bluuebunny/crossref_metadata_2025 huggingface dataset:
Anode Catalyst Layers for AEM-WE: Implementation, Characterisation and Evaluation of Different Synthesis Routes
Authors: Kaufmann Bastian , Hesse Miriam , Pilaski Moritz , Berger Maike , Palkovits Stefan , Palkovits Regina , Welters Martin , Cremer Rainer
Published: December 2024

The global energy sector's transformation and requisite technological shifts present an unprecedented challenge for politics, industry, and research. Green hydrogen, produced through water electrolysis, is pivotal for storing fluctuating renewable electricity and decarbonizing power demanding industries (e.g. steel production). Current electrolysis technologies do not achieve high efficiencies or require critical materials such as iridium, titanium or flourinated polymers. For these reasons, alkaline electrolyte membrane water electrolysis (AEM-WE) has garnered increased attention from industry and research in recent years. The technology involves many construction principles and advantages of the PEM-WE without its disadvantages. However, further research is necessary to understand electrochemical interactions and technical implementation, especially in catalyst-related topics.

In this work, therefore different types of catalyst layers are prepared and characterized. Depending on the catalyst type distinct preparation methods are applied and the resulting layers are evaluated electrochemically. Full cell experiments are conducted with combined membrane electrode assemblies and in conjunction with electrochemical impedance spectroscopy are used to provide information on contact resistance, electrochemical surface area and overall mass activity.

The applied catalytic materials are made by galvanic deposition, corrosion, precipitation and physical vapour deposition of active species on support materials. Based on the employed preparation method the catalyst implementation and subsequent utilization varies. In particular catalysts from precipitation and PVD-coating were studied in terms of deposition configurations, catalyst loading and a comparison to more widespread catalyst systems. Due to the increase of the specific active surface area by the shape of the synthesised core-shell-like particles, even small amounts of active species could be implemented in highly active layers and thus enable high current densities in optimised electrolysers.

Figure 1
(Invited) Understanding the Corrosion of Titanium Porous Transport Layers and Pt Coatings Using Potential and Time-Resolved Inductively-Coupled Plasma Mass Spectrometry
Authors: Myers Deborah J. , Kropf A. Jeremy , Kariuki Nancy N. , Dang Ngoc K
Published: December 2024

Titanium is the state-of-the-art material for porous transport layers (PTLs) for proton-exchange membrane water electrolyzers (PEMWEs) due to its stability and intrinsic electrical conductivity. However, titanium can develop an passivating, insulating oxide layer under the conditions of the PEMWE anode, thus reducing the effective electrical conductivity and cell performance.1 Coating the titanium PTL with platinum group metals is typically used to protect against oxidation.2 The purpose of this work is to investigate dissolution rates of titanium PTLs with and without coatings and of the PGM coatings by measuring the concentrations of metallic species in an aqueous electrolyte as a function of applied potential and environment measured using inductively-coupled mass spectrometry (ICP-MS). Time and potential resolution of the dissolution rates were achieved by coupling an aqueous electrolyte electrochemical flow cell with an on-line ICP-MS. These studies are the basis for establishing the thermodynamic and kinetics of degradation processes to be used for modeling the degradation phenomena as a function of electricity profile at the single cell and stack level. Results of ex situ, post-test and operando X-ray absorption spectroscopy characterization of platinum PTL coatings will also be discussed.

Acknowledgements

This research is supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office under the auspices of the H2NEW Consortium. Argonne National Laboratory is managed for the U.S Department of Energy by the University of Chicago Argonne, LLC, also under contract DE-AC-02-06CH11357.

References

1. Tuan Linh Doan, Han Eol Lee, Syed Shabbar Hassan Shah, MinJoong Kim, Chang-Hee Kim, Hyun-Seok Cho, and Taekeun Kim, Int. J. Energy Res., 45 (2021) 14207.

2. Chang Liu, Meital Shviro, Guido Bender, Aldo S. Gago, Tobias Morawietz, Michael J. Dzara, Indro Biswas, Pawel Gazdzicki, Zhenye Kang, Sarah F. Zaccarine, Svitlana Pylypenko, K. Andreas Friedrich, Marcelo Carmo, and Werner Lehnert, J. Electrochem. Soc., 170 (2023) 034508.
Controlling Current Distributions in a Hydrogen Powered Fuel Cell Hydroxide Exchange Membrane Carbon Capture Device
Authors: Harrington Justin , Setzler Brian P , Yan Yushan
Published: December 2024

Climate change is one of the most pressing social issues in the modern day. CO2 is responsible for most of the greenhouse gases which cause temperature rise. To reach the 1.5 °C temperature rise goal of the Paris Agreement 2-20 gigatons of CO2 will need to be removed from the atmosphere annually1. Direct air capture (DAC) of CO2 is a negative emissions technology which has garnered widespread technological and public interest for its ability to help achieve this 2-20 gigatons of removal. A hydrogen powered fuel cell hydroxide exchange membrane carbon capture (HEMCC) device is a recent electrochemical DAC technology that is capable of continuously capturing CO2 from ambient air at room temperature.

Hydrogen powered HEMCCs capture CO2 using fuel cell chemistries – O2 and H2O present in humidified air react at the cathode with electrons to form hydroxides which then react with CO2 in an acid-base equilibrium to form HCO3
- and CO3
2-. HCO3
- and CO3
2- then move across the hydroxide exchange membrane to the anode where they shift back to CO2 and OH-. H2 supplied to the anode then reacts with the OH- to form H2O and electrons. Electrons move from the anode to the cathode either through an external circuit or, if purposefully shorted to remove the need for extraneous cell hardware, through the membrane itself. If the membrane is purposefully shorted current density is controlled by varying flowrates of H2 to the anode and measuring H2 out of the cell

While purposefully shorting the membrane reduces capital costs, it reduces the CO2 capture efficiency of the HEMCC device. This study focuses on nonhomogeneous current distributions as the cause for the reduced efficiency of the HEMCC device, and how increased kinetic and mass transport overpotentials on the anode can be used to control current distributions within a HEMCC device. By controlling current distributions efficiency can be increased to be comparable to that of a non-shorted HEMCC device.

Ozkan, M., Nayak, S. P., Ruiz, A. D. & Jiang, W. Current status and pillars of direct air capture technologies. iScience
25, 103990 (2022).
Iridium Thrifting and Circularity: Perspective, Progress, and Demonstration from an OEM
Authors: Motz Andrew R , Carmo Marcelo , Capuano Christopher B. , Ayers Katherine E.
Published: December 2024

Proton exchange membrane water electrolysis (PEMWE) is a technology that has promise to help decarbonize the hydrogen sector and thus has recently been receiving significant attention. Incentives across the globe, including in the Hydrogen Hubs in the US and the European Hydrogen Bank, have been announced to support early projects and catalyze the industry. The PEMWE market growth was already starting due to recent technological advances and these incentives are helping further accelerate the industry. This acceleration is evident by the number of press releases on manufacturing capacity expansion and large projects being announced. With this market expansion, the industry will inherently demand more iridium – currently the only commercially viable OER catalyst for PEMWE. The mantra of reduce, reuse, and recycle is being applied to iridium where iridium thrifting (reduce) and circularity (recycle) are focal points.

The first part of this talk will focus on iridium thrifting. Simply reducing the catalyst loading with today’s baseline technology results in performance and durability loss; therefore, advanced materials and technology must be developed to realize the iridium thrifting goals. Performance and durability data will be presented for state-of-the-art catalyst that enable low iridium loadings. The second part of this talk will cover iridium circularity. Various recycling streams exist including manufacturing waste, manufacturing scrap, and end-of-use devices from the field. The value recovery for each of these waste streams will be discussed and data demonstrating full circularity will be presented.
Improved Water Management in Polymer Electrolyte Fuel Cells Utilizing Hybrid Flow Field
Authors: Kim Choeun , Na Youngseung
Published: December 2024

Polymer electrolyte fuel cells (PEFCs) offer a promising alternative energy source for vehicle applications due to their rapid response and moderate operating temperatures. Bipolar plates in the fuel cell stack play a critical role in distributing reactants and collecting products within the cell. Conventional parallel flow field often encounters maldistribution issues, necessitating wide distribution zones. In contrast, serpentine flow field offers even flow distribution but are unsuitable for automotive applications due to high parasitic power requirements to overcome pressure drops. In this study, a hybrid flow field that combines parallel and serpentine designs is introduced to achieve uniform reactant distribution without the need for expansive distribution zones. Through comprehensive electrochemical experiments including polarization curve analysis and electrochemical impedance spectroscopy, the hybrid flow field significantly enhances flow distribution, resulting in higher peak power density and improved stability under high relative humidity and current density conditions. Notably, the hybrid flow field effectively manages water discharge, crucial for maintaining stable cell performance. Furthermore, the findings highlight the impact of flow rate and relative humidity on internal reactant distribution and product discharging, subsequently influencing membrane humidification. Specifically, balanced relative humidity between the anode and cathode enhances membrane humidification, leading to reduced ohmic resistance. This improvement highlights advantages of the hybrid flow field in reactant distribution and water management within PEFCs, offering promising prospects for efficient energy conversion for automotive applications.
Enhanced Durability and Performance of SOEC Stacks at Intermediate-Low Temperature Operation
Authors: Park Hunmin , Kim Sun-Dong , Choi Yoonseok
Published: December 2024

Recognizing the urgent need for sustainable and efficient energy technologies, we have investigated the durability of Solid Oxide Electrolysis Cells (SOECs) over a demanding 1000-hour period at a constant temperature of 650°C. A key discovery was that SOECs equipped with advanced conductive coatings on the separators exhibited a significantly lower degradation rate(-0.7%) compared to traditional cells(29.0%). Cells using these coated separators maintained structural integrity and demonstrated excellent performance at low voltages.

Testing under stringent conditions highlighted the exceptional durability of the coated separators, which is essential for large-scale hydrogen production. The low degradation rate and consistent voltage demonstrate the revolutionary potential to enhance the stability and long-term efficiency of SOECs operated at 650°C.

This research proves the critical importance of separator coatings in developing SOECs that perform operate continuously and perform excellently at low voltage levels in intermediate-low temperature conditions. This study is significant as it presents the first instance of a 650°C operating SOEC stack capable of stable, long-term operation over 1000 hours. Such advancements support the introduction of SOECs into the clean energy market and set the stage for the next generation of technologies essential for a sustainable energy future.
Advanced Bipolar Plates for the Next Generation PEM Water Electrolyzers: Flow-Field Design, Fabrication, and Optimization
Authors: Perkins Ethan Matthew , Bonville Leonard J. , Maric Radenka , Bliznakov Stoyan
Published: December 2024

Flow-fields, responsible for distributing reactants, like water for electrolysis, evenly across the active area of the cell as well as removing by-products, are key to achieving high efficiency and longevity in proton exchange membrane water electrolyzers (PEMWEs). Current problems include the complex interplay between fluid dynamics and electrochemical reactions leading to uneven distribution of reactants, which can cause hot spots and accelerated degradation of the cell components. Furthermore, the geometry of flow channels can result in increased pressure drop and higher energy consumption for the pumping of reactant fluids, directly impacting the overall efficiency and scalability of the technology.

For PEMWEs, hydration of reaction sites in the membrane is a crucial factor that significantly influences their efficiency and performance. This study explores the rapid production and testing of multiple novel flow field geometries, each designed to increase cell performance due to multiple different factors. Each flow-field is designed, fabricated, and tested with a state-of-the- art MEA at operating conditions typical for an industrial electrolyzer. The performance of each flow-field design is compared against all other designs explored. Critical information about the impact of the pressure drop and the flow-field contact area upon the electrode is collected. Using this data, the performance of various flow-field designs is derived and discussed in this work.
(Invited) Optimised PEM Electrolyzer Bipolar Plates for MW Stacks Enabling Efficient Operation and Industrial Manufacturing
Authors: Bouwman Peter Jaime
Published: December 2024

Green Hydrogen production has been allocated an important role as part of energy transition strategy to reduce our CO2 footprint. Electrolyzer stacks have been developed and commercialized to convert pure water into hydrogen and oxygen. Large multinational companies have now entered the “field of hydrogen” with the intent and capacity to industrialise and automate stack manufacturing, thus bringing down costs through the economy of scale.

Our core strength is focused around the bipolar plate design, material choice and protective coating types, for application in an optimized water-electrolyzer stack for PEM or AEM applications. Schaeffler [1] is driving additional technological development projects with strong financial backing of European (CHP) and German funding (H2Giga). PEM water electrolysis is regarded as powerful technology, bringing advantages of limited installation footprint, broad range of operating conditions, especially in terms of dynamic load range and featuring high efficiency between 75-90% (based on HHV) [2].

In this work we estimate how much the stack technology can be improved further by leveraging formed BPP metal structures and optimizing the structural elements and component design using CFD. Especially when scaling stack hardware to larger capacity, there is much emphasis on enhanced thermal management to avoid hot-spots and mitigate non-uniform degradation mechanisms and premature stack failure. Simulation results will show how flow designs could be adapted maintain uniform conditions when scaling up the active area or adding more cells to the stack.

Simulation results will be compared with operational stack data for small screener stacks up to large MW-level cell platforms. We show how we can optimize flowfield flow structures, staying within the manufacturing limits of the material at hand, being titanium or stainless steel. Both processes rely on simulation software [3] to answer many critical questions, including how to identify the most influential parameters for hydrogen production, for example: current density regime, pitch between plate, the temperature of the feedwater, or the outflow water. Also, if there is a separate cooling loop available, we demonstrate what the ultimate thermal control solution could look like to save cost and gain operational lifetime.

The hydrogen economy benefits most from accelerating our iterative pathway towards an optimum BiPolar Plate design comprising a structured flowfield for uniform flow distribution and a material composition bringing overall cost/performance benefits. Once the industry has agreed upon a standardized electrolyzer stack geometry, our combined economy of scale will have a greater positive impact on the business case.

References

[1] K. Rosenfeld, The Stern Stewart Institute, periodical #27 (2023) 20-27.

[2] Y. Wang et.al., Energy Environ. Sci., 15 (2022) 2288-2328.

[3] P. Lyubarskyy, interview Imagining a Hydrogen-Powered Future Thanks to Simulation, (2023).

Figure 1
Time and Potential-Resolved Studies of Bipolar Plate Corrosion for Polymer Electrolyte Membrane Fuel Cells
Authors: Kariuki Nancy N. , Dang Ngoc K , Myers Deborah J. , Papadias Dionissios , Ahluwalia Rajesh
Published: December 2024

Stainless steels are regarded as the reference materials for metal bipolar plates for polymer electrolyte membrane fuel cells (PEMFCs) due to their low cost and weight, high electrical conductivity, flexural strength, ease of machining, and ability to be formed into thin sheets. The main drawback is their susceptibility to corrosion in typical acidic, oxidizing environments of PEMFCs, 1,2,3 which can degrade the performance of the plate and other components of the PEMFC. The simultaneous presence of iron ions released by corrosion of the BPP and hydrogen peroxide is responsible for hydroxyl radical production, resulting in degradation of the membrane and cathode catalyst layer ionomer.4 Applying a protective coating to the metal bipolar plates is an effective way to improve its corrosion resistance.5 This work investigates corrosion rates of SS316L bipolar plates on the basis of the measured concentrations of cations (e.g., Fe, Cr, and Ni) in an aqueous electrolyte as a function of applied potential and corrosion environment.

Techniques employing electrochemical flow cells (EFC) directly coupled to an inductively-coupled plasma mass spectrometer (ICP-MS) allow for more precise time- and potential-resolved detection of dissolved species. This work will report real-time data on leaching of Fe, Cr, and Ni from SS316L substrates subjected to potential cycles using a flow-through electrochemical cell coupled with an on-line ICP-MS instrument, with sub-part per billion (ppb or μg/L) sensitivity, providing the ability to resolve dissolution during potential scans. The results of this work provide a baseline for studying the efficacy of stainless steel bipolar plate coatings in mitigating degradation of PEMFCs.

References

Leng, P. Ming, D. Yang, C. Zhang. J. of Power Sources 451, (2020) 227783.

Kumagai, S.-T. Myung, T. Ichikawa, H. Yashiro, Y. Katada, J. Power Sources 202 (2012) 92.

D. Papadias, R. K. Ahluwalia, J. K. Thomson, H. M. Meyer III, M. P. Brady, H. Wang, J. A. Turner, R. Mukundan, R. Borup. J. of Power Sources 273 (2015) 1237.

Elferjani, G. Serre, B. Ter-Ovanessian, B. Normand. International Journal of Hydrogen Energy 46, (2021), 32226-32241.

Liu, Q. Jia, B. Zhang, Z. Lai, L. Chen. International Journal of Hydrogen Energy 47, (2022) 22915.

Acknowledgements

This research is supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office under the auspices of the M2FCT consortium. Argonne National Laboratory is managed for the U.S Department of Energy by the University of Chicago Argonne, LLC under contract DE-AC-02-06CH11357.
Optimization Potential for Operating PEMFC Systems Under High-Altitude Conditions
Authors: Murschenhofer Dominik , Settele Jonas , Stengele Simon , Bänsch Cornelie
Published: December 2024

The PEMFC technology is on the rise to be implemented as climate neutral power source in next generation aircraft. Despite the PEMFC’s high efficiency at ground level, it suffers from severe power losses when it is operated under high-altitude conditions, i.e. low ambient pressure and temperature.

In this study, a fuel cell system consisting of a 120 cells PEMFC stack, an air blower, an anode recirculation pump and a cooling unit is investigated experimentally inside an altitude test chamber, where the ambient pressure and temperature can be controlled. In an extensive parameter study, the fuel cell’s cathode stoichiometry and the stack temperature are varied while the system is operated at different average cell voltage levels under high-altitude conditions. The ambient pressure is varied between 1000 and 500 hPa, the latter corresponding to an altitude of 5600 m. The air blower inflow temperature is varied between 40 and -30 °C. By means of statistical design of experiment methods an empirical model is derived from the measurements, which represents the system performance depending on the five-dimensional parameter space, i.e. cathode stoichiometry, stack temperature, average cell voltage, ambient pressure and blower inflow temperature.

The model is evaluated in order to identify the optimal parameter configurations for stoichiometry and stack temperature control, yielding the maximum system net power at high-altitude operation. The results show that the negative effects in terms of power losses due to low ambient pressure prevail over low air temperature. However, the low temperature is non-negligible in terms of the air density, affecting the required blower power to maintain a certain stoichiometry and consequently also affecting the system net power. When operating at high-altitude conditions with optimized control parameters, the resulting net power output is significantly higher compared to the net power output obtained with the default control parameters suggested by the manufacturer. The main reason for this power increase can be found in the optimized membrane humidification. Under high-altitude conditions, humidification becomes more sensitive to deviations from the identified optimal control parameters. The results highlight the large optimization potential through altitude-adaptive control of fuel cell systems for aviation applications.
Degradation Analysis of a PEMFC System Operated Under High-Altitude Conditions
Authors: Settele Jonas , Bänsch Cornelie , Murschenhofer Dominik
Published: December 2024

The development of powertrains for upcoming regional aircraft based on polymer electrolyte membrane fuel cells (PEMFCs) opens a promising pathway to decarbonize the aviation sector. However, operating PEMFC systems under high-altitude conditions poses significant challenges, as performance, efficiency, and durability are affected due to the decreased ambient pressure and colder temperatures. To meet the durability requirements of aircraft components and ensure the economic competitiveness of PEMFCs, lifespan extension by mitigating degradation effects deserves high attention.

In this study, a comprehensive experimental degradation analysis is performed by operating an entire fuel cell system inside a temperature-controlled low-pressure chamber. The system under investigation is a self-humidifying 120 cells PEMFC stack, equipped with additional balance-of-plant components including an air blower, a recirculation pump, and a cooling unit. In course of several characterization test campaigns, the non-pressurized PEMFC system is operated for approximately 600 hours at various ambient conditions. These conditions include ambient pressures from 1000 to 500 hPa, corresponding to altitudes ranging from sea level to 18300 ft (5600 m), respectively. The air blower intake temperatures are varied from 40 to -30 °C. To keep track of the system degradation, standardized preconditioning procedures are performed at the beginning of each testing day. During the test campaigns, polarization curves are recorded on a regular basis. In order to remove reversible degradation, reconditioning procedures involving cyclic current jumps are conducted approximately every 100 hours of operation.

The impact of the various environmental conditions on the degradation behavior of the system is evaluated, with particular focus on the sensitivity to reduced ambient temperature and pressure. For the recovery of reversible voltage losses, reconditioning methods are considered to be essential and their applicability to industrial processes is assessed. Preliminary results suggest that operation at high-altitude conditions severely affects the membrane humidification and thus leads to accelerated degradation. However, by adjusting the key control parameters related to water management, such as cathode stoichiometry and stack temperature, the durability may be improved. As a consequence, it is shown, that implementing control strategies optimized for high-altitude operation is crucial not only for performance improvement but also for mitigating excessive degradation.
Dynamic Modeling of Polymer Electrolyte Membrane Water Electrolysis System and Dynamic Response
Authors: SHIN Hee-Sun , Jang Dohyung , Kim Kyong-Hwan , Lim Chang Hyuck , Kang Sanggyu
Published: December 2024

Water electrolysis to produce hydrogen using electric energy is classified into polymer electrolyte water electrolysis, alkaline water electrolysis, solid oxide water electrolysis, and anion exchange membrane water electrolysis according to the type of electrolyte applied. Among them, polymer electrolyte membrane water electrolysis has a lower operating temperature than other types of water electrolysis, and it is possible to operate high-efficiency, high-power density hydrogen production with high current density. In addition, polymer electrolyte water electrolysis has the advantage of fast response to changes in power supply, so empirical studies for green hydrogen production linked to renewable energy are being conducted most actively compared to other water electrolysis. However, research on coupling polymer electrolyte water electrolysis with renewable energy generation with intermittent and irregular power generation has mainly focused on materials, cells, and stacks. In order to keep the hydrogen production reaction of water electrolysis stack stable under the condition of supply power fluctuation, the peripheral devices should be optimally installed and controlled.

In this study, a dynamic model of a polymer electrolyte water electrolysis system was developed using Aspen HYSYS®. To accurately predict the hydrogen production efficiency, a stack model considering electrochemical reactions and crossovers through the electrolyte was developed and internalized in a spread sheet. A heat exchanger model from the model library was used to simulate dynamic changes in the electrolyte temperature flowing through the water electrolysis stack. The developed stack model was extended to a system model by integrating the feed pump, separator, condenser, heater, and cooling system. The developed water electrolysis system model was simulated in connection with power ramp variations and renewable energy output, and the optimal operation strategy of each module unit was derived to ensure the stability of high-purity hydrogen production under transient conditions.
Dynamic Modeling of PEM Water Electrolysis System Based on Detailed 2-D Stack Model
Authors: Shin Haeseong , Jang Dohyung , Kim Kilwon , Kim Kyonghwan , Kang Sanggyu
Published: December 2024

The green hydrogen, which is produced by water electrolysis directly linked to renewable energy, has been attracting more attention recently. Also, many recent projects are aiming at producing hydrogen directly linked to renewable energy. In the case of such water electrolysis devices, it is difficult to know the physical phenomena inside the water electrolysis stack during operation. Additionally, in the case of operation directly linked to renewable energy, safety problems such as explosions may occur depending on the dynamic responsiveness of the water electrolysis stack. In this study, PEM water electrolysis system modeling based on a detailed 2D stack model was developed and analyzed. The 2-D stack was modeled in two directions: functional direction and fluid inlet/outlet direction. The functional direction separates the stack into bipolar plates, porous Transport Layers, electrodes, catalyst layers, and polymer electrolyte membrane. In this model, Energy, momentum and mass conservation are considered for electrochemical reaction, with two-phase flow of water and generated gases of oxygen and hydrogen to model the bubble effect. Other BOPs such as water pump, and heat exchangers are also modeled dynamically based on physics. When the current density increases rapidly, the temperature inside the stack gradually increases by chemical reaction. Additionally, pressure and gas saturation also change due to changes in production of gases, and these variables affect the stack voltage. The changes in each voltage component are shown in Fig. 1, and from this result, temperature was found to have the greatest influence on voltage change. Using this simulation model, it is possible to see the response and performance of the actual system using the digital twin model.

Figure 1
Computational Modeling of Proton Exchange Membrane Electrolyzer
Authors: Haque Shibanul , Aziz Majid , Alkhaldi Shabeeb Ali , Prasad Ajay Krishna
Published: December 2024

Hydrogen holds great promise to help decarbonize our energy sector. Proton exchange membrane electrolyzers (PEMELs) are undergoing rapid development and deployment for the generation of green hydrogen based on renewable sources of electricity. The inherent capacity of PEMELs to readily respond to fluctuations in electricity input is an added advantage for the generation of hydrogen. PEMEL optimization with regard to materials, component design, and operating conditions is critical for high performance and efficiency. The development of a robust computational model for PEMELs can facilitate not only an improved understanding of the relevant physical and electrochemical phenomena but also help to develop and test effective strategies for performance optimization. The current research is aimed at developing a 3D parallel flowfield channel PEMEL model in COMSOL Multiphysics. To date, results have been obtained for a single-phase model with the baseline operating temperature and relative humidity (RH) of 60°C and 90%, respectively, under the following assumptions: (1) the feed gas (water vapor) is treated as an ideal gas, (2) the flow in the channel is laminar and incompressible, (3) membrane, catalyst layer (CL), and porous transport layer (PTL) microstructures are assumed to be homogeneous and isotropic, and (4) all physical and electrochemical processes are considered to be at steady state. The simulated polarization curve was validated against in-house experimental data for Nafion 115 at 60°C. We then investigated the effect of operating temperature and membrane thickness on current density, overpotentials due to cell resistance, and polarization curves. It was observed that the PEMEL performance improved significantly with temperature, owing primarily to the higher protonic conductivity of the membrane and improved catalyst kinetics. Polarization curves were also obtained for Nafion 212 (50.4 µm) and 117 (178 µm) at 80°C and the thinnest membrane, i.e. Nafion 212, performed better than its thicker counterparts due to reduced ohmic losses. We are currently developing a two-phase flow PEMEL model wherein liquid water is supplied to the anode inlet, and oxygen gas mixed with liquid water emerges from the anode exit. At high current density, oxygen bubbles can obstruct the reactant flow to the anode catalyst layer resulting in suboptimal PEMEL performance. Results will be presented for the dynamics of two-phase flow in a PEMEL system under various operating conditions from which we may draw insights to optimize PEMEL performance.
(Invited) A Retrospective View of the Proton Exchange Membrane Fuel Cell from Renaissance to Commercialization
Authors: Wilkinson David P.
Published: December 2024

Initial development of the proton exchange membrane fuel cell (PEMFC) by General Electric in the 1960s and subsequent development of the technology and materials through into the 1980s showed the possibility of commercial applications. However, application of the technology during this time was mainly limited to the Gemini space program with subsequent shelving of the technology for about 20 years. From the late 1980s onwards there has been increasing activity and progress towards commercialization of PEMFC technology in a number of applications. The advancement of PEM electrolysis has also certainly benefited from earlier work on the PEM fuel cell. In some commercial applications today fuel cell technology is already competitive on an economic basis with established and highly developed incumbent technologies such as combustion technologies and other forms of power generation and storage. However, PEM technology faces other implementation challenges such as distribution and infrastructure availability. As fuel cells and electrolyzers move into full commercialization other new opportunities are arising in connecting the “Chemical Economy” with the “Electricity Economy” such as grid energy storage using power to gas, penetration of renewables into the energy mix, and chemical conversion. This is particularly important for the Net Zero 2050 plan, where fuel cells and electrolyzers along with batteries will be key electrochemical engines for the 21st Century.

Significant progress has been made with the PEMFC over the last 35 years in a number of technical areas including reliability, durability, cost reduction, operational flexibility, technology flexibility and integration, fundamental understanding, and life cycle impact. This presentation will cover some of the key developments and learnings over this period of time and provide perspectives on the progress that has been made towards commercialization. Technical progress would include such important areas as precious metal catalyst loading reduction and alternatives, reformate operation, increased power density, freeze start capability, cell reversal tolerance, and water management. In addition to a retrospective view, some of the potential future research and development directions being taken to modify conventional PEMFC technology will also be discussed.
Proton Solubilities in Candidate Protonic Ceramic Fuel Cell Air Electrode Materials from First Principles
Authors: Fisher Craig Andrew James , Taguchi Ayako , Ogawa Takafumi , Kuwabara Akihide
Published: December 2024

Using a mixed protonic-electronic conducting oxide as the air electrode of protonic ceramic fuel cells is one strategy for increasing their electrical efficiency, as this should enable a larger particle surface area to participate in the oxygen reduction reaction. However, because of their complex defect chemistry, few studies have focused on proton solubility in electrode materials, and hence little is known about which materials are able to absorb sufficient protons to support high conductivity. To help identify materials likely to have both high protonic and electronic conductivity, we performed first-principles calculations of 3d transition metal oxide perovskites LnMO3 (Ln = La, Pr, Nd, Sm, Gd; M = Sc, V–Ni), focusing on their hydration enthalpies calculated according to

H2O+v
O
⋅⋅+OO
×→2OHO
⋅, where v
O
⋅⋅ is an oxide-ion vacancy and the proton bonds to an O atom to form a hydroxide ion, OHO
⋅.

We found that hydration becomes less favorable as the number of 3d electrons increases, i.e., as the M-O bonds become less basic. In contrast, electronic conductivity, as assessed from band structure plots and effective masses, generally increases. By comparing the hydration enthalpy to that of prototypical proton electrolyte BaZrO3, good mixed proton-hole conducting oxides are thus likely to be found using transition metals from the middle of the period (M = Cr–Co) when Ln = La. Smaller lanthanides favor easier hydration, however, so that good mixed conducting perovskites containing Fe, Co, and/or Ni may be achievable using lanthanides Pr, Nd or Sm.

Acknowledgment

This work was performed as part of the Development of Ultra-High Efficiency Protonic Ceramic Fuel Cell Devices project (JPNP20003), commissioned by the New Energy and Industrial Technology Development Organization.
Sr Doped LaScO3 Thin Film As Cathodic Functional Layers for Ni-Fe Metal Supported Protonic Ceramic Fuel Cell Using BaZr0.44Ce0.36Y0.2O3 Film
Authors: Kim HyoYoung , Ishihara Tatsumi
Published: December 2024

Metal support proton conducting fuel cells (MS-PCFCs) is expecting as highly efficient and reliable power generation devices. In this study, porous Ni-Fe alloy support PCFCs was studied using BaZr0.44Ce0.36Y0.2O3 (BZCY) film prepared by pulsed laser deposition (PLD) method. For increasing power density, the effects of the La(Sr)ScO3 (denoted LSSc) at the cathodic interlayer were studied. BZCY film was deposited on dense NiO-NiFe2O4 oxide support by PLD, followed LSSc is deposited as a cathode functional layer (CFL). Sm0.5Sr0.5CoO3 (SSC) was used for the cathode, and then NiO-NiFe2O4 was reduced to obtain the porous metal substrate. Humidified H2 and O2 were used for fuel and oxidant, respectively. Metal support BZCY cell was successfully prepared, and open circuit potential (OCV) and maximum power density were 0.99 V and 69 mW/cm2, respectively at 600 ºC. So reasonable power density was achieved on the Ni-Fe support BZCY film. The main potential drop is occurred by ohmic resistance. Effects of the cathodic functional layer were studied, and it was found that La(Sr)ScO3 film at the interlayer between BZCY and SSC was highly effective for increasing the power density of the cell by decreasing IR loss and overpotential. The optimization of LSSc film was performed and the optimum Sr amount was 15 wt % in LSSc film and the thickness was 200 nm. The power density of MS-PCFCs with LSSc15 CFL was 405 mW/cm2 and an open-circuit voltage (OCV) was ca.1.1 V at 600 ºC, as shown in Figure 1. Due to enhanced proton conductivity, interfacial resistance and cathodic overpotential were also decreased. Insertion of LSSc CFL is highly effective for improving the performance of MS-PCFCs.

Acknowledgment; Part of this study was financially supported by New Energy and Industrial Technology Development Organization (NEDO, JPNP20003), Japan

Reference

[1] H. Sumi, H. Shimada, K. Watanabe, Y. Yamaguchi, K. Nomura, Y. Mizutani, R. M. Matsuda, M. Masashi, K. Yashiro, T. Araki, Y. Okuyama, J. Power Sources 2023, 582, 233528

[2] A,Y. Stroeva, and V. P. Gorelov. Russian Journal of Electrochemistry 2012, 48, 1079-1085

Figure 1
(Invited) Interface Engineering to Operate Reversible Protonic Ceramic Electrochemical Cells below 500 °C
Authors: Choi Mingi , Kim Donguk , Lee Tae Kyeong , Lee Jaeyeob , Yoo Hyun Sik , Lee Wonyoung
Published: December 2024

The low-temperature (< 500 °C) operation of reversible protonic ceramic electrochemical cells (PCECs) is desirable in achieving efficient and sustainable electricity generation, as well as green hydrogen production. However, significant interfacial resistance, which contributes to both ohmic and polarization resistance, remains a hurdle in lowering the operating temperature. In this study, we introduce PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) and BaZr0.4Ce0.4Y0.1Yb0.1O3-δ(BZCYYb) mono-grain composite interlayers, which significantly extend the electrode/electrolyte interface and increase the concentration of vertically aligned oxygen vacancies along the heterointerface. This unique design achieves the lowest ohmic and polarization resistances among previously reported values in solid electrolyte-based electrochemical cells. As a result, the PCEC can operate at extremely low temperature of 350 ℃ with an exceptional peak power density of 0.50 W/cm2 in fuel cell mode and current density of 0.25 A/cm2 at 1.3 V in electrolysis cell mode. Furthermore, it demonstrates high energy conversion efficiency and excellent stability under static and dynamic operating conditions.
Operando High Temperature XRD Study of Oxygen Electrodes during SOEC Operation
Authors: Marina Olga A , Coyle Christopher , Karki Surendra B
Published: December 2024

In this work, we attempt to correlate SOEC device performance with the properties of cell materials under real operating conditions. Operando high temperature X-ray diffraction (XRD) characterization of the oxygen electrodes was performed during actual SOEC operation in real time, at high temperatures, using the real reactive gases atmospheres, for up to 1000 hours.

State-of-the-art Ni-YSZ electrode supported SOECs were fabricated using Ni-YSZ hydrogen electrodes, 8YSZ electrolyte, GDC barrier layer, and LSCF-based electrodes. Cells were tested in potentiostatic and galvanostatic modes with 50% steam and 50% hydrogen fed to the hydrogen electrode vs ambient air at 750 and 800oC. Current or voltage were recorded in time, and electrochemical impedance data were collected periodically to monitor the changes in cell ohimic and polarization resistances. XRD scans covering 25 to 85° 2θ with 0.02° steps and a 1.1 second count time per step were initiated every hour. The resulting XRD patterns were processes to identify time-dependent changes in the oxygen electrode. The results revealed chemical changes in the LSCF phase such as appearance of FeOx/CoOx phases and further LSCF phase transition that could help to explain observed cell performance losses in time. Operando measurements allowed for real time chemical phase diagnostics and helped reveal new insights about SOEC degradation mechanisms that are difficult to explain by only post-test SEM/EDS characterization.
Microstructure-Based Modeling of Inner Oxygen Pressure in Solid Oxide Electrolysis Cells: Analysis of Electrode Delamination and Mitigation
Authors: Xue FEI , Lei Yinkai , Cheng Tianle , Yang Tao , Epting William K. , Abernathy Harry W. , Wen You-Hai
Published: December 2024

One major degradation mechanism during long-term operation of solid oxide electrolysis cells (SOECs) is delamination of oxygen electrodes. The driving force for the electrode delamination could be the generated inner oxygen pressure near the electrode-electrolyte interface. Here a microstructure-based electrochemical model, which includes the conduction of electrons and oxygen ions coupled with Butler-Volmer-type chemical reactions at triple-phase-boundaries (TPBs), is employed to investigate the oxygen pressure in lanthanum strontium manganate (LSM)-based SOECs. The model is applied to both two-dimensional (2D) preset microstructures and three-dimensional (3D) realistic microstructures, and the oxygen pressure is analyzed as a function of transport properties and electrode thickness under both potentiostatic operation and galvanostatic operation. The results based on a 2D preset microstructure are shown in the figure. The simulation results suggest the following conditions to suppress electrode delamination under potentiostatic operation: (1) the ionic conductivity of the electrolyte either smaller than a certain threshold or higher than another value; (2) larger ionic conductivities of LSM and yttria stabilized zirconia (YSZ) in the oxygen electrode; (3) smaller ionic conductivity of YSZ in the hydrogen electrode; (4) thicker electrolyte; and (5) thicker oxygen electrode. On the other hand, under galvanostatic operation, the following conditions are favored: (1) larger ionic conductivity of YSZ in the electrolyte and oxygen electrode; (2) larger ionic conductivity of LSM; (3) thinner electrolyte; and (4) thicker oxygen electrode. The simulation results are compared to the analytical solutions of an electrochemical model based on equivalent circuits. With the calculated oxygen pressure as input to a phase-field fracture model, crack initiation and growth at the electrode-electrolyte interface are demonstrated in the simulation results.

Figure 1
(Invited) Understanding the Degradation of Oxide Ion Diffusivity in YSZ Electrolyte for Practical SOC
Authors: Kishimoto Haruo , Bai Qingchuan , Bagarinao Katherine Develos , Ishiyama Tomohiro , Yamaguchi Takuya , Yamaguchi Toshiaki
Published: December 2024

Yttria-stabilized zirconia (YSZ) is the most common and the most reliable electrolyte material for solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs), collectively referred to as solid oxide cells (SOCs). Typical SOCs for practical applications are of the fuel-electrode-supported cell variety because these type of cells could be operated under high current densities. Here, the YSZ electrolyte is co-sintered with porous NiO-YSZ support at temperatures as high as 1400 °C to obtain dense electrolyte layer on the anode. In this process, NiO is expected to diffuse into the YSZ electrolyte. The influence of dissolved NiO into YSZ electrolyte has been investigated in AIST [1-3]. For the YSZ electrolyte with intentionally dissolved NiO, the phase transformation from cubic phase to tetragonal phase is accelerated in the lower oxygen potential range where NiO is reduced to Ni metal in the YSZ electrolyte, consequently, degradation in the conductivity of YSZ electrolyte occurs. In this study, the influence of co-sintering process of YSZ electrolyte with the NiO-YSZ support, i.e. NiO diffusion into YSZ electrolyte under co-sintering process, and its influence on the oxide ion diffusivity of YSZ electrolyte are examined.

YSZ electrolyte layers were prepared on the NiO-YSZ substrates by screen-printing method or dip-coating method, and then co-sintered at high temperatures between 1370 °C to 1550 °C. The co-sintered YSZ/NiO-YSZ half-cells were reduced under dry H2 flow for 5 to 300 hours. The crystal structure and Ni distribution of the YSZ electrolyte layer were analyzed using Raman spectroscopy and high-spatial-resolution SIMS (secondary ion mass spectrometry), respectively. Lastly, the oxide ion diffusivity of the YSZ electrolyte layer was obtained using the oxygen isotope exchange method and high-spatial-resolution SIMS technique.

By co-sintering of YSZ electrolyte and NiO-YSZ support, NiO uniformly diffused into YSZ electrolyte layer, and the amount of dissolved Ni (NiO) increased with increasing sintering temperature. When the half-cell was reduced at 900 °C, a phase transformation of the YSZ electrolyte was clearly observed, moreover, the oxide ion diffusivity of the YSZ electrolyte also decreased. By reduction of the half-cell at 700 °C, such phase transformation could not be observed, however, the oxide ion diffusivity is slightly but clearly decreased. In the presentation, the mechanisms of phase transformation and conductivity degradation will be discussed.

H. Yokokawa et. al., Fuel Cells, 19 (2019) 311–339.

T. Ishiyama, H. Kishimoto, K. D. Bagarinao, K. Yamaji, T. Horita, H. Yokokawa, ECS Transactions, 78 (2017) 321–326.

T. Shimonosono, H. Kishimoto, M.E. Brito, K. Yamaji, T. Horita, H. Yokokawa, Solid State Ionics,225, 69 (2012).