bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and Construction of a LT-PEM Fuel Cell System for Aviation Application
Authors: Bürger Stefan , Cremers Carsten , Urban Niels 
Published: February 2024

Fuel cell technology has gained considerable attention as an alternative power source for mobility applications. Fuel cell systems are already integrated in ground applications like trucks, cars, and busses. One reason is, that they have the potential to provide an environmentally friendly power supply solution compared to traditional combustion engines. Moreover, fuel cell drive trains offer several potential benefits, such as improved energy efficiency, noise reduction and no local emissions and even zero CO2 emission if they are fueled with green hydrogen. On the other hand, there are several key challenges associated with the integration of fuel cell technology into mobility applications, such as safety, durability, weight, and cost. These challenges become even more difficult when flight applications are considered, due to the higher .
We present our research of a fuel cell system design, which is constructed to power a one seat airplane, the Antares E2. This system will utilize compressed Hydrogen as fuel to power up to six electronic motors via an electric bus. The airplane needs 90 kW of power mainly for its electric propulsion and can be operated up to a ceiling altitude of 6500 m (21,300 ft). For redundancy and safety, it is necessary to split the power output to at least two systems. Therefore, each system must have a power output of 45 kW. The fuel cell system's design takes various factors into account, such as lightweight and compact components as well as safety analysis to ensure the operation in flight. To reach aviation standards a full FMEA analysis is conducted, to calculate the risks of operating the systems on an airplane. The goal is to have a fuel cell system which is eligible for operating an aircraft. We want to present first results of our research, consisting of first design to ground operation and include some simulations for flight conditions.
A successful development and certification of this fuel cell system would represent a significant milestone in the pursuit of sustainable aviation technologies, since it would be one of the first system which features approved airworthiness. This technology has the potential to reduce emissions and noise pollution associated with traditional combustion engines. Further research and development efforts are required to optimize the performance and reduce the cost of this fuel cell system.
This work is funded by the Federal Ministry for Digital and Transport (BMDV) in the project “H2GA” under the grant 03B10707. The authors declare that the opinions expressed in this submission are their own and are based on a thorough review of existing scientific literature.
Hydrophobic Conductive Coatings for Fuel Cell Gas Diffusion Layers
Authors: Bodner Merit , Blaschke Fabio , Tritscher Florian 
Published: February 2024

Mass transfer of the reactant gases, water management, thermal and electrical conductivity are all highly depending on the properties of the gas diffusion layer (GDL) in polymer electrolyte fuel cells (PEFCs). GDLs are produced in complex and energy demanding processes including high temperature graphitization and are modified using polytetrafluoroethylene (PTFE) to introduce the hydrophobicity needed to efficiently remove water [1]. PTFE is, however, negatively impacts the required electrical conductivity and is facing an uncertain future with the pending restrictions on the use of perfluoroalkyl substances (PFAS) [2], [3]. Therefore, we have investigated the use of electrically conductive polyaniline (PANI) coatings on carbon fiber substrates with modifications to increase hydrophobicity. As substrate, AvCarb carbon paper EP40 was used and PTFE treated EP40T was used as state-of-the-art reference. EP40 was coated through dip-coating or electro-coating using PANI modified with sodium dodecylbenzenesulphonate as additive to adjust hydrophobicity [4]. With this approach, we have been able to show comparable pore volumes and pore surface areas (Figure 1) through mercury porosimetry as well as comparable hydrophobic properties.
References
[1] A. Ozden, S. Shahgaldi, X. Li, and F. Hamdullahpur, “A review of gas diffusion layers for proton exchange membrane fuel cells—With a focus on characteristics, characterization techniques, materials and designs,” Prog. Energy Combust. Sci., vol. 74, pp. 50–102, 2019, doi: 10.1016/j.pecs.2019.05.002.
[2] E. Dhanumalayan and G. M. Joshi, “Performance properties and applications of polytetrafluoroethylene (PTFE)—a review,” Adv. Compos. Hybrid Mater., vol. 1, no. 2, pp. 247–268, Jun. 2018, doi: 10.1007/s42114-018-0023-8.
[3] ECHA/NR/23/04, “ECHA publishes PFAS restriction proposal,” 2023. https://echa.europa.eu/-/echa-publishes-pfas-restriction-proposal (accessed Mar. 27, 2023).
[4] F. Tritscher, A. Mularczyk, A. Forner-Cuenca, V. Hacker, and M. Bodner, “Surfactant doped polyaniline coatings for functionalized gas diffusion layers in low temperature fuel cells.”, under review

Figure 1: Mercury porosimetry measurements for the bare substrate, the state-of-the-art PTFE treated substrate, as well as hydrophobic PANI coated samples, prepared using dip-coating and electro-coating.

Figure 1
Investigation of Gas Diffusion Layer Degradation in Polymer Electrolyte Fuel Cell Via Chemical Oxidation
Authors: Edjokola Joel Mata , Hacker Viktor , Bodner Merit 
Published: February 2024

The gas diffusion layer (GDL) is a key part of the membrane electrolyte assembly and is critical for the transport of fuel, oxygen and water. The GDL is made up of two layers: macroporous substrate (MPS) and microporous layer (MPL) (1). To achieve the hydrophobicity required for water management, the two layers are typically treated with polytetrafluoroethylene (PTFE) (2). In many long-term experiments, it has been observed that GDL degradation, such as carbon corrosion and PTFE loss, leads to a deterioration of water management, conductivity and mass transport (3).To solve this durability problem, a thorough and in-depth understanding of the GDL degradation mechanism is required. In this study, GDLs are subjected to an accelerated stress test to investigate degradation by chemical oxidation. GDLs are soaked in Fenton's reagent for 24 hours. The hydrophobic properties of pristine and soaked GDLs are compared based on contact angle measurements, thermogravimetry and scanning electron microscopy. In addition, the chemical composition of the solutions before and after the immersion test is analyzed using a total organic carbon analyzer and an ion chromatograph. The results show that the hydrophobicity of GDL exposed to Fenton reagent is decreased by 5 and 4 degrees for the MPL and the MPS respectively. Fig 1. depicts a decrease in surface contact angle, which is associated with surface oxidation and PTFE deterioration.
Acknowledgement
This research work is performed under the project AlpeDHues (AlpeDHues / FFG 889328) which is supported by the Austrian Research Promotion Agency (FFG).
References

C. Csoklich, R. Steim, F. Marone, T. Schmidt and F. Büchi, ACS Applied Materials & Interfaces,
13, 9908–9918 (2021).

A. Ozden, S. Shahgaldi, X. Li and F. Hamdullahpur, Progress in Energy and Combustion Science,
74, 50–102 (2019).

Y. Yang, X. Zhou, B. Li and C. Zhang, Applied Energy,
303, 117688 (2021).

Figure 1
Capillary Pressure Controlled Water Pathways in Gas Diffusion Layers for Polymer Electrolyte Fuel Cells Designed By Additive Manufacturing
Authors: Doerenkamp Tim , Buechi Felix N. , Schmidt Thomas J. , Eller Jens 
Published: February 2024

Polymer electrolyte fuel cells (PEFC) are considered to make a significant contribution to the transition towards carbon free energy conversion, as they produce electric power from hydrogen and oxygen with water as the only by-product [1]. On its way to widespread commercialization, in particular the water management in PEFC is challenging. On one hand, the electrolyte membrane needs to be humidified to be highly conductive for the hydrogen protons. On the other hand, accumulation of the product water in the gas diffusion layer (GDL) on the cathode side mitigates the oxygen transport towards the catalytic surface, which leads to severe performance limitations [2-3]. Previous work has shown that structured GDLs can enhance PEFC performance [5] and additive manufacturing (AM) has been identified as a viable method to fabricate just such [4,6].
Currently available AM technologies are struggling to fulfill the needs in terms of minimal feature size (~8 um fiber diameter) and sample size (at least some cm2). Initial AM prepared GDLs were coarse with finest structures of about 120 um [6] which is in the range of typical GDL thickness. Here, we present AM prepared GDL like structures with 20 um printed features that can reach sizes of some tens of mm2.
The 3D printed structures are designed to guide the product water through the GDL by adjusting the throat size [7] and therefore the capillary pressure, which is required in the water phase to percolate through the throats to the neighboring pore as described by Young-Laplace law. Figure 1 shows tomographic data of a test lattice structure manufactured by high-resolution projection micro stereolithography (PµSL). The concept is validated by measuring the pressure in the water phase as a function of the throat size under ex-situ conditions. The desired percolation path of the water is monitored by 2D as well as 3D image data acquired by X-ray radiography and X-ray tomographic microscopy (XTM), respectively.

Figure caption:

XTM scan of a lattice structure manufactured by P
µ
SL: a) 3D rendering, b) x-z-plane cross section, c) x-y-plane cross section. Slight deformation in the base layers of the lattice structure is observed.

References
[1] O. Z. Sharaf et. al., Renewable and Sustainable Energy Reviews, 2014, 32, pp. 810-853
[2] M. F. Mathias et. al., Handbook of Fuel Cells, 2010
[3] J. Ihonen et. al., Journal of the Electrochemical Society, 2004, 151, pp. A1152-A1161
[4] D. Niblett et. al., Journal of the Electrochemical Society, 2020, 167, 013520
[5] C. Csoklich et. al., Energy & Environmental Science, 2022, 15, 1293-1306
[6] D. Niblett et. al., International Journal of Hydrogen Energy, 2022, 47, pp. 23393-23410
[7] D. Niblett et. al., Journal of Power Sources, 2020, 471, 228427

Figure 1
An Experimental Study on the Correlation between Characteristics of Gas Diffusion Layer and Performance Depending on Relative Humidity Variation in Proton Exchange Membrane Fuel Cell
Authors: Lee So Yeon , Ahn Chi-Yeong , Shim Hyungwon 
Published: February 2024

As it is well known, Gas diffusion Layer(GDL) is a fundamental element to provide more efficient water transport in Proton Exchange Membrane Fuel Cell(PEMFC). Numerous previous studies showed how important and critical GDL is in PEMFC. There have been many efforts to improve the performance of GDL, such as studies on properties, structural improvement, and hydrophobic coating on substrate and micro porous layer. Through these efforts, PEMFC has been developed and also the relationship between GDL and each component was investigated well.
Relative Humidity(RH) is an important factor that affects proton conductivity and mass transport and is also an factor to be considered for water management. Although it should be relatively clear, it is necessary to compare and verify between the numerical study and experimental study since they does not always matches.
In this study, the results were compared with the physical properties of each GDL based on experimental data applying GDL with different characteristics. We studied to reveal the correlation between data such as thickness, porosity, and pore distribution of GDL and I-V Polarization curve conducted by changing RH conditions to investigate performance.
Water Transport Modeling in a Microporous Layer for a Polymer Electrolyte Membrane Water Electrolyzer Having a Gas-Liquid Separating Interdigitated Flow Field
Authors: Nakajima Hironori , Ekström Henrik , Shima Asuka , Sone Yoshitsugu , Lindbergh Göran 
Published: February 2024

A novel interdigitated flow field design for polymer electrolyte membrane electrolyzers (proton exchange membrane water electrolysis cells), which has oxygen exhaust channels separated from pressurized liquid water feeding channels, has been developed for ground and space applications 1), 2). This structure separates oxygen and liquid water inside the anode of the cell. Thereby it dispenses with water circulators for bubble removal from the cell and external separators by natural or centrifugal buoyancy. We thus aim to develop a numerical model for further optimization of the cell design.
Finite element modeling (COMSOL Multiphysics) of water transport is three-dimensionally conducted for the anode porous transport layer coated with a hydrophobic microporous layer (MPL) (SIGRACET 29BC, SGL Carbon Inc.) assembled with the interdigitated flow field. The MPL works to separate evolved oxygen gas exhausted in the through-plane direction and pressurized liquid water injected in the in-plane direction owing to the capillary pressure 2), 3). Prominent leakage of the liquid water to the oxygen channels has not been detected.
Electrochemical kinetic parameters for the model are determined by electrochemical impedance spectra. Current-voltage measurement of the cell is also performed to validate the numerical modeling.
We model the current densities and the current ratio between the reactant liquid water and water vapor at the interface between the MPL and catalyst layer (CL). The model involves fractional bubble coverage of the CL with produced oxygen gas and liquid water saturation in the MPL. The vapor evaporating from the liquid water in the MPL is assumed to be mixed with the evolved oxygen for diffusive water transport. The volumetric evaporation rate is assumed as a function of the liquid water saturation in the MPL.
References
1) Y. SONE, O.S. HERNANDEZ-MENDOZA, A. SHIMA, M. SATO, H. NAKAJIMA, H. MATSUMOTO, Water Electrolysis by the Direct Water Supply to the Solid Polymer Electrolyte through the Interdigitated Structure of the Electrode, Electrochemistry. 89 (2021) 138–140. https://doi.org/10.5796/electrochemistry.20-00145.
2) H. NAKAJIMA, V. VEDIYAPPAN, H. MATSUMOTO, M. SATO, O.S. MENDOZA-HERNANDEZ, A. SHIMA, Y. SONE, Water Transport Analysis in a Polymer Electrolyte Electrolysis Cell Comprised of Gas/Liquid Separating Interdigitated Flow Fields, Electrochemistry. 90 (2022) 017002. https://doi.org/10.5796/electrochemistry.21-00097.
3) H. Nakajima, S. Iwasaki, T. Kitahara, Pore network modeling of a microporous layer for polymer electrolyte fuel cells under wet conditions, J. Power Sources. 560 (2023) 232677. https://doi.org/10.1016/j.jpowsour.2023.232677.
Acknowledgments
This study is based on results obtained from a project, JPNP21014, commissioned by the New Energy and Industrial Technology Development (NEDO).
(Poster Award - Honorable Mention) Durable Polybenzimidazole Anion Exchange Membranes for Alkaline Water Electrolyzers
Authors: Boström Oskar , Choi Seung-Young , Xia Lu , Lohmann-Richters Felix , Jannasch Patric 
Published: February 2024

Water electrolysis under alkaline conditions allows the use of inexpensive non-platinum-group catalysts such as nickel.1, 2 Conventional alkaline electrolyzers usually employ a highly concentrated aq. KOH solution as electrolyte (5-7 M) with a porous diaphragm as separator. Alternatively, protolysable polymers such as polybenzimidazole (PBI) may be swollen with electrolyte and used as ion-solvating membranes.2, 3 However, the chemical stability of the polymers can become a serious issue under these harsh conditions. Operation under more dilute conditions, e.g., up to 2 M KOH, may bring the benefits of the alkaline conditions combined with a longer cell lifetime. Under these conditions, aliphatic cyclic quaternary ammonium (QA) cations, such as piperidinium, have shown excellent stability.
In the present work, performed as part of the EU project “NEXTAEC”, we have designed and synthesized m-PBI grafted with mono- and bis-piperidinium functionalized side chains, respectively (Figure 1a-b). AEMs were prepared from polymers with varying ion exchange capacities and studied at 80 °C containing KOH solutions in the concentration range 0.5-2 M KOH. The membranes were characterized with respect to, e.g., electrolyte solution uptake, alkaline stability, and electrolyser performance (Figure 1c). The uptake showed a strong inverse correlation with KOH concentration, which also affected the electrochemical performance. The stability as evaluated by 1HNMR spectroscopy was excellent showing, in the worst case, less than 8 % ionic loss after 6 months storage in 2 M KOH at 80 °C.

Li, D.; Park, E. J.; Zhu, W.; Shi, Q.; Zhou, Y.; Tian, H.; Lin, Y.; Serov, A.; Zulevi, B.; Baca, E. D.; Fujimoto, C.; Chung, H. T.; Kim, Y. S., Highly quaternized polystyrene ionomers for high performance anion exchange membrane water electrolysers. Nature Energy
2020,
5 (5), 378-385.

Aili, D.; Kraglund, M. R.; Rajappan, S. C.; Serhiichuk, D.; Xia, Y.; Deimede, V.; Kallitsis, J.; Bae, C.; Jannasch, P.; Henkensmeier, D.; Jensen, J. O., Electrode Separators for the Next-Generation Alkaline Water Electrolyzers. ACS Energy Letters
2023, 8 (4),1900-1910.

Aili, D.; Yang, J.; Jankova, K.; Henkensmeier, D.; Li, Q., From polybenzimidazoles to polybenzimidazoliums and polybenzimidazolides. Journal of Materials Chemistry A
2020,
8 (26), 12854-12886.

Marino, M. G.; Kreuer, K. D., Alkaline stability of quaternary ammonium cations for alkaline fuel cell membranes and ionic liquids. ChemSusChem
2015,
8 (3), 513-23.

Figure 1
(Invited) Monopolar and Bipolar Membranes Based on Nanofiber Electrospinning
Authors: Pintauro Peter N. 
Published: February 2024

Cation-exchange, anion-exchange, and bipolar membranes play crucial roles in a variety of electrochemical processes and devices, including chloralkali cells, electrodialysis separations for water purification, proton-exchange membrane and hydroxide-exchange membrane (alkaline) fuel cells, redox flow batteries, and processes for direct air capture of CO2. The incorporation of polymeric nanofibers into such membranes provides an attractive and tunable method of creating materials with new nano-morphologies and highly desirable properties.
The impregnation of an ionomer solution into a pre-formed nonwoven porous mat of electrospun polymer fibers is a well-known method of making reinforced proton-exchange membranes. The use of simultaneous dual-fiber electrospinning or the electrospinning of polymer blends can be used to intermix/incorporate/co-locate dissimilar and incompatible polymers on the nanoscale. Although less studied in the literature, these methods offer many interesting possibilities for new membrane structures with targeted and unique transport and mechanical properties.
In this review talk, the use of dual fiber and blended polymer fiber electrospinning for membrane fabrication will be presented for the following: (1) Nanofiber reinforced cation (proton) exchange membranes, (2) Electrospun NafionTM/PVDF dual fiber and single-fiber membranes for H2/Br2 redox flow batteries, (3) Composite anion exchange membranes, and (4) Bipolar membranes with a 3D nanofiber junction. Materials and methods for membrane fabrication will be described and the properties of the membranes will be discussed.
Advanced PEM Electrolyzer Membrane for Hydrogen Crossover Mitigation
Authors: Yang Fan , Sun Qiang , Mittelsteadt Cortney 
Published: February 2024

Proton Exchange Membrane (PEM) electrolyzers are a promising technology to produce hydrogen as a clean energy carrier. However, a significant challenge is hydrogen crossover, especially at high pressures (>40 bar) and when utilizing thin (<100 um) membranes. This poses significant safety hazard due to the mixing of H2 with oxygen, especially in the balance of plant due to higher void volumes.
Mitigating membrane crossover is therefore critical to the safety of the entire PEM electrolyzer system. Several research groups have demonstrated preliminary works on the H2 crossover mitigated membrane for PEM electrolyzers. Klose et al. [1] implemented a Pt interlayer between one piece of NR212 membrane and a piece of N115 membrane. The work showed significant reduction of H2 crossover in their design compared to the regular PFSA membrane. However, the work only demonstrated the effectiveness of crossover reduction under ambient pressure. Moreover, the spraying method they proposed is not readily scalable. Stahler et al. [2] demonstrated that applying an interlayer between the anode catalyst layer and recombination layer will help to reduce the H2 crossover. However, this work also failed to demonstrate mitigation at high H2 pressure. Additionally, each of these methods used Pt/C in the recombination layer. Carbon, though robust in the fuel cell applications may readily oxidize at the higher electrolyzer potentials. This could have consequences on membrane durability.
Preliminary data has demonstrated that our proposed mitigate strategy can significantly reduce the H2 crossover. The MEA with regular NR212 membrane cannot be operated safely under 70 oC under even mild pressure. However, with our addition of the highly efficient recombination layer, the crossover can be dropped to 6% LEL even at 40 bar. This discovery will help to improve the PEM electrolyzer safety dramatically.

References:

C. Klose et al 2018 J. Electrochem. Soc. 165 F1271

A. Stähler et al 2022 J. Electrochem. Soc. 169 034522
Electrospun High Performance Polymer Reinforced Membranes for Exceptional Durability Fuel Cell Membrane Electrode Assemblies
Authors: Zaton Marta , Donzel Nicolas , Cavaliere Sara , Rozière Jacques , Jones Deborah J. , Nesling Emily , Bobolecki Josef , Buche Silvain 
Published: February 2024

Adequate material selection is one of the most important aspects in component design. Therefore, high-performance polymers have garnered significant interest for Proton Exchange Membrane Fuel Cell (PEMFC) and Water Electrolysis (WE) applications due to their exceptional mechanical, thermal, and chemical properties. This 'beginning by design' strategy requires a deep knowledge of environmental stressors and degradation mechanisms and focuses on proposing next-generation advanced materials able to withstand defined stress conditions for lightweight and heavy-duty transport applications. This presentation presents recent advances and challenges encountered in the preparation of high-performance polymer-reinforced membranes and highlights their specific properties resulting in exceptional durability of nearly 120,000 cycles when tested under combined Open Circuit Voltage (OCV) with Relative Humidity (RH) cycling.
This work was supported by the Fuel Cells and Hydrogen 2 Joint Undertaking under grant agreement No 101006641 IMMORTAL. This Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation programme, Hydrogen Europe and Hydrogen Europe Research.