bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Investigation on Two-Phase Flow Pressure Drop in Cathode Channels of Proton Exchange Membrane Fuel Cells
Authors: Yang Danan , Garg Himani , Andersson Martin 
Published: December 2024

Water management remains a critical challenge in proton exchange membrane (PEM) fuel cells, particularly concerning flooding under high-current density and prolonged operation. Dynamic water distribution directly affects gas phase transport, encompassing convection within gas channels (GCs) and diffusion through porous electrodes. The fluctuation of pressure drop has been highlighted in previous studies [1-3], which is more frequent when compared with that when only single-phase flow in the channel is considered. A reasonable cathode channel pressure drop can benefit fuel cell performance [1] and energy efficiency [4]. Although pressure drop correlations have been conducted experimentally and numerically [5], the pressure drop prediction still needs to be improved, for example, involving the liquid transport from gas diffusion layers (GDLs) [6]. In this study, two-phase flow simulations in an assembled GC and fibrous GDL are conducted by the volume of fluid method in OpenFOAM. To utilize the fibrous GDL structures to mimic the natural breakthrough water, different GDLs are stochastically reconstructed using straight- and curved- cylinders (regarded as carbon fibers) and keeping the same bulk porosity and fiber diameter, as shown in Figure 1. The GC pressure drop is studied in local and total regions in different scenarios, e.g, different GDL structures (see Figure 1(c)), different surface wettability, and different air flow rates. Preliminary results show that the pressure drop does not exhibit a direct correlation with the liquid amount present in the GC, suggesting a multifaceted relationship that extends beyond mere liquid content, as shown in Figure 2. Therefore, it is imperative to explore additional factors that may influence this critical parameter. Figure 3 displays the spatial and temporal distribution of pressure and water cross-section area of 23 cross-section along the GC length direction in 13.5 ms in Case A and B. The breakthrough types in the GDL/GC interface and drainage flow types in GCs are found to relate more to the pressure drop. In future work, we aim to explore all the above scenarios to gain deeper insights into their impact on pressure drop behavior and ultimately enhance our understanding of the complex interactions governing two-phase flow in PEM fuel cell systems.
References

Li, P. Pei, Z. Wu, H. Xu, D. Chen and S. Huang, Applied Energy, 190, 713 (2017).

Liu, L. Guo, R. Zhang, L. Chen and W.-Q. Tao, Applied Energy, 302, 117625 (2021).

Zhang, S. Liu, Z. Wang, R. Li and Q. Zhang, International Journal of Hydrogen Energy, 47, 17713 (2022).

S. Ijaodola, Z. El- Hassan, E. Ogungbemi, F. N. Khatib, T. Wilberforce, J. Thompson and A. G. Olabi, Energy, 179, 246 (2019).

Li, H. Zhou, C. Li, Z. Liu, P. Zhang and C. Lu, Experimental Thermal and Fluid Science, 155, 111198 (2024).

Mortazavi and K. Tajiri, Renewable and Sustainable Energy Reviews, 45, 296 (2015).

Figure 1
Novel Approaches for a Time and Cost Efficient Activation of Polymer Electrolyte Membrane Fuel Cell Stacks
Authors: Zink Stefan , Joerissen Ludwig 
Published: December 2024

Towards a CO2 free energy supply, hydrogen plays an important role as a chemical energy storage capable of storing renewable energy in large dimensions. In this context, fuel cells, such as e.g. polymer electrolyte membrane fuel cells (PEMFC) are going to evolve to a key technology for the conversion of the chemically stored energy back to usable electric energy. Therefore, after decades of fuel cell research, the phase of industrialization of fuel cells has begun recently to provide fuel cells in large quantity for a variety of applications, such as e.g. to power heavy duty vehicles, ships and even airplanes or as stationary power plants.
For PEMFC mass production, the optimization of the manufacturing process of fuel cells is important to decrease the manufacturing time and costs. One of the most time and cost consuming steps during the production of fuel cells is the first time activation. During the so-called break-in, the fuel cell is operated for the first time in order to activate the membrane electrode assembly (MEA). During break-in, the proton conductivity of the membrane is established and the catalyst is activated, but also chemical residues of the production of the fuel cell components were removed. This procedure is necessary for a fuel cell stack to provide its maximum power output and maximum robustness of all single cells. Furthermore, the successful activation of the PEMFC strongly affects the overall lifetime of a fuel cell stack.
To date, a typical break-in of a fuel cell stack takes in between 2 and 8 hours of time, in which a considerable amount of hydrogen and air is required. Thereby, the stack is commonly operated at a high relative humidity doing several cycles of current ramps from minimum to medium or high load interrupted by shutdowns, whereby the first current ramp is usually performed very slowly. Besides the media consumption, the rather long state-of-the-art break-in time calls for a high degree of parallelization of break-in stations at each production line to reach a reasonable output of fuel cell stacks, which is related to high investment costs. An optimization of the break-in process in respect to the necessary time and media consumption significantly reduces the production costs of a PEMFC stack. In this work, several new approaches to activate PEMFCs were introduced in order to decrease the duration and media consumption of the break-in process. Thereby, the common break-in doing several current ramps was replaced by more efficient and promising approaches, such as e.g., hydrogen starvation events or hydrogen pumping. This break-in experiments were performed in short stacks of small scale as well as automotive scale. Finally, the influence of each break-in variation on the performance and durability of the PEMFC was investigated.
Low-Temperature Cation Ordering in Ce0.5-XZr0.5+XO2 Under Precisely Controlled P(O2)
Authors: Okazaki Yume , Ishii Akihiro , Oikawa Itaru , Takamura Hitoshi 
Published: December 2024

CeO2-ZrO2 solid solutions (CZ) with a high oxygen storage capacity (OSC), owing to the valence change of Ce ions upon reduction, have been utilized to control the P(O2) of automobile exhaust purification systems. In the CeO2-ZrO2 system, cation-ordered κ-Ce2Zr2O8 shows the highest OSC; however, cation ordering requires high-temperature heat treatment, typically higher than 1200 °C, under a reducing atmosphere [1], which leads to grain growth and a decrease in OSC. Our previous study revealed that the addition of a small amount of Fe2O3 reduces the cation-ordering temperature to 800 °C, although the mechanism is unknown [2]. In this study, in-situ high-temperature XRD revealed that Fe2O3 plays an important role in cation ordering by precisely controlling P(O2), which assists the nucleation of the ordered phase. Furthermore, the effect of the Ce/Zr ratio on the ordering behavior was investigated because Zr-rich CZ (Ce0.5-xZr0.5+xO2) with a high proportion of Zr is expected to suppress grain growth, thereby improving the specific surface area and OSC. Thus, this study discusses the mechanism of low-temperature cation ordering of Zr-rich CZ solid solutions by Fe2O3 addition and evaluates their OSC.

DFT-based first-principles calculations revealed that Zr-rich Ce0.375Zr0.625O2 was less likely to be ordered than Ce0.5Zr0.5O2 (Ce/Zr=1) because the energy gain resulting from cation ordering was smaller by 0.35 eV/f.u. Meanwhile, in the disordered phases, the oxygen vacancy formation energy was negatively larger by 0.12 eV/f.u. in the Zr-rich CZ than in Ce0.5Zr0.5O2, suggesting that the Zr-rich CZ was more readily reduced. The in-situ high-temperature XRD revealed that Fe2O3-added Zr-rich Ce0.5-xZr0.5+xO2 (0.05 < x < 0.1) was not ordered under dry 10%H2-N2; however, surprisingly, it was successfully ordered under wet 4.5%H2-N2, which provides a weak reducing atmosphere. It should also be noted that Zr-rich CZ without Fe2O3 addition was not ordered, regardless of the gas composition. In addition, the Zr-rich CZ embedded in the mixture of Fe2O3 and Fe3O4 powders and heat-treated at 900 °C showed significant grain growth, which seems to be related to the initial stage of cation ordering. Based on these results, a moderately reducing atmosphere rather than a highly reducing one leads to a deeper reduction of the Zr-rich CZ, which triggers cation ordering. A more detailed thermodynamic discussion is also provided. The cation-ordered Zr-rich κ-Ce1.79Zr2.21O8 showed an excellent OSC of 688 μmol-O2/g at 400 °C excluding the reduction amount of Fe2O3 added, which is 96±6 % of the theoretical OSC, even without precious metal group catalysts.

References

[1] Y. Nagai et al., Catalysis Today, 74 (2002), 225-234.
[2] K. Murakami, J. Mater. Chem. A, 10 (2022), 21291-21299.
Dissociative Oxygen Adsorption and Incorporation in Co3O4-Dispersed BaZr0.9Sc0.1O2.95 for a PCFC Cathode
Authors: Kamohara Shinnosuke , Ishii Akihiro , Oikawa Itaru , Takamura Hitoshi 
Published: December 2024

Proton-conducting fuel cells (PCFCs), which operate at lower temperatures than conventional solid oxide fuel cells (SOFCs) using an oxide-ion conductor, have attracted considerable attention owing to their high energy-conversion efficiency. Even with mobile protons, oxygen reduction reactions at the cathode limit the performance of PCFCs. To improve their cathode properties, a variety of functional oxides, including the so-called triple conductors, which have mobile oxide ions, protons, and holes, have been developed. Our group has focused on the excellent catalytic activity of Co3O4 for the dissociative adsorption of oxygen at elevated temperatures, which is comparable to that of Co-containing mixed conductors with a perovskite-type structure [1,2]. In this study, Co3O4-dispersed proton-conducting oxides, BaZr0.9Sc0.1O2.95, were prepared for use as composite-type cathodes, and their surface oxygen exchange behavior was investigated using the pulse isotopic exchange (PIE) technique.
BaZr0.9Sc0.1O2.95 (BZS10) was prepared using a solid-state reaction method by sintering at 1300 °C for 10 h. To prepare the composite powders, BZS10 powders were ball-milled with x vol%Co3O4 (x = 1, 3, 5, 10, and 50). Prior to PIE, their specific surface area was determined by a BET method for the sample powder heat-treated at 880 °C, which is slightly higher than the highest PIE temperature to avoid morphological and compositional change during PIE. The PIE was performed at 800–200 °C under a 10%O2 atmosphere.
Based on the almost constant lattice constants, regardless of the Co3O4 volume fractions, the composites were successfully prepared as a dual-phase state, unlike Co-doped BZS10 prepared at 1225 °C, which showed a decrease in the lattice constant [3]. At 500 °C, the surface oxygen exchange rate R0
of BZS10 without Co3O4 particles was 4.0×10-6 mol/m2·s. R0
was surprisingly enhanced by an order of magnitude with the addition of only 1 vol%Co3O4. Further addition of Co3O4 exceeding 10 vol% reduced R0
. This trend indicates that the optimum amount of Co3O4 provided sufficient dissociated oxygen on BZS10, which was readily incorporated into BZS10. Their electrochemical properties and detailed microstructural analyses are also discussed.
[1] Y. Tomura et al., J. Mater. Chem. A, 8 (2022) 21634–21641.
[2] A. Ishii et al., ACS Appl. Mater. Interfaces, 15 (2023) 34809−34817.
[3] H. Uehara et al., Int. J. Hydrogen Energy, 47 (2022) 5577−5584.
Optimum Operating Conditions By Co-Electrolysis in Solid Oxide Cell for Fischer-Tropsch Synthesis
Authors: Imabayashi Takumi , Ozeki Takayuki , Asano Koichi 
Published: December 2024

Highly efficient liquid fuel production can be expected by integrating the Fischer-Tropsch (FT) synthesis process at the latter stage of the solid oxide electrolysis cell (SOEC) process and integrating the heat transfer between the processes. However, it is difficult to achieve the high efficiency and durability conditions in SOEC process with the high-yield conditions in FT synthesis process. In this study, the SOEC operating conditions were investigated to improve the efficiency and durability of the integrated production process by thermodynamic equilibrium calculations of the gas composition at the SOEC outlet (FT synthesis inlet) and experiments using a single cell.
Gas compositions of H2/CO=2.0 and high H2 and CO production are favorable for FT synthesis. To achieve these conditions at the SOEC outlet, the SOEC inlet gas must be close to (H2+H2O)/CO2=2.0, and reactant utilization must be high. However, these conditions are likely to cause carbon deposition in SOEC, which can lead to cell damage. An effective way to prevent carbon deposition is to increase the cell temperature because carbon deposition is an exothermic reaction. High temperature conditions have the advantage of lowering the cell voltage in co-electrolysis and preventing carbon deposition, but the life of the cell components may be shortened. Promoting methanation was also an effective way to prevent carbon deposition because of consuming CO, but it may cause lower yields of liquid fuel from FT synthesis. Under pressurized conditions, the volume reduction reaction which includes methanation and carbon deposition is accelerated Therefore, the risk of carbon deposition under pressurized conditions has become highly dependent on the SOEC operating conditions which determine whether methanation or carbon deposition is more promoted. These results clarify the risks associated with changing the operating conditions by co-electrolysis in SOEC and can be used to guide the optimum operating conditions.
Fabrication of Dense Electrolyte for Metal-Supported Solid Oxide Fuel Cells By Plasma Spray Method
Authors: Yashiro Keiji , Matsui Toshiaki , Yamaguchi Mina , Fujisaki Takaya , Kawada Tatsuya 
Published: December 2024

Metal-supported SOFCs (MS-SOFCs) have attracted attention because of their potential for low cost and high mechanical robustness. However, the conventional cell fabrication process is not easily applied to MS-SOFCs. The difficulty of MS-SOFC fabrication is especially to form a dense electrolyte without oxidation and diffusion of the metal support. We’ve tried to use a plasma spray method to prepare the metal supported cells. Then, apparently dense electrolyte layer could be fabricated using doped lanthanum gallate instead of yttria stabilized zirconia. In this paper, electrochemical performance and gas tightness of the cells were evaluated to consider the applicability of plasma spray for MS-SOFC fabrication.
A prepared MS-SOFC consists of porous metal substrate (SUS430), NiO-YSZ anode, Sr-, Mg-doped lanthanum gallate (LSGM9182), and conventional cathode (LSCF6428). The cell components, except for the porous substrate, were deposited by atmospheric pressure plasma spray (APS). Gas tightness of the cell was confirmed by open circuit voltage (OCV) measurement. Cell performance was evaluated by current-voltage measurement and impedance measurement. Post-analysis of the cell was conducted by SEM/EDS.
The measured OCV was confirmed to be equivalent to theoretical value in humidified hydrogen at 973 K. It means the fully dense electrolyte layer could be prepared by plasma spray. Current density of I-V measurement was 0.6 Acm-2 at 0.5 V at 973 K. The impedance results showed larger over potential of anode reaction. This might be caused by anode electrochemical reaction and gas diffusion through anode and substrate layer. Further development of plasma spray anode is necessary for practical application; however, this study confirmed the possibility of the plasma spray method to fabricate the dense electrolyte for MS-SOFCs.
This research was financially supported by NEDO.
Microstructural Analysis of Stainless Steel Support/Ni-YSZ Anode Interface in Metal-Supported SOFCs
Authors: Ishiguro Hikaru , Muroyama Hiroki , Matsui Toshiaki 
Published: December 2024

Solid oxide fuel cells (SOFCs) have attracted attention due to their high energy conversion efficiency and fuel flexibility. However, conventional anode-supported SOFCs composed solely of ceramics are susceptible to thermal stress such as rapid temperature rises and drops, which can cause cell cracks. Therefore, metal-supported SOFCs (MS-SOFCs) have been devised that use a stainless steel with excellent heat resistance as a support. In MS-SOFCs, elemental diffusion from the metal support during the cell manufacturing process causes microstructural changes in electrodes, leading to a reduction in cell performance [1, 2]. Although the microstructure and diffusion state of elements at the support layer/anode interface are different from those of conventional anode-supported cells, the phenomena as well as the chemical and physical states that occur at the interface have not been sufficiently studied. In this study, then, the microstructural characteristics of the stainless steel support/anode interface were quantitatively analyzed to understand the phenomena occurring and to develop methods to suppress the diffusion of metallic elements.
Gd-doped CeO2 (GDC) was coated as a diffusion barrier layer (DBL) on a SUS430 stainless steel substrate by magnetron sputtering, followed by the NiO-YSZ (8 mol% Y2O3-ZrO2) slurry coating. The composition of SUS430 is given in Table 1. Samples without DBL were also fabricated. These samples were sintered at 1250 ºC for 10 hours in 50% H2-50% Ar. Three-dimensional reconstruction of the microstructures of these samples was performed using a focused ion beam-scanning electron microscope (FIB-SEM), and microstructural parameters were calculated. In addition, elemental diffusion at the interface was analyzed using an energy dispersive X-ray spectroscopy (EDS) analysis.
When the sample was sintered at 1250 °C in a reducing atmosphere, the diffusion of Fe was significantly suppressed by the insertion of DBL. Therefore, it was confirmed that the GDC layer is effective to suppress the Fe diffusion as well as to prevent the formation of solid solution with Ni. However, no significant difference in Cr diffusion was observed. Furthermore, SEM observation revealed that the Ni surface was partially covered with Mn-Cr oxides. The formation of such a characteristic structure had a negative effect to reduce the effective triple phase boundary (TPB) length of the anode. Thus, it was concluded that the insertion of GDC layer suppressed the formation of Ni-Fe solid solution, while the patrial coverage of the Ni surface with Mn-Cr oxides reduced the effective TPB length.
Acknowledgements
This paper is based on results obtained from a project, JPNP20003, commissioned by the New Energy and Industrial Technology Development Organization (NEDO).
[1] M.C. Tucker, J. Power Sources, 195, 15 (2010).
[2] T. Franco, et al., ECS Transactions, 7, 771, (2007).

Figure 1
Optimization of the Parameters for Developing the Buffer Layer By Reactive Magnetron Sputtering in Order to Increase the Performance of a SOFC
Authors: Guesnet Laura , Laurencin Jérôme , Vulliet Julien , Briois Pascal 
Published: December 2024

Solid oxide cells (SOCs) are electrochemical devices operating at high temperature. This technology can directly convert fuel into electricity (fuel cell mode – SOFC) or electricity into fuel (electrolysis mode – SOEC). In recent years, the interest on SOCs has grown significantly thanks to the need of massive and low-cost production of H2, and their capability of reversible operation.
The main objectives still remaining for these electrochemical cells are to enhance their initial performances and to increase their durability. The key parameters are obviously the choice of the materials chosen for the functional electrodes, the electrolyte or the barrier layer, but also the microstructures of each layers. It’s well know that the performances could be improved by decreasing the thickness layers, in particular for the electrolyte and the barrier layer which induce additionnal resistances or by increasing their quality (density for instance). The reference cell, used for this study, consists of Ni-YSZ for the hydrogen electrode, YSZ for the electrolyte, GDC for the barrier layer and LSCF for the oxygen electrode. This cell is produced by screen printing and tape casting;
During this work, the production of the GDC barrier layer by physical deposition and more particularly by magnetron cathode sputtering in reactive conditions was studied. The GDC thin film was produced from a metallic target of cerium with 10 atomic % of gadolinium; This layer must have many qualities such as good adhesion, resistant in the conditions of synthesis of the other layers of the cell as well as in the conditions of use, covering, and thin to limit its resistance.The influence of the operating conditions in PVC on the quality of the GDC barrier layer will be discussed such as the bias voltage of the sample holder, the regulation system, the working pressure, etc. for all the synthesis conditions of the SEM observations of raw samples and after heat treatments will be presented; Then, the selected synthesis protocol will be carried out on a reference half-cell (Ni-YSZ/YSZ) and a reference electrode will be deposited using the same method as the reference cell; Electrochemical performance in electrolysis configuration over a temperature range of 700 to 800°C with different flow rate ranges.
Advances in Solid Oxide Electrolysis Cell (SOEC) Technology for Sustainable, Efficient, and Durable Hydrogen Production
Authors: Kim Sun-Dong , Choi Yoonseok , Park Hoonmin 
Published: December 2024

The global transition towards sustainable energy sources has significantly heightened interest in efficient hydrogen production technologies. Among these, solid oxide electrolysis cells (SOECs) have emerged as a standout method for their efficient conversion of electrical and thermal energy into hydrogen through water electrolysis. This study presents recent developments in SOEC technology at the Korea Institute of Energy Research, emphasizing crucial innovations in cell and stack designs that enhance both performance and durability under high-temperature electrolysis conditions.
Our research demonstrates significant improvements in SOECs, aiming to meet the increasing demand for sustainable and efficient hydrogen production. Innovations include the introduction of cells with thicknesses ranging from 250 to 300 microns and enhanced support porosity of over 40%, transitioning from 8YSZ to 3YSZ for support and subsequently to 9.5YSZ for the electrolyte. These materials achieve higher mechanical strengths and reduced area-specific resistance. These advancements have resulted in a 20-25% reduction in power consumption compared to conventional lower-temperature electrolysis methods such as alkaline, PEM, or AEM, which is crucial for scaling hydrogen production.
In stack development, optimized bipolar plate designs and surface treatments have been introduced to ensure efficient steam distribution and effective thermal management. Strategic operational control has maintained stack voltage within optimal ranges (12.8V at 700°C and 14V at 650°C) under a current of 100A, demonstrating robust performance over prolonged periods with minimal degradation—validated by long-term testing showing less than -0.7% degradation per 1000 hours under these specified conditions. Testing and evaluation within the specified range confirmed that there was no observed degradation, considering the reduction in power consumption.
These improvements not only showcase our commitment to advancing SOEC technology but also pave the way for its broader application and commercialization. This aligns with global efforts to utilize renewable and nuclear energy resources for environmentally friendly hydrogen production, addressing technical challenges associated with high-temperature electrolysis, and contributing to the low-carbon solution in the global energy transition.

Figure 1