Spatially resolved degradation effects in membrane-electrode-assemblies of vehicle aged polymer electrolyte membrane fuel cell stacks

Ettingshausen, Frank; Kleemann, Joerg; Michel, M. F.; Quintus, Martin; Fueß, H.; Roth, Christina

doi:10.1016/j.jpowsour.2009.06.003

Cited by 37 publications

(21 citation statements)

References 17 publications

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“…In previous studies [20] we were able to correlate the formation of platinum precipitations in the membrane with an increased cell resistance. The EOL polarisation curve of the start/stop MEA also exhibits an increased negative slope in the so called ohmic region of the curve, which is related to the electrical resistance of the cell.…”

Section: Migration and Deposition Of Platinum In The Membranementioning

confidence: 93%

“…Moreover, dissolved platinum ions can migrate into the electrolyte membrane. To our knowledge, the presence of platinum in the membrane has first been observed by Aragane et al [15], and the formation of precipitations was studied in more detail in follow up publications [16][17][18][19][20] by several authors. In addition to the loss of electrochemically active catalyst also the resistance of the MEA is likely to be affected by the formation of precipitates in the membrane [20].…”

Section: Introductionmentioning

confidence: 90%

“…Since accelerated degradation in specific regions of the MEA (e.g. fuel inlet [20]) could affect the results, the TEM samples were always taken from the middle region of the MEA. The TEM analyses were performed on a Jeol JEM-3010 transmission electron microscope operating at 300 kV acceleration voltage with a LaB 6 cathode.…”

Section: Original Research Papermentioning

confidence: 99%

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Dissolution and Migration of Platinum in PEMFCs Investigated for Start/Stop Cycling and High Potential Degradation

et al. 2011

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Dissolution and migration of platinum due to start/stop degradation and increased cathode potentials were studied for commercial membrane electrode assemblies (MEA). The chosen conditions closely mimic real situations in automotive operation. In start/stop tests, we observed a strongly enhanced platinum dissolution due to the dynamic interplay of repeated cell start‐up and consecutive normal fuel cell operation, which is related to platinum oxidation (start‐up) and reduction (normal operation) cycles. Consequently, the performed test protocols distinguish between dynamic and static load profiles. Electrochemical investigations before and after degradation monitor the loss in cell performance. Since electron microscopy offers the unique possibility to unravel and distinguish degradation due to carbon corrosion and agglomeration or platinum dissolution, a focus was set on this method. For the start/stop MEA pronounced platinum dissolution accompanied by the formation of large platinum precipitations in the membrane was found. Carbon corrosion was also observed, but did not lead to a significantly reduced porosity and loss in platinum dispersion. In contrast, the MEA which was exposed to high constant potentials exhibited severe damage to the 3D cathode structure due to carbon corrosion. However, no pronounced platinum dissolution was observed and only few Pt precipitations were found in the membrane itself.

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Section: Migration and Deposition Of Platinum In The Membranementioning

confidence: 93%

Section: Introductionmentioning

confidence: 90%

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Dissolution and Migration of Platinum in PEMFCs Investigated for Start/Stop Cycling and High Potential Degradation

et al. 2011

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“…49 However, Inaba et al remarked that the heat generated by the combustion can cause fatal damage of already degraded membranes. 50 A decrease in the ionic conductivity for aged MEAs that exhibit Pt precipitation was noted by Ettingshausen et al 51 They interpreted this effect as a blocking of ionic channels by Pt particles.…”

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confidence: 90%

Microscopic Investigation of Platinum Deposition in PEMFC Cross-Sections Using AFM and SEM

Helmly

Hiesgen

Morawietz

et al. 2013

J. Electrochem. Soc.

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Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to investigate platinum (Pt) deposition in the membrane of degraded proton exchange membrane fuel cells (PEMFCs). This study focuses on Pt distribution and microscopic aspects of accelerated membrane degradation. To facilitate post-mortem analysis, a 4-cell stack was specially designed with cells composed of two membranes. Considerable Pt deposition was observed in both membranes and at their interface. Significant crystallite growth in the form of a Pt band and membrane thinning was present in the membrane at the cathode side, which supports the hypothesis that Pt deposition accelerates polymer decomposition. Furthermore, a large continuous area of Pt crystals across the whole cathode membrane was detected. In addition, conductive AFM measurements revealed electronic connections across the membrane. These results indicate the formation of electronic short-circuits in the cell due to the accumulation of Pt particles, which has not been previously reported. Moreover, AFM proved to be more sensitive to detect Pt deposits and its effects than SEM.

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“…While the starvation can easily be suppressed by increasing the fuel and air flow rates, it is not an economically efficient approach to improve the fuel cell performance. One of the major problems with starvation is the possibility of reaching to corrosive potentials in the anode which can considerably decrease the durability of the electrode [1]. The anode starvation can also result in carbon corrosion in the cathode [2].…”

Section: Introductionmentioning

confidence: 99%

Study of anode and cathode starvation effects on the impedance characteristics of proton exchange membrane fuel cells

Niya

Phillips

Hoorfar

2016

Journal of Electroanalytical Chemistry

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Spatially resolved degradation effects in membrane-electrode-assemblies of vehicle aged polymer electrolyte membrane fuel cell stacks

Cited by 37 publications

References 17 publications

Dissolution and Migration of Platinum in PEMFCs Investigated for Start/Stop Cycling and High Potential Degradation

Dissolution and Migration of Platinum in PEMFCs Investigated for Start/Stop Cycling and High Potential Degradation

Microscopic Investigation of Platinum Deposition in PEMFC Cross-Sections Using AFM and SEM

Study of anode and cathode starvation effects on the impedance characteristics of proton exchange membrane fuel cells

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