Materials and characterization techniques for high-temperature polymer electrolyte membrane fuel cells

Zeis, Roswitha

doi:10.3762/bjnano.6.8

Cited by 174 publications

(130 citation statements)

References 70 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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“…The MEA is usually consisted of a PEM (solid electrolyte) and two symmetrical electrodes (anode and cathode) which have precious metal catalysts (e.g., Pt) (Huang et al, 2006;Lai et al, 2012) and non-platinum group metals (Reshetenko, et al, 2016) supported by carbon materials (e.g., carbon black, fiber, and nanotube). Additionally, it is common that the bipolar/end plates and GDLs (e.g., carbon paper (CP) or carbon cloth (CC)) are made using carbon materials (Dicks, 2006;Wissler, 2006;Tran et al, 2015;Zeis, 2015). In recent years, research trends of PEMFCs have focused on accelerating the sluggish kinetics of cathode catalyst, minimizing overall Pt content, and increasing membrane proton conductivity (Scofield et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Effect of Operating Conditions on PAHs Emission from a Single H2-O2 PEM Fuel Cell

Huang

Ming-sheng

Tsai

et al. 2016

Aerosol Air Qual. Res.

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This study investigates the emissions of polycyclic aromatic hydrocarbons (PAHs) from a single hydrogen-oxygen proton exchange membrane (PEM) fuel cell (FC) under different flowrates, temperatures, sampling periods, and membrane-electrode assemblies (MEAs). The results show that Nap, PA, BeP, FL, Pyr, BbC, Ant, and Flu were dominant in anode and cathode emissions of the single PEMFC under different operating conditions. The emission concentrations of Total-PAHs and Total-BaP equivalent carcinogenic potency (BaP eq ) were lower from the anode than from the cathode emission. Moreover, the concentrations of molecular-weight (MW) classified PAHs were in the order low (L) MM-> high (H) MW-> middle (M) MW-PAHs. When the anode/cathode gas flowrates were greater or smaller than 52/35 sccm but at the same sampling volume, the emission concentrations of Total-PAHs and Total-BaP eq increased. The concentration of Total-PAHs decreased but the mass of Total-PAHs increased with the increase of sampling time. However, 64% and 82% of PAH mass were emitted within 12 and 24 h, respectively, based on 36 h sampling at anode/cathode gas flowrates = 52/35 sccm. The concentrations of Total-PAHs or Total-BaP eq of anode or cathode emission were slightly higher at 90°C than at 65°C.The performances of commercial MEAs were in the order SGL < E-TEK < GORE. Nevertheless, the concentrations of anode or cathode emission Total-PAHs or Total-BaP eq for the PEMFC using different MEAs followed the order GORE > E-TEK2 > E-TEK > SGL, while the sums of anode and cathode Total-PAHs emission factors varied with the order SGL > E-TEK > E-TEK2 > GORE (13.3 ± 0.55, 11.5 ± 0.21, 7.91 ± 0.47, and 3.17 ± 0.22 µg g -1 -MEA, respectively). When using the (lab-made) E-TEK2 as the MEA of PEMFC, the PAH profiles of anode and cathode emission gases were similar to those of some carbon materials.

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“…An H 2 -O 2 PEMFC has the main components of membrane-electrode assembly (MEA), gasdiffusion layer (GDL), and bipolar/end plate (Huang et al, 2006;Lai et al, 2012;Tenson and Baby, 2017). It is common that a PEM is symmetrically sandwiched by anode and cathode to prepare the MEA; moreover, the electrodes usually contain precious metal catalysts (e.g., Pt) (Huang et al, 2006;Lai et al, 2012), Pt-based alloys , or non-platinum group metals (Reshetenko, et al, 2016) supported by carbon materials (e.g., carbon black, fiber, and nanotube) which are also used for the fabrication of bipolar/end plates and GDLs (e.g., carbon paper or cloth) (Tran et al, 2015;Zeis, 2015;Lee and Lee, 2016).…”

Section: Introductionmentioning

confidence: 99%

Gas- and Water-Phase PAHs Emitted from a Single Hydrogen-Oxygen PEM Fuel Cell

Huang

Tsai

Chen

et al. 2018

Aerosol Air Qual. Res.

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This study focuses on the comparison between gas-and water-phase polycyclic aromatic hydrocarbons (PAHs) emitted from a single hydrogen-oxygen proton exchange membrane (PEM) fuel cell (FC) at different flowrates and temperatures. The results show that among 21 PAHs, the most and least dominant species were Nap and BeP, respectively. At 65°C, the concentrations of individual gas-and water-phase PAHs decreased with increasing flowrate, and the PAH concentrations were lower at the anode than those at the cathode. The concentrations of gas-phase Total-PAHs and Total-BaP eq were slightly lower at 65°C than those at 90°C, but an opposite trend was observed for water-phase ones. The temperature influenced water-phase PAH concentration profiles more than gas-phase ones, and the gas-and water-phase PAHs had different concentration profiles. The performance of membrane-electrode assembly (MEA) decreased with increasing flowrate or temperature. The emission factor (EF) sum (anode + cathode) for gas-or water-phase Total-PAHs increased with increasing flowrate. This tendency was also true for gas-phase Total-PAHs EFs but not for water-phase ones when raising the temperature from 65°C to 90°C. At 65°C and 52/35 sccm, the EF sums of water-phase Total-PAHs and TotalBaP eq were 2.18 ± 0.04 and 0.09 ± 0.00 µg g-MEA -1 , respectively-smaller than those of gas-phase ones (3.02 ± 0.09 and 0.12 ± 0.00 µg g-MEA -1 , respectively). More environmental concern should be directed at emitted gas-phase PAHs than at water-phase ones because the anode and cathode water effluents are usually recycled during PEMFC operations.

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Materials and characterization techniques for high-temperature polymer electrolyte membrane fuel cells

Cited by 174 publications

References 70 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

Effect of Operating Conditions on PAHs Emission from a Single H2-O2 PEM Fuel Cell

Gas- and Water-Phase PAHs Emitted from a Single Hydrogen-Oxygen PEM Fuel Cell

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