Experimental investigation and numerical simulation of the electrolyte loss in a HT-PEM fuel cell

Lang, Sebastian; Kazdal, Timur; Kühl, Frank; Hampe, Manfred J.

doi:10.1016/j.ijhydene.2014.11.041

Cited by 41 publications

(22 citation statements)

References 31 publications

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“…However, understanding of the degradation mechanisms related to PA volume variations due to concentration changes, 5 and redistribution of phosphoric acid in the membrane electrode assembly (MEA) is still limited. Additionally, the interaction of the PBI polymer backbone with PA, the acid doping level [6][7][8] as well as the membrane synthesis method have a significant influence on properties such as conductivity, mechanical stability.…”

Section: High Temperature Polymer Electrolyte Fuel Cells (Ht-pefc) Armentioning

confidence: 99%

Operando X-ray Tomographic Microscopy Imaging of HT-PEFC: A Comparative Study of Phosphoric Acid Electrolyte Migration

Eberhardt

Marone

Stampanoni

et al. 2016

J. Electrochem. Soc.

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Synchrotron based X-ray tomographic microscopy was used to image the redistribution of phosphoric acid in HT-PEFC due to electrolyte migration from cathode to anode. The acid migration rate, transference number of the hydrogen phosphate ion and flooding of the anode gas diffusion layer (GDL) was analyzed for MEAs with different membrane acid doping levels (24-36 mgcm −2 ) and membrane materials (imbibed m-polybenzimidazole (PBI) and polyphosphoric acid (PPA) processed p-PBI). The most influential factors for the acid migration rate are current density and the amount of free acid in the membrane. High doping level of the membrane and current density above 0.4 A cm −2 significantly increase the migration rate. From the migration rates apparent transference numbers for the hydrogen phosphate anions in the order 10 −5 to 10 −4 are calculated at the high current densities. Besides the membrane properties, also the influence of the microstructure of the porous transport layers was analyzed. Most probably cracks in the catalyst and microporous layers facilitate the migration of acid into the anode GDL. High temperature polymer electrolyte fuel cells (HT-PEFC) are operating at temperatures up to 200• C using phosphoric acid (PA) doped polybenzimidazole (PBI) based membranes. This fuel cell technology has a range of beneficial properties. At the higher operating temperatures, the tolerance to fuel gas impurities increases significantly and operation with CO levels of up to 3% and H 2 S up to 10 ppm can be achieved.1,2 Consequently, a fuel processing unit can more easily be thermally integrated into the fuel cell system and used for reforming hydrocarbon-based fuels in the absence of an additional selective CO oxidation gas clean-up step. Furthermore, phosphoric acid exhibits comparable proton conductivity to typical PFSA-type membranes 3 without the need of additional gas humidification due to a fast proton hopping mechanism.4 At a cell temperature of 160• C the higher value waste heat is more easily used than with standard low temperature PEFC technology, therefore HT-PEFC have a significant potential for stationary combined heat and power applications (CHP).The advantageous characteristics of HT-PEFC are based on the physico-chemical properties of the phosphoric acid electrolyte, such as high conductivity due a fast Grotthus like charge transport 4 and low PA vapor pressure. However, understanding of the degradation mechanisms related to PA volume variations due to concentration changes, 5 and redistribution of phosphoric acid in the membrane electrode assembly (MEA) is still limited. Additionally, the interaction of the PBI polymer backbone with PA, the acid doping level 6-8 as well as the membrane synthesis method have a significant influence on properties such as conductivity, mechanical stability.Since phosphoric acid is not covalently bound to the polymer structure of the membrane, a minor part of the ionic current is also carried by the hydrogen phosphate anions, which have a have a small, but finite transference...

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Section: High Temperature Polymer Electrolyte Fuel Cells (Ht-pefc) Armentioning

confidence: 99%

Operando X-ray Tomographic Microscopy Imaging of HT-PEFC: A Comparative Study of Phosphoric Acid Electrolyte Migration

Eberhardt

Marone

Stampanoni

et al. 2016

J. Electrochem. Soc.

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“…While the aforementioned degradation mechanisms may all be influential during start-stop cycling operations, it is not obvious which degradation mechanism is more dominant during constant current operations. According to the experimental measurements of Lang et al [9], the rate of voltage degradation of HT-PEMFCs during the start-stop cycling operation was only slightly higher than that measured at a constant current density of 0.5 A cm À2 (17.2 vs. 15.3 mV/h). Furthermore, the amount of PA loss collected by several groups during their long-term degradation tests seemed to be minimal compared to the total amount of PA initially doped in the membrane [9,32,33,35].…”

Section: Introductionmentioning

confidence: 90%

“…According to the experimental measurements of Lang et al [9], the rate of voltage degradation of HT-PEMFCs during the start-stop cycling operation was only slightly higher than that measured at a constant current density of 0.5 A cm À2 (17.2 vs. 15.3 mV/h). Furthermore, the amount of PA loss collected by several groups during their long-term degradation tests seemed to be minimal compared to the total amount of PA initially doped in the membrane [9,32,33,35]. In this study, we performed numerical degradation studies of HT-PEMFCs using a three-dimensional (3-D) HT-PEMFC model developed in the previous studies [23,36e40].…”

Section: Introductionmentioning

confidence: 90%

“…Therefore, the catalyst degradation is more exacerbated during start-stop load cycling compared to a constant current load [34]. On the other hand, it is believed that the PA evaporation driven by temperature rise and PA dilution by water condensation during the shut-down and subsequent cool-down procedures are significant contributors to the PA loss [9,31]. While the aforementioned degradation mechanisms may all be influential during start-stop cycling operations, it is not obvious which degradation mechanism is more dominant during constant current operations.…”

Section: Introductionmentioning

confidence: 99%

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Numerical degradation studies of high-temperature proton exchange membrane fuel cells with phosphoric acid-doped PBI membranes

Won

2016

International Journal of Hydrogen Energy

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“…The impedance spectrum spreads and moves to the right during degradation, which manifest itself by an 270 increase in the series resistance (the first intersect with the real axis), and more significantly expressed by an increasing real part of the low frequency part of the spectrum. The observed ageing mode is common for high temperature PEM fuel cells [37,38,39]. Thus, it is evident that an impedance 275 based FDI algorithm for fuel cell applications needs to be robust towards degradation.…”

Section: Fdi Algorithmmentioning

confidence: 99%

Fault detection and isolation of high temperature proton exchange membrane fuel cell stack under the influence of degradation

Jeppesen

Araya

Sahlin

et al. 2017

Journal of Power Sources

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This study proposes a data-drive impedance-based methodology for fault detection and isolation of low and high cathode stoichiometry, high CO concentration in the anode gas, high methanol vapour concentrations in the anode gas and low anode stoichiometry, for high temperature PEM fuel cells. The fault detection and isolation algorithm is based on an artificial neural network classifier, which uses three extracted features as input. Two of the proposed features are based on angles in the impedance spectrum, and are therefore relative to specific points, and shown to be independent of degradation, contrary to other available feature extraction methods in the literature. The experimental data is based on a 35 day experiment, where 2010 unique electrochemical impedance spectroscopy measurements were recorded. The test of the algorithm resulted in a good detectability of the faults, except for high methanol vapour concentration in the anode gas fault, which was found to be difficult to distinguish from a normal operational data. The achieved accuracy for faults related to CO pollution, anode-and cathode stoichiometry is 100 % success rate. Overall global accuracy on the test data is 94.6 %.

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Experimental investigation and numerical simulation of the electrolyte loss in a HT-PEM fuel cell

Cited by 41 publications

References 31 publications

Operando X-ray Tomographic Microscopy Imaging of HT-PEFC: A Comparative Study of Phosphoric Acid Electrolyte Migration

Operando X-ray Tomographic Microscopy Imaging of HT-PEFC: A Comparative Study of Phosphoric Acid Electrolyte Migration

Numerical degradation studies of high-temperature proton exchange membrane fuel cells with phosphoric acid-doped PBI membranes

Fault detection and isolation of high temperature proton exchange membrane fuel cell stack under the influence of degradation

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