bluuebunny/crossref_metadata_2025 huggingface dataset:
Advancing PEMFC Bipolar Plate Design: Biomimetics, Simulation, and Surrogate Modeling By Deep Neural Networks for Optimized Performance
Authors: Fedi Baptiste , Boucher Aurélien
Published: December 2024

Proton exchange membrane fuel cells (PEMFC) represent a promising solution in the transition to cleaner and more sustainable energy sources. Their efficient and environmentally friendly operation relies in part on the performance of bipolar plates. These key components play a crucial role in the uniform distribution of reactants and the evacuation of products, directly impacting the overall efficiency of the fuel cell. By optimizing the design of bipolar plates, particularly through simulation, it is possible to significantly improve the operation of these cells.

The use of biomimetics design in bipolar plate design offers an innovative approach to maximize active species concentration, facilitate product evacuation, and reduce pressure drop. Drawing inspiration from natural structures and mechanisms, such as leaf vascular networks, optimized channel configurations can be designed to promote uniform and efficient flow of reactants and products across the plate. This approach not only enhances overall fuel cell performance but also reduces environmental footprint by optimizing resource utilization.

The use of multiphysics simulation provides a valuable tool to predict the behavior of PEMFCs based on operational parameters such as gas fluxes and operating voltage/current density. Focusing on the operating power per unit area of the bipolar plate's active surface, as well as the distribution of partial pressures in gas, water, and temperature within the cell, simulation allows for a thorough understanding of the complex interactions within the system. This enables optimization of operating conditions to enhance energy efficiency and durability of PEMFCs.

Developing a surrogate model, with Comsol Multiphysics, for bipolar plate design holds significant interest in creating an application able of real-time prediction of the impact of minor geometry modifications on local concentration distributions within the channels of the bipolar plate and gas diffusion layers (GDLs) using deep neural networks. This approach enables rapid assessment of design variations, facilitating optimization efforts and informed decision-making. By harnessing the power of deep learning, the surrogate model enhances efficiency in the design process, streamlining iterations and minimizing experimental testing requirements. This innovative approach accelerates the development of high-performance fuel cell systems.

The developed strategy combines biomimetics for designing optimized bipolar plates, multiphysics simulation to predict PEMFC behavior, and the development of a surrogate model to accelerate prototyping phase.
(Invited) Optimized Conditioning and Performance of PEM Fuel Cell Stacks
Authors: Dombrovskis Johanna , Shokhen Victor , Kylhammar Lisa , Bodén Andreas
Published: December 2024

The fuel cell market is maturing, and the production volumes are increasing. In parallel, expectations on performance, lifetime and operational range for fuel cell stacks are growing. As fuel cell technology matures, more fuel cell stacks are used in real life applications instead of laboratory environment. These positive developments bring with them new challenges and opportunities to learn.

Several of these challenges and their impact on stack design and validation will be discussed. The focus will be on optimization of useful stack power density, fuel cell stack conditioning, enlarging the LT-PEM fuel cell operation range and on durability testing.

This talk addresses why conditioning and durability testing are closely connected and illustrates how this can impact stack platform and fuel cell development. In addition, the interactions between power density, stack integration and stack operational window are illustrated showing how each of these parameters could be optimized utilizing a current distribution plate and what trade-offs are relevant for optimized fuel cell stack and system performance.

Powercell is active in various market segments and has developed stacks and stack components for ~20 years. The optimizations and trade-offs described hinge heavily on key PEM stack requirements which can be widely different in different PEM fuel cell market sectors, as illustrated by the emerging usage of fuel cells in aviation.
Dynamic Simulation of a Hybrid PV/Awe/SOFC Stand-Alone System for Heat and Power Generation
Authors: Ham Jinyoung , Kang Sanggyu , Jang Dohyung , Shin Haeseong , SHIN Hee-SUN
Published: December 2024

Global energy demand increased from 528 EJ in 2012 to 604 EJ in 2022, with CO2 emissions rising from 34 Gt to 36.8 Gt during the same period. According to the IEA, global energy demand is projected to reach 670 EJ by 2030. To meet this energy demand and simultaneously reduce greenhouse gas emissions, the capacity for renewable energy installations is expanding. However, renewable energy faces the issue of lacking flexibility to balance supply and demand due to its intermittency and variability. Sector coupling, which converts power to heat (P2H), gas (P2G), and liquid fuels (P2L), can overcome the flexibility challenges of renewable energy by integrating energy across sectors (power, transportation, industry, agriculture, and residential). As an energy storage medium, hydrogen serves as a key component in P2G and P2L and holds potential as a future energy carrier.

The residential sector requires both heat and electricity, yet the power supply through photovoltaics (PV) leads to an imbalance between energy demand during day and night. To alleviate this energy imbalance while flexibly meeting heat and electricity demands, a hydrogen-based 'PV-AWE-Batt-SOFC' hybrid system was proposed. Numerous previous studies have performed capacity optimization of hybrid systems with cost as the objective function. However, research on Energy Management Strategies (EMS) for stable operation of each system in conjunction with renewable energy is limited. Therefore, a stable hybrid system EMS based on the analysis of the dynamic behavior of AWE and SOFC needs to be established.

In this study, a dynamic model of the PV-AWE-Batt-SOFC hybrid system was developed using AMESim®. The AWE system consists of a stack, pump, heat exchanger, gas-liquid separator, cooling system, condenser, oxygen catalytic combustor, and dryer. The SOFC system comprises a stack, blower, heat exchanger, and after-burner. The stack was modeled with an in-house code to accurately resolve the electrochemical reactions. To establish a stable EMS for the hybrid system integrated with renewable energy, the dynamic behavior of both the AWE and SOFC systems was analyzed, and EMS scenarios were proposed. The scenarios were evaluated by comparing the state of charge of the battery and the state of charge of the hydrogen tank. Analyzed parameters in the AWE system include stack temperature/voltage, condenser temperature/hydrogen purity, oxygen catalytic combustor temperature/conversion rate, and dryer temperature/hydrogen purity. In the SOFC system, analyzed parameters are stack temperature/voltage/fuel utilization, and after-burner temperature/conversion rate.

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Electrochemical Modeling of a Commercial Polymer Electrolyte Fuel Cell Using 3-D Micro-Computed Tomography
Authors: White Zakar , Swider-Lyons Karen , Litster Shawn
Published: December 2024

Challenges remain with the accurate modeling and optimization of gas transport in polymer electrolyte membrane fuel cells (PEMFCs) due to the complexity of calculating transport across the relevant domains and structures in a fuel cell. Each cell comprises two bipolar plates (BPPs) compressed around a membrane electrode assembly (MEA). The bipolar plates (BPPs) are a multifunctional component having flow fields with mm-sized features designed for reactant delivery and heat and water management. The MEA comprises a 5-layer structure with microporous catalyst and gas diffusion layers (GDLs) on either side of a proton exchange membrane (PEM). Actual cell designs are further constrained by their materials, and manufacturing cost and speed.

Prior work primarily focuses on modeling the flow fields in metal BPPs as idealized geometries, neglecting the inherent curvature introduced during the stamping manufacturing process and the compression and thickness variation of the MEA layers. To create high-performance cells, it is necessary to understand the detailed interaction of the BPPs and MEAs in practical, manufactured fuel cell stacks.

In this work, a compressed short stack of unit cells from a decommissioned commercial fuel cell electric vehicle (FCEV) was resolved in three dimensions (3-D) using a micro-computed tomography instrument (micro-CT) capable of imaging large samples (up to 30 cm). Representative images from across the cell domains are shown in Figure 1. The 3-D images were subsequently segmented and meshed for computational fluid dynamics (CFD) modeling. Simulations of transport and electrochemical phenomena were performed using commercial CFD software using custom codes. Simulation results were used to assess the performance of a mesh-type cathode flow field design with secondary flows as well as the impact of compression, and stamped plate curvature. The results highlight the significant impact of the induced convective transport in the gas diffusion layers (GDLs) has on the performance of a practical fuel cell.

Acknowledgements: This material is based upon work supported by Plug Power Incorporated.

Figure Collage: Left – 3D Micro-CT Images of the BPPs and components of an MEA, Center - Meshing faces, Right – Relative Humidity Profile

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Multiscale Simulation of Internal Reforming Solid Oxide Fuel Cells to Capture Complex Reaction Phenomena
Authors: Abbasi Hamid , Babaei Masoud , Theodoropoulos Constantinos
Published: December 2024

In our previous work, we successfully employed a multiscale modelling approach to simulate solid oxide fuel cells (SOFCs) fuelled by pure hydrogen [1]. This approach effectively captured the interplay between electrochemical and transport phenomena at various scales within the SOFC. Here, we extend this framework to investigate the complexities of internal reforming SOFCs (IR-SOFCs) fuelled by hydrocarbon fuels, such as methane. IR-SOFCs offer fuel flexibility but introduce significant modelling challenges due to the inclusion of steam methane reforming (SMR) within the anode[2]. Accurately capturing this process requires accounting for several complexities.

A multiscale modelling approach that can handle the interplay of several complex phenomena in IR-SOFCs. SMR involves a series of interconnected reactions with intricate mechanisms [3]. Unlike SOFCs working with pure hydrogen fuel, SMR reactions in IR-SOFCs may operate far from chemical equilibrium under certain operating conditions. To capture this condition, rigorous kinetic modelling across different length scales is needed. Finally, a significant challenge lies in describing the coupling between the electrochemical reactions at the anode and the chemical reactions of SMR. These phenomena are intrinsically linked, as the reforming process consumes reactants (steam and methane) that are also crucial for the electrochemical oxidation at the anode. An effective modelling framework must seamlessly integrate the transport and reaction phenomena occurring at both micro and macro scales within the SOFC electrodes. By addressing these challenges, our multiscale modelling framework aims to provide a more comprehensive understanding and optimization of IR-SOFC performance.

References:

[1] H. R. Abbasi, M. Babaei, A. Rabbani, and C. Theodoropoulos, ‘Multi-scale model of solid oxide fuel cell: enabling microscopic solvers to predict physical features over a macroscopic domain’, in Computer Aided Chemical Engineering, vol. 52, Elsevier, 2023, pp. 1039–1045.

[2] K Tseronis, I.S. Fragkopoulos, I. Bonis, and C. Theodoropoulos. Detailed Multi‐dimensional Modeling of Direct Internal Reforming Solid Oxide Fuel Cells, Fuel Cells vol. 16, no 3, pp. 294-312, 2016, https://doi.org/10.1002/fuce.201500113.

[3] E. S. Hecht et al., ‘Methane reforming kinetics within a Ni–YSZ SOFC anode support’, Appl. Catal. Gen., vol. 295, no. 1, pp. 40–51, Oct. 2005, doi: 10.1016/j.apcata.2005.08.003.
Perovskite Anode for SOFCs Running on Dry Reforming of CH4
Authors: Yoon Sung Pil , Cho Albert Won , Jun Young Bae , Audasso Emilio , Kim Kab In
Published: December 2024

Dry reforming of biogas, which contains methane and carbon dioxide, for use as fuel in Solid Oxide Fuel Cells (SOFCs) can achieve superior efficiency and carbon neutrality compared to conventional steam reforming. In this study, we investigated Sr1-xLaxTi1-yRuyO3 (SLTRO) perovskite cathode materials for SOFCs with high electrical conductivity and excellent catalytic activity for dry reforming. La+3 doping on the Sr+2 site of the basic SrTiO3 (STO) perovskite material enhanced electronic conductivity, while simultaneous exsolution of Ru+4 doped on the Ti+4 site at high temperatures facilitated the formation of numerous Ru nanoparticles on the surface. The SLTRO cathode material with exsolved Ru nanoparticles exhibited high catalytic activity for dry reforming, with methane conversion rates of 85% and carbon dioxide conversion rates of 83% at the SOFC operating temperature of 700°C. Notably, it maintained a degradation rate of less than 1%/1000 hours without carbon deposition during dry reforming operation at 700°C for over 1000 hours. Additionally, we will report the electrochemical properties and performance of SOFC cells equipped with SLTRO cathodes.

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Ultrathin Triple Conducting Oxide Interlayer for Protonic Ceramic Electrochemical Cells Fabricated by Chemical Solution Deposition
Authors: Kim Dongyeon , Kim Hyeonggeun , Yu Hyeongmin , Oh Seeun , Lee Kang Taek
Published: December 2024

Protonic ceramic electrochemical cells (PCECs) offer the capability to enhance electrochemical properties across various energy conversion systems, efficiently transforming chemical fuels into electricity and vice versa, operating at temperatures below 600 °C. However, poor contact between the oxygen electrode, which possesses triple conductivity (H+/O2-/e-), and the electrolyte results in elevated ohmic resistance, impeding the electrochemical reactions of PCECs. To improve the adhesion between the oxygen electrode and the electrolyte layer, various vacuum deposition techniques such as pulsed laser deposition and atomic layer deposition have been proposed for thin-film interlayer fabrication. Nonetheless, the high cost, intricate procedures, and scalability challenges associated with vacuum-based processes may render them unsuitable for industrial applications. Herein, we present a straightforward method for depositing an ultrathin triple-conducting oxide interlayer using the chemical solution deposition technique. This thin interlayer was effectively deposited between the electrolyte and the oxygen electrode layer, leading to a decrease in ohmic resistance and showcasing the enhanced performance of PCECs. Our results provide valuable insights into overcoming the current challenges encountered by PCECs and highlight the potential for large-scale system applications.
(Invited) Bi-Functional Oxygen Electrodes for Reversible Solid Oxide Cells
Authors: Gopalan Srikanth
Published: December 2024

Solid oxide electrochemical cells operated reversibly in fuel cell and electrolysis modes (rSOCs), can enable the incorporation and integration of far greater amounts of solar and wind energy into our power grid. When deployed as islanded systems, they can also function as distributed generation systems thereby decreasing our reliance on the power grid. In this talk, we present results on rSOCs based on rare earth nickelate – rare-earth doped ceria composite oxygen electrodes that exhibit excellent reversible behavior when switched cyclically between solid oxide fuel cell (SOFC) and solid oxide electrochemical cell (SOEC) modes of operation. The cyclic mode-switching operation mitigates against cell degradation when compared to operating in single mode operation in electrolysis mode. Further, we have used distribution of relaxation times (DRT) analysis of impedance spectra obtained from single-mode (electrolysis) operated cells, and cells operated in switched-modes, to obtain clues into cell degradation mechanisms.
Mechanism of Hydride-Ion Diffusion in the Oxyhydride of Barium Titanate: Insights from Quasielastic Neutron Scattering
Authors: Lavén Rasmus , Fine Lucas , Koza Michael , Karlsson Maths
Published: December 2024

Perovskite type oxyhydrides, of the form ATiO3-xHx (A = Ba, Sr, and Ca, and x < 0.6) are a novel class of mixed-anion materials displaying high hydride-ion conductivity. The high hydride-ion conductivity may be exploited for applications such as in energy storage and conversion devices, and in catalyst technologies for hydrogenation reactions, bu the conductivity mechanism is not fully understood. Here, in a quasielastic neutron scattering study of the oxyhydride of barium titanate, with different levels of anion vacancies, we show that the rate of hydride-ion diffusion increases with an increasing level of anion vacancies, and that the presence of anion vacancies is a necessity for hydride-ion conductivity. The conductivity mechanism is highly temperature dependent. Below 350 K, the hydride ions undergo jumps amongst nearest neighbor anion vacancies acting as jumping sites, whereas at temperatures between 350 and 550 K the hydride ions also undergo jumps amongst second nearest neighbor sites in the material. The jump diffusion dynamics are characterized by an average relaxation time on the order of 10 ps with a diffusion coefficient of the order of 10-5 cm2/s. For temperatures above 300 K, an additional, slower timescale process, on the order of 100 ps, which may be related to nearest neighbour hydride-ion jumps in different types of local structures with different anion and vacancy concentrations and distributions is observed. Tailoring of the local structure with respect to the concentration and distribution of anion vacancies may thus be a promising route towards optimizing the hydride-ion conductivity towards specific applications
(Invited) Recent Advances in Protonic Ceramic Electrochemical Cells at KAIST
Authors: Lee Kang Taek
Published: December 2024

Protonic ceramic electrochemical cells (PCECs) offer a promising pathway for sustainable energy conversion and storage, operating at temperatures below 600°C. However, several challenges, including sluggish kinetics at the oxygen electrode and the formation of secondary phases within perovskite electrolyte materials, have hindered their widespread adoption. In this presentation, we highlight recent results aimed at overcoming these hurdles and advancing the performance of PCECs at KAIST. Firstly, we present an innovative approach to mitigate processing-related issues in PCECs. By employing a microwave-assisted sintering process (MW-PCEC), we significantly reduce sintering times while suppressing undesirable cation diffusion and grain growth. This results in PCECs with stoichiometric electrolytes and nanostructured fuel electrodes, leading to substantial enhancements in electrochemical performance. Secondly, we tackle the challenge of developing efficient and stable proton-conducting electrolytes. We introduce a novel high entropy perovskite oxide (HEPO) material, with superior conductivity and chemical stability, even in the presence of contaminants like CO2. Utilizing this electrolyte, we fabricate reversible PCECs (R-PCECs) with unprecedented performance, setting new benchmarks in power density and current density. Furthermore, we address the issue of sluggish reaction kinetics at the oxygen electrode by introducing bifunctional oxygen electrodes based on bimetal-doped BaCoO3-𝛿 (BCO). Through doping, we transform BCO into cubic perovskite, enhancing water uptake and hydration abilities, thereby improving proton transport properties. PCECs incorporating these electrodes exhibit record-high power densities, showcasing the potential of rational electrode design for achieving high performance. Overall, our research represents a comprehensive approach to advancing the performance of PCECs through innovative materials design and processing techniques. By addressing critical challenges and pushing the boundaries of current capabilities, we would like to pave the way for the widespread implementation of PCECs as efficient and sustainable energy conversion devices.
Effect of Y Doping on Proton Conductivity of BaCo0.4Fe0.4Zr0.2-XYxO3-Δ (BCFZY) Proton Ceramic Fuel Cell (PCFC) Cathodes
Authors: Kim Chiyoung
Published: December 2024

Solid oxide fuel cells (SOFCs) are recognized as highly efficient renewable energy devices. However, their high operating temperatures (800–1000°C) present severe challenges, including material degradation and reduced energy conversion efficiency. Protonic ceramic fuel cells (PCFCs) have been developed to address these issues by operating at lower temperatures (400–700°C). PCFCs utilize proton conduction in oxide, which has a lower migration barrier than the oxygen ion conduction in SOFCs, making them promising for high performance at reduced temperatures. Nevertheless, current PCFC performance still falls short of SOFC performance, primarily due to sluggish oxygen reduction reaction (ORR) kinetics at the cathode perovskite materials. Enhancing the reaction kinetics necessitates the development of a cathode with high proton conductivity, which can broaden the reaction area within the cathode material. Doping with yttrium (Y) in perovskite material has been a potential solution for enhancing proton conductivity in cathode materials. Y doping in BaZrO3-based electrolytes has successfully led to the development of fast proton-conducting electrolytes for PCFCs. Y doping has also been introduced to the cathode perovskite material, BaCo0.4Fe0.4Zr0.1Y0.1O3-δ (BCFZY), by substituting Y for Zr atoms in BaCo0.4Fe0.4Zr0.2O3-δ (BCFZ) materials. BCFZY has shown potential as a cathode material aiming for high proton conductivity. It demonstrates superior performance in reducing oxygen while concurrently conducting electrons, oxygen ions, and protons. However, the exact effects of Y doping on BCFZY performance are not fully understood, even though research has indicated that the amount of Y doping in BCFZY significantly influences cell performance, including proton conductivity and area-specific resistance (ASR). In this study, we examined the effect of Y doping on the proton conductivity of BCFZY material. The critical question is whether Y doping affects proton diffusion or proton concentration, the main components of proton conductivity. To analyze proton diffusion, we employed density functional theory (DFT) to investigate the impact of Y doping on the proton self-diffusion coefficient. For proton concentration, we applied thermodynamics and defect models to assess the effects of Y doping. Finally, we validated and refined our findings using proton conductivity data from our experimental collaborators, Duffy et al. Our results indicate that Y doping in the BCFZY system slightly impacts proton diffusion, alters the proton uptake mechanism, and can significantly increase hydrogen concentration. This study provides insights for designing high-performance BCFZY materials or perovskite materials for PCFCs that contain redox-inactive acceptor dopants like Y.
Electropositive Metal Doping into Lanthanum Hydride for H− Conducting Solid Electrolyte Use at Room Temperature
Authors: Kobayashi Genki , Izumi Yoshiki , Takeiri Fumitaka , Okamoto Kei , Saito Takashi , Kamiyama Takashi , Kuwabara Akihide
Published: December 2024

Hydride ion (H–) conductors have made remarkable progress in recent years; in particular, the fluorite-type LaH3–δ series exhibits high conductivity around room temperature. However, its intrinsic character of hydrogen non-stoichiometry still makes its application as a solid electrolyte challenging, for which high electronic insulation is essential. Here, Sr-substituted LaH3–δ with slight O2– incorporation, represented as La1–xSrxH3–x–2yOy (0.1 ≤ x ≤ 0.6, y ≤ 0.171), is synthesized, which exhibits H– conductivity of 10–4 - 10–5 S cm–1 at room temperature. The galvanostatic discharge reaction using an all-solid-state cell composed of Ti|La1-xSrxH3-x-2yOy|LaH3–δ shows that the Ti electrode is completely hydrogenated to TiH2 for x ≥ 0.2, whereas a short circuit occurs for x = 0.1. These experimental observations, together with calculation studies on the density of states and the defect formation energy, provide clear evidence that electropositive cation, such as Sr, doping critically suppresses the electron conduction in LaH3–δ. Achieving a superior H–conducting solid electrolyte is a novel milestone in the development of electrochemical devices that utilize its strong reducing ability (Eº(H–/H2) = –2.25 V vs. SHE), such as batteries with high energy density and electrolysis/fuel cells with high efficiency. References: [1] Yoshiki Izumi, Fumitaka Takeiri, Kei Okamoto, Takashi Saito, Takashi Kamiyama, Akihide Kuwabara, Genki Kobayashi, Adv. Energy, Mater., 13, 2301993 (2023).
Simulation of a Reversible Solid Oxide Cell Operating in Dual Mode with Experimental Validation
Authors: Najafianashrafi Zabihollah , Mora Joy Marie , Salehian Shadi , Chuang Po-Ya Abel
Published: December 2024

This work presents a comprehensive analysis of a reversible solid oxide cell (SOC) operating in dual mode, which allows for both hydrogen production for electrolysis mode and power generation under fuel cell mode. Employing an analytical model, we explore the dynamic behavior and efficiency of the SOC under varying operational conditions. The model covers several components, including a NiO-YSZ fuel-side support and functional layer, a YSZ electrolyte, a GDC interlayer, and an air-side made up of LSCF+GDC and LSCF. The study highlights the ability to switch between the electrolysis to fuel cell modes, depending on the supply dynamics and energy demand. The model incorporates key electrochemical reactions, ion transport mechanisms, and mass transfer processes, providing detailed insight into the internal functioning of the fuel cell. The model predicts the performance of a single-cell SOC in dual mode using humidified hydrogen with targeted dew points of 81.8°C (50 kPa), 69.1°C (30 kPa), and room temperature (3 kPa) at the fuel side and 21% O2 and 79% N2 at the air-side at different operating temperatures of 700°C, 660°C, 620°C, and 580°C. Experimental validation is conducted to ensure the reliability of the model's predictions, with results showing a strong correlation between the simulated data and observed performances. The findings underscore the potential of dual-mode SOCs in enhancing the flexibility and sustainability of energy systems, particularly in applications where both power and hydrogen are required. The findings suggest that while concentration overpotentials are generally lower, activation and ohmic overpotentials predominantly dictate the overall potential loss in the cell, underlining the importance of minimizing them to boost cell performance.

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Developing Cobalt-Free, Strontium Titanium Ferrite Based Air Electrodes for Solid Oxide Cells
Authors: Hong Junsung , Reinke Jakob Michael , Barnett Scott A
Published: December 2024

The development of stable air electrodes for Solid Oxide Cells operating at reduced temperatures (≤700°C) creates unique material design challenges. These electrodes must not only show excellent oxygen evolution and oxygen reduction reaction rates, but also be able to maintain these fast rates over the 40,000hr lifetimes envisioned for solid oxide cells. One material of significant interest for this is Sr(Ti0.3Fe0.7)O3-δ (STF), which is a mixed ionic-electronic conducting (MIEC) perovskite that has shown performance similar to that of LaxSr1-xCoyFe1-yO3-δ (LSCF) (1). Performance and stability substantially better than that of LSCF can be achieved by substitution of as little as 7% Cobalt onto the B-site of STF. (2) Reducing or eliminating the Cobalt while maintaining performance is desirable to avoid issues with its toxicity, availability, and cost. In this work, we explore Cobalt-free STF-based air electrodes; strategies explored include composites of STF and Gd0.1Ce0.9O2-δ (GDC), PrOX infiltration, and alternative B-site substitutions of STF with Ni and Cu.

One of the aims of GDC-STF composite electrodes is to improve the thermal expansion coefficient (TCE) match and adhesion with the GDC reaction barrier layer, presumably making them more robust in thermal cycling. The 50% STF – 50 % GDC composites yielded polarization resistance values similar to those of pure STF electrodes, ~ 0.2 Wcm2 at 700C in air. Over the temperature range of 200°C-850°C, the coefficient of thermal expansion (CTE) of STF-GDC closely matches the CTE of GDC (~12×10-6 K-1), representing a significant improvement compared to STF. As previously discussed by Lu et al (3), the performance of pure STF electrodes can be significantly improved by infiltration with PrOx. Here we show that infiltration of STF-GDC composites with 1, 2, or 3 PrOx infiltration steps significantly decreases initial polarization resistance, e.g., from 0.5 to < 0.2 Wcm2 at 650C, with two infiltration steps yield the lowest polarization resistance. Furthermore, long term stability tests over >2 kh show that STF-GDC electrode degradation rates can be decreased by a factor of 4 through infiltration.

Additional results for STF substituted with alternatives to Co, including Cu, Ni, and Cu-Ni, will be presented, along with the effects of exsolution induced by pre-reduction.

S.-L. Zhang, D. Cox, H. Yang, B.-K. Park, C.-X. Li, C.-J. Li and S. A. Barnett, Journal of Materials Chemistry A, 7, 21447 (2019).

S.-L. Zhang, H. Wang, M. Y. Lu, A.-P. Zhang, L. V. Mogni, Q. Liu, C.-X. Li, C.-J. Li and S. A. Barnett, Energy & Environmental Science, 11, 1870 (2018).

M. Y. Lu, R. Scipioni, B.-K. Park, T. Yang, Y. A. Chart and S. A. Barnett, Materials Today Energy, 14, 100362 (2019).
Designing SOC Electrodes for Better Lifetime Performance
Authors: Abernathy Harry , Epting William K. , Lei Yinkai , Liu Jian
Published: December 2024

As part of the US Department of Energy’s Reversible Solid Oxide Fuel Cell (R-SOFC) and H2NEW programs, the National Energy Technology Laboratory (NETL) solid oxide cell (SOC) research group focuses on characterizing SOC degradation and improving the lifetime performance of SOC electrodes. A major tool used by NETL is its multiphysics performance degradation modeling framework, which considers microstructure, electrochemistry and mass/charge transport when simulating the lifetime energy/hydrogen output of an SOEC/SOFC sample. By simulating thousands of potential electrode microstructures varied across over 10 independent microstructural parameters, NETL analyzes which electrode features have the greatest impact on lifetime performance. Simulations and experiments are also used to explore how much lifetime performance can be increased by creating more advanced electrodes using additive manufacturing and electrode infiltration or by adjusting the operating conditions. The talk will review the current capabilities of the degradation modeling framework and will use case studies to provide lessons on SOC electrode design and operation.
Advancing Production of e-Fuels through Pressurized Co-Electrolysis in Solid Oxide Electrochemical Cells
Authors: Kupecki Jakub , Niemczyk Anna , Bąkała Maciej , Motyliński Konrad , Kosiorek Magdalena , Jagielski Stanisław
Published: December 2024

Solid oxide electrolyzers (SOE) offer a great advantage over low-temperature electrolyzers, which makte them great candidates for intregration with downstream processes for synthesis of e-fuels. Moreover, SOE can be operated in co-electrolysis mode which makes it possible to simultaneously reduce H2O and CO2 in an electrochemical process. Such a mode of operation results in mixture of H2, CO, H2O and CO2 which can be directly fed to Fischer-Tropsch synthesis. Additionally, co-SOE can be pressurized in order to increase activation resistance and elevate partial pressures of reactants at the triple phase boundary.

Despite the great potential, up to date SOE were pressurized in only a few laboratories worldwide, therefore literature data are limited.

In the recent study, two batches of 5 cm x 5 cm Ni-8YSZ supported cells with LSC oxygen electrode were investigated. The commercial cells and cells produced in house at the Institute of Power Engineering - National Research Institute. Experimental studies included operation at the ambient pressure and measurements under pressurized conditions. The experimental campaing was constrained by two parameters (whichever occurs first): voltage equal 1.4 V or reaching limiting concentration of reactants at the outlet which correspond to carbon desposition isotherm under given working conditions.

Upon completion of the in operando analysis, area specific resistance (ASR) was calculated and analyzed (see Fig. 1). Post-mortem analysis of cross-sections and central location in the electrode-support was investigated using SEM-EDS analysis. Finally, results of the experimental studies were used for the development of model of co-electrolysis in order to determine the performances of same cells operated under ambient and pressurized conditions beyond standard conditions. Application of a dedicated model based on artificial neural included implementation of Adam ‘Adaptive Moment Estimation’ which was chosen as it introduces an adaptive learning rate for each parameter. With such an approach the optimization became more precise. The design of the network targeted minimization of the number of hidden layers and neurons to mitigate the risk of overfitting. Model was found to precisely predict the current-voltage characteristics of co-SOE under ambient and pressurized conditions (see Fig. 2). Pressurization of co-SOE is qualitatively and quantitatively assessed as a promising process for generating substrates for reaction in which liquid e-fuels are produced.

The work integrates experimental tools and numerical modeling in order to predict performance and composition of gases exiting co-SOE which are feed Fischer-Tropsch synthesis. The general requirements of the downstream process are presented and discussed.

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Advanced Chemical-Free Boron Removal Technique through Bipolar Membrane Electrodialysis for Seawater Reverse Osmosis Permeate
Authors: WU MIN Chen , Hou Chia-Hung
Published: December 2024

The increasing threat of water scarcity poses a significant challenge to water-intensive industries in Taiwan. There is a pressing requirement to increase freshwater production from seawater and wastewater. In the existing seawater treatment process, two-pass reverse osmosis (RO) and pH adjustment are generally adopted. The first stage RO aims at removing salts within normal pH levels, while the second stage RO focuses on eliminating boron under high pH conditions (>10). Under alkaline conditions, the dominant species, borate ions, are more readily rejected by RO membranes due to their larger hydrated size and negative charge. However, these procedures require substantial chemical dosing and energy consumption, which is uneconomical and environmentally unsustainable. Hence, the urgent need to replace the second stage RO with alternative technologies featuring low operational costs and chemical dosing is evident.

Recently, bipolar membrane (BPM) has drawn increasing attention due to the ability to produce acids and bases from the corresponding salt solutions without chemical addition. Under reverse bias, water dissociation reaction occurs, generating protons and hydroxyl ions from water molecules. The H+ and OH− migrate through the cation and anion exange layer of the BPM, leading to the formation of acidic and alkaline pH on opposite sides of the membrane and creating a pH gradient across the BPM.

The aim of the study is to achieve boron removal without chemical addition using bipolar membrane electrodialysis (BMED).The characteristics of the commercial BPM, including current-voltage curve and co-ion leakage ratio, are first analyzed. Subsequently, a 4-channel BMED system will be developed to simultaneously remove boron in the alkaline chamber while concentrating boron in the acidic chamber. Increasing the pH value in the alkaline chamber to above the pKa value of 9.24 effectively converts boric acid into brate ions, facilitating efficient boron removal in BMED. In addition, the feasibility of using BMED for boron removal will be further examined under different operational conditions, such as applied voltage (3 V, 4 V, and 5 V), flow rate (5 mL/min and 10 mL/min), and influent boron concentration (0.5 mM, 1 mM, and 10 mM), in sigle-pass mode. This study provide an alternative solution for the treatment of boron in seawater.

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(Invited) Electrocatalytic Synthesis of Ammonia and Urea
Authors: Kwon Youngkook
Published: December 2024

The electrocatalytic hydrogen cycle with nitrogen and carbon resources is of emerging interest for renewable energy and environment. Among nitrogen species, electrosynthesis of ammonia (NH3) from N2 or NOx and urea (CO(NH2)2) from N2 or NOx together with CO2 have attracted great attention with substantial progress in recent years as clean and energy-saving approach, to potentially replace the commercialized energy- & capital-intensive Haber-Bosch process.

In order to accelerate the ammonia production rate, nitric oxide (NO) can be employed and converted to ammonia with high selectivity by capturing NO with FeII-EDTA.1) However, low concentration and the low solubility of NO (~1.94 mM in water at 25°C) is expected to affect ammonia production rate from direct electrochemical NO reduction reaction (NORR) in aqueous electrolytes. In order further increase the ammonia production rate, we employed a gas diffusion electrode (GDE) to circumvent the mass transport issue with a dilute NO gas.2) In addition, urea was successfully synthesized using Cu with atomic-scale spacings between copper facets, which lowers the energy barrier for C-N coupling and enhances the reaction kinetics, therefore leading to improved urea formation from co-reduction of carbon dioxide and nitrate in a flow-cell system.3)

1) ACS Energy Lett., 2020, 5, 3647-3656.

2) ACS Energy Lett., 2022, 7, 958-965.

3) Energy Environ. Sci., 2023, 16, 2003-2013.
Redox Chemical Transformation of Organic and Inorganic Compounds in Frozen State - Intrinsic Electron Transfer Processes in Ice
Authors: Kim Kitae
Published: December 2024

Ice is one of the most abundant substances on Earth. However, little research has been done on ice as a medium for chemical reactions. Most of chemical reactions take place slowly when temperature drops based on Arrhenius Equation
(k=A·e-EA/RT). However, it has been found that several chemical processes markedly accelerated in ice phase. For example, Takenaka et. al. reported that the NO2
- oxidation to NO3
- in the presence of O2 which is very slow reaction in aqueous solution was markedly accelerated (appx. 105 times) by freezing. The enhanced chemical transformation is attributed to the Freeze Concentration Effect, whereby organic and inorganic compounds are separated from ice crystals and highly concentrated in unfrozen parts or ice grain boundaries.

In this presentation, we want to introduce accelerated chemical redox reactions in frozen state such as 1)enhanced redox dissolution of metal oxide/clay minerals in ice and the novel process for the new mineral formation 2)accelerated chemical transformation of iodine species in frozen state, and 3)
accelerated redox transformation of organic and inorganic pollutants in ice such as Cr(VI)/organic reductants, Cr(VI)/As(III), Cr(VI)/H2O2, Cr(VI)/NO2
- and Cr(VI)/phenolic pollutants systems. The detailed research background, experimental conditions, mechanistic explanation, and effects on climate changes will be discussed in the presentation.
Electrochemical Chloride Activation by Iridium-Doped Tin Oxide for Oxidative Treatment of Urine Wastewater
Authors: Lim Jonghun
Published: December 2024

The escalating presence of nitrogen pollutants in urine wastewater poses a significant environmental challenge. Among the array of methods available to tackle this issue, electrochemical oxidation processes that produce reactive chlorine species (RCS) from readily available chloride ions appear as a promising solution. Despite the investigation of various anode materials, current options continue to face challenges such as low selectivity in generating reactive chlorine species (RCS), instability, and significant energy consumption. This study investigated iridium-doped tin oxide (Ir-SnO2) as an efficient, stable, and energy-saving anode for RCS-mediated treatment of urine wastewater. The Ir-SnO2 anode surpassed counterparts like IrO2 SnO2 and Sb-SnO2, showcasing its superior electrochemical performance marked by high current density, minimal charge transfer resistance, and a significant active surface area. Additionally, it attained outstanding current efficiency of 91.7% and energy efficiency of 7.79 mmol Wh-1 for generating reactive chlorine species (RCS) at 30 mA cm–2 in a diluted 0.1 M chloride solution. Density functional theory (DFT) calculations corroborated experimental findings, indicating that the introduction of Ir to SnO2 boosts chlorine adsorption by altering the electronic structure, thereby reducing overpotential and enhancing electrocatalytic activity for chlorine evolution reactions. Ir-SnO2 also showcased impressive effectiveness in removing ammonia nitrogen, total nitrogen, and chemical oxygen demand, achieving efficiencies of 100%, 97.8%, and 89.1%, respectively. These outcomes rivaled those attained by IrO2 (dimensional stable anode, DSA), surpassing the performance of the boron-doped diamond (BDD) anode. Additionally, Ir-SnO2 demonstrated the lowest energy consumption compared to benchmark DSA and BDD anodes when treating urine wastewater. In stability evaluations, the Ir-SnO2 electrode maintained a stable anodic cell potential for 100 hours of continuous electrolysis in a 0.1 M NaCl electrolyte and remained operational over five cycles without any signs of deactivation.
Combined Electrolysis of Seawater and Wastewater for Decentralized Water Reuse and H2 Production
Authors: Cho Kangwoo
Published: December 2024

The current societal pursuit towards carbon neutrality would necessitate self-contained systems, ultimately to be independent on the existing water and energy grid. On-site wastewater treatment and reuse can reduce water and waste transportation, in-turn decreasing the carbon footprint for sanitation and hygiene. Electrochemical oxidation processes (EOPs) have emerged as a promising way of decentralized treatment of toilet wastewater and effluent reuse. On the other hand, a distributed and point-of-use electrolysis of locally available, nontraditional water sources including wastewater (effluent) can be involved within the H2 economy, reducing costs and CO2 emission from H2 transportation. This study proposes wastewater electrolysis cells (WECs) for localized wastewater treatment coupled with conversion of redundant renewable energy into H2. In the single-compartment WEC, therefore, oxygen reduction reaction competes with the hydrogen evolution reaction (HER), substantially decreasing the current and energy efficiency. Relatively low-grade H2 (< 60%) in mixture with N2 and CO2 can be utilized by combustion. This approach might be more available and appropriate practice in household and community level. This presentation also introduces recent electrocatalysts to overcome the bottlenecks of WEC such as requirements of precious elements based electrocatalysts and unsatisfactory selectivity of chlorine evolution reaction. These includes i) NiFe2O4 and CoSb2O6 with tiny amounts of Ir, and ii) precious metal cations (Ru and cocatalysts) atomically anchored on Magneli phase Ti4O7.
In-Situ Visualization and Quantification of Precipitate Fouling on Gas-Diffusion Electrodes in Carbon-Containing and Ocean Water Electrolytes
Authors: Silcox Rachel , France Nicole , Bala Chandran Rohini
Published: December 2024

Proton coupled electron transfer reactions that change the pH at electrode-electrolyte interfaces are at the heart of many electrochemical reactions. Specifically, an increase in pH accompanies H2 evolution and CO2 reduction with relevance to fuels production from water and CO2 electrolysis or pH-swing processes for CO2 removal. When this increase in pH occurs in carbon-containing and/or ocean water electrolytes, it leads to salt precipitation and fouling in porous electrodes. Magnesium hydroxide and calcium carbonates are suspected precipitates in ocean water solutions, while potassium carbonates are the only possible precipitates in many CO2 reduction scenarios. This study develops and experimentally demonstrates a custom H-cell design that enables in-situ visualization of pH changes occuring during hydrogen evolution from a commercially available 0.5 mg/cm2 Pt-C carbon paper gas-diffusion electrode. Bulk pH is measured by a pH probe and this is used to calculate a local pH, based on the Nernst diffusion layer thickness. Fouling extents are further characterized through optical visualization of the surface and the chemical composition is characterized by tracking characteristic absorption peaks in the infrared spectra. Experiments are conducted at several different current densities to explore the effect of local pH on the rate and extent of precipitate formation and dissolution. Results reveal that fouling due to the formation of hydroxide precipitates occurs on electrode surfaces, even when the bulk pH conditions are not large enough to cause precipitation. This underscores the necessity to track local pH conditions. Results also demonstrate the significant precipitation observed in ocean water solutions with relevance to ocean water electrolysis and oceanic CO2 removal, as compared to solutions buffered with bicarbonate ions. Initial results also indicate how the rate of precipitate formation and removal from the porous surface is connected to the current density and pH conditions.
NiFeCrMnTiOx As an Active Electrocatalysts for Hydrogen Production from Anion Exchange Membrane (AEM) Saline Water Splitting
Authors: Selvam Praveen Kumar , Riaz Muhammad Sohail , Farràs Costa Pau
Published: December 2024

Anion exchange membrane (AEM) saline water electrolysis is one of the promising ways to produce green hydrogen at a low cost in the long term. However, suitable electrocatalysts for hydrogen and oxygen evolution reactions for saline water splitting have not yet been figured out. Here, we report a non-noble transition metal-based high entropy oxide nano electrocatalysts Ni0.2Fe0.2Cr0.2Mn0.2Ti0.2Ox for hydrogen and oxygen evolution reactions in saline water electrolysis. The electrocatalysts were synthesized by using co-precipitation technique, further synthesized electrocatalysts were in-situ characterized in X-ray diffraction (XRD), scanning electron microscopy (SEM), Transition electron microscopy (TEM), Raman spectroscopy, and ex-situ characterized in linear sweep voltammetry (LSV), chronopotentiometry, and impedance studies. Further, Membrane Electrode Assembly (MEA) was fabricated, assembled, and tested in a single-cell anion exchange membrane saline water electrolyzer.