'mild' (local) starvation and 'severe' (overall) starvation. 11 In case of overall fuel starvation, the cell voltage reaches negative values the cause being an increase of the anode potential to values larger than 1.0 V while the cathode potential remains at 'normal' working potential smaller than 1.0 V. 60 Under these conditions severe catalyst corrosion was observed at the anode and to a lesser extend at the cathode 60 and carbon dioxide 61 and oxygen 62 are observed in the anode off gas. The sources are carbon corrosion from reaction with water and possibly water electrolysis at very high anode potentials.…”

Section: F154mentioning

confidence: 99%

Accelerated Degradation of High-Temperature Polymer Electrolyte Fuel Cells: Discussion and Empirical Modeling

Reimer

Schumacher

Lehnert

2014

J. Electrochem. Soc.

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Accelerated stress tests are commonly applied in order to obtain a prediction of fuel cell life time within a short testing period. The stress test in this work considers a fuel cell which is constantly under load with frequent periods of very high current. Four different cells were operated each with a specific load profile. As a result severe performance degradation was observed in the region of high current densities. A short overview over the phenomena which may contribute to this specific fuel cell degradation is compiled from literature. Based on this overview major degradation modes are identified and combined with a simple polarization curve model. The modeling results allow for two different interpretations. Carbon corrosion reactions can explain the observed effects if cell voltage is assumed as the driving force for degradation. A better fit was obtained by using the overall heat flux as degradation criterion. In this case an increase in local temperature could lead to redistribution and loss of phosphoric acid from the MEA. The expected lifetime of a polymer electrolyte fuel cell (PEFC) ranges from 5 000 h for mobile application to 40 000 h for stationary application.1,2 In order to gain information about time dependent degradation in advance accelerated test protocols are used.3,4 Depending on the design of these tests valuable information about the nature of the main degradation mode under the applied operation conditions can be obtained. Despite the difference in operation conditions for PEFC, HT-PEFC and PAFC the structure and material of the electrodes are almost the same. Consequently, observed degradation phenomena show strong similarities.5 A good description of these phenomena can be found in several review papers 6-13 as well as in at least four books 1,2,14,15 where recent experimental facts and interpretations are summarized. A compact description can also be found in a recent review paper on modeling transport phenomena in PEFCs. 16 The purpose of this paper is to present the results of a specific accelerated degradation test for high temperature polymer electrolyte fuel cells (HT-PEFC) with phosphoric acid doped polybenzimidazole (PBI/H 3 PO 4 ) membranes. The fuel cell is constantly under load with frequent periods of very high current. In order to accelerate degradation effects the fuel cell is operated beyond it's point of maximum power. A simple polarization curve model is used as starting point for the analysis of data. Based on this first analysis a degradation model is proposed which allows for a straightforward physical interpretation. The complexity of degradation effects which occur simultaneousy usually leads to models which either resolve a specific mechanism in depth or describe more general effects. This paper aims at general effects which requires a broader understanding of degradation. In the following it is attempted to provide an overview over the phenomena which may contribute to fuel cell degradation. Based on this overview major degradation modes are identified and ...

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Degradation Caused by Dynamic Operation and Starvation Conditions

Ohs

Sauter

Maaß

2012

Fuel Cell Science and Engineering

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Polarization study of a PEMFC with four reference electrodes at hydrogen starvation conditions

Cited by 153 publications

References 17 publications

A review on performance degradation of proton exchange membrane fuel cells during startup and shutdown processes: Causes, consequences, and mitigation strategies

A review on performance degradation of proton exchange membrane fuel cells during startup and shutdown processes: Causes, consequences, and mitigation strategies

Accelerated Degradation of High-Temperature Polymer Electrolyte Fuel Cells: Discussion and Empirical Modeling

Degradation Caused by Dynamic Operation and Starvation Conditions

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