Design of a reference electrode for high-temperature PEM fuel cells

Kaserer, Sebastian; Rakousky, Christoph; Melke, Julia; Roth, Christina

doi:10.1007/s10800-013-0567-9

Cited by 28 publications

(17 citation statements)

References 41 publications

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“…Degradation due to CO is mainly associated with reduced free reaction sites due to its adsorption on the Pt electrode surface [6,17,21]. It is an effect that can be reversed after reconditioning of the stack [44].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Impedance Spectroscopy (EIS) Characterization of Reformate-operated High Temperature PEM Fuel Cell Stack

Sahlin

Araya

Andreasen³

et al. 2017

IJPER

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This paper presents an experimental characterization of a high temperature proton exchange membrane fuel cell (HT-PEMFC) short stack carried out by means of impedance spectroscopy. Selected operating parameters; temperature, stoichiometry and reactant compositions were varied to investigate their effects on a reformate-operated stack. Polarization curves were also recorded to complement the impedance analysis of the researched phenomena. An equivalent circuit model was used to estimate the different resistances at varying parameters. It showed a significantly higher low frequency resistance at lower stoichiometry. Both anode and cathode stoichiometric ratio had significant effects on the stack performance during the dry hydrogen and reformate operation modes. In both cases the effects faded away when sufficient mass transport was achieved, which took place at λ anode = 1.3 for dry hydrogen, λ anode = 1.6 for reformate operation and λ cathode = 4. The work also compared dry hydrogen, steam reforming and autothermal reforming gas feeds at 160• C and showed appreciably lower performance in the case of autothermal reforming at the same stoichiometry, mainly attributable to mass transport related issues. In a CO poisoning analysis the stack showed good tolerance to concentration up to 1% CO in the fuel stream.

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Section: Introductionmentioning

confidence: 99%

Electrochemical Impedance Spectroscopy (EIS) Characterization of Reformate-operated High Temperature PEM Fuel Cell Stack

Sahlin

Araya

Andreasen³

et al. 2017

IJPER

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“…Figure a shows the cell potential drops to 0 mV when a concentration of 10 vol % CO is reached, indicating severe poisoning at this point. The trend of the anode overpotentials, as determined by hydrogen pump experiments or by simulation, is added to this graph to complement the information. The reference μ for the evaluation of Δ μ was always that without CO at the OCP [see Eq.…”

Section: Resultsmentioning

confidence: 99%

“…When using hydrogen from a steam‐reforming system as the anode feed for the fuel cell, in addition to small amounts of CO, H 2 O will also be present . To account for this additional fuel component, we investigated species adsorbed during the anode reaction in the presence of both CO and water with realistic concentrations.…”

Section: Resultsmentioning

confidence: 99%

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Following Adsorbate Coverage on Anodes of High‐Temperature Polymer Electrolyte Membrane Fuel Cells in the Presence of CO and H₂O by using In Operando X‐ray Absorption Spectroscopy

et al. 2015

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Application of the Δμ X‐ray absorption near‐edge spectroscopy analysis technique to a polybenzimidazole‐membrane‐based high‐temperature (170 °C) polymer electrolyte membrane fuel cell (PEMFC) under varying conditions reveals binding‐site details for H, CO, and biphosphate on a platinum nanoparticle anode surface. A synergistic interplay between CO and biphosphate adsorption is found, so that with increasing CO in the gas feed (below 3–4 % in H2), an increased biphosphate coverage becomes visible, apparently because small amounts of adsorbed CO force more localization of the phosphate species, which is believed to be adsorbed on top of the existing H overlayer. Increasing the concentration of CO (well above 4 %) causes CO poisoning to takeover and dramatically decrease the activity, though, compared to low‐temperature PEMFCs, huge amounts of CO can still be tolerated. Adding small amounts of water (less than 7 mg min−1) with CO to the anode feed reduces the amount of adsorbed phosphate and, thereby, increases the activity.

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“…3 Recently, external RE systems for fuel cells with solid ion-conducting junctions based on Nafion tubing or the PBI/H 3 PO 4 polymer were published. 4,5 Here we present the design and test of an external RE system with solid junction specifically developed for pressurized electrochemical cells. The most meaningful RE to study ORR with respect to fuel cells is the RHE, which is a hydrogen electrode immersed in the same electrolyte and at 1 bar H 2 partial pressure.…”

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confidence: 99%

Design and Application of External Reference Electrode for Kinetic Studies at Elevated Temperatures and Pressures

Fleige

Wiberg

Arenz

2017

J. Electrochem. Soc.

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We present the design and application of an external reference electrode (RE) system for kinetic studies of the oxygen reduction reaction (ORR), the cathode process in high temperature proton exchange membrane fuel cells (HT-PEMFCs), at elevated temperatures and pressures inside an autoclave. The RE system comprises a solid ion-conducting junction based on Nafion tubing. External RE was a reversible hydrogen electrode (RHE) calibrated reproducibly relative to an internal RHE with an uncertainty <±5 mV over the temperature range of 25-170 • C. Functionality of the RE system was tested by measuring ORR in concentrated H 3 PO 4 relative to a calibrated external RHE. Thus, we are confident that the development is a useful and versatile tool for kinetic studies at elevated temperatures and pressures. Fast and reliable testing of fuel cell catalysts at relevant conditions is of high importance for academia and industry alike. Recently, we introduced an elevated pressure and temperature rotating disk electrode (RDE) system that allows electrocatalytic measurements under well-defined mass transport conditions 1,2 . The setup comprised an internal silver wire RE that enabled a stable determination of the reference potential, but the obtained calibration relative to an internal RHE lacked the required accuracy (< ± 5 mV) for accurate kinetic measurements. We therefore avoided in our previous work the determination of absolute kinetic rates of the ORR at elevated temperature and pressure. An approach to more reliable reference potentials in pressurized cells is to use external RE configurations.3 Recently, external RE systems for fuel cells with solid ion-conducting junctions based on Nafion tubing or the PBI/H 3 PO 4 polymer were published. 4,5Here we present the design and test of an external RE system with solid junction specifically developed for pressurized electrochemical cells. The most meaningful RE to study ORR with respect to fuel cells is the RHE, which is a hydrogen electrode immersed in the same electrolyte and at 1 bar H 2 partial pressure. 6 Thus, we applied an external RHE and calibrated it separately relative to an internal RHE, as its determination in situ 7,8 is not practical in pressurized cells. Application of the calibrated external RE was tested for studying ORR in conc. H 3 PO 4 at elevated temperatures. Such conditions are highly relevant for high temperature proton exchange membrane fuel cells (HT-PEMFC), but usually not accessible to RDE studies due to the low oxygen solubility in the electrolyte. The results demonstrate that our development enables meaningful kinetic studies in pressurized cells and thereby overcomes the significant accuracy issues related to internal REs operated at elevated temperatures. ExperimentalThe electrolyte used in this study was 85 wt% H 3 PO 4 (Suprapur, Merck). The gases used were supplied from gas cylinders (Air Liquide, Denmark) and had a purity of at least 99.995%. The electrochemical cell was placed inside an autoclave as described previously.

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Design of a reference electrode for high-temperature PEM fuel cells

Cited by 28 publications

References 41 publications

Electrochemical Impedance Spectroscopy (EIS) Characterization of Reformate-operated High Temperature PEM Fuel Cell Stack

Electrochemical Impedance Spectroscopy (EIS) Characterization of Reformate-operated High Temperature PEM Fuel Cell Stack

Following Adsorbate Coverage on Anodes of High‐Temperature Polymer Electrolyte Membrane Fuel Cells in the Presence of CO and H₂O by using In Operando X‐ray Absorption Spectroscopy

Design and Application of External Reference Electrode for Kinetic Studies at Elevated Temperatures and Pressures

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Design of a reference electrode for high-temperature PEM fuel cells

Cited by 28 publications

References 41 publications

Electrochemical Impedance Spectroscopy (EIS) Characterization of Reformate-operated High Temperature PEM Fuel Cell Stack

Electrochemical Impedance Spectroscopy (EIS) Characterization of Reformate-operated High Temperature PEM Fuel Cell Stack

Following Adsorbate Coverage on Anodes of High‐Temperature Polymer Electrolyte Membrane Fuel Cells in the Presence of CO and H2O by using In Operando X‐ray Absorption Spectroscopy

Design and Application of External Reference Electrode for Kinetic Studies at Elevated Temperatures and Pressures

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Following Adsorbate Coverage on Anodes of High‐Temperature Polymer Electrolyte Membrane Fuel Cells in the Presence of CO and H₂O by using In Operando X‐ray Absorption Spectroscopy