bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) In-Depth DC and Low Frequency Noise Characterization of Nanosheet FETs at Room and Cryogenic Temperatures
Authors: Cretu Bogdan , Tahiat Abderrahim , Veloso Anabela , Simoen Eddy
Published: May 2023

In this work, an in-depth static and low frequency noise characterization of nanosheet FETs, consisting of two vertically stacked silicon channels per device, is performed. A comparison of the performances from n- versus p-channel FETs operated at 300 K and 78 K, in terms of static and low frequency noise parameters variability, is also discussed. The main electrical parameters are estimated from the I-V characteristics using access resistance robust methodologies. An additional criterion demonstrating that the extracted parameters are not influenced by the second mobility attenuation factor is proposed. The low frequency noise studies prove that the dominant flicker noise mechanism is linked to correlated carrier number and mobility fluctuations, with additional access resistances noise contribution in very strong inversion. The importance of the considered total flicker noise model on the estimation of the Coulomb scattering coefficient is highlighted.
(Invited) Strategies for Characterization and Parameter Extraction of Vertical Junction-Less Nanowire FETs Dedicated to Design Technology Co-Optimization
Authors: Maneux Cristell , Mukherjee Chhandak , Deng Marina , Larrieu Guilhem , WANG Yifang , Wesling Bruno , Rezgui Houssem
Published: May 2023

In the era of emerging computing paradigms and artificial neural networks, hardware and functionality requirements are in the surge. In order to meet low power and latency criteria, new architectures for in-memory computing are being explored as alternatives to traditional von Neumann machines, which requires technological breakthrough at the semiconductor device level such as vertical gate-all-around junctionless nanowire field effect transistors (VNWFET), that can address many process challenges such as downscaling, short-channel effects, compactness and electrostatic control. Its integration in the mainstream design flow is not straightforward and requires design technology co-optimization (DTCO) at an early stage. This invited paper explores strategies for accurate characterization and parameter extraction of the VNWFETs to feed the compact models allowing DTCO-efficient strategies.
(Invited) High-Performance Field-Effect Transistors Based on Two-Dimensional Materials for VLSI Circuits
Authors: Knobloch Theresia , Selberherr Siegfried , Grasser Tibor
Published: May 2023

At present, silicon very large-scale integration has reached channel thicknesses of 7 nm. However, further scaling is becoming increasingly challenging as the gate electrostatics requires a significant reduction in channel thickness to about a fourth of the gate length. Consequently, the gate length of high-performance field-effect transistors is 16 nm at the state-of-the-art, and it is projected to stall at 12 nm for the 1.5 nm node and the following nodes, according to the International Roadmap for Devices and Systems. At these nodes, two-dimensional materials could potentially replace silicon as the channel material as they maintain sizable mobilities at atomic thicknesses, providing improved gate control in stacked channel nanosheet transistors. However,there are several challenges to overcome for FETs based on 2D mate-rials to serve as the front-end devices in VLSI circuits.
Cu(InGa)(SeS)2 Electrodeposition from a Single Bath Using Pulsing Current Technique
Authors: Saeed Mahfouz
Published: May 2023

Cu(In,Ga)(S,Se)2 (CIGSS) due to its greater band gap, has potential advantages over CuInGaSe2 (CIGS) as a photovoltaic film. Due to its lower capital cost and relatively high productivity, electrodeposition is a particularly appealing method for producing such solar materials (1-5). However, none describes the full production of such a molecule without the necessity for extra sulfur addition from the vapor phase4. Several recent articles disclose CIGSS electrodeposition. We introduce here the pulsing current method to dilute electrolytes used in previous work (6-7). Because of the diluted electrolyte composition, CIGSS can be directly electrodeposited from a single bath with a pulsing technique. The bath composition is 0.45 mM CuCl2-H2O; 0.4 mM InCl3; 0.77 mM H2SeO3; 0.51 mM GaCl3; and 0.3 mM Na2S2O3. PHydrion is applied to buffer the electrolyte to pH=2, and 0.7 M LiCl is applied as a supporting electrolyte. The flow was quantitatively characterized by agitation electrodeposition, which was done at room temperature onto a revolving disk electrode. Mass transport's impacts on deposit composition and substrate adherence are examined in various electrode rotation speeds and are represented by sample polarization curves. There was no requirement for the inclusion of metals from the gas phase during the subsequent annealing stage, which was carried out in an argon atmosphere. Two separate samples of absorber were evaluated for final sulfur atomic ratios of 5% and 15%. Utilizing the Energy-dispersive X-ray spectroscopy method, the final composition was calculated (EDS). CIGSS crystallography was analyzed using the XRD method.
Reversible Total Ionizing Dose Effects in NiO/Ga2O3 Heterojunction Rectifiers
Authors: Li Jian-Sian , Chiang Chao-Ching , Xia Xinyi , Stepanoff Sergei , Haque Amanul , Wolfe Douglas , Ren Fan , Pearton Stephen J
Published: May 2023

NiO/Ga2O3 heterojunction rectifiers were exposed to 1Mrad fluences of Co-60 g-rays either with or without reverse biases. While there is small component of Compton electrons (600 keV), generated via the interaction of 1.17 and 1.33 MeV gamma-photons with the semiconductor, which in turn can lead to displacement damage, most of the energy is lost to ionization. The effect of the exposure to radiation is a 1000x reduction in forward current and 100x increase in reverse current in the rectifiers, which is independent of whether the devices were biased during this step. The on-off ratio is also reduced by almost 5 orders of magnitude. There is a slight reduction in carrier concentration in the Ga2O3 drift region, with an effective carrier removal rate of < 4 cm-1. The changes in electrical characteristics are reversible by application of short forward current pulses during repeated measurement of the current-voltage characteristics at room temperature. There are no permanent total ionizing dose effects present in the rectifiers to 1 Mad fluences, which along with their resistance to displacement damage effects indicate these devices may be well-suited to harsh terrestrial and space radiation applications if appropriate bias sequences are implemented to reverse the radiation-induced changes.
Durability and Performance of Poly(norbornene) Membranes and Ionomers in Alkaline Electrolyzers
Authors: Park Habin , Tee Hui Min , Shah Parin , Dietrich Chandler , Kohl Paul
Published: May 2023

The anion conductive ionomer in the oxygen-producing anode is a critical part of the three-dimensional electrode in the anion exchange membrane alkaline electrolysis. In this study, self-adhesive anode ionomers were designed to chemical bond the anode catalyst particles to the porous transport layer and to the ionomer. It was found that high ion exchange capacity ionomers were not needed for effective electrode polarization because the anode was fed with alkaline electrolyte through the flow channel. The hydrophobic nature of anode ionomer and intimate contact with the catalyst by chemical bonding to the catalyst was key to improving anodic polarization and cell durability. The catalyst and self-adhesive ionomer contents of anode were optimized for the mechanically durable and energy-efficient alkaline water electrolysis.
Preparation of Membrane Electrode Assemblies Using Waste Tire Derived Carbon Supported Platinum Catalyst
Authors: Raudsepp Annabel , Jäger Rutha , Nerut Jaak , Valk Peeter , Teppor Patrick , Koppel Miriam , Aruväli Jaan , Laanemäe Joel , Lobjakas Wiljar , Lust Enn
Published: May 2023

Carbon supported Pt catalyst materials were synthesized from waste tire derived carbon by two different methods (microwave and refluxing). Catalysts and carbons were physically (XRD, N2 sorption analysis, TGA) and electrochemically characterized (RDE, CV, PEMFC single cell measurements). The RDE measurements were performed in 0.1 M HClO4 solution. For PEMFC single cell measurements, membrane-electrode assembly systems (MEAs) were prepared from catalyst materials by using different methods of coating the cathode layer and additional treatments. Catalysts were sprayed onto the membrane or GDL. In addition, MEAs were prepared where the catalyst was pipetted into GDL in several drops. Some of the MEAs were additionally treated with extra layer of Nafion and hot-pressed. The highest power density (0.42 W cm−2) was achieved with the MEA where the Pt catalyst synthesized via refluxing method was coated on the GDL with multiple drops and additional treatments were applied.
Optimizing Bilayer Electrolyte Thickness Ratios for High Performing Low-Temperature Solid Oxide Fuel Cells
Authors: Pesaran Alireza , Hussain A. Mohammed , Ren Yaoyou , Wachsman Eric
Published: May 2023

Over the last several years, significant developments have been made in bilayer electrolytes (e.g. GDC(Ce0.9Gd0.1O2-δ)/ESB((Er0.20Bi0.80O1.5)) suitable for low-temperature operating solid oxide fuel cells (SOFCs). Such bilayer electrolytes offer the potential for developing high performing LT-SOFCs by lowering the ohmic area specific resistance (ASR), and by improving the open circuit voltage (OCV) of mixed ionic/electronic conducting (MIEC) type electrolyte (e.g., GDC). However, optimizing the thickness ratio of the bilayer electrolyte is essential to achieve high power densities at low-temperatures (650-500 ℃). Here, we made a systematic study by varying the thickness ratios between GDC and YCSB((Bi0.75Y0.25)1.86Ce0.14O3±δ) bilayer electrolytes on an anode-supported LT-SOFCs, in all cases, the maximum power density (MPD) of the bilayer electrolyte cells is higher than pristine GDC based cells with reduced ohmic ASR values. Specifically, a high MPD of ~1 W/cm2 at 650 ℃ was achieved on a GDC(20μm) / YCSB(12μm) bilayer electrolyte based SOFC.
Three-Dimensional Microstructural Analysis for the Characterization of Failure Mechanisms of a Novel SOEC
Authors: Wehner Luzie , Lenser Christian , Dzieciol Krzysztof , Wessel Egbert , Malzbender Jürgen , Schwaiger Ruth
Published: May 2023

A novel fuel electrode-supported electrolysis cell has been developed as promising candidate for hydrogen production at intermediate temperatures. It contains a Ni-GDC electrode functional layer, a three-layer GDC-YSZ-GDC electrolyte and an LSC air electrode. Although this cell enables improved performance compared to state-of-the-art YSZ electrolyte-based cells, especially at lower operation temperatures, 700 °C and below, and electrolysis currents around 1.2-1.7 A cm-2 a voltage drop and subsequently crack formation in the electrolyte was observed in initial studies. In the current work, FIB/SEM and X-ray computed tomography are used for microstructural investigations. Based on calculated microstructural parameters the suitability of the methods for an assessment of the failure mechanisms are discussed.
Development of Multiple Ceramic Coatings on Porous Tubular Metal Support
Authors: Sahu Sulata Kumari , Panthi Dhruba , Du Yanhai
Published: May 2023

Dip coating was used to develop anodic half-cell for micro-tubular metal-supported solid oxide fuel cells (MS-SOFCs) economically. Ni–scandia-stabilized zirconia (SSZ) and SSZ were used as anode functional layer and electrolyte, respectively. Successive coatings of the SOFC functional layers were applied onto the porous metallic support using a dip coating technique. Additionally, to prevent delamination between the metal support and anode functional layer, an intermediate layer consisting of stainless steel powder, Ni, and yttria-stabilized zirconia (YSZ) was introduced. After coating, the individual layers were fired in a reducing atmosphere at 1000 °C followed by co-sintering of metal/anode/electrolyte multilayers at 1350°C. Microstructure of the sintered cells was characterized using scanning electron microscopy (SEM). General problems encountered during the fabrication of anodic half-cell for MS-SOFCs by a cost-effective dip coating followed by co-sintering route have been investigated. The sintering conditions and multilayer designs were studied to minimize the metal support oxidation and ceramic layer peeling during co-sintering.
Long-Term Sulfur Tolerance of Solid Oxide Fuel Cells with Alternative Titanate-Based Fuel Electrodes
Authors: Christensen Jens Ole , Longo Gino , Bausinger Holger , Mai Andreas , Sudireddy Bhaskar Reddy , Hagen Anke
Published: May 2023

Currently, solid oxide fuel cell systems rely on upstream desulfurization units to prevent sulfur poisoning of the state-of-the-art anodes based on Ni-cermets. Next-generation anode materials should be sulfur tolerant, without compromising the performance, to reduce system complexity and cost. In this study, all-ceramic La0.4Sr0.4Fe0.03Ni0.03Ti0.94O3 (LSFNT) anodes, infiltrated with Ni:Ce0.8Gd0.2O1.9 (CGO) or FeNi:CGO electrocatalysts, were integrated into large-area electrolyte supported cells. The cells were tested together with a SoA cell with Ni/CGO cermet anode in a short stack configuration using reformed grid natural gas and an upstream, bypassable desulfurization unit. The cell performances before exposure to sulfur were similar for all cell types at 850 °C. Exposure to sulfur revealed different degradation mechanisms. TheSoA cell shows a fast, initial degradation followed by limited further degradation. In contrast, the FeNi:CGO infiltrated LSFNT anode appears sulfur tolerant initially, followed by accelerated degradation of >50% kh-1 over long-term sulfur exposures. The Ni:CGO infiltrated LSFNT anode is remarkably sulfur tolerant.
The Effect of Operating Temperature on Galvanostatic Operation of Solid Oxide Electrolysis Cells
Authors: Bilalis Vasileios , Li Bowen , Frandsen Henrik Lund , Chen Ming
Published: May 2023

This study aims to investigate the effect of operating temperature on the galvanostatic operation of SOECs. Durability tests are conducted at four different temperatures but under the same current density. The analysis of the EIS data recorded during operation shows that the polarization and ohmic resistance increase considerably faster at lower temperatures. It also reveals that the main cause of degradation originates from the degradation of the Ni-YSZ electrode. Microstructure analysis reveals changes in the porosity and the %Ni atomic percentage in the active Ni-YSZ electrode layer, indicating that Ni migrates from the electrode/electrolyte interface towards the neighboring support layer. Over time, the resistance and overpotential attributed to Ni-migration exhibit linear increase. However, increase of temperature decreases their degradation rates. Overpotential thresholds for severe degradation of the Ni-YSZ electrode are identified at 750 oC and 800 oC but not at 850 oC and 900 oC due to the lower developed overpotentials.
Vanadium-Doped Ni/YSZ Anode Functional Layers for Solid Oxide Fuel Cells Produced via Magnetron Sputtering
Authors: Steier Katharina , Kelly Peter James , Kulczyk-Malecka Justyna
Published: May 2023

The electrode performance of solid oxide fuel cells (SOFCs) strongly depends on their microstructural characteristics, such as the porosity, percolated paths of ionically and electronically conductive phases and in particular, the grain size. Deploying alternative manufacturing techniques, such as magnetron sputtering, that deposits nanostructured materials results in finer particle sizes and thus, increases the quantity of triple-phase boundaries in the anode functional layer (AFL) for SOFCs. Nanostructured NiO-YSZ thin films have been previously produced by reactive pulsed DC magnetron co-sputtering of metallic targets of zirconium-yttrium and nickel, defining the optimal deposition parameters to create state-of-the-art AFLs. Based on recent studies 1–3, the future of oxide-based anode materials for SOFCs will greatly focus on advancing the electrocatalyst through alternative non-precious metal doping and increasing the cell performance by tailoring the microstructure of the AFL. Therefore, in this study, vanadium oxides were doped into SOFC anodes using different concentrations to study their influence on the structural and morphological properties of magnetron-sputtered AFLs.
Fabrication of Durable and High-Performance Flat Tubular Anode-Supported Solid Oxide Cells for Stack Application
Authors: Rehman Saeed Ur , Hassan Muhammad Haseeb , Batool Syeda Youmnah , Lee Seung Bok , Kim Hye-Sung , Song Rak-Hyun , Lim Tak-Hyoung , Hong Jong-Eun , Park Seok Joo , Joh Dong Woo
Published: May 2023

Solid oxide cell (SOC) technology is highly admissible for distributed power generation since it enables the most efficient and clean conversion of fuels into energy and heat. SOCs are also regarded as a potential technology for their decisive role in strengthening the hydrogen economy concept by storing renewable energy resources such as green hydrogen and synthetic fuels. In this work, high-performance and durable flat tubular anode-supported SOC is developed for SOC stack applications. NiO-8YSZ composite flat tubular anode support is fabricated by employing an extrusion process. Anode functional layer and electrolyte layers are deposited by the dip-coating technique, whereas the GDC diffusion barrier, LSCF-GDC composite cathode, and Ag-glass composite interconnect layers are fabricated by the conventional screen-printing process. Finally, the prepared flat tubular SOCs possess an active cathode area of 45 cm2 and demonstrated a high-power density of ~430 mW cm-2 at operating current density, voltage, and temperature conditions of 501 mA cm-2, 0.87 V, and 700 °C. During a long-term stability test at 700 °C for 1000 h, the SOC showed a voltage improvement of 0.013 % while operating at a fuel efficiency of 65%. The flat tubular anode-supported SOC’s high performance and durable operation showed its potential for commercial applications in distributed power generation and hydrogen production. Together with the research to further enhance the SOC’s performance and stability, the flat tubular SOC stack design and fabrication are also in progress.
Development of High-Entropy Alloy (HEA) Anode for Carbon-Free and Electrochemically-Stable Operation of SOFC on Hydrocarbon Fuels
Authors: Lee Kevin X , Singh Prabhakar , Hu Boxun , Dubey Pawan , Belko Seraphim
Published: May 2023

High-entropy alloy (HEA) anode, consisting of multicomponent alloy and gadolinium-doped ceria (GDC) powders, were synthesized and evaluated for ethanol steam reforming under SOFC operating conditions using a fixed-bed reactor as well as electrochemical performance using a button cell test configuration. Both bench-top and cell tests were conducted at 700 °C with a steam-to-carbon (S/C) ratio of 2. While Ni anode showed filamentary carbon formation, and performance degradation with time, HEA/GDC catalyst showed stable performance without carbon deposition. As an anode, HEA/GDC demonstrated high electrochemical stability and comparable current density compared to the Ni electrode.
Improving Gas Diffusion in Solid Oxide Cells Through Laser-Ablated Electrode Supports
Authors: Ganti-Agrawal Saahir , Cox Dalton , Barnett Scott A
Published: May 2023

In Ni-YSZ electrode-supported cells, gas diffusion through the electrode support layer can be a significant limitation at high H2 or H2O utilization and high temperature. Conventionally, higher-porosity electrode supports are used to improve diffusion, but this diminishes the cell’s structural integrity. Alternative fabrication methods like freeze-casting and 3D-printing allow for the creation of hierarchical structures with cutouts in the cell surface that improve gas diffusion, but these methods require redesigning processing procedures to obtain the desired materials properties. This work explores the use of laser ablation to pattern cutouts into the electrode support after sintering, enabling a faster mass transport without redesigning the entire fabrication process. Current-voltage measurements of symmetric Ni-YSZ electrode-supported cells with one patterned and one un-patterned electrode demonstrate that laser-patterning improves limiting current density and effective diffusivity by as much as 30%. Mechanical testing of patterned and un-patterned cells demonstrates that patterned cells suffer relatively small reductions in fracture strength.
Sr3Fe1.5Zn0.5O7-δ as Cathode for Protonic-Conducting Solid Oxide Fuel Cells with Enhanced Oxygen Reduction Reaction Activity
Authors: Sun Yueyue , Liu Zhengrong , Zhou Zilin , Yang Jiaming , Zhao Hongfei , Yin Chaofan , Wu Kai , Zhou Jun
Published: May 2023

Perovskite oxides have attracted intensive attention for their good electrochemical performance and stability as electrodes for protonic ceramic fuel cells (PCFCs). However, operating under high temperatures and various atmospheres results in a large polarization resistance and sluggish oxygen reduction reaction (ORR) in cathodes. Here, Zn was successfully doped into Sr3Fe2O7-δ (SFO) Ruddlesden-Popper (RP) perovskite cathode and the Sr3Fe1.5Zn0.5O7-δ (SFZ05) shows a superior ORR activity. The polarization resistance of SFZ05 is 0.072 Ω·cm-2, which is 47% lower than that of the undoped SFO, and the maximum peak power density of the single-cell of NiO-BaZr0.1Ce0.7Y0.2O3-δ(BZCY)|BZCY|SFZ05 reaches 523.56 mW·cm-2 at 750℃, increased by 22% than SFO. The improvement is attributed to the formation of oxygen vacancies and the increase of proton conductivity. These results display that SFZ05 is a promising candidate for a highly active and stable cathode for PCFCs.
Perovskite-Based Materials As Alternative Fuel Electrodes for Solid Oxide Electrolysis Cells (SOECs)
Authors: Winterhalder Franziska Elisabeth , Alizad Farzin Yousef , Guillon Olivier , Weber Andre , Menzler Norbert H.
Published: May 2023

Perovskites show high potential as alternative fuel electrodes in solid oxide electrolysis cells (SOECs) due to their high chemical stability, high conductivity, good catalytic activity and cost-effectiveness. In this work, four perovskites (strontium-iron-niobate double perovskite (SFN), strontium-iron-titanate (STF), lanthanum-strontium-titanate (LST), and lanthanum-strontium-iron-manganese (LSFM)) were examined as fuel electrode materials for SOECs. First, the chemical stability of the perovskites in a reducing atmosphere and the reactivity between the electrode and electrolyte material were analyzed. Besides featuring good chemical stability under reducing conditions, SFN double perovskite and LST exhibit the lowest interaction with the electrolyte (yttria-stabilized zirconia, 8YSZ) after thermal treatment. The results indicate a need for a barrier layer between the tested electrode materials and the YSZ electrolyte to achieve sufficient cell performance throughout its operation in the electrolysis mode. After thoroughly evaluating all preliminary tests, STF was chosen for the first subsequent electrochemical tests. Initial impedance measurements of symmetrical electrolyte-supported cells consisting of pure STF-based electrodes with and without a barrier layer between the electrodes and the electrolyte were conducted to obtain a base for further optimization. For the 5STF fuel electrode, the obtained EIS data confirm the conclusion from the reactivity experiments. Applying a barrier layer at the 5STF fuel electrode/ electrolyte interface is needed to reduce the cell´s ohmic and polarization resistances.
The Topsoe Perspective: From Electrode Nanostructures to MW Scaled SOEC Systems
Authors: Hauch Anne , Blennow Peter Gustav , Dalby Kim N. , Drasbæk Daniel Bovin , Heiredal-Clausen Thomas , Padinjarethil Aiswarya Krishnakumar , Perin Giovanni , Rass-Hansen Jeppe , Sala Elena Marzia , Tiruvalam Ramchandra
Published: May 2023

This paper provides an overview of Topsoe’s expertise, results, and initiatives in the field of solid oxide electrolysis cell (SOEC) technology. Topsoe’s expertise span from studies of materials’ properties, electrode nanostructures via electron microscopy, electrochemical performance of cells and stacks via impedance spectroscopy, to the design of stacks and MW-sized systems, and towards commercialization of our Topsoe SOEC electrolyzer plants. A short up-date on the newly initiated activities on production facilities for up-scaling of SOEC cells and stack production is included. The paper will review key challenges for state-of-the-art SOEC cells and stacks with a focus on electrochemical performance and durability, and microstructural integrity required for a commercially viable SOEC technology. Topsoe has the expertise in a variety of relevant downstream process; however, the work presented here will focus on the steam electrolysis application of SOEC for generating green hydrogen e.g., for ammonia production.
Bioethanol-Aided Electrolysis of H2O
Authors: Lo Faro Massimiliano , Ometto Felipe , Perez Joelma , Ticianelli Edson
Published: May 2023

This manuscript describes a novel electrochemical process for the electrochemical production of H2 using a solid oxide electrochemical cell. Part of the energy required for the process was supplied by ethanol, which was oxidized at the anode of a fully perovskite cell. In this experiment, we used a tailored cobaltite for the electrodes and a gallate-based perovskite electrolyte (La0.9Sr0.1Ga0.8Mg0.2O3-δ - LSGM) as the supporting element of an electrolyte-supporting cell (ESC). The present manuscript presents preliminary results from tests concerning LSGM structural analysis to demonstrate its robustness to reducing atmospheres, electrochemical experiments carried out in a complete cell between 700 °C and 800 °C, and surface analysis of the electrodes. With current densities over 1 A cm-2 and voltages between 0.27 and 0.41 V, this electrochemical process demonstrates a viable method for producing green hydrogen.
Accelerated Stress Testing of Solid Oxide Electrolysis Cells in a Symmetric Steam-Rich Atmosphere
Authors: Rose Christian , Mastropasqua Luca , Brouwer Jack
Published: May 2023

Commercialization of solid oxide electrolyzers is restricted by rapid degradation mechanisms of the electrodes, most notably nickel migration and agglomeration which leads to reduced activation sites at the triple-phase boundary. It is desirable to understand the process by which this phenomenon occurs not only to minimize it, but to intentionally induce it in a method which can compare the longevity of various chemistries. The objective of this research is to establish a protocol which mimics long-term electrode degradation. It is hoped that this will lead to a standardized procedure for comparing the projected long-term performance of solid oxide electrolysis cells. To promote degradation, operation at high steam partial pressure (>95% molar concentration) is employed.
Cathode Surface Segregating Modification for Boosting Oxygen Reduction Reactions: Coupling Theory and Experiment in Proton Conducting Solid Oxide Fuel Cells (H-SOFCs)
Authors: Xu Xi , Bi Lei , Skinner Stephen J
Published: May 2023

Computational simulation, based on Density Functional Theory (DFT), was carried out to develop a more powerful cathode material, La0.35Bi0.15Sr0.5FeO3-δ (LBSF), based on a first-generation cathode material, La0.5Sr0.5FeO3-δ (LSF) for use in proton-conducting solid oxide fuel cells (H-SOFCs). The calculation results show that the Bi substitution causes an oxygen p band center shift, which accelerates the oxygen reduction reaction (ORR). To prove this prediction, LBSF and LSF was synthesized successfully, and each surface was also characterized with X-ray photoelectron spectroscopy (XPS) and low energy ion scattering (LEIS), observing a surface Sr segregation and change after Bi substitution. The change proves an effective modification of surface segregation component. Subsequently, LBSF, applied into H-SOFCs, shows excellent performance with a peak power density of 1630 mW cm-2 at 700 ℃ when this material was employed as a cathode in a full H-SOFC.
Oxidation Process of Ni Cathode in CO2 Electrolysis in SOEC: X-Ray and DFT Study
Authors: Watanabe Hirotatsu , Higashidani Syo , Tawa Aoba , Ban Ikken , Ogura Teppei
Published: May 2023

CO2 oxidation of Ni cathode in CO2 electrolysis in solid oxide electrolysis cell (SOEC) was studied experimentally and through first-principles density functional theory (DFT) calculation. Ex-situ analyses of Ni/YSZ surface after CO2 electrolysis were performed using SEM and XRD. As a result, less oxidation of Ni was found in CO2 electrolysis mode at high current density (-280 mA/cm2), whereas Ni was oxidized at low current density (-140 mA/cm2). DFT calculation showed CO2 reduction was more stable than Ni oxidation at the Ni/YSZ interface. The electrolysis mode can enhance the oxidation tolerance of the Ni electrode due to the oxygen transfer. It was also implied that the electrolyte structure could improve the oxidation tolerance.
Performance and Electrochemical Behavior of LSM Based Fuel Electrode Materials Under High Temperature Electrolysis Conditions
Authors: Vibhu Vaibhav , Vinke Izaak , Eichel Rudiger-A , de Haart L.G.J. (Bert)
Published: May 2023

Ni-YSZ is known as the state-of-the-art fuel electrode material for solid oxide cells. However, this conventional fuel electrode experiences severe degradation due to Ni- agglomeration and migration away from the electrolyte. Therefore, to avoid such issues, we have considered Ni free electrodes i.e. La0.6Sr0.4MnO3 (LSM) based perovskite oxides as fuel electrode. Under reducing atmosphere, the LSM perovskite phase transforms into a Ruddlesden-Popper (La0.6Sr0.4)2MnO4±δ phase. In addition to pure LSM fuel electrode, we have also investigated the performance of LSM+YSZ (50:50 wt %) and LSM+GDC (50:50 wt %) composite electrodes. The electrolyte-supported single cells were prepared using 8YSZ electrolyte supports, and in all cases, LSM+YSZ/LSM oxygen electrodes were used. The current-voltage characteristics show good performance for LSM and LSM+GDC fuel electrode containing single cells. However, a lower performance is observed for LSM+YSZ fuel electrode containing single cell. For instance, a current density of 997, 1025, and 511 mA.cm-2 at 1.5 V, are obtained for LSM, LSM+GDC, and LSM+YSZ fuel electrode containing single cells respectively, with 50% N2 and 50% H2O feed gas mixture.
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: May 2023

A half-cell comprising of a Ni/3YSZ support, a Ni/CGO10 active fuel electrode, a thin ScYSZ electrolyte and a CGO10 barrier layer was realized through tape casting, lamination and co-sintering. After screen printing of air electrode and contact layer, the cell was electrochemically tested using EIS at open circuit voltage. At 750°C in 50/50 H2O/H2 ohmic resistance (Rs) was encouraging at 0.18 Ω.cm2. Polarization resistance (Rp) was however significantly larger than state of the art (SoA) cells at 0.45 Ω.cm2. From electrochemical analysis the causes for the large Rp are hypothesized to be poor air electrode performance and low fuel electrode performance. This transaction paper includes a description of ongoing activities to improve the electrochemical performance of this cell concept to approach or surpass SoA fuel electrode supported solid oxide cells (FE-SOC) relying on Ni/YSZ electrodes.
Modeling and Analysis of Polarization Losses in Solid Oxide Fuel Cells with Linear Siloxane Contamination
Authors: Rukmini Adrija , Ghotkar Rhushikesh , Riley Derall , Tian Jiashen , Milcarek Ryan J
Published: May 2023

In this study, the degradation of the solid-oxide fuel cell (SOFC) nickel-yttria stabilized zirconia anode under decamethyltetra-siloxane (L4) contamination is examined. A model is developed for the polarization losses based on the charge transfer coefficient, α, and diffusion layer thickness, į, and fitted to the experimental data to understand how the siloxane degrades the SOFC performance with time. Ohmic losses are dominant in the anode due to much higher anode thickness (380 µm) compared to electrolyte thickness (13 µm). Activation losses vary with α, which decreases from 0.31 to 0.25. Mass transport losses vary with both į and α, with įincreasing from 28 µm to 45 µm. The results of the model indicate that the total polarization losses increase for each subsequent time interval, with a total increase of approximately 45% from 0 to 180 min. Activation losses dominate the polarization losses initially but decrease in their total contribution while mass transport losses increase.
Configurations and Operation Methods of Diesel-Based Solid Oxide Fuel Cell System
Authors: Lu Yang , Liu Yaodong , Han Minfang
Published: May 2023

Solid oxide fuel cell (SOFC) can use a wide variety of carbon-based fuels. Diesel can act as a high-quantity fuel because of its high heat value and ease of transport. In this study, three different system configurations were proposed by a model in ASPEN PLUS V12 and fitted by data measured in the large size cell. The effects of key operation parameters, including reforming temperature, steam-to-carbon ratio (S/C) and recycling rate of the anode off-gas, were studied, which were characterized by the system efficiency and output power. As a result, the highest system efficiency was gotten with a water condenser and an anode off-gas recycling module in the system. The best operation method occurs when the thermal load of the diesel reformer is compensated by the heat released by anode off-gas combustion. This research will lay a theoretical foundation for the upcoming design of a physical diesel-based SOFC system.
SOFC-VPSA System for Power Generation with CO2 Separation
Authors: Wei Xinyi , Sharma Shivom , Marechal Francois , Van herle Jan
Published: May 2023

To meet “net zero” emission target for greenhouse gases in the year 2050, it is essential to retrieve most of the produced CO2 from emission intensive activities and store it permanently underground. This study considers integration of a 10 kW solid oxide fuel cell (SOFC) system with vacuum pressure swing adsorption (VPSA). In the integrated system, a small amount of electricity needed for the VPSA directly comes from SOFC system. The oxygen produced by VPSA is used to complete the oxidation of the unconverted fuel from the anodic side of SOFC, and then CO2 is separated automatically after the water condensation. Moreover, in this study, SOFC with VPSA has been optimized for minimizing the energy requirement and number of heat exchangers. Eight heat exchangers have been sized. Finally, the integrated system has waste heat available, to valorise the waste heat of the system, a steam cycle has been integrated for producing around additional electricity, to improve the overall efficiency. Finally, economic analysis has been performed, to understand its market competitiveness.
The Performance of Solid Oxide Fuel Cells Based on Methanol Solution
Authors: Yang Benrui , Liu Yaodong , Zhu Jianzhong , Han Minfang
Published: May 2023

Methanol generally needs a steam reforming process before being used in solid oxide fuel cells (SOFCs). This paper calculated and tested the composition of methanol reforming gas under different steam-to-carbon ratio (S/C ratio) and temperature. Results show that when the temperature is between 720°C and 820°C, experiment results are almost consistent with calculation results. When the temperature is around 620°C, a significant deviation exists between the experiment and calculation results, indicating that methanol conversion is incomplete. When the S/C ratio needs to be higher than 1.2 due to the equipment's limit, the appropriate reaction condition is 725°C and S/C ratio of 1.2. Methanol reforming gas under this condition was tested on a commercial SOFC. The peak power is 39.31W under 750°C and 46.97W under 800°C. The highest electrical efficiency reaches 52.4% when fuel utilization is 80%. These results provide a research basis for the future application of methanol in SOFCs.
Oxygen Ion Conduction Property of Solid Oxide Membrane Based on Multi-scale Analysis
Authors: Ijichi Takumi , Nagashima Hiroki , Hartwell Alexander , Ahn Jeongmin , Tokumasu Takashi
Published: May 2023

There have been reports of decreased ion transport properties at the grain boundaries (GB). Multiscale analysis is necessary to analyze the relationship between small-scale phenomena near the GB and large-scale ion transport properties across the membrane. We perform bottom-up analysis from Density Functional Theory (DFT) to kinetic Monte Carlo methods. In this study, we analyzed the effect of GB on ion transport properties using DFT-based molecular dynamics (MD) simulation. The following results were obtained by changing the number of SrSc0.1Co0.9O3-δ (SSC) and Sm0.2Ce0.8O2-δ (SDC) unit cells in the dual-phase solid oxide electrolyte membrane (SOEM). As the crystal size of SSC increased, both the diffusion coefficient and activation energy increased. As the crystal size of SDC increased, the diffusion coefficient decreased, and the activation energy increased. Furthermore, the calculated diffusivity of the x, y, and z directions show that the diffusivity was decreasing in the direction of the GB exist.
Spatially Heterogeneous Chemistry Observed using NIRTI on SOFC Anodes
Authors: Pomeroy Elias D , Steinhurst Daniel , Tsoi Stanislav , Kirtley John David , Eigenbrodt Bryan , Owrutsky Jeffrey , Maza William A , Walker Robert A.
Published: May 2023

Solid oxide fuel cells (SOFCs) are high temperature electrochemical conversion devices which are challenging to study due to their high operating temperature and dual atmosphere requirements. Traditional tools to study SOFCs are unable to resolve any spatial dependent chemistry which may be occurring on the cell. This study used Near Infrared Thermal Imaging (NIRTI) to identify spatially varying temperature changes indicative of heterogeneous chemistry occurred during C remediation reactions using gas phase oxidants and electrochemical oxidation on anode-supported SOFCs. The spatial dependences observed are probably due to kinetics and transport of the oxidizing species involved, which may provide insight for modeling SOFC kinetics and operation.
Development of Large Area Protonic Ceramic Cells for Stack Implementation
Authors: Schmider Daniel , Notar Catherine , Dailly Julian
Published: May 2023

The path towards stack implementation of protonic ceramic cells (PCCs) in order to provide a promising alternative to solid oxide fuel cells requires upscaling to larger cell areas, entailing manufacturing challenges. This work presents the manufacture of large area (>30 cm2, up to 78 cm2) protonic ceramic half-cells and cells based on a NiO-BCZY811 fuel electrode and BCZY721 electrolyte, using a wet chemical process. To achieve these sizes, the sintering temperature was lowered to 1300 °C using a ZnO sintering aid. Furthermore, the sintering configuration and ink composition were adjusted along the upscaling steps. A cell with 39 cm2 total area and 20 cm2 active area was successfully tested in fuel cell conditions and a power density of P=162 mW/cm2 has been measured at 650°C at a cell voltage E=0.7V.
A 3D Simulation of DC-Biased Electrochemical Impedance of Solid Oxide Electrolysis Cell: Effects of Delamination
Authors: Jayapragasam Puvikkarasan , Wen Yeting , Huang Kevin , Jin Xinfang
Published: May 2023

Solid oxide electrolysis cell (SOEC) is one of the best candidates for hydrogen production with zero carbon footprint, but cell degradation limits its implementation for long-term application. In this study, a three-dimensional (3D) button cell configuration model is used to study the oxygen electrode (OE) delamination, which is the major cause for the cell degradation during polarization life cycle. A composite lanthanum strontium cobalt ferrite (LSCF) and gadolinium doped ceria (GDC) is used as OE material. From the initial observation by solving for species transport equations for different crack propagation, it was found that cell degradation was largely dependent on relative area cracked at OE/electrolyte (EL) interface and independent of direction or shape of crack propagation. Electrochemical impedance spectroscopy (EIS) from physics-based model under DC bias is implemented to examine closely the electrochemical properties variation with aid of experiment measurement.
Comparative Study of Thermodynamic Performance and System Characteristics of Solid Oxide Fuel Cell System with Three Different Fuels
Authors: Jeong Kwangnam , Lee Jiyong , Hong Jongsup
Published: May 2023

This work focuses on the fuel characteristic of the Solid Oxide Fuel Cell (SOFC) system. Three types of fuel have been considered and two type of the SOFC system layout have been analyzed with in-house SOFC system simulator (H-Twin). In the case of non-recirculation system, ammonia fed system shows the highest efficiency. In the case of recirculation system, methane fed system show the highest efficiency. The hydrogen-fed system shows the lowest efficiency in both types of systems.
Development of Direct-Ammonia Solid Oxide Fuel Cells (DA-SOFCs) and the Effect of Incorporating Internal Ammonia Decomposition Catalysts
Authors: Yang Sungeun , Kim Hayoung , Oh Seongkook , Gokbayrak Attila Alkim , Lee JaeHyuck , Oh Min Jun , Ji Ho-il , Yoon Kyung Joong , Son Ji-Won , Lee Jong-Ho
Published: May 2023

Direct-ammonia solid oxide fuel cells (DA-SOFCs) are among the most efficient power sources that use ammonia. The high operating temperature of SOFCs enables ammonia decomposition reaction to proceed inside the anode compartment of SOFCs. Coupling exothermal SOFC operation and endothermal ammonia decomposition reaction increases the efficiency of the device. DA-SOFCs function as well as hydrogen-fueled ones over 750 °C. Recently we have reported that DA-SOFCs suffer significant performance loss under 650 °C, especially the high-performance cells. We discuss a range of phenomena taking place inside the anode compartment of DA-SOFCs: interconnect, current collector, and anode support. Interconnect and current collector have the capability of decomposing significant amounts of ammonia. Nevertheless, incorporating a catalyst is important at low operating temperatures.
Long-Term Stability of Perovskite-Based Fuel Electrode Material Sr2Fe2-XMoxO6-δ – GDC for Enhanced High-Temperature Steam and CO2 Electrolysis
Authors: Wolf Stephanie E. , Vibhu Vaibhav , Coll Carla L. , Eyckeler Niklas , Vinke Izaak C. , Eichel Rudiger-A , de Haart L.G.J. (Bert)
Published: May 2023

Severe performance loss of state-of-the-art Ni-cermet fuel electrodes has been observed due to Ni particle agglomeration and Ni migration away from the triple-phase boundary at the active electrode layer. Investigation of Ni-free perovskite Sr2Fe2-xMoxO6-δ (SFM)–30 wt% Ce0.8Gd0.2O2-δ (GDC) as fuel electrode material showed good redox stability in oxidizing and reducing atmospheres. These characteristics meet exactly the targeted requirements for new solid oxide electrolyzer materials. A comparison of SFM and SFM-GDC fuel electrodes showed similar performance for H2O, CO2, and co-electrolysis between 750 °C and 900 °C. Long-term degradation measurements and post-test SEM-EDX analysis clarified that SFM-GDC exhibits good phase stability in comparison to pure SFM fuel electrodes. The composite fuel electrode Sr2Fe1.1Mo1.0O6-δ–30 wt% Ce0.8Gd0.2O2-δ (SFM15-GDC) reached polarization resistances (RP) in the same range as Sr2Fe1.0Mo1.0O6-δ with around 127 mΩ∙cm² and 137 mΩ∙cm at 900 °C in steam electrolysis.
Studying the Sulfur Poisoning Mechanism of Solid Oxide Fuel Cells by Means of Patterned Nickel/Yttrium-Stabilized Zirconia Electrodes
Authors: Li Xiaoxiao , Wang Yuqing , Wang Yinan , Shi Yixiang
Published: May 2023

Sulfur causes Ni-based ceramic anode poisoning and thus shortens the life of the cell. Therefore, it is important to clarify the mechanism of sulfur poisoning to improve cell performance and lifetime. However, there is still some controversy about the mechanism of sulfur poisoning. In this work, Ni-patterned electrodes were used to investigate the mechanism of sulfur poisoning under different H2S concentrations and current densities. The electrochemical performance decreased with the H2S concentration increasing from 0 to 5 ppm due to the decrease of H2 reaction active sites. When further increasing the H2S concentration to 50 ppm, the performance showed a different trend and recovered to the initial performance without H2S due to the electrochemical oxidation of H2S. Increasing the current density was found to alleviate sulfur poisoning to some extent. The patterned electrode demonstrated a useful tool for the study of H2S poisoning mechanism.
Performance Improvement of Proton Ceramic Fuel Cells through Surface Treatment of Cobalt Oxide Nanoparticles on Perovskite Oxide
Authors: Jeong Heon Jun , Park Hyun Soo , Kim Keun Hee , Chang Wanhyuk , Kim Yoon Seong , Choi Yun Sung , Shim Joon Hyung
Published: May 2023

This study reports on the performance improvement of a protonic ceramic fuel cell (PCFC) after a CoOx nanoparticle treatment has been applied to a PrBa0.5Sr0.5Co2-xFexO5+δ(PBSCF) cathode with a perovskite structure. CoOx nanoparticles are deposited on the sintered PBSCF surface using a plasma-enhanced (PE) atomic layer deposition (ALD) process, thereby avoiding any unwanted reactions or phase changes. The CoOx nanoparticles are successfully deposited uniformly onto the entire surface of the porous and complex cathode structure. A constant deposition rate is observed because of the self-limiting characteristics of the ALD process by a thickness difference as a function of a change in the cycle count. In our experiment, the performance of the fuel cells increases by approximately 36 % compared with the untreated cells at an operating temperature of 650 °C. In addition, all cells feature long-term stability. Impedance analysis reveals that the CoOx nanoparticle treatment results in a significant polarization and some ohmic loss improvement within all temperature regions. This is due to the synergistic effect with PBSCF and self-catalytic effects. The results imply that the proposed method enables high-performance PCFC fabrication; additionally it helps lowering the operating temperature.
Examination of Morphological and Chemical Properties of Ni-BZY Anodes and their Influence upon Methane Reactivity and Electrochemical Performance of Protonic-Ceramic Fuel Cells
Authors: Hadi Abdul-Sommed , Morrow Fiona , Kirtley John David
Published: May 2023

Ni-BZY (yttrium-doped barium zirconate) has drawn recent interest for application in protonic ceramic fuel cells (PCFCs) due to BZY’s superior protonic conductivity and stability in reforming environments containing CO2 and H2O. Additionally, Ni and BZY form unique nano/microstructures thought to synergistically facilitate reforming. While PCFCs with Ni-BZY anodes have demonstrated stable long-term performance, little is known about the material’s transformations during operation and subsequent impact on electrochemical metrics. To address this knowledge gap, we constructed PCFCs consisting of Ni-BZY anodes sintered onto a ~600 μm BZY electrolyte complete with a LSCF/BCZY cathode. The electrochemical performance of these cells is compared at 600-700 °C while operating with humidified hydrogen, neat methane, and steam reformed methane (1CH4:1H2O). Insights into morphological and chemical changes are provided by pre- and post-mortem analysis of the anode via Raman spectroscopy, X-ray diffraction, and SEM. Phase transformations, agglomeration and coking all appeared to contribute to performance degradation.