42 research outputs found
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Durability Study of Membrane Electrode Assembly for Heavy-Duty Fuel Cells
No full textPolymer electrolyte membrane fuel cells (PEMFCs) are a zero emission replacement for heavy duty applications due to their range, energy density and fast refueling times.[1] In 2020, the U.S. Department of Energy (DOE) lunched the Million Mile Fuel Cell Truck (M2FCT) consortium to fund fuel cell R&D to meet heavy duty truck standards.[2] Durability studies focusing on heavy-duty applications for advanced materials testing under the M2FCT consortium have been extensively explored and continue to be analyzed to standardize the evaluation of next generation fuel cell materials.
This study combines in situ electrochemical characterization with ex situ analysis of single cell PEMFCs membrane electrode assemblies (MEAs) to predict long-term durability for heavy-duty applications. Various accelerated stress test (AST) parameters were analyzed to determine the stressors affecting the long-term durability. Local degradation resulting from repeated high voltage to low current cycles was analyzed by testing state-of-the-art materials. High potential holds at various conditions were analyzed to determine membrane chemical degradation. Repeated wet and dry cycles were performed to test the membrane mechanical durability. In situ electrochemical analysis include mass activity, electrochemical surface area, hydrogen crossover, and polarization curves were collected and compared among the MEAs. Ex situ analysis includes quantification of membrane thinning at end of life and fluoride emission rate measurement for water effluent throughout the test was conducted to study the membrane degradation.
Acknowledgement:
This work was supported by the Hydrogen and Fuel Cell Technologies Office (HFTO), Office of Energy Efficiency and Renewable Energy (EERE), US DOE through the Million Mile Fuel Cell Truck (M2FCT) consortium, technology managers G. Kleen and D. Papageorgopoulos.
References:
David A. Cullen, K. C. Neyerlin, Rajesh K. Ahluwalia, Rangachary Mukundan, Karren L. More, Rodney L. Borup, Adam Z. Weber, Deborah J. Myers, and Ahmet Kusoglu, New roads and challenges for fuel cells in heavy-duty transportation. Nat. Energy, 2021. 6(5): 462-474.
DOE Launches Two Consortia to Advance Fuel Cell Truck and Electrolyzer R&D. 2020; Available from: https://www.energy.gov/eere/articles/doe-launches-two-consortia-advance-fuel-cell-truck-and-electrolyzer-rd
Author Correction: Grooved electrodes for high-power-density fuel cells
No full textCorrection to: Nature Energy. Published online 25 May 2023. This paper was originally published under a standard Springer Nature license (© The Author(s), under exclusive licence to Springer Nature Limited). It is now available as an open-access paper under a Creative Commons Attribution 4.0 International license, © The Author(s). The error has been corrected in the online version of the article
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(2021-2022 ECS Toyota Young Investigator Fellowship) Understanding and Suppression of Cation Transport into Polymer Electrolyte Membrane Fuel Cell
No full textPolymer electrolyte membrane fuel cells (PEMFCs) are a viable zero-emissions option for the electrification of the heavy duty transportation sector. However, PEMFCs still suffer from degradation of materials over the fuel cell lifetime. Cation contaminants can be generated from corrosion of bipolar plates and balance of plant components, water contaminants, and environmental sources (e.g., Fe3+, Ca2+, Na+), making them present in the fuel or oxidant stream during operation(1). Cations have been shown to be detrimental to the performance of the PEMFC by reducing water uptake, ionic conductivity, and O2 transport, resulting in performance loss and degradation. Metal cations such as Fe3+ can also lead to chemical degradation of the membrane ionomer (2-4). It is critical to understand the mechanism and rate of cation transport from the bipolar plate channel to the membrane to develop mitigation strategy to suppress the cation transport.
In this work, we present the study of the cation (Fe3+) transport mechanism through the gas diffusion layer (GDL) by introducing a cation solution in the cathode channel. Transport rates across the GDL are studied using an ex-situ GDL holder where Fe solution is introduced in the GDL substrate side with water transported through to the microporous layer side (MPL) and is collected and analyzed for Fe concentration, as shown in Figure 1a. Effect of the Fe concentration on transport rates is also studied using computational modeling. Understanding of the transport mechanism is then leveraged to identify mitigation solutions and suppress cation transport from the flow field to the electrode using a GDL with dual MPL architecture as shown in Figure 1b. Optimization of the dual MPL architecture for both durability and performance is also presented.
Acknowledgements
This research is supported by the 2021-2022 ECS Toyota Young Investigator fellowship and U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office, through the Million Mile Fuel Cell Truck Consortium (M2FCT). Authors acknowledge the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory (LANL).
References
D. D. Papadias, R. K. Ahluwalia, J. K. Thomson, H. M. Meyer, M. P. Brady, H. L. Wang, J. A. Turner, R. Mukundan and R. Borup, Journal of Power Sources, 273, 1237 (2015).
R. K. Ahluwalia, D. D. Papadias, N. N. Kariuki, J. K. Peng, X. P. Wang, Y. F. Tsai, D. G. Graczyk and D. J. Myers, Journal of the Electrochemical Society, 165, F3024 (2018).
J. P. Braaten, X. M. Xu, Y. Cai, A. Kongkanand and S. Litster, Journal of the Electrochemical Society, 166, F1337 (2019).
A. Kneer, J. Jankovic, D. Susac, A. Putz, N. Wagner, M. Sabharwal and M. Secanell, Journal of The Electrochemical Society, 165, F3241 (2018).
Figure
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(Invited) Progress in Nafion™ Membrane Development for Proton Exchange Membrane Water Electrolyzers
No full textProton exchange membrane water electrolyzers (PEMWE) have received significant recent attention in order to address the burgeoning need for low/zero-carbon sources of hydrogen at scale. PEMWE devices are an attractive source of “green” hydrogen due to their relatively compact size, scalable construction, high efficiency, and proven durability. They also integrate well with intermittent electricity sources and can deliver elevated hydrogen outlet pressures to reduce parasitic efficiency losses associated with hydrogen compression.1 Membranes made from Nafion™ perfluorosulfonic acid (PFSA) polymer have been the leader in PEMWE device application for decades, due to their high proton conductivity and chemical durability in the hot, acidic PEMWE environment. Traditional Nafion™ membranes in this application, however, comprise thick films (>100 µm) where ohmic-driven voltage losses due to proton transport resistance are high. To maximize the electrical efficiency and hydrogen production of PEMWE applications, and help drive hydrogen costs below $2/kg, new membranes – specifically engineered for low proton transport resistance and high durability in a PEMWE environment – are required. A multigenerational plan has been established to improve the performance of Nafion™ membranes while maintaining their best-in-class durability. One major contributor to membrane improvement is a reduced proton transport resistance inherent in thinner membranes. However, as membranes become thinner, they invite higher gas crossover, especially in a differential pressure environment. Novel mitigation strategies are required to ensure safe operation and long lifetimes of the thinnest membranes in advanced PEMWE membrane concepts.2-3 In this presentation, an overview of the activities and strategic developments within Nafion™ membranes for water electrolyzers will be summarized. The multigenerational product development program will be discussed, highlighting the significant contribution possible from Nafion™ membrane development to green hydrogen proliferation. Ayers, K.; Danilovic, N.; Ouimet, R.; Carmo, M.; Pivovar, B.; Bornstein, M., Perspectives on Low-Temperature Electrolysis and Potential for Renewable Hydrogen at Scale. Annual Review of Chemical and Biomolecular Engineering 2019, 10 (1), 219-239.Klose, C.; Trinke, P.; Böhm, T.; Bensmann, B.; Vierrath, S.; Hanke-Rauschenbach, R.; Thiele, S., Membrane Interlayer with Pt Recombination Particles for Reduction of the Anodic Hydrogen Content in PEM Water Electrolysis. J. Electrochem. Soc. 2018, 165 (16), F1271-F1277.Baker, A. M.; Babu, S. K.; Mukundan, R.; Advani, S. G.; Prasad, A. K.; Spernjak, D.; Borup, R. L., Cerium Ion Mobility and Diffusivity Rates in Perfluorosulfonic Acid Membranes Measured via Hydrogen Pump Operation. J. Electrochem. Soc. 2017, 164 (12), F1272-F1278. Ayers, K.; Danilovic, N.; Ouimet, R.; Carmo, M.; Pivovar, B.; Bornstein, M., Perspectives on Low-Temperature Electrolysis and Potential for Renewable Hydrogen at Scale. Annual Review of Chemical and Biomolecular Engineering 2019, 10 (1), 219-239. Klose, C.; Trinke, P.; Böhm, T.; Bensmann, B.; Vierrath, S.; Hanke-Rauschenbach, R.; Thiele, S., Membrane Interlayer with Pt Recombination Particles for Reduction of the Anodic Hydrogen Content in PEM Water Electrolysis. J. Electrochem. Soc. 2018, 165 (16), F1271-F1277. Baker, A. M.; Babu, S. K.; Mukundan, R.; Advani, S. G.; Prasad, A. K.; Spernjak, D.; Borup, R. L., Cerium Ion Mobility and Diffusivity Rates in Perfluorosulfonic Acid Membranes Measured via Hydrogen Pump Operation. J. Electrochem. Soc. 2017, 164 (12), F1272-F1278. Figure
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Accelerated Stress Testing (AST) Protocol Development for Heavy-Duty Fuel Cells
No full textAbstract:
Polymer electrolyte membrane fuel cells (PEMFCs) are promising for heavy duty applications due to their unique scalability in terms of both power and energy [1], and the U.S. Department of Energy (DOE) established the Million Mile Fuel Cell Truck (M2FCT) consortium in 2020 to advance fuel cell truck R&D[2, 3]. The 2025 end-of-life (EOL) target of M2FCT is to achieve 2.5 kW/gPGM at 0.7 V after 25, 000 hour-equivalent accelerated durability test. Several novel materials have been developed and integrated into membrane electrode assemblies (MEA) and catalysts that meet the EOL target after 90,000 potential cycles in H2/N2 have been reported. However, these reports do not imply that the M2FCT 2025 target has been met since development of the durability protocol and lifetime prediction models for heavy-duty fuel cells are ongoing efforts. The tentative heavy-duty MEA accelerated stress test (AST) protocol consists of H2/Air potential cycling under elevated temperature (90 °C) [4], which the consortium is still actively refining based on the feedback received from the AST Working Group (ASTWG).
In this talk, we will systematically summarize the results from the 500-hour H2/Air testing MEA AST, together with various characterization results from microscopy and X-ray analysis, as well as nondispersive infrared to measure support carbon corrosion and fluoride emission rates to measure membrane degradation. With better understanding of the degradation for each component under different testing conditions, we will illustrate the effect of RH (30%, 50%, 90%, and 100%) on the degradation rates of the membrane and catalyst and explain the rationale behind the proposed MEA AST protocol. The degradation rates from the MEA AST protocol were fit into lifetime prediction models and acceleration factors were calculated based on different RHs and cathode catalyst loadings. Refinement of the protocol based on feedback received will also be briefly introduced.
Acknowledgment:
We acknowledge the financial support for this work from the U.S. DOE) Hydrogen and Fuel Cell Technologies Office (HFTO) through the M2FCT consortium, technology managers Greg Kleen and Dimitrios Papageoropoulos.
References:
David A. Cullen, K. C. Neyerlin, Rajesh K. Ahluwalia, Rangachary Mukundan, Karren L. More, Rodney L. Borup, Adam Z. Weber, Deborah J. Myers, and Ahmet Kusoglu, New roads and challenges for fuel cells in heavy-duty transportation. Nat. Energy, 2021. 6(5): 462-474.
Million Mile Fuel Cell Truck (M2FCT) Consortium Launched. 2020; Available from: https://millionmilefuelcelltruck.org/news.
DOE Launches Two Consortia to Advance Fuel Cell Truck and Electrolyzer R&D. 2020; Available from: https://www.energy.gov/eere/articles/doe-launches-two-consortia-advance-fuel-cell-truck-and-electrolyzer-rd.
Accelerated Stress Testing (AST) Protocols for Heavy-Duty Fuel Cells. 2024; Available from: https://millionmilefuelcelltruck.org/ast-protocols
Effect of Hygrothermal Ageing on PFSA Ionomers' Structure/Property Relationship
No full textPerfluorosulfonic-acid (PFSA) membranes are frequently subjected to high humidity and temperature cycles during fuel-cell operation. It is of great interest to understand how the properties of the membrane change with ageing conditions and time. In this study, we investigate how the properties of as-received and pretreated Nafion membranes change after exposure to hygrothermal ageing, including the chemical structure, mechanical properties, water uptake, ionic conductivity, and morphology. Our findings demonstrate that anhydrides form during ageing via a condensation reaction, which results in chemical crosslinks that impair the membrane functionalities by reducing water uptake and conductivity and increasing the storage modulus and α relaxation temperature. In addition, a membrane aged in a 75% relative humidity environment exhibits more dramatic changes compared to that aged in 100% conditions. It is also shown that the impact of ageing can be recovered through a post-treatment by boiling the membrane in strong acid
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(Invited) Membrane Degradation in Polymer Electrolyte Membrane Fuel Cells for Heavy Duty Applications
No full textPolymer electrolyte membrane fuel cells (PEMFCs) are being considered for heavy duty applications, and the DOE has established various performance and durability targets to enable their adoption.1. The key differences between light and heavy-duty application of fuel cells is their increased durability and operating efficiency requirements for heavy duty applications when compared to the lower cost requirement for light duty applications. While higher catalyst loadings can be utilized to increase the fuel cell performance and catalyst lifetime, membrane durability could be a significant outstanding challenge. Membranes are expected to last 25,000 hours to 30,000 hours for heavy duty applications and the Million Mile Fuel Cell Truck Consortium (M2FCT) is evaluating various membrane technologies for use in heavy duty drive cycles. Current state of the art membranes with both mechanical and chemical stabilization have already met light-duty durability requirement of 5000+ hours and have the potential to meet 25,000+ hour lifetimes. This talk will describe the various membrane related accelerated stress tests (ASTs) developed by the consortium and will present membrane durability results obtained from long-term (500 hours) fuel cell operation at elevated temperature (90 oC). Both the mechanical and chemical durability of membranes will be discussed with particular emphasis and fluoride emission rates (FERs) and lifetime predictions.
Acknowledgement:
This work was supported by the Hydrogen and Fuel Cell Technologies Office (HFTO), Office of Energy Efficiency and Renewable Energy, US Department of Energy (DOE) through the Million Mile Fuel Cell Truck (M2FCT) consortia, technology managers G. Kleen and D. Papageorgopoulos.
References:
1.https://www.hydrogen.energy.gov/pdfs/19006_hydrogen_class8_long_haul_truck_targets.pd
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Ce Cation Migration and Diffusivity in Perfluorosulfonic Acid Fuel Cell Membranes
No full textA hydrogen pump experiment was utilized to simultaneously determine the migration and diffusivity of Ce ions in perfluorosulfonic acid (PFSA) ionomer membranes over a range of temperatures and relative humidities. Ce ion migration profiles were quantified as a function of charge transfer through the cell using X-ray fluorescence (XRF). Competing transport phenomena were decoupled by fitting XRF profile data with our previously-developed one-dimensional model, which was updated with improved conductivity and water uptake relations. Measured transport values showed good agreement with the Einstein relation and Okada transport theory, implying that conductivity can be used to estimate migration and diffusivity of cations in other cation/PFSA systems. Results presented here may be used to populate device-level models in order to further understand the effects of cation transport on fuel cell performance and durability to determine the mitigation controls for cation stabilization
(Invited) Membrane Degradation in Polymer Electrolyte Membrane Fuel Cells for Heavy Duty Applications
No full text
