bluuebunny/crossref_metadata_2025_split huggingface dataset:
Approaches for Optimum Thermal Management of SOFC Cells: Fitting Operating Conditions & Smart Cell Design
Authors: Judez Xabier , Jimenez-Martín Gonzalo , Aguado Mónica , Garbayo Iñigo 
Published: September 2023

The thrust of green hydrogen as energy vector for the consolidation of a net-zero emitting global energy system implies the necessity of a fast development of high performing and highly efficient fuel cells and electrolyzers. Among the commercial choices, solid oxide cells can be considered as a better performing alternative compared to commercial proton exchange membrane and alkaline technologies. The benefits of this kind of technology arise from their higher operating temperatures of around 700-900 ºC, which results in improved kinetics and favored thermodynamics, allowing to reach unrivaled conversion efficiencies and reduced electricity consumption. Furthermore, this allows operating the cell reversibly in both fuel cell (SOFC) and electrolysis (SOE) modes.
However, cell overheating and non-uniform temperature distribution can lead to an acceleration of degradation processes and cell cracking and sintering, which challenges long-term cell stability. In this sense, modeling at cell level enables to optimize operating conditions, improve cell design and predict and minimize such phenomena. Simulations allow mimicking the response of the cells and stacks at diverse operating scenarios and accelerates the optimization process minimizing experimental efforts; saving materials, time, and economical resources. We model SOFC/SOE cell behavior by means of Computational Fluid Dynamics (CFD), solving the mass, species, momentum, energy and current conservation equations, as well as electrochemical reaction models.
In this work, a detailed methodology to guide design of the thermal management of SOFC by means of CFD and numerical optimization tools is proposed. These approaches combine acting both on operating conditions and cell geometry. Initially, we study the influence of inlet gas flows and describe a procedure to optimize the flows while maximizing the energetic outcome. Afterwards, we describe how numerical methods can allow fitting feed gas temperatures to avoid overheating. Finally, we go a step further by optimizing cell interconnect plate geometries to minimize internal temperature gradients. All in all, we demonstrate how CFD studies can accelerate SOFC cell design in order to maximize performance and extend lifespan.

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Nanostructured LSC Thin Film Electrodes with Improved Electrochemical Performance and Long-Term Stability
Authors: Bagarinao Katherine Develos , Celikbilek Ozden , Kerherve Gwilherm , Fearn Sarah , Skinner Stephen J , Kishimoto Haruo 
Published: September 2023

Nanostructured La0.6Sr0.4CoO3-δ (LSC) thin film electrodes exhibit exceptionally high oxygen surface exchange properties, surpassing those of conventional microscale electrode structures, which are desirable for application in solid oxide cells (SOC) [1-2]. On the other hand, the LSC nanostructures also tend to undergo significant morphological changes at typically high temperatures required for SOC operation, leading to rapid degradation in performance. Here, towards the goal of improving the long-term stability of electrochemical performance of nanostructured LSC thin films, a systematic investigation of the effect of processing temperatures on long-term stability was carried out [3]. By varying the deposition temperature (500 °C to room temperature), the as-grown characteristic nanostructures of LSC thin films prepared using pulsed laser deposition can be tuned from highly dense nanocolumnar grains to nanofibrous structures with high porosity. Variations in the deposition temperature also resulted to differences in the proportion of surface-bound/lattice-bound Sr and Co2+/Co3+ at the surfaces of the as-grown LSC thin films; however, prolonged annealing at 700 °C in air essentially transforms the surfaces to a final state with mostly lattice-bound Sr and Co3+. Nevertheless, LSC films with initially nanofibrous structures are found to be less prone to the grain sintering effect occurring at high temperatures and exhibit less degradation of the electrode polarization resistance as compared to well-dense films. Using lower deposition temperatures, cation interdiffusion occurring at LSC/GDC interfaces is also significantly suppressed, thus leading to better interfacial stability as compared to those prepared at higher deposition temperatures. These results highlight the relationship between characteristic nanostructures of thin film electrodes and electrochemical performance and provide guidance on designing electrodes with improved long-term stability.
[1] J. Januschewsky, M. Ahrens, A. Opitz, F. Kubel and J. Fleig, Adv. Funct. Mater., 2009, 19, 3151–3156.
[2] J. Hayd, L. Dieterle, U. Guntow, D. Gerthsen and E. Ivers-Tiffee, J. Power Sources, 2011, 196, 7263–7270.
[3] K. Develos-Bagarinao, O. Celikbilek, R. A. Budiman, G. Kerherve, S. Fearn, S. J. Skinner and H. Kishimoto, J. Mater. Chem. A, 10, 2445-2459 (2022).
Performance Evaluation of an Anode-Supported Solid Oxide Fuel Cell Short-Stack Operating with Different Hydrogen-Natural Gas Blends as Stationary Combined Heat and Power System
Authors: Monforti Ferrario Andrea , Santoni Francesca , Marino Francesco , Alfano Antonio , Stenius Julius , Noponen Matti , Neubauer Raphael , Cigolotti Viviana 
Published: September 2023

One of the most promising characteristics of Solid Oxide Fuel Cells (SOFCs) is the possibility to process a wide variety of fuels with high electrical efficiencies, when compared to other types of fuel cells. Considering the prospected transition of the Natural Gas (NG) grid to hydrogen to decarbonize the gas sector, SOFCs could play a crucial role as efficient and clean stationary Combined Heat and Power (CHP) systems.
In this work a 15-cell SOFC short-stack (Anode Supported, cell area 121 cm2) has been analysed experimentally under different compositions resembling possible short-, medium- and long-term gas grid scenarios (100% NG, 67%H2 blend in NG and 100%H2) which have been obtained by a preliminary system-level simulation which takes into account operating conditions of the stack and fine-tuning of the system parameters (e.g. Recirculation Rate RR, once through Fuel Utilization FUot, global Fuel Utilization FUtot) to optimize the overall system-level efficiency. Several tests were run at different temperatures (640-710 °C), Fuel Utilization (FU, 50%-70%) and at current loading (15-30 A - part/full load), characterizing in detail the stack response from an electrochemical (polarization curves and short-term stability tests) and chemical conversion point of view (gas chromatographic analyses in OCV and under load), as well as mapping its performances in stationary conditions (output power and stack-level efficiency). The conversion efficiency has been assessed in detail with different approaches at both stack and cell level, considering both once-through (stack-level) and total (system) FU rates.
After having confirmed that the stack performances in reference testing conditions are fully aligned to the stack manufacturer data, confirming the test bench setup validity, the foreseen testing campaign has been carried out showing compatibility of the SOFC stack in the investigated conditions. The results show that from a pure performance point of view the 100%H2 composition obtains highest voltage and power at nominal conditions due to losses of the reformate compositions due to lower OCV values and kinetic behaviour of the chemical reaction chains. Instead, from an efficiency point of view the reformate conditions obtain higher stack-level efficiency (72.02% for the 67%H2+NG; 69.45% for the 100%NG) respect to the 100%H2 compositions (68.61%) due to the lower input fuel calorific value. The comparison of the different efficiency definitions provides further insight on the process and system level. By comparing reference testing conditions before and after the testing campaign it is possible to confirm that no significant degradation has occurred at global stack level in all the compositions.

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Ion Beam as an External and Dynamic Metal Reservoir to Induce Nanoparticle Exsolution in Oxides
Authors: Wang Jiayue , Woller Kevin B. , Yildiz Bilge 
Published: September 2023

A central theme in solid oxide fuel cells (SOFC) and electrolyzers (SOEC) is to design stable and catalytically active solid/gas interfaces toward desired reactions. A recent advance in this regard is to synthesize nanoparticles decorated electrodes in a process termed “exsolution”. Exsolution generates stable and catalytically active metal nanoparticles via phase precipitation out of a host oxide. Unlike traditional nanoparticle infiltration techniques, the nanoparticle catalysts from exsolution are anchored in the parent oxide. This strong metal-oxide interaction makes the exsolved nanoparticles more resistant against particle agglomeration as compared to the infiltrated ones. In addition, the exsolved particles also open up the possibility of regeneration of catalysts. To date, the concept of exsolution has been successfully applied to a number of applications including SOFC/SOEC, ceramic membrane reactors, chemical looping combustion, and (electro)catalysis.
As the exsolution process starts with a solid-solution that contains the to-be-exsolved transition metal ions, this method is often limited by the intrinsic solubility limit of the host oxide. Here, we propose that ion beam irradiation to be a unique tool to promote exsolution as it can introduce defects and dopants into the host oxides and at concentrations higher than thermodynamic limits. Moreover, due to the surface sputtering effect, ion beam irradiation can modulate the surface morphology, creating novel nanostructures.
To demonstrate this approach, we chose thin-film perovskite SrTi0.65Fe0.35O3 (STF) and fluorite Ce0.5Zr0.5O2 (CZO) as model systems, both of which are promising materials in SOFC and SOEC. We modulated metal exsolution in both materials with in-situ 10-150 keV Ni irradiation at 800 °C in vacuum. Ni irradiation on STF controllably changed the exsolved particle composition from unitary Fe to bimetallic Fe-Ni. Moreover, it also reduced the particle size down to sub-2 nm, which outperforms other tuning methods thus far in the literature. As a result, the irradiation-modified STF demonstrated superior catalytic activity toward room-temperature oxygen evolution reactions (OER) than the conventional thermally exsolved STF. Regarding CZO, Ni irradiation also decorated the surface with well-dispersed nanoparticles, leading to enhanced high-temperature H2O splitting kinetics. The effective size and composition control over exsolution highlights the utility of metal ion beams in promoting and tailoring exsolved nanocatalysts for a broad range of applications in clean energy and fuel conversion.

Figure 1
Experimental Study on High-Efficiency Microtubular Solid Oxide Fuel Cell Stacks Using Various Fuels
Authors: Shi Jixin , Yao Yue , Zhang Ruiyu , Wang Yuqing , Fan Junhua , Shi Yixiang , Liang Bo , Cai Ningsheng 
Published: September 2023

Abstract: Microtubular solid oxide fuel cells (mtSOFCs) are a clean and low carbon emission power generation technology that has great prospects in the field of portable power generation. Improving the power generating efficiency and broadening the variety of fuels available can significantly improve the performance of portable power generation devices based on mtSOFCs. In this study, mtSOFC stacks assembled by mounting modular substacks in an array on a designed fuel/air distribution base were tested. By changing the connection of the substacks’ current collection nodes, the influence of circuit connection modes on the overall output performance of the stack was studied. At a temperature of 700℃ and a fuel feed of hydrogen, the mtSOFC stack composed of 6 substacks in series can achieve a maximum power of 296 W. Fuel cascade utilization was realized by transferring the spent fuel gas from the upstream substacks to the downstream substacks. A maximum power generation efficiency of 45.7% was achieved in the two-cascade stack. The feasibility of using liquified fuel gas (ammonia, propane and diesel) as fuel for the mtSOFC stack has also been experimentally verified. A total continuous discharge time of more than 100 h was achieved at an average power ≥ 180 W under different fuel conditions.
Key words: Microtubular SOFC; Substack array; Fuel cascade utilization; Liquified fuel gas; Ammonia
Current Status of Ceres Electrolysis Programme
Authors: Hjalmarsson Per , Harman Jonathan , Macauley Chandra , Methley Ian , Ryley Joshua , Zerfa Amin , Hargrove Caroline , Selby Mark 
Published: September 2023

This report provides an update on Ceres SOEC programme. Since its start Ceres’ state of art technology has been evaluated in electrolysis mode, both experimentally and using modeling at cell, stack, and system level, in parallel to developing its first 1 MW scale demonstrator system.
Electrochemical performance, measured at cell level, shows similar performance in EC and FC mode within nominal operating conditions. Durability of stack repeat units has been measured experimentally at a range of different conditions. The degradation rate during the initial ~5000 hrs was found to range from 15-25 mΩcm2/khrs with a decaying trend over time. Degradation behaviour has been correlated with boundary conditions to provide a tool for optimizing and predicting life.
A stack Multiphysics model has been developed that considers the electrochemical reactions as well as transfer of heat, fluids, and charge. The model was validated against stack test data with very good correlation and is being used for predictive analysis of stack performance under relevant conditions. The results show that Ceres stack will work equally effective in electrolysis mode as it does in fuel cell mode.
Finally, performance of SOEL systems incorporating Ceres electrolyser stacks have been evaluated by system modelling at different boundary conditions. This allows us to assess system efficiency and levelized cost of hydrogen for different scenarios and sets of assumptions.
Influence of Microstructure on the Sulfur Tolerance of Ceria-Based Anodes in Low Temperature SOFC
Authors: Kullmann Felix , Schwiers Alexander , Juckel Martin , Menzler Norbert H. , Weber Andre 
Published: September 2023

Hydrocarbon fuels such as natural gas, propane or biogas commonly contain small amounts of impurities like sulfur which result in a strong degradation of the cell performance in the intensively studied Ni/YSZ cermet anode [1-3]. The sulfur poisons the nickel catalyst and hinders the electrooxidation of hydrogen [2-3].
At common SOFC operation temperatures of 700 to 900 °C the polarization resistance of a Ni/CGO fuel electrode is less influenced by sulfur [3-5]. With a modification of the surface by infiltration of Ni and / or ceria nanoparticles the impact can be even reduced [5-6]. The trend to a much lower operating temperature of SOFCs [7-8] even below 600 °C raises the question to what extend the sulfur tolerance of ceria-based fuel electrodes is maintained.
In this study we analyze the impact of H2S on the polarization resistance of ceria-based fuel electrodes at operation temperatures around 600 °C. Ni/ceria anodes, differing in their microstructure, are investigated by electrochemical impedance spectroscopy (EIS). The distribution of relaxation times (DRT) analysis is applied to deconvolute the electrochemical processes followed by a complex nonlinear least square approximation to quantify the loss processes and the impact of sulfur amounts of 0.1-3 ppm. Compared to previous results [5] the polarization resistance increases more significantly at 600 °C than at 750 °C. The influence of the microstructure will be discussed in detail.

References:

[1] A. Weber, Fuel Cells, 21, 440 (2021).
[2] A. Kromp, S. Dierickx, A. Leonide, A. Weber and E. Ivers-Tiffée, J. Electrochem. Soc., 159, B597 (2012).
[3] A. Weber, S. Dierickx, N. Russner and E. Ivers-Tiffée, ECS Trans., 77, 141 (2017).
[4] M. Riegraf, M.P. Hoerlein, R. Costa, G. Schiller and K.A. Friedrich, ACS Catal., 7, 7760 (2017).
[5] A. Weber, T. Dickel and E. Ivers-Tiffée, in Proceedings of the 12th European SOFC & SOE Forum, B0507 (2016).
[6] T. Hays, A.M. Hussain, Y. Huang, D.W. McOwen and E.D. Wachsman, ACS Appl. Energy Mater., 1, 1559 (2018).
[7] R. Leah, A. Bone, M. Lankin, A. Selcuk, R. Pierce, L. Rees, D. Corcoran, P. Muhl, Z. Dehaney-Steven, C. Brackenbury, M. Selby and S. Mukerjee, ECS Trans., 57, 461 (2013).
[8] R. Leah, A. Bone, P. Hjalmarsson, A. Selcuk, M. Lankin, M. Rahman, A. Clare, G. Reade, F. Felix, J. De Vero, X. Wang, S. Mukerjee and M. Selby, ECS Trans., 103, 679 (2021).
Recovery and Delay of Impurity-Induced Poisoning of Oxygen Exchange Kinetics in Mixed Conducting Oxides Via Controlled Surface Acidity
Authors: Seo Han Gil , Tuller Harry L. 
Published: September 2023

The oxygen exchange kinetics in mixed conducting oxide surfaces are critical to a variety of energy-related technologies, including solid oxide fuel/electrolyser cells (SOFCs/SOECs), permeation membranes, batteries, and sensors. Such devices, however, commonly suffer from performance degradation from impurity-poisoning during long-term operation, for example, chromia poisoning in SOFCs from metal interconnects or silica from furnace refractories. The acidity/basicity of binary additives has recently been found to be a sensitive descriptor for determining the oxygen exchange coefficient (kchem
) of mixed ionic/electronic conducting oxides (MIEC), systematically varing by over 6 orders of magnitude via controlled surface infiltration with binary oxides. These huge variations in kchem
are attributed to changes in surface electron concentration induced by the additives.
Inspired by these ideas, in this work we first demonstrate the ability to recover the oxygen exchange kinetics of MIEC oxides (e.g. Pr0.1Ce0.9O2-δ
(PCO) and Sr(Ti,Fe)O3 (STF)) by counteracting acidic infiltrant’s impact on degradation, e.g. by chromia or silica, by compensating with a basic infiltrant like lithia or calcia. Further, we further demonstrate the ability to enhance impurity tolerance of MIEC oxides by pre-coating basic additives onto the electrodes. Such pre-treatments not only markedly improve the initial kchem
of the pristine MIEC oxides, but markedly lower the rate of degradation induced by subsequent coatings with acidic poisons. Electrical conductivity relaxation measurements on porous MIEC specimens were used to examine the impact of infiltrants on kchem
. In parallel, the area-specific resistance of screen-printed symmetric cells (cathode|electrolyte|cathode) were examined by electrochemical impedance spectroscopy.
Effect of Water Vapor and Hydrogen Concentration on Power Generation Characteristics of Protonic Ceramic Fuel Cell
Authors: Nagata Yohei , Araki Takuto , Li Kunpeng , Ryogo Takatera , Murakami Takeru , Kuroha Tomohiro , Mikami Yuichi , Yamauchi Kosuke , Mori Masashi , Matsuda Ryuma , Kobayashi Shun 
Published: September 2023

The proton and hole conductivities of BaZrO3-based perovskites depend on partial pressures of oxygen and water vapor. These conductivities affect the power generation characteristics of Proton Ceramic Fuel Cells (PCFCs) using the perovskite as an electrolyte. In this study, the effect of humidification conditions on the power generation characteristics of an anode-supported PCFCs was investigated.
The configuration of the anode-supported PCFC was La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode/BaZr0.8Yb0.2O3-δ(BZYb) electrolyte/Ni-BZYb anode. The diameter of the effective cathode area was approx. 10 mm. The cathode gas composition was fixed at 97% concentration of air and 3% concentration of water vapor. The concentration of water vapor in the anode gas was controlled to be 3-69%. The current density-voltage characteristics and AC impedance were measured by Bio-Logic SP-150.
In all water vapor concentration conditions, the cell showed the highest OCV (approximately 1 V) at 3% concentration of water vapor. However, the maximum power density was highest at 30% concentration of water vapor (346 mW/cm2). The highest maximum power density at 30% concentration of water vapor can be explained by the following reason. The OCV values decrease with increasing the concentration of water vapor because of decreasing the concentration of hydrogen. On the other hand, from the results of impedance measurements, the ohmic resistance of the cell decrease with increasing the concentration of water vapor because of increase of proton conductivity of the cell. Thus, the increase of cell voltage by increase of proton conductivity should be higher than the decrease of OCV values.
【Acknowledgements】
This presentation is the result of the research and development of ultra-efficient proton-conducting ceramic fuel cell devices, JPNP20003, funded by the New Energy and Industrial Technology Development Organization (NEDO), Japan. We would like to express our gratitude to all parties involved.
Development of Fuel Electrode Supported Solid Oxide Cell with Ni/CGO Active Layer
Authors: Klitkou Morten Phan , Lopez de Moragas Albert , Taubmann Julian , Khajavi Peyman , Pirou Stéven , Frandsen Henrik Lund , Hendriksen Peter Vang 
Published: September 2023

Increasing the current density, at which substantial lifetime can be achieved, is one way to lower the cost of solid oxide electrolysis cell (SOEC) technology. Many state-of-the-art fuel electrode supported SOECs employ Ni/8YSZ fuel electrodes. These degrade at high current density because the increased fuel electrode overpotential accelerates Ni depletion/migration and loss of percolation in the Ni/8YSZ structure. This limits maximum current density. The stability for Ni/CGO (Ce0.9Gd0.1O1.95) fuel electrodes is not documented quite as well, but several reports show very stable fuel electrode performance for Ni/CGO in electrolyte supported cells. Good fuel electrode stability with Ni/CGO was also found in our tests at 750°C above -1.1 A/cm2 as shown in Figure b). To exploit this high current density performance stability at intermediate SOEC operating temperatures (~750ºC) we are working to incorporate Ni/CGO in a co-sintered thin electrolyte cell.
This contribution will give select results from our ongoing efforts to incorporate a Ni/CGO active layer into a fuel electrode supported SOEC consisting of a Ni/3YSZ support and a thin stabilized zirconia electrolyte. Half cells consisting of Ni/3YSZ support, Ni/CGO fuel electrode, zirconia electrolyte and CGO barrier layer have been successfully co-sintered, as shown in Figure a). Results from full cell tests based on these architectures will be reported.
To evaluate the general feasibility of the cell concept in parallel with cell manufacturing, supporting studies have been carried out. The chemical expansion of CGO caused by strongly reducing conditions at the fuel electrode is a potential mechanical threat to the cell concept. Initial modelling has shown a technologically relevant operating range with respect to gas composition, temperature and current density where the cell is predicted by modelling to stay intact. As shown in Figure c) thermoneutral operation falls well within the boundaries of mechanically safe operation. Subsequent experimental testing has even showed that the model gave a conservative estimate of the safe range, as we were unable to enforce a mechanical failure by testing under conditions of very strong chemical expansion (predicted expansion of 2%). In-situ XRD studies revealing strain levels and phases present have been performed to elucidate why mechanical failure does not occur, even under very strong reduction.
Beyond that, we are also testing the durability of Ni/CGO electrodes on commercial electrolyte supported cells to verify that stable electrode performance can be achieved under conditions relevant to fuel electrode supported SOECs with a thin electrolyte. So far these tests show no change in the polarization resistance contribution from the charge transfer reaction denoted Rp,lf, after operation at 0.5-1.3 A/cm2 regardless of current density.

Figure 1