bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding Durability of Polymer Electrolyte Membrane Water Electrolyzers
Authors: Li Kui , Yu Haoran , Gawas Ramchandra , Cullen David A. , Myers Deborah J. , Kropf A. Jeremy , Sweers Matthew , Mukundan Rangachary , Spendelow Jacob S. , Komini Babu Siddharth
Published: December 2024

Hydrogen is positioned to play a pivotal role in the future energy landscape, bolstered by the increasing adoption of renewable energy sources. The U.S. Department of Energy (DOE) has initiated the Hydrogen earth shot, with a goal of achieving a cost target of $1 per kilogram of hydrogen within a decade. Polymer electrolyte membrane water electrolyzers (PEMWE) are at the forefront of enabling hydrogen production from renewable electricity. Yet, achieving the 80000 h operational lifetime remains a critical challenge for the commercial viability of PEMWE.1 An in-depth understanding of the conditions affecting the degradation of critical PEMWE components including the catalyst layer, membrane, and porous transport layers is crucial for achieving the durability target of PEMWE.

In this study, we explore the effect of various operating conditions, such as temperature, pressure, and cycling vs. hold of voltage or current, and the membrane electrode assembly composition, including catalyst loading, membrane thickness, and incorporation of gas recombination catalyst (GRC), on degradation in PEMWE. To assess the degradation rate, our protocol involved long duration durability tests, alternating between high and low current density cycles with long holding periods and rapid cycling. Electrochemical characterization including polarization curve, electrochemical impedance spectroscopy, and cyclic voltammetry will be presented. Additionally, electron microscopy and X-ray spectroscopy analysis provides insight into changes in the catalyst layer. The second part of the study focuses on understating membrane degradation in PEMWEs. Through periodic analysis of the cathode and anode effluent water during long duration current density holds, the fluorine emission rate (FER) was estimated, a key metric for assessing membrane and ionomer loss. Preliminary investigation reveals that incorporation of GRC in the membrane reduces hydrogen crossover, thereby lowering the FER and the degradation rate. This study enhances our understanding of PEMWE degradation, offering critical data to develop accelerated stress test (AST) protocols.

Acknowledgment:

This research is supported by the U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office through the Hydrogen from Next-generation Electrolyzers of Water (H2NEW) consortium.

Reference:

Tomic, A. Z., Pivac, I., Barbir, F., Journal of Power Sources (2023) 557
How to Assess the Degradation of the PEM Water Electrolysis Anode Catalyst on a Lab Scale?
Authors: Rogler Mirjam , Wagner Richard , Thiele Simon , Suermann Michel
Published: December 2024

Proton exchange membrane water electrolysis (PEMWE) is an established technology to produce green hydrogen. Further improvements in terms of material (cost) reduction, performance, and durability are required to meet the ramp-up targets of a large-scale production of PEMWE stacks and to reduce the levelized costs of hydrogen production. It is key to maintain or even increase the durability of the iridium-based anodic catalyst layer while further reducing its raw metal demand.

Usually, the development of novel materials used as anode catalysts is progressing faster than the evaluation under PEMWE conditions in cell and stack tests. Therefore, accelerated stress tests (ASTs) have to be developed.1, 2 ASTs are degradation mechanism-specific protocols that have a targeted and accelerated effect, and significantly reduce the required test time.

In this work, several voltage-controlled AST protocols and their application in PEMWE cell tests with various anode catalyst types and iridium loadings are analyzed. The AST protocols consist of rapid changes in the voltage between 1.9 V and either 1.25 V, open circuit voltage or 0 V. For reference the voltage is kept constant at 1.9 V. The effects of these protocols on the kinetic parameters of the oxygen evolution reaction (OER), e.g. the apparent exchange current density and the Tafel slope, are evaluated using three different methods. As state of the art, the voltage breakdown analysis (VBA) method is used and directly compared to two other methods, i.e. the constant Tafel slope (CT-VBA)3 method and the OER mass activity method. Furthermore, the influence of dynamic potential profiles on the kinetic overpotential is analyzed with an overpotential difference approach. Depending on the method used, the resulting trends for the OER kinetic parameters diverge. In doing so, we want to raise awareness about the strengths, weaknesses and limitations of each method and their impact of the respective interpretation.4

References

S. M. Alia, S. Stariha and R. L. Borup, J. Electrochem.
Soc.,
166(15), F1164-F1172 (2019).

A. Weiß, A. Siebel, M. Bernt, T.-H. Shen, V. Tileli and H. A. Gasteiger, J. Electrochem.
Soc.,
166(8), F487-F497 (2019).

M. Rogler, M. Suermann, R. Wagner, S. Thiele and J. Straub, J. Electrochem. Soc.,
170(11), 114521 (2023).

M. Rogler, et al., to be submitted.
Optimized Nifemn Layer Double Hydroxide Catalyst Enables Stable and Efficient Seawater Splitting
Authors: Wu Chang , Sharma Shailendra Kumar , Marshall Aaron Timothy
Published: December 2024

In the pursuit of sustainable energy solutions, seawater splitting has emerged as a promising approach to meet the increasing global demand for clean hydrogen fuel. Unlike freshwater resources, which are limited and face competition for various essential purposes such as drinking, agriculture, and industry, seawater offers a vast and readily available source for hydrogen production. However, a significant challenge in seawater splitting arises from the competition between Chlorine Evolution Reaction (ClER) and Oxygen Evolution Reaction (OER), which can impede hydrogen production and compromise catalyst stability. In this study, we developed an efficient NiFeMn LDH material as an anode catalyst for seawater splitting. Our findings demonstrate that the LDH catalyst exhibits robust electrochemical performance in seawater, comparable to its performance in freshwater systems. Furthermore, we utilized in-situ X-ray Absorption Spectroscopy (XAS) to investigate the real-time electronic structure variations of the Ni, Fe, and Mn elements in both seawater and freshwater environments. Notably, the incorporation of Mn dopants was found to play a crucial role in enhancing the stability and performance of the NiFeMn LDH catalyst.
Modeling Gas Bubbles in Water Electrolyzers across Length Scales
Authors: Davis Jonathan T. , Seung Kansas , Guo Jack , Ferron Thomas J , Aydin Fikret , Hammons Joshua Aaron , Lin Tiras Y , Kang Shinyoung
Published: December 2024

As water electrolyzers scale to larger current densities, reactor designs must be re-evaluated to handle the subsequently high rates of gas bubble formation. Without proper transport, gas bubbles can become entrained on the electrode surface, block active sites, and hamper the flow of water and ions. These events decrease the energy efficiency of the electrolyzer, and over time can even lead to the mechanical failure of components within the device. Modeling the transport behavior of gas bubbles can guide the design of electrodes, porous transport layers, and flow fields. Gas bubble transport is notoriously complicated, however, with physical interactions spanning across several length scales and time scales. This talk explores how we can use multiscale modeling tools to deconvolute this problem and improve our understanding of gas transport in electrochemical systems. At the surface scale, we use molecular dynamics simulations to explore the relationship between nanobubbles, surface defects, and dissolved hydrogen. At the continuum scale, a volume of fluid model can be used to explore the relationship between fluid flow and macroscopic bubble transport. Using 3D printing, we can manufacture optically transparent pores to visualize the flow of bubbles to begin validating these models.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Elucidating Degradation Mechanisms through Modeling of Proton-Exchange Membrane Electrolytic Cells
Authors: Karyofylli Violeta , Danner Yannik , Raman K. Ashoke , Hammacher Linus , Kungl Hans , Karl André , Jodat Eva , Eichel Rudiger-A
Published: December 2024

Proton exchange membrane (PEM) electrolytic cells (ECs) have gained significant importance in the realm of hydrogen production. With the increasing demand for commercializing PEMECs, there is a pressing need for enhancing their performance and durability. In addition to experiments, macro-scale modeling plays a pivotal role in comprehending the multi-physics processes within PEMECs.

This presentation highlights the development of physics-based and data-based models tailored for PEMECs. They serve as the foundation for elucidating degradation mechanisms of PEMECs, aiming to prolong their lifespan and improve their efficiency for a quick technology ramp up. These models explore the electrochemical processes and transport phenomena occurring within the porous transport layers (PTLs), catalyst layers (CLs), and the PEM. The high-aspect-ratio PEMECs are well-suited for one-dimensional (1D) analysis [1-3]. The 1D analysis is implemented in Python, with COMSOL also utilized for 2D and 3D simulations.

Unfortunately, the complex nature of PEMECs as thermal, fluidic, and electrochemical systems poses challenges in accurate diagnostics. Modeling these cells involves addressing uncertainties in operational conditions, material properties, and design features. Additionally, uncertainties in experimental data, model selection, parameters, and model inadequacies must be carefully considered during PEMEC modeling. While uncertainty quantification (UQ) and sensitivity analysis (SA) can unveil how uncertainties propagate from input parameters to the output of PEMEC models, UQ has not been extensively integrated into PEMEC modeling. Finally, this presentation underscores the potential benefits of physics-based modeling combined with UQ and SA for PEM electrolysis [3].

Acknowledgment:

Financial support was provided by the German Federal Ministry of Education and Research (BMBF) within the H2Giga project DERIEL (grant number 03HY122C).

Literature:

[1] P. Trinke, 2021.

[2] P. A. García-Salaberri, J. Power Sources, 2022, 521.

[3] V. Karyofylli, Y. Danner, K. Ashoke Raman, H. Kungl, A. Karl, E. Jodat, R.-A. Eichel, J. Power Sources, 2024, 600, 234209.
Influence of Electrolyte Supply Scheme in Anion Exchange Membrane Water Electrolysis
Authors: Ito Hiroshi , Kageyama Akane , Ohtsuka Shyota , Ishida Masayoshi , Tateno Hiroyuki
Published: December 2024

Recently, anion exchange membrane water electrolyzers have been attracting attention as a low-cost, high-performance water electrolysis system. In AEM water electrolysis, although water as fuel is consumed at the cathode, “cathode dry operation”, in which electrolyte solution is supplied only to the anode, can be applied. This operation scheme enables relatively dry hydrogen to be extracted from the cathode and has the advantages of simplifying the hydrogen purification line and facilitating pressurized operation. However, our previous study [1] has shown that cathode dry operation also has the problem of significant mass transfer overpotential due to water transport through the membrane.

In this study, both the bilateral electrolyte supply operation, in which the electrolyte solution is also supplied to the cathode, and the cathode dry operation were applied to the same cell, and the effects of the electrolyte supply scheme on the electrolysis performance were compared and examined.

Acknowledgement

This work was supported partly by the New Energy and Industrial Development Organization (NEDO) through the Advancement of Hydrogen Technologies and Utilization Project (P 14021). The authors wish to express their gratitude to Tokuyama Corporation for their support and helpful advice.

Reference

[1] R. Wang et al., Int. J. Hydrog. Energy, 47, 40835 (2022).
Time and Potential-Resolved Studies of Porous Transport Layers for PEM Water Electrolyzers Using on-Line ICP-MS
Authors: Dang Ngoc K , Kariuki Nancy N. , Myers Deborah J.
Published: December 2024

Proton exchange membrane water electrolysis (PEMWE) is considered a promising technology for widespread hydrogen production from renewable energy sources due to its high efficiency, ability to rapidly respond to changes in variable electricity input, the high purity of the hydrogen produced, and many other advantages. One of the key components of PEMWE cells is the porous transport layer (PTL), which facilitates water transport to and oxygen removal from the anode catalyst layer. The properties of the PTL, such as thickness, porosity, composition and permeability, significantly affect the performance and efficiency of PEMWEs. Titanium is the state-of-the-art material for PTL. In spite of its high corrosion resistance, Ti-PTL on the anode tends to grow a thick oxide layer at the high potentials of the PEMWE anode. The resulting high interfacial contact resistance between the PTL and the catalyst layer leads to a decrease in the overall efficiency of the electrolysis process.1 Coating Ti parts with precious metals such as platinum (Pt) or iridium (Ir) is often used to protect against oxidation. 2,3 Our focus in this work is to study corrosion degradation of the anode Ti-PTL with and without coatings, as well as the corrosion of the coatings.

Inductively coupled plasma mass spectrometry (ICP-MS) connected on-line to an electrochemical flow cell (EFC) provides a highly sensitive technique to analyze the dissolution elements at trace levels (<ppb) under variable experimental conditions. This work will report the impact of several parameters, such as applied potential, potentiodynamic profile characteristics (e.g., hold time, scan rate, upper and lower potential limits), and temperature on the corrosion processes of Ti-PTL with and without coatings and of the Pt and Ir coatings. The corrosion rate data will be used to model degradation mechanism of PTL coatings towards mitigating degradation of PEMWE systems.

References

Prestat. J. Power Sources 2023, 556, 232469.

Liu, M. Carmo, G. Bender, A. Everwand, T. Lickert, J.L. Young, T. Smolinka, D. Stolten, W. Lehnert. Electrochemistry Communications 2018, 97, 96.

S. Gago, S.A. Ansar, B. Saruhan, U. Schulz, P. Lettenmeier, N.A. Cañas, P. Gazdzicki, T. Morawietz, R. Hiesgen, J. Arnold, K.A. Friedrich. J. Power Sources 2016, 307,815.

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 under contract DE-AC-02-06CH11357.
Technoeconomic Analysis and Comparison of PBI-Based Aqueous and Anhydrous HCl Electrolysis Processes
Authors: Felix Olusegun Odunayo , Shimpalee Sirivatch , Meekins Benjamin
Published: December 2024

In this talk, we develop full electrolysis processes, including balance of plant equipment, and compare the economics and production of both a state-of-the-art aqueous HCl electrolyzer and fully anhydrous HCl electrolyzer. We demonstrated recently that a PBI membrane enables the direct electrolysis of anhydrous HCl1,2 , producing separated and high purity hydrogen and chlorine product streams. Development of this process from lab-scale to industrial-scale, however, requires consideration of not just the electrolyzer itself, but also the pre- and post-electrolyzer equipment needed to handle the inlet and outlet material streams. It is also important to compare any newly proposed or demonstrated process to the current state-of-the-art to better understand where the new process either excels or falls short.

Our approach involved developing a full electrolyzer model in Aspen Custom Modeler (ACM), facilitating the comparison of parameters such as single-pass conversion of HCl and current densities across various operating conditions. Notably, this model permits the optimization of operating parameters without presuming fixed conversions, distinguishing it from most models employing Aspen Plus. We also aim to validate this model against our experimental results to assess its accuracy. Furthermore, we conduct a detailed techno-economic analysis of the pre- and post-electrolyzer units, followed by the optimization of post-processing unit operations. Our objective is to identify the most cost-effective and sustainable means of production.

We will show that while the anhydrous electrolyzer, taken alone, requires more input power than its aqueous counterpart, the full anhydrous electrolysis process is both cheaper to build and operate and uses less energy overall. We consider the impact of hydrogen production on the economics of the anhydrous process, and we show how operating the anhydrous electrolyzer at different conversion efficiencies impacts the overall production rate and operating cost. Finally, we will note potential improvements in the anhydrous electrolysis process by identifying equipment that represent major impacts on energy and financial costs.

K. Likit-anurak et al., International Journal of Hydrogen Energy, 47, 26859–26864 (2022).

K. Likit-anurak et al., ACS Appl. Energy Mater., 6, 5429–5434 (2023).
PGM-Free Catalyst Modification for Air-Breathing Stacks
Authors: Kieltyka Mackenzie R. , Singell Julian , Allen Jabari , Rockward Tommy , Kreller Cortney R. , Wilson Mahlon S. , Jernigen Jeremy D. , Borup Rod L.
Published: December 2024

The operation and viability of an air-breathing fuel cell stack will heavily depend on the cleanest available local air, unless its cathode is tolerant to impurities. Previous research on the impact of air impurities showed deleterious impacts on overall performance utilizing platinum catalysts. To date, fuel cell research findings using air impurities employing non-platinum catalysts, platinum group metal-free (PGM-free), is scarce. To test the viability of a PGM-free stack, a miniature four-cell stack with PGM-free catalyst was assembled to compare with results from a standard eight-cell stack Pt-based catalyst, in both H2/Air and H2/O2. A promising open current voltage was obtained, offering a comparable statistic to what would be expected from a platinum-based stack of the same size. Prior research has shown higher performance for PGM-free membrane-electrode assemblies in terms of current density at the desired operating voltage, but significant performance loss after testing indicates poor stability. Repeated testing of the PGM-free stack showed such a decrease in current density performance at designated voltages after initial testing, followed by stability in results. Further testing with exposure to impurities is expected to demonstrate tolerance and reversibility in a PGM-free stack once initial stability is obtained. The purpose of this project is to develop a fuel-cell stack to meet specific power output requirements utilizing PGM-free cathode catalyst.
A Thermodynamic Analysis of a Proton Exchange Membrane Electrolyzer
Authors: Vlachaki Eirini , Lekatsas Konstantinos , Berning Torsten
Published: December 2024

A thermodynamic, first law analysis was conducted to understand the temperature of a proton exchange membrane electrolyzer when operated at a constant voltage and feed water flow rate. It emerged that at certain values for both voltage and flow rate, the electrolyzer could work in two operation modii: a high stoichiometry, low current modus where most of the feed water just flows through the electrolyzer unreacted and the electrolyzer itself remains cold, and the preferred low stoichiometry, high current modus that results in a much higher operating temperature. A start-up procedure has to be developed to activate the latter. Overall, the measured electrolyzer temperatures are in very good agreement with the calculated ones.
Engineering the Diaphragm to Minimize Gas Crossover in Alkaline Water Electrolysis
Authors: Gellrich Florian , Kraglund Mikkel Rykær , Jensen Jens Oluf , Stiesdal Henrik
Published: December 2024

Hydrogen, a versatile energy carrier, is essential for the transition to renewable energy systems. Electrolytically produced hydrogen using renewable sources is a core technology for decarbonizing industries and societies. However, at the end of 2021, electrolysis contributed only about 4% of global hydrogen production [1].

Various electrolytic hydrogen production techniques exist, including Proton Exchange Membrane Electrolysis (PEMEC), Solid Oxide Electrolysis (SOEC), Anion Exchange Membrane Electrolysis (AEMEC), and liquid Alkaline Water Electrolysis (AEL) [2]. AEL is the most mature and scalable technology, and it doesn't require precious metals. However, for efficiencies comparable to other techniques, AEL typically operates at low current densities of 0.2-0.5 A/cm2 (100% of rated current density). A porous diaphragm separates the produced hydrogen and oxygen in AEL.

A key limitation to part-load operation of electrolyzers is hydrogen crossover into the oxygen stream, posing a safety hazard at concentrations exceeding 4%. Diffusion of dissolved gases through the diaphragm is the main crossover mechanism in balanced AEL systems and depends on electrolyte concentration and supersaturation [3]. Therefore, addressing supersaturation can significantly enhance AEL operational flexibility [4]. While crossover is marginally affected by current density, the 2% hydrogen-in-oxygen safety limit necessitates AEL shutdown at roughly 25% of rated current density to prevent hazardous mixtures.

Stiesdal Hydrogen is a climate change company developing next-generation Alkaline Water Electrolysis systems. Our hydrogen electrolyzers operate within a pressure tank, eliminating the need for a hydrogen compressor and enabling direct production at up to 35 bar. To achieve operational flexibility below 25% of rated current density without sacrificing efficiency, we have engineered a novel diaphragm with a pore structure optimized to mitigate gas crossover.

[1] IRENA Hydrogen Overview https://www.irena.org/Energy-Transition/Technology/Hydrogen downloaded on 17/04 2024 08:00 MET

[2] J. Hnát et al 2020 New Perspectives on Hydrogen Production, Separation, and Utilization 91-117

[3] P. Trinke et al 2018 J. Electrochem. Soc.
165 F502

[4] M. T. de Groot et al 2022 Int. J. Hydrogen Energy
47 82
Flow-Field Designs for PEM Water Electrolysis Cells: Performance and Contact Behavior
Authors: Weiland Oskar , Stein Lukas , Venkatesan Prasad , Trinke Patrick , Bensmann Boris , Hickmann Thorsten , Hanke-Rauschenbach Richard
Published: December 2024

Introduction

This study examines the influences of flow field designs on Proton Exchange Membrane (PEM) water electrolysis cells. The flow field structure has an impact on fluid and heat distribution which in turn influences the performance locally [1]. In addition, different designs affect the mechanical compression through the layers. This can lead to unfavourable contacting between the layers, which also affect the cell performance.

Methods

Ten different flow field designs are tested in a 4 cm2 single cell setup. The designs include a variation of parallel channel and rib widths and distances (Fig 1.a), a serpentine channel arrangement (Fig 1.b), planar geometries without connecting channels (Fig 1.c) and block geometries (Fig 1.d). Polarisation curves and high frequency resistance (HFR) are measured and Tafel analysis are done to evaluate the performance. Residual overpotentials including mass transport are extracted. Additionally, pressure measuring films are used to qualitatively measure the mechanical pressure distribution in the membrane-electrode assembly (MEA).

Results

The HFR of the different designs differs by up to 32 %. This is the main driver in the polarisation curve differences shown in Fig. 2. However, it appears that the flow field structure (channel width, channel position) and contact area between end-plate and PTL is strongly affecting the interface of the porous transport layer (PTL) and the MEA in a multiple manner. A poorly designed flow field leads to electrochemically inactive MEA areas, whereas optimal designs benefit from a homogenous mechanical pressure distribution for optimal contact between PTL and MEA. This also influences the residual overpotential in different ways.

References

[1] A. C. Olesen, S. H. Frensch and S. K. Kær, Electrochimica Acta,
293, 476–495 (2019).

The authors gratefully acknowledge funding by BMWK (German Federal Ministry of Economic Affairs and Climate Action) in the framework of the project TICOB (FKZ 03EI3048B).

Figure 1
Baselining Unitized Reversible Fuel Cells with Low Catalyst Loadings: Performance and Durability Insights
Authors: Li Yuanchao , Arman Tanvir Alam , Komini Babu Siddharth , Spendelow Jacob S.
Published: December 2024

Unitized Reversible Fuel Cells (URFCs) combines the functionality of hydrogen fuel cells and water electrolyzers into a single device, offering high energy density for energy conversion and storage. However, their commercial viability is deterred by the high precious group metal (PGM) loadings. Conventional URFCs utilize 1 mg/cm2 of Pt and 1 mg/cm2 of IrO2 in the oxygen electrode, posing economic and sustainability challenges.

This study investigates the performance and durability implications of minimizing PGM loadings in oxygen electrode which utilizes a mixture of IrO2 and Pt black to facilitate oxygen evolution and oxygen reduction reaction respectively. We also examine the effect of the porous transport layer (PTL) morphology and wettability on the URFC performance and durability. Accelerated stress test (AST) protocol was developed to evaluate the performance loss across both fuel cell and water electrolyzer mode of URFC operation. Additionally, this research provides a detailed characterization of loss in active area, change in catalyst layer structural, and PTL wettability offering insights into the degradation mechanism in URFCs.

This study not only establishes a foundational benchmark for understanding the URFC performance and durability at low catalyst loadings but also highlights the critical need for strategic component selection and activation methods to enhance the system's overall efficiency and durability, marking a significant step towards the realization of more sustainable energy solutions.
Assessing the Performance of Gas Diffusion Electrodes: Varying Pt Loading and Manufacturing Techniques
Authors: Rockward Tommy , Singell Julian , Kwei Victoria , Allen Jabari , Ruiz Christian , McBride Michael , Borup Rod L. , Kreller Cortney R.
Published: December 2024

It has been reported that the amount of platinum in a fuel cell electrode can govern performance, cost and durability of the fuel cell stack. This study focuses on utilizing platinum black as the electrochemically active catalyst in an 8-cell miniature fuel cell stack and assessing the minimal electrode loading required to meet specific targeted performance requirements. Unlike typical catalyst, platinum black catalyst is unsupported (i.e. platinum is not decorated on to carbon substrates). A catalyst ink solution is prepared and is dispersed onto a gas diffusion layer (GDL) using either a spray coating instrument or slot die coater as the manufacturing technique to form the gas diffusion electrodes (GDEs). XRF elemental analysis is used to confirm the platinum content. The FC stacks are all assembled with identical materials and components, excluding the GDEs at the cathode. The cathodes were manufactured with different platinum loadings. The stacks are operated in dead-end mode, which means there is no outlet for the fuel and oxidant to exit. Finally, each stack is subjected to an identical test protocol in galvanostatic mode, and the corresponding voltage outputs are compared. The assessment of these results will aid in establishing large scale manufacturing of GDEs.
Investigation of the Effect of Ammonia As Ambient Air Contaminant on PEM Fuel Cell Stack Performance and Degradation Using EIS, Thda and Different Gas Analysis Methods
Authors: Özel Tansu , Bürger Stefan , Cremers Carsten
Published: December 2024

The negative effects of airborne contaminants on polymer electrolyte membrane fuel cell (PEMFC) have already been shown in several publications. [1] Among these contaminants, ammonia (NH3) with its multistep reversible and irreversible effects is particularly significant. Recent studies on air quality in urban areas have revealed a notable increase in ammonia levels within a span of two years. [2] This rapid increase can be attributed to the growing prevalence of EURO-6 diesel vehicles equipped with selective catalytic reduction (SCR) cats, which results in ammonia slip during the nitrogen oxide reduction process in diesel engines. [2]

Ambient air is the most common used oxidant gas in mobile and stationary PEM fuel cell systems. The performance of fuel cell can suffer beyond the oxygen gain from airborne contaminants, which also have the potential to accelerate degradation. To prevent that airborne contaminants reach the fuel cell cathode, air filter systems consisting of particle filter and specially for fuel cell requirements developed filter are installed at the cathode inlet. Despite the installation of an air filter system, airborne contaminants can still reach the fuel cell cathode.

The focus of this investigation is on the effects of ammonia in PEM fuel cell stacks. In contrast to single cell operation, stack operation can introduce additional effects such as cell-to-cell inhomogeneities and varying degrees of ammonia-induced degradation among cells. For the investigation, experiments with a PEMFC stack are going to be done on a fuel cell testbed equipped with an impedance analyzer. Ammonia is going to be mixed into the cathode air in the ppb range. Its effects on PEMFC stack performance are going to be investigated with electrochemical impedance spectroscopy (EIS) and total harmonic distortion analysis (THDA). The cathode exhaust gas is also going to be analyzed by gas analyzers such as FTIR gas analyzer and mass spectrometry.

It is planned to test the PEMFC stack under different operating conditions like temperature, relative humidity and pressure of inlet gases, with various parameters and different cathode gas mix ratios while monitoring possible conversion of impurities via FTIR and the stack state of health using THDA and conventional technologies to understand the link between the effect of ammonia on fuel cell stack performance, on its lifetime and to determine possible early indicators.

References

[1] Misz, U., Talke, A., Heinzel, A., and Konrad, G. 2016. Sensitivity Analyses on the Impact of Air Contaminants on Automotive Fuel Cells. Fuel Cells 16, 4, 444–462.

[2] R. Wegener, U. Javed, R. Dubus, and D. Klemp. 2024. Investigations of Air Quality Aspects with the Urban Climate Model PALM4U.
(Invited) Structure/Transport Relations in Electrolytes: What Have We Learned from Modeling in the Past Quarter Century?
Authors: Paddison Stephen J.
Published: December 2024

The development of highly efficient energy conversion devices that utilize sustainable fuel sources with components that are thermally stable, chemically robust, and economically and environmentally feasible and sensible is an important research trust. The electrolyte in low temperature fuel cells is typically an ion containing polymer: either a proton exchange membrane (PEM) or an anion exchange membrane (AEM). Of the many properties that are critical to the effective function of a membrane as the electrolyte and separator in a fuel cell none is more important than the ionic conductivity. The hydrated morphology of either a PEM or an AEM determines many aspects that govern the transport of species (i.e., H2O, H+(H2O), and/or OH-(H2O)). Transport mechanisms in these soft materials are complex as they involve interactions of the cations and anions, the mobile and tethered ions with the water, and the relaxation dynamics of the polymeric backbones and side chains.

Over the past 30 years, numerous theoretical and computational studies have been undertaken with a focus at understanding ion and water transport in PEMs and AEMS. This talk will attempt to review what has been learned over the past 25 years from modeling and simulation on the connections, correlations, and relations of polymer structure and architecture to transport properties.
(Invited) Investigation of Co-Free Cathode Composited with Proton Conductors for Protonic Ceramic Fuel Cells with Yb-Doped BaZrO3 Electrolyte
Authors: Watanabe Konosuke , Shimada Hiroyuki , Sharma Aman , Fujioka Masaya , Yamaguchi Yuki , Nomura Katsuhiro , Sumi Hirofumi , Mizutani Yasunobu
Published: December 2024

Protonic ceramic fuel cells (PCFCs) are expected to gain significant advantage from the use of Co-free cathodes. This shift can lead to reduced manufacturing costs and enhance durability performance. In our previous study, the investigation compared the power generation characteristics of PCFCs with BaZr0.8Yb0.2O3-δ
(BZYb) electrolytes utilizing cathodes composed of La0.6Sr0.4FeO3-δ
(LSF) as a Co-free cathode material and La0.6Sr0.4CoO3-δ
(LSC) or La0.6Sr0.4Co0.2Fe0.8O3-δ
(LSCF) as Co-containing cathode materials composited with BZYb. Consequently, the PCFC with an LSF-BZYb cathode exhibited lower performance compared to the PCFCs with LSC-BZYb and LSCF-BZYb cathodes due to the higher electrode polarization resistance.

In this study, the challenges associated with achieving high-performance Co-free cathodes that can match the performance of Co-containing cathodes are presented, along with the mechanism to enhance performance. To improve performance, the use of La0.65Ca0.35FeO3-δ
(LCaF), as a Co-free cathode, in addition to LSF, which has been reported to demonstrate high performance in SOFCs, was explored. Additionally, LCaF was composited with BaCe0.7Zr0.1Y0.1Yb0.1O3-δ
(BCZYYb), known for its higher proton conductivity and easier sinterability than BZYb.

When comparing the power generation characteristics of PCFCs with LCaF-BZYb and LSF-BZYb cathodes, the PCFC with LCaF-BZYb cathode exhibited higher ohmic and electrode polarization resistances. These results were attributed to weak adhesion between the electrolyte and cathode, resulting in lower performance than the PCFC with LSF-BZYb cathode.

Furthermore, when comparing the power generation characteristic of the PCFC with a composite cathode of LCaF and BCZYYb with the LCaF-BZYb cathode, the ohmic and electrode polarization resistances were significantly lower. This improvement was attributed to the advanced sintering of BCZYYb and the connected percolation of the proton-conducting network. Consequently, the performance of the PCFC with the LCaF-BCZYYb cathode surpassed that of the LCaF-BZYb cathode and was comparable to Co-containing cathodes such as LSC-BCZYYb cathode.

In conclusion, for Co-free cathodes in PCFCs, it is crucial to composite them with proton conductors possessing better sinterability, such as BCZYYb, to achieve higher performance.

Acknowledgements: This work is based on the results obtained from a project (JPNP20003) commissioned by the New Energy and Industrial Technology Development Organization (NEDO), Japan.
Faradaic Efficiency Acquisition Along with Hydrogen Generation Measurement of Proton Conducting Solid Oxide Electrolysis Cells: Insights from Idaho National Laboratory
Authors: Zhao Zeyu , Deng Hao , Wang Wanhua , Wu Wei , Liu Bin , Ding Dong
Published: December 2024

Proton conducting solid oxide electrolysis cells (p-SOECs) represent emerging technologies for hydrogen production, theoretically capable of yielding pure hydrogen at one electrode without carbon emissions. However, owing to the multi-charge-carrier nature inherent in proton-conducting materials, encompassing protons, oxygen ions, electrons, and holes, thorough evaluation of energy conversion efficiency is imperative to identify promising candidates for practical deployment. Faradaic Efficiency (FE) serves as a crucial parameter delineating the efficacy with which external energy (electrons) is harnessed for the hydrogen evolution reaction. Presently, FE values span a considerable spectrum, despite similar materials and devices being assessed across disparate research laboratories. Consequently, the prevalence of uncertainty and skepticism regarding comprehensive assessments of materials and devices may significantly impede the advancement of p-SOECs. We propose an examination of FE measurement protocols and associated deviations in FE calculations, drawing upon recent practices elucidated by the Idaho National Laboratory. Such an endeavor not only aids newcomers to the field but also furnishes guidance for the comparative analysis of results obtained from diverse laboratory settings and research groups.
Computational Prediction of Proton-Conducting Perovskite Properties Under Realistic Conditions
Authors: Deng Hao , Liu Bin , Ding Dong
Published: December 2024

Measurements of proton-conducting Perovskite properties under extreme conditions remain challenging due to the limitation of experimental techniques. As a powerful tool, molecular dynamic (MD) simulation can provide abundant information on well-defined systems under realistic conditions. However, quantum-chemistry-based MD simulations are computationally expensive, while traditional potentials lack accuracy and training efficiency, especially for multi-element systems like Perovskite. Recently, machine learning potential (MLP) has attracted much attention since this tool empowers MD simulations with accuracy and efficiency. In this presentation, we will discuss the properties prediction of INL-developed benchmarking Perovskite, PrNi1-δCoδO3 (PNC), as an example based on density functional theory (DFT) and a well-trained sparse Gaussian process (SGP) potential. Properties, including expansion, diffusivity, and mechanical properties, which significantly influence the electrochemical cell efficiency and durability, were predicted under extreme conditions. The established protocol provides a versatile avenue for future proton-conducting perovskite investigations.
New Observations on Material Processing and Investigation on Long Term Stability for Proton Conducting Solid Oxide Electrolysis Cells (P-SOEC)
Authors: Wang Wanhua , Wu Wei , Zhao Zeyu , Ding Hanping , Chen Fanglin (Frank) (Frank) , Ding Dong
Published: December 2024

New clean energy technologies with higher energy conversion efficiency and lower emissions are needed to meet the global energy and climate change challenges. As an efficient clean energy conversion device, solid oxide electrolysis cells (SOEC) have emerged as a promising avenue for hydrogen production, garnering considerable attention in recent years. Compared with conventional oxygen ion-conducting SOECs (O-SOECs), proton-conducting solid oxide electrolysis cells (P-SOEC) can operate at a lower temperature (400-600°C) because of the generally lower activation energy associated with proton conduction in oxides compared to oxygen ion conduction, thereby reducing operating costs and the need for high-temperature material technology. Central to the functionality of P-SOECs is the proton-conducting electrolyte, which profoundly influences the electrochemical performance and stability of the cell. Extensive researches have been conducted to develop and design excellent protonic ceramic as electrolyte materials. However, the challenge remains on delivering high conductivity after experiencing the high-temperature ceramic heat treatments. In this work, we reported segregation phenomenon during the aging process of the most employed protonic ceramics and its significant impact on microstructure and conductivity. We also investigate the long term stability of the P-SOEC under varied conditions with different electrolytes.
(Invited) Impact of Sr-Containing Secondary Phases on Oxide Conductivity in Solid-Oxide Electrolyzer Cells
Authors: Rowberg Andrew , Slomski Heather S , Kim Namhoon , Strange Nicholas A. , Gorman Brian , Shulda Sarah , Ginley David , Kweon Kyoung E. , Wood Brandon C.
Published: December 2024

Solid oxide electrolyzer cells (SOECs) are among the most promising devices for producing hydrogen from the electrolysis of water, as they can be operated using excess heat. However, due to their high operating temperatures, they can suffer from materials degradation phenomena, including the segregation of cation species across the cells. Notably, in SOECs based on yttria-stabilized zirconia (YSZ) as the oxide-conducting electrolyte, strontium segregation from the air electrode through the barrier layer toward the electrolyte can lead to the formation of certain unwanted secondary phases, including SrO and SrZrO3.

Here, use density-functional theory (DFT) calculations based on a hybrid functional in conjunction with energy dispersive x-ray spectroscopy (EDS) to characterize these Sr-containing secondary phases and to quantify their impact on oxide conductivity in SOECs. Using our DFT calculations, we calculate the mobility and concentration of oxygen vacancies in each material, which we combine to estimate their oxide ion conductivity. We find that SrO has a low oxide ionic conductivity that will dramatically reduce SOEC performance if it is present in thick, continuous layers. Similarly, we find that SrZrO3 does not have a high conductivity due to low intrinsic vacancy concentrations; however, doping SrZrO3 with yttrium will raise oxygen vacancy concentrations and thereby oxide conductivity, even to the point of parity with YSZ. Yttrium-doping of SrZrO3 is likely, considering that it is present in YSZ alongside zirconium, which reacts with strontium to produce SrZrO3.

Our EDS analysis of post-operando SOECs confirms that Y is present as a majority impurity in SrZrO3 precipitates, while other dopants, which we find will generally reduce oxide conductivity, have significantly lower concentrations. Furthermore, EDS does not reveal large concentrations of SrO, implying that it will not form in sufficiently thick layers to block oxide conductivity, at least until the duration of testing considered here.

Our work provides a comprehensive analysis into the role that Sr-containing secondary phases play in YSZ-based SOECs, along with insights that can be used to engineer better performing and more resilient devices.

Part of this work was performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Part of this work was performed by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308.
(Invited) Degradation Mechanisms and Mitigation Strategies for High-Temperature Solid Oxide Cells
Authors: Yoon Kyung Joong
Published: December 2024

Solid oxide cell technology represents one of the most efficient methods for energy conversion and has been the subject of extensive research over the past few decades. With significant technological progress, solid oxide fuel cells (SOFCs) have made their way into the market, steadily increasing their market share across various sectors for power generation. Additionally, solid oxide electrolysis cells (SOECs) have attracted substantial interest recently as a highly promising method for the clean production of hydrogen and various chemicals. However, the economic competitiveness of SOFCs and SOECs against conventional fossil fuel-based technologies remains a challenge, with cell and stack lifetimes being a critical factor. Operating at high temperatures, both SOFCs and SOECs are prone to various degradation phenomena, which have been a focal point in their development. SOECs operate under an even harsher environment, leading to additional degradation mechanisms beyond those observed in SOFCs. Studying the degradation mechanisms of SOFCs and SOECs is challenging, primarily due to limitations in characterization techniques. However, recent advancements in characterization techniques for high-temperature phenomena, coupled with theoretical modeling tools, have significantly enhanced our understanding. This progress has provided valuable insights into strategies to prolong the lifetime of SOFC/SOEC cells and stacks. This presentation will review recent advancements in degradation studies and discuss mitigation strategies for major degradation issues, including Cr poisoning, electrode delamination, and Ni agglomeration.
Scale-up Synthesis of Oxygen Electrode for Protonic Ceramic Electrochemical Cells (PCECs)
Authors: Li Haixia , Bian Wenjuan , Zhao Zeyu , Zhang Yuchen , Sun Quanwen , Ding Dong
Published: December 2024

Protonic ceramic electrochemical cells (PCECs) have emerged as a promising avenue for electrochemically converting the chemical energy in hydrogen into power through fuel cell mode or hydrogen production in electrolysis cell mode, with notable efficiency. The oxygen electrode within PCECs plays a crucial role in facilitating water oxidation and oxygen reduction reactions, pivotal steps for both electrolysis and fuel cell operation, particularly at reduced temperatures. Nevertheless, achieving reproducibility and scalability in electrode material synthesis has presented a significant challenge. In this study, we introduce a scalable synthesis method aimed at enabling the mass production of electrode raw powders along with a better integration approach for large cell fabrication/manufacturing. Additionally, the electrochemical stability of PCECs, particularly under high steam concentration (~50%), can be enhanced by reducing interfacial resistance through optimization of oxygen electrode microstructure, particle size, and catalytic activity. Our developed scalable synthesis approach provides a practical solution for mass-producing oxygen electrodes, thus advancing the efficient fabrication and widespread adoption of PCECs in energy conversion applications.
Enhanced Sintering of Refractory Protonic Ceramic Electrolyte by Dual Phase Reaction
Authors: Lee Jong-Ho , Kim Junseok , Choi Sihyuk , JI HO-IL , Kwon Deok-Hwang , Yang Sungeun , Yoon Kyung Joong , Son Ji-Won
Published: December 2024

Proton conducting oxides, commonly used as electrolytes in ceramic electrochemical cells, boast remarkable proton conductivity, facilitating efficient energy conversion. However, their refractory nature presents challenges in achieving the ideal electrolyte structure and properties. Our novel approach utilizes reaction sintering to effectively lower the electrolyte's sintering temperature, resulting in stable and excellent electrolytic properties. This method transforms a two-phase mixture (comprising fast and slow-sintering phases) into a single-phase compound and densifies the electrolyte in a single-step heating cycle. During the reaction sintering process, rapid growth of the fast-sintering phase grains occurs due to its superior sinterability, aided by Ostwald ripening exhibited by the smaller slow-sintering phase. Lowering the sintering temperature preserves the intended initial stoichiometry of the electrolyte material, leading to a significant enhancement in electrochemical performance.