bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Heterogeneous Materials Integration for Wide Bandgap Semiconductors
Authors: Goorsky Mark S. , Liao Michael Evan , Huynh Kenny , Wang Yekan , Carson Brandon , Matto Lezli , Bhalla-Levine Aviram
Published: November 2022

The study of interfaces for both epitaxial and wafer-bonded systems draws from materials science, electrical engineering, and mechanical engineering and involves advanced materials characterization techniques. Low temperature wafer bonding has been leveraged to produce a wide array of materials combinations, most notably silicon-on-insulator structures. However, bonded interfaces can impact the electrical or thermal transport across such interfaces. In this presentation, we provide a few examples in semiconductor-based systems to address the ability to study and modify different, technologically important, interface combinations as a function of processing, such as annealing. The materials combinations primarily involve wide bandgap materials combinations including GaN|Si to b-Ga2O3 | SiC as well as bonding to single crystal diamond. In addition, we describe the role of the relative lattice orientation across semiconductor-semiconductor interfaces on transport properties and polarization engineering to producing high performance heterointerfaces. Our main goal is to be able to study and engineer the interfaces to optimize properties and ultimately, device performance.
Investigation into the Influence of Substrate Dislocations in 4H-SiC on the Subsequent Epitaxy and Resultant Device Performance
Authors: Hamann Danielle Marie , Sunkari Swapna , Justice Joshua , Das Hrishikesh
Published: November 2022

As the demand for SiC based devices continues to grow, there is an aggressive push to drive down sources of yield loss and device failures. One route to mitigate this issue is via connection of device yield loss to defects in the bare substrate material. Here, high throughput X-ray topography in conjunction with KOH etching and photoluminescence imaging were utilized to detect and classify various substrate dislocations. Subsequent epitaxial layers, grown on the substrates from various vendors, were analyzed using a confocal microscope to determine which substrate defects propagated into the epi. Data indicates that there is a good correlation between substrate BPDs nucleating into epitaxial stacking faults. This is supported by data from hundreds of different boules demonstrating that there is a relationship between the number of BPDs in the substrate and the number of partials and stacking faults detected in the resultant epitaxial layer. BPDs are not the only substrate dislocation nucleation source as the data also suggests other parallel sources are involved. Thousands of MOSFET and Diode devices were analyzed to understand the influence that substrate defects, propagated to the epitaxial layers, have on device leakage and yield loss. It was determined that MOSFET devices are more sensitive to the stacking faults that nucleate from the substrate dislocations compared to Diodes. While most of the stacking faults and other dislocations that occur in the epi layers do not independently result in device failures or leakage, an increase in the density of these defects within a die, can lead to increased leakage and decreased device performance. The inherent variability of these relationships requires the analysis of very large numbers of wafers to see the clear trends. This work uses a combination of X-ray and photoluminescence detection techniques to trace dislocations in substrates that nucleate into epitaxy layers and result in device leakage and failure over hundreds of wafers and thousands of devices. This correlation between device characteristics and crystal dislocations provides necessary information in determining which defects are most necessary to reduce or eliminate to improve device yield and performance.
Predicting Local Transport Phenomena of PEMFC Catalyst Layers Using a Network Approach
Authors: Alam Shahriar , Medici Ezequiel , Tajiri Kazuya , Allen Jeffrey S
Published: November 2022

A unique network approach has been developed to predict the movement of ions, reactant gas, and water both in the pore and ionomer phase inside a catalyst layer of PEMFC under various operating conditions. Separate networks for each of the catalyst layer reactive transport paths have been generated in the model and transport equations are applied therein. The simulation results provide insight into the coupling between overall PEMFC performance and local phenomena for different catalyst layer properties (porosity, ionomer to carbon ratio, ionomer volume fraction, catalyst loading, etc.), which can work as a guideline for the premanufacturing of catalyst layers and post-manufacturing testing tool.
Developing Next Generation High Performance Polymer Electrolyte Membrane Fuel Cells Using Metal Foam As Gas Diffusion Layer
Authors: Zhu Gaohua , Wang Liang , Zhou Yuqing , Kawai Hiroyuki , Ando Masaki , Dede Ercan M. , Jia Hongfei , Zenyuk Iryna V. , Banerjee Debasish
Published: November 2022

In recent years, low-temperature polymer electrolyte membrane fuel cells (PEMFCs) have played an increasingly important role in zero emission strategy to halt climate change. The performance improvement is a particular focus of fuel cell research and development, with water management being one of the major areas of interest. Here we report the development of a novel metal foam gas diffusion layer (GDL) material with embedded gas flow channels. Owing to the porous nature of the gas channel walls, the membrane electrode assembly (MEA) performance is significantly improved as a result of enhanced mass transport. Unprecedented high power density of 2.09 W/cm2 was observed at 90% relative humidity, and 2.04 W/cm2 for 149% relative humidity, which are respectively 12% and 37% improvement over current state-of-the-art low temperature PEMFC performance. Furthermore, we demonstrated that with our metal foam GDL, it is possible to simplify the flow field design on the bipolar plate, leading to manufacturing cost reduction of the fuel cell components. The work provides new pathway to achieve both high performance and low cost for fuel cells, water electrolyzers and other related technologies.
Insights into PEMFC Water Management with Different Layer Properties
Authors: Sabharwal Mayank , Wang Shiyi , Arman Tanvir Alam , Komini Babu Siddharth , Pasaogullari Ugur , Spendelow Jacob S. , Kusoglu Ahmet , Weber Adam Z.
Published: November 2022

Hydrogen based proton-exchange-membrane fuel cells (PEMFCs) provide a sustainable, potentially decarbonized solution to meet the future energy needs for mobility applications especially heavy-duty vehicles. Water management plays a critical role in determining the performance and efficiency of PEMFCs.1 Low water content in the membrane-electrode assembly (MEA) can lead to membrane dehydration and subsequently increased ohmic overpotentials, while high water content can result in local flooding of the porous media, thereby leading to mass-transport limitations. The structure and properties of the porous media and membrane govern the water transport in the MEA and thus, parameterizing the effect of these properties on the water balance in the MEA is important for the design of next generation materials, a task that mathematical modeling is ideally suited to tackle.

In this work, a 2D half-land half-channel MEA model,2 modified to explicitly include gas crossover, is used to study the effect of different layer properties on PEMFC performance. The model is used to examine both impact of membrane thickness in traditional PEMFCs, as well as water management with thicker electrodes and asymmetric diffusion media with non-platinum-group-metal PEMFCs. For the former, the tradeoffs between crossover and water gradients versus ohmic losses is quantified including explicit membrane-thickness-dependent properties.3 For the latter, specific cases of diffusion media with different pore size distributions and permeabilities is explored. Water-balance and voltage-breakdown analysis elucidate the design parameters limiting the PEMFC performance.

References

A. Z. Weber et al., Journal of The Electrochemical Society, 161, F1254–F1299 (2014).

L. M. Pant, S. Stewart, N. Craig, and A. Z. Weber, Journal of The Electrochemical Society, 168, 074501 (2021).

X. Luo et al., Journal of The Electrochemical Society, 168, 104517 (2021).
The Impact of Coating Defects on Water Transport in the Gas Diffusion Layer of PEM Fuel Cells
Authors: Herescu Alexandru
Published: November 2022

Present study suggests that the breakthrough pressure of a mixed-non-wetting (MNW) meniscus is highly sensitive to the extent of coating defects. On the other hand, the wetting meniscus breakthrough pressure showed little sensitivity to the geometry of the pore. Hydrophobic coatings such as PTFE are used to improve the water transport behaviour of the gas diffusion layer. Improved performance is typically associated with high breakthrough pressure, as evidenced by experiments. Simulations employing pores consider the influence of the pore geometry, and that of heterogeneous wetting and pinning conditions of the water droplets in contact with the GDL fibrous matrix. This model examines the water percolation behaviour at pore level, the pore being defined as a contact line of an evolving droplet in contact with fibers. In contrast with the pores of a pore-network model, the pore-level model captures the evolution of a liquid-gas interface having both pinned and free contact line segments. The mixed-non-wetting behaviour is caused by the hydrophobic coating which allows parts of the meniscus contact line to deform freely in contact with the fibers, while other parts of the meniscus remain pinned due to coating defects. The MNW meniscus is critical to establishing a high breakthrough pressure and a small characteristic droplet volume. The influence of the coating defects is simulated by MNW menisci having various ratios of pinned-to-free contact line segments.
Imaging Liquid Water in a PEFC with High-Energy X-Ray Compton Scattering
Authors: Tsuji Naruki , Miyazawa Tetsuya , Kaneko Takuma , Orikasa Yuki , Tsuji Yoichiro , Uchimoto Yoshiharu , Imai Hideto , Sakurai Yoshiharu
Published: November 2022

Water management is important for stable operation of PEFCs (Polymer Electrolyte Fuel Cells), since the proton conductivity depends on water content and excessive water hinders electrochemical reactions. As the durability of PEFC has become a major issue, the correlative behavior between liquid water and cerium oxides (radical scavengers) is drawing much attention. Till now, the water content and its inhomogeneous distributions have been reported by neutron radiography and X-ray computed tomography (CT). In this paper, we present a high-energy Compton scattering imaging (CSI) technique for non-destructive observation of liquid water in PEFC.

The advantage of high-energy CSI over X-ray CT is that the CSI technique has direct access to a two-dimensional cross section inside a PEFC without its rotation. The radiation damage on polymer electrolyte membranes is negligibly small since the photoelectric absorption is substantially reduced at such high-energy X-rays. Although high-energy X-ray CT is not sensitive to light-element materials, X-ray Compton scattering has its sensitivity to light elements.

Figure 1 shows the cross-sectional images of GDL (Gas Diffusion Layer) materials and liquid water [1]. The GDL materials are made of porous carbon fibers and carbon composites with Teflon treatment, TGP-H-300 (TORAY Industries, Inc., Tokyo, Japan). The area of the cross sections is 2mm x 2mm, and its thickness is 10μm. The spatial resolution is 75 μm. Figure 1(a) shows the image of dry GDL materials, displaying the distribution of carbon fibers and carbon composite, and Figure 1(b) does the difference image between dry and wet, representing the liquid water distribution. Negative contributions are observed in the carbon fiber and carbon composite region, which indicates possible interactions between the GDL materials and liquid water.

In this presentation, applications to a model cell under operation are also presented, together with correlation mappings of liquid water and cerium. The capability of CSI for vehicles’ PEFCs (TOYOTA MIRAI) is also discussed.

This work was performed under the NEDO FC-Platform project.

[1] N. Tsuji et al., Appl. Sci.
11, 3851 (2021)

Figure Caption:

Fig.1: Cross-sectional images of GDL materials and liquid water.

Figure 1
(Digital Presentation) Small-Angle Neutron Scattering Analysis of Fuel Cell Materials
Authors: Suzuki Jun-ichi , Kawamura Yukihiko , Ohishi Kazuki , Shibayama Mitsuhiro , Hiroi Kosuke , Takata Shin-ichi , Kawakita Yukinobu , Otomo Toshiya , Imai Hideto , Ohki Maria , Asaoka Takahiko , Tsuji Yoichiro , Amemiya Kazuki
Published: November 2022

In order to improve the reaction efficiency of fuel cells, the structure of carbon and ionomer affecting electronic and proton conduction and the distribution of voids affecting oxygen diffusion and drainage have been studied to find the guideline for the optimum structure of the catalyst layer. In this study we are developing a method to evaluate the dispersed structure of carbon and ionomer and the thickness of the ionomer layer by using the small and wide angle neutron scattering instrument, TAIKAN at the Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). The dependence of ionomer-to-carbon weight ratio of small-angle neutron scattering (SANS) cross section of the solid carbon catalyst layer and the hollow carbon catalyst layer was evaluated comparatively. Furthermore, the relative humidity dependence of SANS cross section of the solid carbon catalyst layer and the hollow carbon catalyst layer was also evaluated by using the contrast variation method.

This presentation is based on results obtained from a project, JPNP20003, subsidized by a New Energy and Industrial Technology Development Organization (NEDO).
Comparing and Contrasting Fuel Cell and Electrolyzer Characterization Techniques
Authors: Mukundan Rangachary , Komini Babu Siddharth , Myers Deborah J. , Cullen David A. , Alia Shaun M , Borup Rod L.
Published: November 2022

This talk will discuss several characterization techniques that have traditionally been used to characterize the performance and durability of fuel cells and discuss their implications to electrolysis systems. With the announcement of the DOE’s hydrogen shot to get the price of clean hydrogen to $1/kg in a decade, there has been an increased emphasis on improving the durability of Polymer electrolyte membrane electrolysis systems. This talk will discuss various in-operando, in-situ and ex-situ characterization techniques used to study and track the durability of both electrolysis and fuel cell systems. The presentation will include work from the DOE’s Million Mile Fuel Cell Truck (M2FCT) and Hydrogen from Next generation of Electrolyzers of Water (H2NEW) consortiums.

In specific, the talk will discuss various electrochemical characterization techniques including cyclic voltammograms, Impedance Spectroscopy and limiting current measurements that can be used to highlight changes in the polarization behavior of fuels cells and electrolyzers. We will also discuss the usefulness of Fluoride emission rate of the effluent water and CO2 concentration in the exhaust in tracking membrane and carbon degradation respectively. Finally, we will present results from various in-situ/ex-situ techniques including Xray analysis and microscopy to track changes in catalyst composition and morphology over time and correlate those changes to device performance.
Comparison of Serpentine and Interdigitated Monopolar Plates on the Performance of an Anion Exchange Membrane Fuel Cell By CFD
Authors: Valentín Reyes Jonathan , Leon Sotelo Maria Isabel Isabel , Nava José L. , Perez Tzayam , Romero Tatiana
Published: November 2022

The continuous energy demand and the growing population have focussed the scientific research on developing alternative energy sources or green fuels.

The anion exchange membrane fuel cell (AEMFC) arises as an excellent alternative because of its low-cost electrocatalyst used at the cathode, energy production, and no pollutants emissions to the environment. Nowadays, several studies have been conducted to improve the performance of the AEMFC modifying membrane materials, types of gas diffusion layers (GDL), and catalysts, among other cell components.

However, the design of the flow channels by changing plate topologies and materials is still under development. About flow channels topologies, conventional geometries array (pin, straight, parallel, and serpentine) flow fields lead the flow in the direction parallel to the electrode surface, and the reactive gas flow towards the catalyst layer (CL) mainly by molecular diffusion. On the other hand, interdigitated flow fields provide convection velocity normal to the CL and forced convection flow in GDL for better mass transfer. The interdigitated flow fields could prevent water flooding and improve high current density operations performance.

These flow fields have been tested in proton exchange membrane fuel cells (PEMFC) with excellent results at low current densities. Nonetheless, there is an essential balance and management of water in an AEMFC. It presents simultaneous production and consumption of water in anode and cathode, respectively, where the production is twice the consumption.

Poor water management could provoke anode flooding or membrane drying. These scenarios are undesirable due to mass transport limitations, membrane polymer degradation, and cathodic channels flow can be flooded. Therefore, an appropriate design of flow field that allows the correct water balance on AEMFC is needed for optimal performance.

This research deals with the computational fluid dynamic (CFD) comparison of serpentine and interdigitated flow fields on the performance of an AEMFC. For the development of this model, the Navier-Stokes and Brinkmann equations were implemented for momentum transfer. In addition, the average mixture model represents the transport of chemical species, and the Butler-Volmer equation denotes the electrochemical reaction at the CL; water balance is analyzed at low and high current densities to evaluate the scenarios above mention.

Preliminary results indicate that a serpentine design is functional at the anode due to the water management is favored. An interdigitated flow field is implemented at the cathode to improve the distribution of the reactants from channels until the CL.
(2021-2022 ECS Toyota Young Investigator Fellowship) Understanding and Suppression of Cation Transport into Polymer Electrolyte Membrane Fuel Cell
Authors: Arman Tanvir Alam , Sabharwal Mayank , Neyerlin Kenneth C. , Spendelow Jacob S. , Weber Adam Z. , Pasaogullari Ugur , Mukundan Rangachary , Borup Rod L. , Komini Babu Siddharth
Published: November 2022

Polymer electrolyte membrane fuel cells (PEMFCs) are a viable zero-emissions option for the electrification of the heavy duty transportation sector. However, PEMFCs still suffer from degradation of materials over the fuel cell lifetime. Cation contaminants can be generated from corrosion of bipolar plates and balance of plant components, water contaminants, and environmental sources (e.g., Fe3+, Ca2+, Na+), making them present in the fuel or oxidant stream during operation(1). Cations have been shown to be detrimental to the performance of the PEMFC by reducing water uptake, ionic conductivity, and O2 transport, resulting in performance loss and degradation. Metal cations such as Fe3+ can also lead to chemical degradation of the membrane ionomer (2-4). It is critical to understand the mechanism and rate of cation transport from the bipolar plate channel to the membrane to develop mitigation strategy to suppress the cation transport.

In this work, we present the study of the cation (Fe3+) transport mechanism through the gas diffusion layer (GDL) by introducing a cation solution in the cathode channel. Transport rates across the GDL are studied using an ex-situ GDL holder where Fe solution is introduced in the GDL substrate side with water transported through to the microporous layer side (MPL) and is collected and analyzed for Fe concentration, as shown in Figure 1a. Effect of the Fe concentration on transport rates is also studied using computational modeling. Understanding of the transport mechanism is then leveraged to identify mitigation solutions and suppress cation transport from the flow field to the electrode using a GDL with dual MPL architecture as shown in Figure 1b. Optimization of the dual MPL architecture for both durability and performance is also presented.

Acknowledgements

This research is supported by the 2021-2022 ECS Toyota Young Investigator fellowship and U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office, through the Million Mile Fuel Cell Truck Consortium (M2FCT). Authors acknowledge the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory (LANL).

References

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

R. K. Ahluwalia, D. D. Papadias, N. N. Kariuki, J. K. Peng, X. P. Wang, Y. F. Tsai, D. G. Graczyk and D. J. Myers, Journal of the Electrochemical Society, 165, F3024 (2018).

J. P. Braaten, X. M. Xu, Y. Cai, A. Kongkanand and S. Litster, Journal of the Electrochemical Society, 166, F1337 (2019).

A. Kneer, J. Jankovic, D. Susac, A. Putz, N. Wagner, M. Sabharwal and M. Secanell, Journal of The Electrochemical Society, 165, F3241 (2018).

Figure 1
In-Situ X-Ray Scattering Study of Iridium Oxide Catalyst for Polymer Electrolyte Membrane Water Electrolyzer during Ink Sonication and Drying Process
Authors: Park Jaehyung , Kariuki Nancy N. , Myers Deborah J.
Published: November 2022

Polymer electrolyte membrane water electrolyzers (PEMWEs) offer greenhouse gas emission-free hydrogen production for fuel cell vehicles and other industrial uses when using renewable energy sources [1]. Unsupported iridium oxide (IrO2) is the most active stable oxygen evolution reaction (OER) catalyst utilized in the anode of the PEMWE [2]. The atomic and microstructure of IrO2 catalysts and electrodes and interactions between and ionomer and catalyst can affect the ultimate performance of the PEMWE anode. These properties and phenomena may be controlled by the interactions of the ionomer in the catalyst-ionomer ink, by the effect of ink solvent composition on those interactions, and by the ink mixing and coating procedures. The microstructure evolution of the IrO2 catalyst during ink processing has not yet been identified. This presentation will describe relationships between ink formulation, electrode morphology, and performance for the IrO2-based PEMWE anodes. Moreover, the results of the evolution of the catalyst layer during the ink drying process as a function of solvent removal rate and solvent identity will be discussed. This study uses the in-situ technique of ultra-small angle X-ray scattering (USAXS) combined with small angle X-ray scattering to determine particle size distributions and the extent of IrO2 agglomeration in the inks and electrodes during the ink mixing/settling and drying processing. The effects of ionomer concentration, catalyst concentration, and solvent composition on the microstructure of the catalyst inks and electrode are correlated with the PEMWE performance and operando diagnostic data.

Acknowledgements

This work was supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office under the H2NEW Consortium. This work was authored in Argonne National Laboratory, a U.S. Department of Energy (DOE) Office of Science laboratory operated for DOE by UChicago Argonne, LLC under contract no. DE-AC02-06CH11357. This research used the resources of the Advanced Photon Source (APS), a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

References

[1] M. Carmo, D. L. Fritz, J. Mergel, D. Stolten, A Comprehensive Review on PEM Water Electrolysis, Int. J. Hydrogen Energy 2013, 38, 4901−4934.

[2] H. Yu, N. Danilovic, Y. Wang, W. Willis, A. Poozhikunnath, L. Bonville, C. Capuano, K. Ayers, R. Maric, Nano-size IrOx catalyst of high activity and stability in PEM water electrolyzer with ultra-low iridium loading, Applied Catalysis B: Environmental 2018, 239, 133-146.
(Digital Presentation) Validation of Python-Based Automated Analysis Approach for Processing STEM/EDS Maps of Catalyst Samples in AEMFCs – a Comparative Study
Authors: Batool Mariah , O. Godoy Andres , Birnbach Martin , Dekel Dario R. , Jankovic Jasna
Published: November 2022

Technological innovations in the field of materials science are often connected to the nanometric scale material evaluation which requires utilizing a combination of advanced characterization techniques. The extensive data acquired from these characterization techniques necessitates meticulous and efficient analysis, which can only be accomplished by automated digital image and data processing techniques. The development of such techniques will aid further advancements in the design of functional materials. In this work, we report a novel automatic analysis approach using data acquired by the Scanning Transmission Electron Microscopy (STEM) and Energy Dispersive Spectroscopy (EDS) to determine the component distribution and microstructure descriptors for an anion exchange membrane fuel cell (AEMFC). The current research aims to validate the automated approach by comparison to a manual image processing method based on ImageJ reported in a previous study [1]. STEM and EDS data for three different Pd/CeOx-based catalyst samples with varying bulk atomic fractions of Ce/Pd were collected and analyzed. The STEM/EDS data was used to investigate how the interfacial contact area and agglomerate size distributions of Pd and Ce can be related to the microstructural-level interactions and processes and potentially affect the electrochemical performance of an anion exchange membrane fuel cell (AEMFC). The comparison highlighted the strengths and limitations of both automated and manual approaches and offered substantial justification to predict how excessive Ce agglomeration can be linked to a reduction in the electrochemical performance of the fuel cell.

[1] R. K. Singh et al., “Synthesis of CeOx-Decorated Pd/C Catalysts by Controlled Surface Reactions for Hydrogen Oxidation in Anion Exchange Membrane Fuel Cells,” Adv. Funct. Mater., vol. 30, no. 38, 2020, DOI: 10.1002/adfm.202002087.
Quantitative Analysis of Fuel Cell Cathode Catalyst Layer Degradation Using Scanning Transmission Electron Microscopy and Energy Dispersive Spectroscopy
Authors: Coats Matthew , Medina Samantha , Braaton Jonathan , Cheng Lei , Craig Nathan , Johnston Christina , Pylypenko Svitlana
Published: November 2022

Proton exchange membrane fuel cells (PEMFCs) are a central technology for the electrification of the heavy-duty automotive fleet, ultimately enabling reduced carbon emissions. However, improvements in lifetime and cost are necessary before mass adoption of PEMFC vehicles is achieved. Significant research into analyzing and mitigating degradation of catalyst layers (CLs) is ongoing and this work highlights a transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) approach aimed at quantifying electrochemically active surface area (ECSA) loss through the thickness of CLs resulting from electrochemical-applied, catalyst-specific accelerated stress tests or ASTs.

Several mechanisms contribute to degradation of the catalysts in PEMFCs, including Ostwald ripening, coalescence, and formation of a Pt band within the membrane, which result in decreased active surface area throughout the CL. TEM has often been used in conjunction with electrochemical testing to infer changes in the catalyst nanoparticle size, distribution, and changes to the support materials within the catalyst layer (CL) to investigate catalyst. Typically, high-magnification TEM with high-resolution are used to infer localized changes within the CL by examining shape and size to provide information concerning the degradation mechanism. Low-magnification TEM is typically used to observe changes in the support, ionomer, and catalyst distribution. Here we use a quantitative approach to show elemental differences within the CL by using scanning transmission electron microscopy and energy dispersive spectroscopy maps (STEM/EDS) for a given MEA that underwent catalyst-specific ASTs. This approach uses the fluorine to platinum ratio (F/Pt) from a fresh sample as a benchmark to track loss of Pt through the thickness of the CL of aged samples. This information can then be used to compare differences in various locations on the MEA in relationship to gas inlets and outlets as well as changes induced by different stressors during the catalyst ASTs. This analysis complements studies using bulk techniques, such as electrochemical ECSA via cyclic voltammetry and micro-X-ray diffraction (µ-XRD), to confirm trends in CL degradation.
Decoding the Electro-Chemo-Mechanical Coupling in Core-Shell Nanoparticles for PEFC Catalyst Layers
Authors: Goswami Navneet , Mukherjee Partha P.
Published: November 2022

Core-shell nanostructured catalysts possess a novel architecture where a major portion (core) of the nanoparticle is composed of cheaper materials such as Cobalt, Palladium, Copper, etc., with only a small portion (shell) being the expensive Platinum (Pt) thus enabling the reduction of Pt loading in the catalyst layer. These core-shell nanocatalysts are known to exhibit better mass activity than their monolithic counterparts. In this context, tuning the core can result in a change in both mechanical and geometrical properties, and in turn, can influence the stability. Specifically, designing an interface with surface stresses that makes the structure of the nanostructured catalysts resistant to dissolution would be pivotal towards achieving enhanced durability in PEFC systems. The lattice mismatch between the core and shell is a key intrinsic parameter that governs a transition towards a thermodynamically metastable state. In this work, the mesoscale underpinnings of such metastability on the underlying electro-chemo-mechanical coupling and the resulting influence on degradation-performance interactions will be analyzed. Further, the role of molar volumes and elastic moduli of such core-shell pairs on the evolution of stress states and degradation landscape will be investigated. Design criteria including the influence of shell thickness in protecting against degradation will be delineated.
Automating Correlative Electron Microscopy for Heavy Duty Fuel Cell Development
Authors: Cullen David A. , Yu Haoran , Zachman Michael J. , Park Jaehyung , Kariuki Nancy N. , Hu Leiming , Mukundan Rangachary , Neyerlin K.C. , Myers Deborah J.
Published: November 2022

The efficiency and durability of proton exchange membrane fuel cells has come to the forefront of research and development efforts as sustainable transportation applications shift from passenger to heavy duty vehicles. Complementary research expertise and advanced instrumentation are required to accelerate materials discovery and degradation mitigation of fuel cell components, with significant attention on catalysts, ionomers and membranes. The scanning transmission electron microscope (STEM) is among the key characterization techniques for accelerating materials and device development, providing key insights into atomic scale structure. Automating STEM data acquisition and analysis enables large data sets with improved statistical relevance and throughput will expand the impact of this method in the rapid materials and accelerated stress test development.

We will show how the latest instrument developments in automation and high speed detectors enable new insights into catalyst structure and electrode layer degradation. This includes correlative, multimodal STEM techniques, such as aberration-corrected imaging, secondary electron detection, energy dispersive X-ray spectroscopy, cryogenic microscopy and 4D-STEM, to build a more comprehensive view of the effect of particle size and composition on surface strain and durability. These results will be correlated with information obtained from X-ray scattering techniques and fuel cell performance testing to understand the type and degree of degradation occurring during accelerated stress tests under development for heavy duty applications. The prospect of automated electron tomography coupled with identical location (IL)-STEM to provide detailed three-dimensional information on catalyst-support interactions will also be discussed.

This material is based on work performed by the Million Mile Fuel Cell Truck (M2FCT) Consortium, technology managers Greg Kleen and Dimitrios Papageorgopoulus, which is supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office. Electron microscopy research was supported by the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. The X-ray scattering experiments were performed at beamline 9-ID-C at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). Use of the APS, an Office of Science user facility operated by ANL, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AS02-06CH11357
Biomimetic Microchannels for the Passive Management of Water in PEM Fuel Cells
Authors: Chadwick Eric Alexander , Shrestha Pranay , Parmar Harsharaj Birendrasingh , Bazylak Aimy , Schulz Volker
Published: November 2022

In polymer electrolyte membrane (PEM) fuel cells, the bipolar plates (BPPs) are responsible for the transport of reactants (via embedded flow fields), heat, and electrons, and account for 18-28% of the cost of fuel cell systems1. Thus, there is a great opportunity to improve the energy density of PEM fuel cells by improving the functions of BPPs, such as providing liquid water management, which affects reactant delivery and heat distribution. Previous work has shown that mass transport losses due to liquid water accumulation under the lands and channels of PEM fuel cell flow fields limit the power density of fuel cells2. Previous work has demonstrated that water will preferentially flow in a desired direction by implementing biomimetic wicking structures3; however, such wicking structures have not been previously implemented into a fuel cell. Furthermore, the design of BPPs has not been tailored to target areas of water accumulation.

In this work, biomimetic geometries that promote passive unidirectional water wicking were implemented in a PEM fuel cell flow field to enhance liquid water removal and the distribution of reactant gases. The BPPs were characterized via constant current electrochemical testing and electrochemical impendence spectroscopy (EIS) to elucidate the dominant losses observed during operation. Operando synchrotron X-ray radiography was performed during the electrochemical testing in order to quantify the liquid water accumulation on the cathode side of the PEM fuel cell. The spatial distribution of liquid water was combined with EIS characterizations to explain the performance of the designs at high current densities, where mass transport losses typically dominate. The results from this work can be used to further optimize the design of PEM fuel cell bipolar plates in order to produce more efficient fuel cell stacks and drive PEM fuel cells into the global energy market.

References

Y. Wang, D. F. Ruiz Diaz, K. S. Chen, Z. Wang, and X. C. Adroher, Materials Today, 32, 178–203 (2020).

N. Ge et al., Electrochimica Acta, 328, 135001 (2019).

J. Feng and J. P. Rothstein, Journal of Colloid and Interface Science, 404, 169–178 (2013).
(Invited) Sustainable Platinum Group Metal (PGM) Recycling of Proton Exchange Membrane Fuel Cells and Electrolyzer Cells (PEMFCs & ECs) As a Vital Step Towards Truly Renewable and Green Energy Conversion Technologies
Authors: Andersen Shuang Ma , Sharma Raghunandan , Larsen Lars Christian , Larsen Mikkel Juul Juul , Grahl-Madsen Laila
Published: November 2022

Owing to their strong catalytic nature and high robustness under various conditions, platinum group metals (PGMs) are state-of-the-art electrocatalysts for proton exchange membrane fuel cells and electrolyzer cells (PEMFCs & ECs) of superior performance and long stability. However, PGM supplies involving limited natural reserves, energy intensive mining process and related environment issues raise increasing concerns. As an indispensable (though insufficiently developed) aspect of the PEM technologies, sustainable PGM recovery and reuse can fundamentally tackle those concerns and serve as a strong support to further secure widespread commercialization of the technologies.

Due to the popular use of perfluorinated sulfonic acid as proton conduction component, PGMs in PEMFCs&ECs are not suitable for recycling through the traditional pyrometallurgical route, which operates at a temperature over 1500°C. Burning of the electrodes releases huge amount of emission, which is not only harmful to the environment and human, but also corrosive to the process infrastructure.

An alternative PGM recycling process using a hydro-electrochemical route1, 2 reveals many advantages, including high extraction efficiency, environmental friendliness, recovery of multiple components, low demand for operation conditions & maintenance, etc. Adopting the intrinsic degradation mechanisms of the PGM nanoparticles in combination with surface potential modulation, dissolution behavior of typical PEMFC&EC electrocatalysts have been systematically investigated. Under optimal parameters, a recovery efficiency of over 99% was successfully achieved for platinum electrocatalyst. Moreover, new catalysts prepared from the recycled precursor demonstrated competitiveness to that of commercial equivalents.

In project 3R, as a joint effort of fuel cell industries, recycling companies and academics supported by Danish Energy Agency, the achievements document a valuable milestone towards truly renewable and green energy conversion technologies.

Acknowledgment

Financial support from Danish Energy Agency EUDP project 3R, Nr. 64019-0551; Innovation Fund Denmark, InnoExplorer program, Nr. 9122-00112; Danish ESS lighthouse on hard materials in 3D, SOLID, Grant number 8144-00002B; Energi Fyns Udviklingsfond.

Corresponding author

Shuang Ma Andersen: mashu@igt.sdu.dk

Reference

Sharma, R.; Gyergyek, S.; Andersen, S. M. ChemSusChem
2018, 11, (21), 3742-3750.

Sharma, R.; Rode Nielsen, K.; Brilner Lund, P.; Bredmose Simonsen, S.; Grahl-Madsen, L.; Ma Andersen, S. ChemElectroChem
2019, 6, (17), 4471-4482.
Influence of Operating Parametres on PEM Based Ecmr for Hydrogen Production in Pressurised Condition
Authors: Vinnakota SRI Harsha Sri Harsha , Balaji R , Brindha A.S , Neelakantan Lakshman , Ramya Krishnan
Published: November 2022

Hydrogen has the potential to promote the development of new, innovative and environmentally friendly solutions for future demands which would help for the smooth energy transition from fossil fuels. Though hydrogen has a high potential to replace fossil fuels, the challenges associated with the hydrogen value chain are in the production, storage, transportation and distribution stages.

Electrolysis of water in PEM based system is a single step green hydrogen production process while integrated with renewable energy resources. However, this energy-intensive process makes the hydrogen production cost high and it is pave way for adopting the grey hydrogen or blue hydrogen production route as an intermediate stage for the transition from fossil fuel to hydrogen fuel economy. In this context PEM based Electrochemical Methanol Reformer (ECMR) technology has unique advantages such as low electrical energy consumption than water electrolysis and it can be easily integrated with renewable energy sources. Further, it can be operated at near ambient temperature and doesn’t require any hydrogen purification system, unlike a chemical reformer. Currently, PEM based water electrolyzer is producing pressurized hydrogen, which will eliminate the need for an external hydrogen compressor for its storage. Further, the influence of operating parameters on the operation of PEM water electrolyser under pressurised conditions is studied in the literature. However, this aspect of the study is not well studied and not much literature is available on PEM based ECMR systems. The present work, it is aimed to systematically study the effect of various operating parameters on the performance of ECMR under pressurised operation conditions and the obtained results are discussed. It shows the operation of ECMR under pressurised condition are promising and it will eliminate the need for an external H2 compressor system for hydrogen storage like PEM based water electrolyzer.

Keywords: Hydrogen, PEM based Electrochemical reformer, pressurised hydrogen
Optical Observation of Water and Hydrogen Bubble in Cathode Toluene-Methylcyclohexane Flow inside Direct Toluene Hydrogenation Cell
Authors: Shigemasa Kaito , Jang Sunpil , Reyna Fatima , Inoue Kaisei , Araki Takuto , Terao Takuma , Nagasawa Kensaku , Mitsushima Shigenori
Published: November 2022

Introduction

Energy transport and storage system should be considered with new energy source installation such as solar and wind power. There are some methods for it, and organic hydride methods are highly paid attention. In these methods, toluene-methylcyclohexane (MCH) conversion system is a good candidate as an energy transport and storage system with some reasons such as easy handling, affinity with Japanese current infrastructure, and so on. In the toluene-MCH conversion system, direct-toluene hydrogenation is especially paid attention since the system can be easier and exothermic heat loss reaction is less than other methods, so total efficiency of direct method gets higher than other methods.

However, there are some problems on it, and the most serious problem is optimizing water management in cathode [1,2]. In cathode, toluene and MCH are flowing, and water appears in cathode porous transport layer (PTL) by being transported from anode then the water interrupts fuel supplies and the conversion rate from toluene to MCH gets lower. Therefore, water management should be optimized for higher performance of the system. However, there is no research which is focusing on water movement in this system as far as we know.

Therefore, in this study, the original cell was investigated which had a visualization window on the cathode surface and allowed us to visualize the water movement during operating the system, and water movement was investigated. Fig. 1 shows the cell configuration and the actual picture from visualization window. As shown in Fig.1(a), the original cell was developed. In the left side, there is a visualization window with sapphire glass and the surface of the cathode PTL can be shot by hi-speed camera and so on. Fig.1(b) shows the example of visualization results. The cell was set with the gravity direction lower side and flow direction upper. The image shows us cathode PTL and toluene-MCH flow with water droplet and hydrogen bubble. As it can be seen in Fig.1(b), there are some droplets with several sizes. The 0.5 – 1.5 mm diameter droplets can be recognized as water droplet by seeing the movement with movie. By using this system, the effects of different anode supplies were discussed on water and hydrogen generation.

Reference

[1] K. Nagasawa et al., Electrochemistry, 339-344, 86 (2018)

[2] K. Nagasawa et al., Electrocatalysis, 164-169, 8 (2017)

Figure 1
(Invited) Compact Design of HT Pefmc Stacks with Advanced Cooling
Authors: De Castro Emory Sayre , Kaye Ian , Chen Ru , Pavlik Thomas
Published: November 2022

ADVENT Technologies is an innovation-driven company in the fuel cell and hydrogen technology space. Our vision is to accelerate electrification through advanced materials, components, and next-generation fuel cell technology. Our technology applies to electrification (fuel cells) and energy storage (flow batteries, hydrogen production) markets, and we intend to commercialize it through partnerships with Tier1s, OEMs, and System Integrators.

In 2021 SerEnergy A/S, fischer Eco Systems and UltraCell LLC merged into one Advent organization, launching the Company into the forefront of fuel cell and systems companies that supply the entire technology chain from components to MEAs to stacks and systems. Currently Advent has operations in Boston, Massachusetts; Livermore, California (USA); Athens and Patras (GR); Aalborg (DK); Achern (DE); Manila (Philippines); and headquarters in Boston.

Applications for the current HT PEM technology are limited to those that can operate on relatively lower current density compared to state-of-the-art LT PEM, and thus transportation applications were largely focused toward HT PEM stacks acting as efficient battery range extenders using fuels such as methanol. On the other hand, LT PEM fuel cell stacks are limited when it comes to heavy duty applications such as fuel cell electric trucks and aeronautical applications due to a limited heat gradient for cooling.

A HT PEM MEA that operates at higher current over a wider range of temperatures including start up at under 100 °C would represent a paradigm shift in the HT PEM field and open up a wide range of new applications including competing in areas traditionally dominated by LT PEM while at the same time solving the burden of cooling for heavy duty applications. Furthermore, stacks that operate over 120 °C are amendable to advanced, compact cooling systems that have the potential to greatly reduce the fuel cell system weight and volume.

In a competitive process, Advent was selected as the commercialization partner for a new HT PEM technology pioneered by US Department of Energy scientists at Los Alamos National Laboratories. This next generation HT PEM technology is based on strongly formed ion pairs between a charged membrane and phosphoric acid, and has been shown to operate at far higher current density than possible with current HT PEM MEAs while at the same time exhibiting substantially lower degradation rates. This presentation will focus on the current status of our commercialization of the ion pair technology as well as introduce innovative cooling methodologies that leverage the higher operating temperature of HT PEM.