Long Term Testing in Continuous Mode of HT‐PEMFC Based H<sub>3</sub>PO<sub>4</sub>/PBI Celtec‐P MEAs for μ‐CHP Applications

Moçotéguy, P.; Ludwig, Bastian; Scholta, Joachim; Barrera, Regina; Ginocchio, S.

doi:10.1002/fuce.200800134

Cited by 62 publications

(29 citation statements)

References 34 publications

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“…However, although necessary for better understanding of the aging mechanisms occurring in "real life" fuel cell systems, studies focusing on degradation at the stack level are far from numerous [5]. Particularly, heterogeneous degradation between the stack cells, that represents a major issue in PEMFC as system lifetime is often determined by the less effective cell, remains very little investigated [6,7]. Consequently, more information is needed on the individual behavior of each cell during long term stack testing, although time consuming as reported for instance by Cleghorn et al [8].…”

Section: Introductionmentioning

confidence: 98%

Heterogeneous Aging Within PEMFC Stacks

Chatillon¹,

Bonnet²,

Lapicque³

2014

Fuel Cells

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International audienceEvaluation of PEM fuel cell aging occurring in various operating conditions is usually conducted in single cell configuration for which various electrochemical methods can be used. Aging phenomena in stack is often investigated either in a global manner or by basic measurements of variables, e. g. individual cell voltages. This paper presents the results of aging investigation of three-cell stacks using crossed linked electrochemical methods giving access to the time variations of ohmic and charge transfer resistance of the three cathodes, as well as the electrochemical surface area and the fuel crossover over more than 1,000 h at 0.3 A cm(-2) upon air humidification. Consistency between the various methods employed was discussed and demonstrated. In addition to the case of a stack formed by three sane cells, the case of a stack comprising a defective cell - previously aged under oxidative conditions - placed between two sane MEAs was investigated: the pre-ageing of this cell was shown to slightly accelerate the aging under long-term operation. Besides, it was observed that in both stacks, the back cell - i.e. located far from the stack inlet and outlet suffered much more from the long-term run than the two other cells

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Section: Introductionmentioning

confidence: 98%

Heterogeneous Aging Within PEMFC Stacks

Chatillon¹,

Bonnet²,

Lapicque³

2014

Fuel Cells

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“…Mocoteguy et al [13] also observed that the high frequency loop disappears with increase in degradation, which makes it plausible to suggest that the disappearance of this loop is related to increased degradation from poisoning due to methanol.…”

Section: Overall Eismentioning

confidence: 93%

“…This is in agreement with the degradation rate claimed by BASF for the MEA. Mocoteguy et al [13] found a higher voltage drop rate of À41 mV/h over a period of 505 h on a Celtec-P1000 MEA, at a higher current density of 0.4 A/cm 2 and temperature of 160 C. In comparison, operation in the presence of 5% by volume of methanol-water vapor mixture in the anode feed gas shows a degradation rate of À900 mV/h, which is evidently deviated from the case of a pure hydrogen operation. Li et al [24] worked with reformate in their long-term durability tests with a voltage drop rate of À20 mV/h, which however cannot be directly compared with the current work as they used natural gas reformate.…”

Section: Overall Durabilitymentioning

confidence: 98%

Investigating the effects of methanol-water vapor mixture on a PBI-based high temperature PEM fuel cell

Araya

Andreasen

Nielsen

et al. 2012

International Journal of Hydrogen Energy

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“…The number of start/stop cycles is closely related to the overall lifetime of the fuel cell if the induced degradation effects are not mitigated. If, for instance, a HT-PEFC is used in a combined heat and power (CHP) [10][11][12] system, it is conceivable that several hundred cycles will be accumulated, which can lead to a rapid and irreversible damage of the stack. 13 It is necessary, therefore, to improve the understanding of the start/stop mechanism in order to deduce appropriate mitigation strategies.…”

mentioning

confidence: 99%

On the Positive Effect of CO during Start/Stop in High-Temperature Polymer Electrolyte Fuel Cells

Engl

Käse

Gubler

et al. 2014

ECS Electrochemistry Letters

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The influence of CO in the fuel gas on cathode carbon corrosion during start/stop cycles in high temperature polymer electrolyte fuel cells (HT-PEFC) was investigated. The fuel cell underwent simulated start/stop cycles with a constant time interval, reactant gas flow rate and temperature by switching between H 2 /CO mixtures and O 2 at the fuel electrode. The results reveal that increasing amounts of CO in the fuel gas reduce the amount of carbon corrosion at the air electrode. Therefore, HT-PEFC operation with CO containing fuel has the benefit of mitigating start/stop induced degradation effects. One of the most beneficial and unique features of a hightemperature polymer electrolyte fuel cell (HT-PEFC) is the capability to tolerate orders of magnitude lager amounts of CO (up to 3%) 1,2 compared to a LT-PEFC (approx. 10 ppm).3 Therefore, the system can be used to generate electricity from hydrogen-rich reformate gases without complex and energy intensive CO-cleanup.Nevertheless, the HT-PEFC can suffer from numerous degradation effects in different locations of the membrane electrode assembly (MEA), 4 e.g. pinhole formation in the membrane, acid evaporation and membrane thinning. 5,6 Electrodes can also represent a major area of degradation. Interestingly, specific degradation mechanisms, such as carbon corrosion, catalyst detachment and catalyst particle growth (Ostwald-ripening) can be found in the LT-PEFC as well. Additionally, structural changes and acid flooding of the porous layers of the cell can occur. All degradation mechanisms are complex functions of the specific operation conditions, making their individual identification challenging. Hence, it is necessary to gain insight into limitations of MEA lifetime, which is the key to successful development of mitigation strategies to reach the desired lifetimes, i.e. >40.000 hours 6 for stationary applications.One of the specific degradation triggers is known as "reversecurrent decay" or "start/stop"-mechanism, respectively. 7-9 This degradation mode is induced during fuel cell start-up or shut-down, when air or pure oxygen and fuel gas co-exist in the fuel electrode compartment (see Figure S1 and its description in the supplemental material). This mechanism can be one of the main reasons for carbon corrosion at the air electrode. The number of start/stop cycles is closely related to the overall lifetime of the fuel cell if the induced degradation effects are not mitigated. If, for instance, a HT-PEFC is used in a combined heat and power (CHP) 10-12 system, it is conceivable that several hundred cycles will be accumulated, which can lead to a rapid and irreversible damage of the stack.13 It is necessary, therefore, to improve the understanding of the start/stop mechanism in order to deduce appropriate mitigation strategies. Mitigation strategies can be divided into two categories. One is focused on developing new materials, such as carbon free electrodes [14][15][16] or selective hydrogen oxidation catalysts. 17-19The second category consists of system st...

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Long Term Testing in Continuous Mode of HT‐PEMFC Based H₃PO₄/PBI Celtec‐P MEAs for μ‐CHP Applications

Cited by 62 publications

References 34 publications

Heterogeneous Aging Within PEMFC Stacks

Heterogeneous Aging Within PEMFC Stacks

Investigating the effects of methanol-water vapor mixture on a PBI-based high temperature PEM fuel cell

On the Positive Effect of CO during Start/Stop in High-Temperature Polymer Electrolyte Fuel Cells

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Long Term Testing in Continuous Mode of HT‐PEMFC Based H3PO4/PBI Celtec‐P MEAs for μ‐CHP Applications

Cited by 62 publications

References 34 publications

Heterogeneous Aging Within PEMFC Stacks

Heterogeneous Aging Within PEMFC Stacks

Investigating the effects of methanol-water vapor mixture on a PBI-based high temperature PEM fuel cell

On the Positive Effect of CO during Start/Stop in High-Temperature Polymer Electrolyte Fuel Cells

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Product

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Long Term Testing in Continuous Mode of HT‐PEMFC Based H₃PO₄/PBI Celtec‐P MEAs for μ‐CHP Applications