Degradation of polymer electrolyte membrane fuel cells repetitively exposed to reverse current condition under different temperature

Jo, Yoo Yeon; Cho, EunAe; Kim, Jung Hyeun; Lim, Tae‐Hoon; Oh, In‐Hwan; Kim, Soo-Kil; Kim, Hyung‐Juhn; Jang, Jong Hyun

doi:10.1016/j.jpowsour.2011.08.035

Cited by 45 publications

(29 citation statements)

References 15 publications

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“…[16] Whereby the t mem refers to the membrane thickness (15 or 18 μm) and the apparent activation energy for proton conduction (E act H + ) was taken as 6 kJ/mol. 22 The electrical bulk and contact resistances (η [18] Under the simplifying assumption that the OER in the electrolytic part of the cell can be neglected, an analytical expression for the polarization curve of the electrolytic cell could be obtained. However, in the case of using a cathode catalyst with a graphitized carbon support, the effective potential in the cathode of the electrolytic part of the cell increases to values at which the OER currents become substantial, so that this simplifying assumption is not anymore satisfied.…”

Section: Kinetic H 2 /Air Anode Susd Modelmentioning

confidence: 99%

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PEM Fuel Cell Start-up/Shut-down Losses vs Temperature for Non-Graphitized and Graphitized Cathode Carbon Supports

Mittermeier

Weiß

Hasché

et al. 2016

J. Electrochem. Soc.

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One of the key figures for the success of proton exchange membrane fuel cells (PEMFCs) in automotive applications is lifetime. Damage of the cathode carbon support, induced by hydrogen/air fronts moving through the anode during start-up/shut-down (SUSD), is one of the lifetime limiting factors. In this study, we examine the impact of varying the temperature at which SUSD events take place, both experimentally and by a kinetic model. For MEAs with conventional carbon supports, the model prediction of carbon oxidation reaction (COR) currents as a function of temperature matches well with the temperature dependence of experimentally determined SUSD degradation rates (predicting ≈8-fold lower COR currents compared to ≈10-fold lower measured degradation rates at 5 • C compared to 80 • C). This, however, is not the case for MEAs with graphitized carbon supports, where a factor of ≈39 lower COR currents are predicted when decreasing SUSD temperature from 80 to 5 • C, in contrast to the measured decrease by a factor of ≈10. As we will show, this is explained by a change of the governing degradation mechanism from predominantly carbon corrosion induced losses at higher temperature to predominantly voltage cycling induced platinum surface area losses near/below room temperature. several practical aspects of automotive PEMFC operation remain challenging to date.5 One such phenomenon is the degradation caused by start-up and/or shut-down (SUSD) of the PEMFC, where a H 2 /air anode gas front moves through the anode flow-field, which was first discussed in the scientific literature by Reiser et al. 6 in 2005 (note that it was described in the patent literature as early as 2002 7 ). Typically, during an uncontrolled shut-down, air will leak slowly into the H 2 compartment through leaks in the back-pressure valve, through the stack sealing or by crossover through the membrane, which was found to lead to substantial damage of the cathode catalyst carbon support in the MEA (membrane electrode assembly). 6 One of the early methods to mitigate this damage was the use of a controlled shut-down, in which a high-flow air purge of the anode compartment was applied in order to minimize the H 2 /air anode front residence time, which is proportional to the induced damage. 8The reactions occurring during the passing of the H 2 /air anode front through the anode flow-field are listed in Figure 1a (slightly modified from what was shown in Ref. 9 and 10), illustrating the partially H 2 -filled (lower left segment, colored in red) and partially air-filled (upper left segment, colored in blue) anode, opposite of the air-filled cathode flow-field (right blue segments) and separated by the proton conducting membrane (orange). While electrons can be well conducted in-plane, mainly via the diffusion media (DM) and flow fields (FF), the in-plane proton conduction resistance through the membrane is very high, so that significant proton conduction in-plane can be supported only over very short distances across the H 2 /air anode front, namely over a ...

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Section: Kinetic H 2 /Air Anode Susd Modelmentioning

confidence: 99%

“…16 Only in the studies by Kreitmeier et al 17 and by Jo et al 18 the temperature was varied while Figure 1. Schematic of a start-up and/or shut-down (SUSD) event in a PEMFC, sketching the passage of a H 2 /air anode front through the anode flow-field (H 2 -filled regions in red, air-filled regions in blue) while the cathode flow-field is filled with air.…”

mentioning

confidence: 99%

PEM Fuel Cell Start-up/Shut-down Losses vs Temperature for Non-Graphitized and Graphitized Cathode Carbon Supports

Mittermeier

Weiß

Hasché

et al. 2016

J. Electrochem. Soc.

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“…As shown in several operating parameters [33][34][35][36][37][38][39] that can have an impact on the degradation rate of PEMFCs under startup and shutdown cycles, including cathode humidity [37,38], cell temperature [33], application of a dummy load [35,36], and gas supply sequences [34]. The hydrogen/air interface during the startup and shutdown processes was mimicked by purging the anode and cathode channels with air after continuous air and hydrogen were supplied.…”

Section: Accelerated Lifetime Tests Under Startup-shutdown Cyclesmentioning

confidence: 99%

“…After the start/stop cycles, the relative number of particles with a diameter ≤2.5 nm declined from 57.20% in a fresh MEA to 1.92%. Cho et al combined the results of cross-sectional SEM and TEM to evaluate Pt/C degradation [33,34,36,38,39,45,59].…”

Section: Agglomeration And/or Dissolution Of Pt Particlesmentioning

confidence: 99%

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

264

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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“…Our previous studies [11e13] confirmed that the cathode degradation depended significantly on the relative humidity (RH) [11], cell temperature [12], and residual oxygen partial pressure in the gas channels [13]. With increasing RH, cell temperature, and oxygen partial pressure, the cell degradation was accelerated, likely due to an increase in the oxidation reaction rates of Eqs.…”

Section: Introductionmentioning

confidence: 77%

Effects of Pt loading in the anode on the durability of a membrane–electrode assembly for polymer electrolyte membrane fuel cells during startup/shutdown cycling

Eom¹,

Kim²,

Cho³

et al. 2012

International Journal of Hydrogen Energy

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Degradation of polymer electrolyte membrane fuel cells repetitively exposed to reverse current condition under different temperature

Cited by 45 publications

References 15 publications

PEM Fuel Cell Start-up/Shut-down Losses vs Temperature for Non-Graphitized and Graphitized Cathode Carbon Supports

PEM Fuel Cell Start-up/Shut-down Losses vs Temperature for Non-Graphitized and Graphitized Cathode Carbon Supports

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

Effects of Pt loading in the anode on the durability of a membrane–electrode assembly for polymer electrolyte membrane fuel cells during startup/shutdown cycling

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