Platinum–cobalt catalysts for the oxygen reduction reaction in high temperature proton exchange membrane fuel cells – Long term behavior under ex-situ and in-situ conditions

Schenk, Alexander; Grimmer, Christoph; Perchthaler, Markus; Weinberger, Stephan; Pichler, Birgit Elvira; Heinzl, Christoph; Scheu, Christina; Mautner, Franz-Andreas; Bitschnau, Brigitte; Hacker, Viktor

doi:10.1016/j.jpowsour.2014.05.023

Cited by 47 publications

(19 citation statements)

References 51 publications

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“…Distribution of relaxation times (DRT) analysis is another method of analyzing impedance data, in which the impedance spectra are represented by an infinite number of infinitesimal parallel R C-elements in series [39]. The impedance data is then resolved on the basis of the time constants and presented as a distribution of these time constants that represent the electrochemical processes in the fuel cell [40]. Further description of DRT analysis and its use in fuel cells can be found in the literature [39,[41][42][43][44].…”

Section: Discussionmentioning

confidence: 99%

Effects of Impurities on Pre-Doped and Post-Doped Membranes for High Temperature PEM Fuel Cell Stacks

Araya

Thomas²,

Lotrič

et al. 2021

Energies

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In this paper, we experimentally investigated two high temperature polymer electrolyte membrane fuel cell (HT-PEMFC) stacks for their response to the presence of reformate impurities in an anode gas stream. The investigation was aimed at characterizing the effects of reformate impurities at the stack level, including in humidified conditions and identifying fault features for diagnosis purposes. Two HT-PEMFC stacks of 37 cells each with active areas of 165 cm2 were used with one stack containing a pre-doped membrane with a woven gas diffusion layer (GDL) and the other containing a post-doped membrane with non-woven GDL. Polarization curves and galvanostatic electrochemical impedance spectroscopy (EIS) were used for characterization. We found that both N2 dilution and impurities in the anode feed affected mainly the charge transfer losses, especially on the anode side. We also found that humidification alleviated the poisoning effects of the impurities in the stack with pre-doped membrane electrode assemblies (MEA) and woven GDL but had detrimental effects on the stack with post-doped MEAs and non-woven GDL. We demonstrated that pure and dry hydrogen operation at the end of the tests resulted in significant recovery of the performance losses due to impurities for both stacks even after the humidified reformate operation. This implies that there was only limited acid loss during the test period of around 150 h for each stack.

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Section: Discussionmentioning

confidence: 99%

Effects of Impurities on Pre-Doped and Post-Doped Membranes for High Temperature PEM Fuel Cell Stacks

Araya

Thomas²,

Lotrič

et al. 2021

Energies

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“…Therefore, in this work, DRT, which does not presume the number of time constants a priori, was adopted for the analysis of the impedance spectra. It is a method based on the fact that impedance spectra can be represented by an infinite number of infinitesimal differential R C-elements in series, and therefore, the electrochemical processes represented by the impedance data can be resolved on the basis of their time constants and presented as a distribution of these time constants [34]. Each impedance spectrum was deconvoluted by DRT using a freely available MATLAB application (DRTtools), where Equation (1) was discretized into a limited amount of time constants according to Equation (2) [32,[35][36][37]:…”

Section: Discussionmentioning

confidence: 99%

Fault Characterization of a Proton Exchange Membrane Fuel Cell Stack

et al. 2019

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In this paper, the main faults in a commercial proton exchange membrane fuel cell (PEMFC) stack for micro-combined heat and power ( μ -CHP) application are investigated, with the scope of experimentally identifying fault indicators for diagnosis purposes. The tested faults were reactant starvation (both fuel and oxidant), flooding, drying, CO poisoning, and H2S poisoning. Galvanostatic electrochemical impedance spectroscopy (EIS) measurements were recorded between 2 kHz and 0.1 Hz on a commercial stack of 46 cells of a 100- cm 2 active area each. The results, obtained through distribution of relaxation time (DRT) analysis of the EIS data, show that characteristic peaks of the DRT and their changes with the different fault intensity levels can be used to extract the features of the tested faults. It was shown that flooding and drying present features on the opposite ends of the frequency spectrum due the effect of drying on the membrane conductivity and the blocking effect of flooding that constricts the reactants’ flow. Moreover, it was seen that while the effect of CO poisoning is limited to high frequency processes, above 100 Hz, the effects of H2S extend to below 10 Hz. Finally, the performance degradation due to all the tested faults, including H2S poisoning, is recoverable to a great extent, implying that condition correction after fault detection can contribute to prolonged lifetime of the fuel cell.

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“…In terms of demonstrated usefulness of alloys in a HT-PEMFC, recent work by Schenk et al examines Pt-Co [116]. The authors developed a custom catalyst fabrication process designed to fit into a continuous production process and overcome some of the limitations, inefficiencies, and labor intensive steps of alloying metals for fuel cell use.…”

Section: Orr Catalyst Activity In Free Electrolyte: Alternative Catalystmentioning

confidence: 99%

Catalyst, Membrane, Free Electrolyte Challenges, and Pathways to Resolutions in High Temperature Polymer Electrolyte Membrane Fuel Cells

2017

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High temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) are being studied due to a number of benefits offered versus their low temperature counterparts, including co-generation of heat and power, high tolerance to fuel impurities, and simpler system design. Approximately 90% of the literature on HT-PEM is related to the electrolyte and, for the most part, these electrolytes all use free phosphoric acid, or similar free acid, as the ion conductor. A major issue with using phosphoric acid based electrolytes is the free acid in the electrodes. The presence of the acid on the catalyst sites leads to poor oxygen activity, low solubility/diffusion, and can block electrochemical sites through phosphate adsorption. This review will focus on these issues and the steps that have been taken to alleviate these obstacles. The intention is this review may then serve as a tool for finding a solution path in the community.

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Platinum–cobalt catalysts for the oxygen reduction reaction in high temperature proton exchange membrane fuel cells – Long term behavior under ex-situ and in-situ conditions

Cited by 47 publications

References 51 publications

Effects of Impurities on Pre-Doped and Post-Doped Membranes for High Temperature PEM Fuel Cell Stacks

Effects of Impurities on Pre-Doped and Post-Doped Membranes for High Temperature PEM Fuel Cell Stacks

Fault Characterization of a Proton Exchange Membrane Fuel Cell Stack

Catalyst, Membrane, Free Electrolyte Challenges, and Pathways to Resolutions in High Temperature Polymer Electrolyte Membrane Fuel Cells

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