Degradation heterogeneities induced by repetitive start/stop events in proton exchange membrane fuel cell: Inlet vs. outlet and channel vs. land

Durst, Julien; Lamibrac, Adrien; Charlot, F.; Dillet, Jérôme; Castanheira, Luis; Maranzana, Gaël; Dubau, Laëtitia; Maillard, Frédéric; Chatenet, Marian; Lottin, Olivier

doi:10.1016/j.apcatb.2013.03.021

Cited by 140 publications

(132 citation statements)

References 47 publications

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“…11 Durst et al also used a segmented cell to correlate the local performance loss of the catalyst layer (CL) with its degradation. 12 However, these measurements have included the * Electrochemical Society Member. z E-mail: uchidam@yamanashi.ac.jp effects of both the SU and the SD on both the cell performance and the catalyst degradation, so that the individual effects of each are still unclear.…”

mentioning

confidence: 99%

Durability of Pt Catalysts Supported on Graphitized Carbon-Black during Gas-Exchange Start-Up Operation Similar to That Used for Fuel Cell Vehicles

Yamashita

Itami²,

Takano³

et al. 2016

J. Electrochem. Soc.

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We investigated the durability of cathode catalysts during a start-up (SU) process similar to that used in actual polymer electrolyte fuel cell vehicle operation. The durability of Pt supported on graphitized carbon black (Pt/GCB) catalysts was evaluated in the practical SU process, i.e., the anode gas was successively cycled between air, hydrogen, and nitrogen. The effect of the SU process on the cell performance was evaluated using two types of catalysts (commercial Pt/GCB, and that prepared in house by the "nanocapsulemethod," n-Pt/GCB). The polarization curves and cyclic voltammetry were evaluated before and after the SU evaluation. The degradation of Pt nanoparticles and carbon supports was analyzed by transmission electron microscopy, scanning transmission electron microscopy, and micro-Raman spectroscopy. We also applied glancing incidence X-ray diffraction in order to observe the depth profiles of the Pt crystallite sizes in various interfacial regions. From these analyses, we found that the degradation of the Pt catalyst occurred not only in the gas outlet region but also the gas inlet region of the cathode. The degradation in the inlet region is ascribed to both the interim electrochemical evaluations and the potential fluctuations, which cause a dissolution of Pt nanoparticles used during the SU process. Polymer electrolyte fuel cells (PEFCs) are able to convert chemical energy directly to electrical energy with high efficiency and have shown promise to be an eco-friendly power source for residential cogeneration systems and fuel cell vehicles (FCV).1-3 Nevertheless, the widespread commercialization of PEFCs has been impeded because of the large amount of the platinum catalyst required, which must be minimized to reduce the system cost. 4 The minimization can be achieved, for example, by the improvement of utilization of Pt nanoparticles dispersed on carbon black supports (Pt/CB) with high surface area used as the cathode catalyst for PEFCs as well as the improvement of the durability. During the start-up and shutdown (SU/SD) cycles of the PEFCs, air and H 2 coexist transiently in the anode until the replacement of the former with the latter (or vice versa) is completed. Reiser et al. showed that this situation causes the cathode potential to climb to more than 1.5 V due to the so-called "reverse current mechanism", 5 which significantly accelerates the degradation of the catalyst due to the oxidation of the CB and the agglomeration or dissolution of the Pt nanoparticles. 6 In our previous research, we have developed a graphitized carbon black (GCB) supported Pt catalyst prepared by the "nanocapsule method" (n-Pt/GCB) to improve the performance of Pt catalysts. 7-9The high dispersion of the Pt nanoparticle catalyst particles on the GCB support prepared by this method provides enhanced oxygen reduction reaction (ORR) activity. It was also found that the durability of the n-Pt/GCB catalyst was improved during a potential cycling evaluation that simulated the variation of the cathode potential during the...

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mentioning

confidence: 99%

Durability of Pt Catalysts Supported on Graphitized Carbon-Black during Gas-Exchange Start-Up Operation Similar to That Used for Fuel Cell Vehicles

Yamashita

Itami²,

Takano³

et al. 2016

J. Electrochem. Soc.

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“…2), as it has been established for PEFC cathodes. [29][30][31][32] In an attempt to further differentiate these kinetic and mass transport contributions to the overall performance loss (cf. η HOR and η tx,anode in Equation 2), the recording of polarization curves at the beginning and end of the AST was followed by H 2 -pump experiments (see Experimental section for details), whereby the combination of the high Pt loading of the commercial cathode GDE (0.4 mg Pt /cm geom .…”

Section: Resultsmentioning

confidence: 99%

Unsupported Pt₃Ni Aerogels as Corrosion Resistant PEFC Anode Catalysts under Gross Fuel Starvation Conditions

Henning

Shimizu

Herranz

et al. 2018

J. Electrochem. Soc.

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Mitigating catalyst corrosion is crucial for the commercial success of polymer electrolyte fuel cells (PEFCs). Novel catalysts that can withstand the harsh conditions in case of gross fuel (i.e. H 2 ) starvation events at the PEFC anode are needed to increase the fuel cell stack's service life and to meet the durability targets set for automotive applications. To make progress in this respect, we have tested an unsupported, bimetallic Pt 3 Ni alloy (aerogel) catalyst at the PEFC anode and subjected it to a stress test that mimics the high potentials (≥ 1.5 V vs. the reversible hydrogen electrode) encountered upon fuel starvation. In contrast to commercial carbon-supported platinum catalysts (Pt/C), the Pt 3 Ni aerogel displays excellent durability and performance retention in end-oflife fuel cell polarization curves. Additionally, the aerogel catalyst shows ≈35% higher surface-specific activity for the hydrogen oxidation/evolution reaction than Pt/C. These results highlight the great potential of using novel unsupported catalysts at the anode of PEFCs. Polymer electrolyte fuel cells (PEFCs) customarily rely on platinum nanoparticles supported on carbon (Pt/C) to catalyze the anodic hydrogen oxidation and the cathodic oxygen reduction reactions (HOR and ORR, respectively, leading to anode and cathode sometimes being referred to as hydrogen-and oxygen-electrodes).1,2 Among the latter, the ORR is catalytically more demanding, and thus higher Pt loadings are implemented in PEFC cathodes vs. anodes (up to ≈0.4 vs. ≈0.05 mg Pt /cm 2 geom ).3 Irrespectively of this activity difference, both anodic and cathodic Pt/C catalysts suffer from significant corrosion of the carbon support during the high potential excursions (> 1 V vs. the reversible hydrogen electrode, V RHE ) concomitant to PEFC operation, which limits the device's service life.4 Potentials ≥ 1.5 V RHE on the cathode side can for instance be caused by PEFC start-up/shut-down and local fuel starvation. 5,6 To minimize the damage of these start-up/shut-down events, technical solutions like a highflow air purge of the anode compartment that minimizes the residence time of the H 2 /air anode front have been developed. 7 On the other hand, complete absence of fuel in the anode compartment under load leads to the so called gross hydrogen starvation. This is typically triggered by the blockage of hydrogen gas inlets in an individual anode flow field by liquid water which, in order to sustain the cell current, leads to an anode potential increase up to a value at which water oxidation and carbon support corrosion can occur.8 Most importantly, unlike in the start-up/shut-down degradation discussed above, these hydrogen starvation issues are difficult to overcome by engineering solutions. Alternatively, material-based mitigation strategies include composite anode electrodes exhibiting high HOR and oxygen evolution reaction (OER) activity, as well as corrosion-resistant, non-carbon supported or even completely support-free catalysts. 9Inspired by the latter approach, an...

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“…Frequent dynamic processes can affect the durability of fuel cell system, which has limited its large-scale commercialization [216][217][218]. Therefore, it is important and urgent to investigate the PEMFC dynamic processes and promote effective mitigation strategies [219][220][221].…”

Section: Development Of High-durability Processing Technologiesmentioning

confidence: 99%

“…And it is believed that the major cause of performance degradation during those processes is the local gas mixture at the anode called hydrogen/air interface or fuel/air interface [221]. Before startup, both the anode and cathode are exposed to air.…”

Section: Startup/shutdown Processesmentioning

confidence: 99%

“…Frequent load changing leads to voltage fluctuations ranging from 0.4 V to 1.0 V (vs. RHE) [227]. During the load variation processes, the anode voltage is usually considered as 0 V due to the fast hydrogen oxidation reaction (HOR) rate and barely changes, while the cathode frequently fluctuates [221]. When a feedback system is used to control the load variation of PEMFCs, air starvation temporarily occurs due to the air supply rate lagging the loading rate [228].…”

Section: Load Variation Processesmentioning

confidence: 99%

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Recent Progress on the Key Materials and Components for Proton Exchange Membrane Fuel Cells in Vehicle Applications

Wang

Peng

et al. 2016

Energies

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Fuel cells are the most clean and efficient power source for vehicles. In particular, proton exchange membrane fuel cells (PEMFCs) are the most promising candidate for automobile applications due to their rapid start-up and low-temperature operation. Through extensive global research efforts in the latest decade, the performance of PEMFCs, including energy efficiency, volumetric and mass power density, and low temperature startup ability, have achieved significant breakthroughs. In 2014, fuel cell powered vehicles were introduced into the market by several prominent vehicle companies. However, the low durability and high cost of PEMFC systems are still the main obstacles for large-scale industrialization of this technology. The key materials and components used in PEMFCs greatly affect their durability and cost. In this review, the technical progress of key materials and components for PEMFCs has been summarized and critically discussed, including topics such as the membrane, catalyst layer, gas diffusion layer, and bipolar plate. The development of high-durability processing technologies is also introduced. Finally, this review is concluded with personal perspectives on the future research directions of this area.

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Degradation heterogeneities induced by repetitive start/stop events in proton exchange membrane fuel cell: Inlet vs. outlet and channel vs. land

Cited by 140 publications

References 47 publications

Durability of Pt Catalysts Supported on Graphitized Carbon-Black during Gas-Exchange Start-Up Operation Similar to That Used for Fuel Cell Vehicles

Durability of Pt Catalysts Supported on Graphitized Carbon-Black during Gas-Exchange Start-Up Operation Similar to That Used for Fuel Cell Vehicles

Unsupported Pt₃Ni Aerogels as Corrosion Resistant PEFC Anode Catalysts under Gross Fuel Starvation Conditions

Recent Progress on the Key Materials and Components for Proton Exchange Membrane Fuel Cells in Vehicle Applications

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Degradation heterogeneities induced by repetitive start/stop events in proton exchange membrane fuel cell: Inlet vs. outlet and channel vs. land

Cited by 140 publications

References 47 publications

Durability of Pt Catalysts Supported on Graphitized Carbon-Black during Gas-Exchange Start-Up Operation Similar to That Used for Fuel Cell Vehicles

Durability of Pt Catalysts Supported on Graphitized Carbon-Black during Gas-Exchange Start-Up Operation Similar to That Used for Fuel Cell Vehicles

Unsupported Pt3Ni Aerogels as Corrosion Resistant PEFC Anode Catalysts under Gross Fuel Starvation Conditions

Recent Progress on the Key Materials and Components for Proton Exchange Membrane Fuel Cells in Vehicle Applications

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Product

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Unsupported Pt₃Ni Aerogels as Corrosion Resistant PEFC Anode Catalysts under Gross Fuel Starvation Conditions