bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Low-temperature SOECs with Excellent Performance for CO2 and H2O Co-Electrolysis
Authors: Shiming Hu , Li Yitong , Tian Yunfeng , Chi Bo , Pu Jian
Published: July 2021

Because of the advantages of high efficiency, safety, pollution-free and the waste gas can be converted into clean fuel (such as methane) in situ [1], using the solid oxide electrolysis cells (SOECs) to co-electrolyze water and carbon dioxide to produce oxygen has great application potential in the aerospace field. As early as the 1960s, NASA has begun to research on the use of SOECs to supply oxygen to astronauts [2]. However, the existing SOECs can only operate in high temperature range (750~850 ºC) with short lifetime and high energy consumption [3]. Therefore, it is urgent to reduce the operating temperature of SOECs in order to extend the operating life and shorten its start-up time, then providing a feasibility guarantee for its service in the aerospace industry.

However, lowering the cells’ operating temperature will bring about the problem of low oxygen ion conductivity. There are two strategies to solve this problem. One is to select materials with high oxygen ion conductivity in the low temperature range; the other is to reduce the thickness of the electrolyte layer to shorten the mass transfer distance. Herein, GDC was selected as the thin electrolyte material. And by adjusting the paste ratio of screen-printing method and sintering process parameters, the thickness of the dense electrolyte layer can be reduced to <5 μm. Besides, Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) and GDC are mechanically mixed as the anode materials. The measured ohmic resistance and polarization resistance are only 0.079 and 0.019 Ω·cm2 at 650 ºC, and the maximum output power density reaches 1.229 W/cm2 in SOFC mode. In SOEC mode, the steam and carbon dioxide are injected into the cell at a volume ratio of 3:1. The output current density is as high as 1.2 A/cm2 at 650 ºC under an applied voltage of 1.1 V. All these results confirm that the cells are promising for the applications in low temperature SOECs.

References

[1] A. Hauch, R. Kungas, P. Blennow, A. B. Hansen, J. B. Hansen, B. V. Mathiesen, et al. Recent advances in solid oxide cell technology for electrolysis. Science, 2020, 370(6513).

[2] H. Xu, M. M. Maroto-Valer, M. Ni, J. Cao and J. Xuan. Low carbon fuel production from combined solid oxide CO2 co-electrolysis and Fischer-Tropsch synthesis system: A modelling study. Applied Energy, 2019, 242: 911-918.

[3] Y. Wang, W. Li, L. Ma, W. Li and X. Liu. Degradation of solid oxide electrolysis cells: Phenomena, mechanisms, and emerging mitigation strategies—A review. Journal of Materials Science & Technology, 2020, 55: 35-55.
Stable High Performance Rare-Earth Nickelate Based Oxygen Electrodes for Reversible Solid Oxide Fuel Cells and Electrolyzers
Authors: Banner Jane , Akter Ayesha , Pietras John , Wang Ruofan , Sulekar Soumitra , Marina Olga A , Gopalan Srikanth
Published: July 2021

The performance of composite rare-earth nickelate-rare-earth doped ceria composite oxygen electrodes, with a high concentration of rare-earth doping in ceria to stabilize the nickelate phases are reported. Additionally, the stability of these compositions is reported at both the sintering (1240°C) and operating temperatures (800°C). Specifically, a lanthanum nickelate La2NiO4+δ (LNO) -45 mol% lanthanum doped ceria (LDC45) oxygen electrode has been tested in both solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) modes. The performance of this cell has been compared with a composite oxygen electrode comprising 20 mol% strontium doped lanthanum manganite (LSM)-10 mol% scandia 1 mol% ceria stabilized zirconia (SSZ) electrode. The LNO–LDC45 composite oxygen electrode shows a 65% increase in current density at 0.8 V, and a 260% increase in current density at 1.2 V compared to LSM-SSZ oxygen electrodes in SOFC and SOEC mode respectively. Additionally, long term performance data shows that this superior performance can be maintained for long operating times at 1.2 V in SOEC mode at 800°C. Supplemental cell tests also show comparable performance for a composite neodymium nickelate Nd2NiO4+δ (NNO)- 50 mol% neodymium doped ceria (NDC50) and a composite LNO- 50 mol% lanthanum doped ceria (LDC50) electrode.
B-Site Sc Doping of La0.6Ca0.4Fe0.8Ni0.2O3-
d as an Electrode for Solid Oxide Cells
Authors: Tian Yunfeng , Wang Xinxin , Ling Yihan , Chi Bo , Pu Jian
Published: July 2021

Reversible solid oxide electrochemical cell (RSOC) is a competitive option which has attracted increasing focus on alleviating some environmental problems and energy crisis with the capability of reversibly operating in solid oxide fuel cell (SOFC) mode and solid oxide electrolysis cell (SOEC) mode [1].

Solid oxide cells (SOCs) have received increasingly attention due to their high efficiency and broad applications. However, electrodes with rapid hydrogen oxidation reaction (HOR), oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO2RR), oxygen evolution reaction (OER) and sufficient durability play a key role in solid oxide cells. A multifunctional perovskite oxide La0.6Ca0.4Fe0.8Ni0.2O3-δ (LCFN) has been investigated as an electrode for SSOCs in our previous work. The results confirm that LCFN shows excellent ORR, OER, CO2-RR and HOR catalytic activity [2-3]. However, the investigation of LCFN for SOCs has been hindered due to the lack of stability. Herein, a novel perovskite La0.6Ca0.4Fe0.7Sc0.1Ni0.2O3-δ (LCFSN) is investigated as an electrode of SOCs. Its structural stability has been improved under H2 atmosphere. The polarization resistance (Rp) of the electrode LCFSN is only 0.147 Ω cm2 at 800 °C under air. The single cell Ni-YSZ/YSZ/GDC/LCFSN displays a peak power density of 1.36 W/cm2 in fuel cell mode and a low Rp value of 0.131 Ω cm2. Most importantly, the cell exhibits admirable durability of 130 h without apparent degradation. All these results suggest that LCFSN is a promising candidate electrode for SOCs.
Properties and Performance of Electrolyte Supported SOFCs with EB-PVD Gd-Doped Ceria Thin-Films
Authors: Han Feng , Riegraf Matthias , Sata Noriko , Bombarda Ilaria , Liensdorf Tom , Sitzmann Carolin , Langhof Nico , Schafföner Stefan , Walter Christian , Geipel Christian , Costa Rémi
Published: July 2021

High temperature solid oxide fuel cell (SOFC) is regarded as a unique electrochemical device to convert the chemical energy of a large diversity of fuels into electricity and heat with high efficiency and low emission. The electrolyte-supported cell (ESC) design is proven to be one of the most feasible SOFC technologies for commercial applications. Thickness reduction of yttria stabilized zirconia (YSZ) electrolyte supports without sacrifice of mechanical strength is favorable for cell performance enhancement.

In this work, dense gadolinium-doped ceria (GDC) thin-films with thickness in the range of 0.15-0.5 µm were fabricated as Sr-barrier layers on the cathode side, and as strength-balance and adhesion layer on the anode side by electron beam physical vapor deposition (EB-PVD) method. Replacing the state-of-the-art screen-printed GDC layers, the approach with YSZ substrate sandwiched in between two GDC thin-films was proposed not only to prevent the formation of interfacial secondary phase on the cathode side, but also to increase the overall robustness of ESCs. Investigated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), it was confirmed that 0.5 µm thick GDC thin-films were effective to suppress the formation of Sr-zirconate phase at the YSZ/GDC interface. In comparison to reference cells with screen-printed GDC layers, higher breaking loads were recorded on the cells with PVD-GDC thin-films by Ring-On-Ring bending tests, showing considerably improved mechanical properties. Current-voltage characteristics and electrochemical impedance spectroscopy demonstrated that the performance of the as-prepared ESCs with GDC thin-films was comparable to the reference cells. Operated at 860 °C, the ESC with 0.5 µm GDC thin-film outperformed other tested cells with 0.15 µm or 0.3 µm GDC layers, and delivered a power density of 0.55 W•cm-2 at a cell voltage of 0.7 V. The results achieved in this work can be considered as step stones for the further development of ESCs with reduced electrolyte thickness, sufficient robustness and improved performance.

This work is financially supported by the German Ministry for Economic Affairs and Energy (BMWi) within the framework of the project “Kostenoptimierter Stack und verbessertes Offgrid-System (KOSOS)” with grant number of 03ETB005C.
A High Performance La0.2Sr0.8Co0.8Fe0.2O3-δ Catalyst As an Oxygen Electrode for Reversible Solid Oxide Cells at Intermediate Temperature
Authors: KIM Doyeub , Park Jin Wan , Chae Munseok S , Jung Incheol , Park Jeong Hwa , Kim Kyeong Joon , Lee Jong Jun , Jung Chanhoon , Lee Chan-Woo , Hong Seung-Tae , Lee Kang Taek
Published: July 2021

Solid oxide cells (SOCs) have been reported as promising energy production and storage devices due to their high efficiency and low pollutant emissions. A key barrier to achieve high performance of SOCs is high electrode polarization resistance which attributes to the sluggish kinetics of oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs) at reduced temperatures. One of the potential oxygen electrodes is a perovskite La0.6Sr0.4Co0.2Fe0.8O3-
δ(LSCF6428) with mixed ionic and electronic conduction (MIEC) because of its considerable conductivities and good chemical compatibility with conventional electrolyte materials such as ceria-based oxides. However, upon long-term operation under fuel cell conditions, the LSCF6428 electrode is usually subjected to severe degradation of ORR kinetics owing to chemical instability. It has been well known that the tailoring the chemical composition of the perovskite material strongly modulates their electrochemical activities and oxygen ion transport properties.

In this study, we synthesized the La0.2Sr0.8Co0.8Fe0.2O3-
δ (LSCF2882) and systematically investigated its characteristics on intrinsic properties. In addition, we evaluated oxygen transport kinetics and electrochemical performance of LSCF2882 as an oxygen electrode for reversible SOC applications.
Quantitative Analysis of Solid-State Energy Devices Via 3D Reconstruction Using a FIB/SEM Dual Beam System
Authors: Bae Kyung Taek , Park Joonam , Joh Dong Woo , Park Jeong Hwa , Kim Dohwan , Jeong Wooyoung , Nam Ji-Eun , Lee Myeong Ju , Shin Dong Ok , Lee Yong Min , Lee Kang Taek
Published: July 2021

To lower the carbon emission from the rising consumption of fossil fuels, electrochemical devices such as fuel cells and batteries, which can produce or store electricity from renewable resources, are attracting attention. Both systems require an electronically insulating solid membrane, which separates the cathode and anode to prevent short-circuiting. To improve the performance of porous electrodes, researchers have focused on tuning the electrode microstructure. The addition of highly ionic conducting materials to the electrode is commonly used to maximize the reaction site density. However, microstructural features, such as particle size distribution, electrochemically active site density and connectivity of each phase, are difficult to quantify only using conventionally used characterization methods such as scanning electron microscopy (SEM).

One well-established method for obtaining three-dimensionally interconnected microstructural information is serial sectioning using a FIB/SEM dual beam system. Using this technique, more reliable and accurate quantification of the SOFC and ASSLIB electrodes microstructure are available. Also, the quantified features will be reflected in the responses of electrochemical impedance spectroscopy (EIS) measurements. These results can provide a link between them. Therefore, the aim of this study is to three-dimensionally reconstruct the microstructure of solid-state energy devices via FIB/SEM dual beam system and to quantify their microstructural features. Also, these results will be combined with the electrochemically analyzed properties to further understanding their relationship with microstructural properties.
Development of Flowerlike Ce1-XZrxO2-δ-Dispersed Paper-Structured Catalyst for Direct-Biogas SOFC
Authors: Tu Phuc Hoan , Sakamoto Mio , Sasaki Kanzunari , Shiratori Yusuke
Published: July 2021

Performance of direct internal reforming (DIR)-solid oxide fuel cell (SOFC) can be improved by the application of the paper-structured catalyst (PSC) on the anode material. In the ceramic fiber network of the PSC, any kinds of functional materials can be easily dispersed during paper-making process.

The solid solution based on the equimolar mixture of ceria and zirconia (Ce0.5Zr0.5O2-δ), hereafter called CZ, is a promising oxide support of the Ni metal catalyst due to its high specific surface area and high oxygen storage capacity (OSC). By employing the two-step hydrothermal process developed in this study, we could successfully prepare the CZ with flowerlike geometry, which can prevent Ni from sintering under reducing atmosphere.

Ni-loaded PSCs with and without the dispersion of CZ, Ni/CZ-PSC and Ni-PSC, respectively, were prepared. Structures of the PSCs were characterized by X-ray diffractometry (XRD), BET specific surface area measurement, field emission scanning electron microscopy (FESEM), inductively coupled plasma spectrometry (ICP) and thermogravimetric analysis (TG). Catalytic performances of these PSCs for the dry reforming of methane (DRM) in the feed of the equimolar mixture of CH4 and CO2 were evaluated by an automatic gas chromatograph (GC) with the posttest analysis by FESEM observation, temperature-programmed oxidation (TPO) and TG to estimate carbon deposition.

In the durability (160 h) tests of the prepared-PSCs for DRM at 750oC under gas hourly space velocity (GHSV) of 2300 h-1 revealed that, for both cases with and without CZ dispersion, methane conversions were stable with the degradation rates (estimated after 10 h) of 13.7 and 21.8% 1000 h-1, respectively. TG measurements after the 160 h tests under oxidizing atmosphere in the range from 300 to 750oC revealed that the weights of the deposited carbon were 0.2 and 3.4 folds of those of PSCs for Ni/CZ-PSC and Ni-PSC, respectively. In the case without CZ dispersion (Ni-PSC), after the TG measurement to burn out the deposited carbon, Ni agglomeration and its detachment from the ceramic fiber could be clearly observed. On the other hand, for the Ni/CZ-PSC, these phenomena were considerably suppressed thanks to the flowerlike morphology for better dispersion of Ni metal particles and higher OSC of CZ solid solution to consume deposited carbon by the lattice oxygen.

The developed PSCs will be applied on the anode of electrolyte-supported cell to demonstrate the stable operation of DIR-SOFC fueled by biogas (direct-biogas SOFC).
Stability of Nickel/Scandia-Doped-Stabilized-Zirconia Composite Anode Under High Fuel Utilization Conditions
Authors: Taniguchi Shunsuke , Miyara Kengo , Kawabata Tsutomu , Uryu Chie , Inoue Yuko , Chou Jyh-Tyng , Sasaki Kazunari
Published: July 2021

Microstructure change of nickel/scandia-doped-stabilized-zirconia (Ni/ScSZ) composite anode near the electrode reaction sites was investigated with increasing pH2O and current density. Electrolyte supported cell with ScSZ electrolyte was operated at 700oC under the gas composition of x%H2O-(50-x)%H2-50%N2. In the Ni/ScSZ anode, Sc dissolved into the adjacent Ni and concentrated at the center of the Ni particle. Dissolution of Sc from ScSZ was enhanced under high pO2 or high current density. Oxidation and reduction of Ni accompanied by the electrode reaction under such severity conditions affected microstructure of the Ni particles.

This research was supported by New Energy and Industrial Technology Development Organization (NEDO) on "Fundamental study for rapid evaluation method of SOFC durability".
Correlation Between Microstructure and Macroscopic Properties of Solid Oxide Fuel Cell Composite Anode: Mesoscale Modeling and Deep Learning with Convolutional Neural Network
Authors: Liu Xuhao , Zhou Shihao , Yan Zilin , Zhong Zheng , Shikazono Naoki , Hara Shotaro
Published: July 2021

In this paper, we propose a framework for studying the linkage between microstructure and performance of Ni-YSZ anode in solid oxide fuel cells (SOFCs) by using meso-scale modeling and deep learning. The discrete element method (DEM) and the mesoscale kinetic Monte Carlo (KMC) method were respectively used to model the particle packing and sintering of composite Ni-YSZ anodes. Anodes with various microstructures were numerically synthesized by varying volume fraction, sizes and size distributions of solid phases and pores. Then, representative volume elements (RVEs) of anode microstructures were meshed for finite element modeling of the effective elastic modulus and thermal coefficient of expansion of the anode based on the homogenization theory. The triple phase boundary length density (
L

TPB), tortuosity factor for each phase were also calculated based on RVEs.

Based on a large dataset which consists of various anode microstructures (represented as ternary image stacks) and corresponding macroscopic properties, a deep convolutional neural network (CNN) was trained to capture the nonlinear functional relationship between anode microstructures and macroscopic properties. The deep learning CNN model was finally well validated against extra new samples with excellent predictive performances. This indicates that the CNN model can be used as a surrogate model for rapid direct access to macroscopic properties of composite anodes, if the microstructure of the anode is known. The macroscopic properties can be further used for continuum modeling of SOFCs.

This framework is highly extendable for other single-phase or composite electrodes of SOFCs. In addition, the proposed framework provides a new ideal for multiscale and multiphysics modeling of SOFCs.
Experimental Investigation of an Anode Supported SOFC Stack Under High Direct Internal Reforming Conditions
Authors: Hauck Maximilian , Herrmann Stephan , Fischer Felix , Weinrich Jeremias , Steinrücken Benjamin , Spliethoff Hartmut
Published: July 2021

Direct internal reforming (DIR) of hydrocarbons like methane can help improve both economics and efficiency of solid oxide fuel cell (SOFC) systems. The endothermic reforming reaction yields chemical energy in form of hydrogen by directly utilizing waste heat from the cells, which is more efficient than other concepts like partial oxidation (POX) of the fuel gas. Furthermore, DIR cools the stack, reducing the need for excess air. The parasitic power consumption of the air blower is reduced, as well as investment costs for blowers and external reformers. However, DIR can potentially damage SOFC stacks due to thermal gradients and resulting stresses. Furthermore, in case of natural gas, usually some degree of external reforming is needed to convert heavy hydrocarbons like ethane, since these would cause carbon depositions on the SOFC anode.

In this paper, we present experimental data from the operation of an anode supported short stack from Ningbo SOFCMAN Energy Technology. Natural gas was used as fuel, and the stack was operated under varying degrees of DIR. The reforming level was adjusted using an electrically heated reformer, and monitored with an online gas analysis. Up to 90 % internal reforming has been demonstrated without signs of carbon deposition or cell fracture. Increasing the degree of DIR had a moderate adverse effect on the stack performance. Possible reasons for this behavior are discussed.

These results show that operation of stacks from Ningbo SOFCMAN Energy Technology under high degrees of DIR is feasible, while some performance decrease has to be expected.
Joint Strength of a Braze Sealant with Metallic Interconnect in Solid Oxide Fuel Cell
Authors: Tseng Yu-Wei , Lin Chih-Kuang , Huang Liang-Wei , Liu Chien-Kuo , Lee Ruey-Yi
Published: July 2021

To meet the quick start-up characteristics of metal-supported solid oxide fuel cell (MS-SOFC), brazing seals have been used in many MS-SOFC systems. During the cyclic operation of SOFC, thermal stresses are unavoidably generated due to temperature gradient and mismatch of coefficient of thermal expansion (CTE) between components. Excessive thermal stresses may damage the structural integrity of an SOFC stack, which in turn reduces the efficiency and lifetime of the SOFC. Therefore, it is essential to study the mechanical properties of the joint between braze sealants and metallic interconnects at room temperature (RT) and operating temperatures for developing a reliable MS-SOFC stack. The aim of this study is to investigate the mechanical strength of a braze sealant/metallic interconnect joint in SOFC. The braze sealant used is a silver-based alloy which is developed at the Institute of Nuclear Energy Research (INER) for MS-SOFC. The metallic interconnect used is a commercial ferrite stainless steel (Crofer 22 H). Two types of sandwich-like joint specimens are made to determine the shear and tensile joint strength at RT and 750 °C. Experimental results indicate that a bonding time of 30 min produces better joint strength at RT than 20 and 40 min, and it is thus selected as the bonding time for the specimens used in the subsequent tests. For tensile loading mode, the joint strength at RT and 750 °C is of 30.63 ± 3.2 MPa and 13.43 ± 0.99 MPa, respectively. For shear loading mode, the joint strength at RT and 750 °C is of 40.02 ± 2.88 MPa and 10.06 ± 0.36 MPa, respectively. Fractography analysis reveals that regardless of testing temperature, fracture of the tensile specimens occurs at the interface between the braze sealant and the Cr2O3 oxide layer and occasionally within the Cr2O3 oxide layer. When the testing temperature of the shear specimens is increased from RT to 750 °C, the location of rupture changes from the interface between the braze sealant and Crofer 22 H to the interface between the braze sealant and the Cr2O3 oxide layer.
Degradation Analysis of SOFC Performance for Long-Term Operation with High Fuel Utilization
Authors: Ido Akifumi , Imabayashi Takumi , Asano Koichi , Yamamoto Tohru , Morita Hiroshi , Mugikura Yoshihiro
Published: July 2021

A national project in Japan for SOFC development has been initiated from FY2020 to FY2024 in NEDO’s project in order to establish the method for degradation diagnosis of SOFC stacks with durability and reliability for 130,000 hours or the method for evaluation of expanding application. Central Research Institute of Electric Power Industry (CRIEPI) has operated three types of SOFC stacks, which are developed by KYOCERA, MORIMUA SOFC TECHNOLOGY, and DENSO and investigated their long-term durability in this project.

We have developed the electrode polarization model for SOFC performance which is able to express the SOFC performance such as Nernst loss, cathode overvoltage, anode overvoltage, and internal resistance (IR) loss under various conditions with high prediction accuracy. Each SOFC stack has been operated with high fuel utilization (Uf = 80% and 85%) as a severe condition for high efficiency towards 20,000-hours operation, and degradation factors for SOFC durability has been analyzed by using our electrode polarization model. Analysis results until now showed that dominant degradation factors for both Uf = 80% and 85% were increase of cathode overvoltage or IR loss as same as that of the SOFC stacks in the previous term [1]. Although anode overvoltage was a minor degradation factor, increase rate of anode overvoltage under Uf = 85% was relatively larger than that under Uf = 80%.

In addition, thermal property testing will be conducted for each SOFC stack in order to include temperature term into our electrode polarization model. This new model can predict SOFC performance more accurately under various operating conditions.

This work has been carried out under the project of the New Energy and Industrial Technology Development Organization (NEDO), Japan as a contract research. We would like to express our gratitude to NEDO, KYOCERA, MORIMUA SOFC TECHNOLOGY, Denso as well as to university partners and National Institute of Advanced Industrial Science and Technology (AIST).

Reference

[1] A. Ido et al., ECS Transactions, 91(1), 801-808 (2019).
Electrochemical Performance of Pr0.8Ca0.2Fe0.8Co0.2O3-δ as Air Electrode for Reversible Solid Oxide Cells
Authors: Li Yitong , Tian Yunfeng , Chi Bo , Pu Jian
Published: July 2021

Energy and environmental issues have always been topics of great concern to the world in recent years. The production of electricity from solar and wind energy has increased dramatically. These significant developments in renewable energy technologies are now driving the development of a method to efficiently store and transport the inherently intermittent electricity from these natural resources [1]. Under this situation, the emergence of reversible solid oxide cells (RSOCs) has been attracted widespread attention. As a clean and efficient electrochemical conversion device, RSOCs can link electrical and chemical energy and convert flexibly, which is of great significance for power generation and energy storage [2]. It can operate in two modes: (i) as solid oxide fuel cells (SOFCs) for power production and (ii) as solid oxide electrolysis cells (SOECs) for hydrogen and oxygen production [3].

Herein, we successfully synthesized a novel perovskite Pr0.8Ca0.2Fe0.8Co0.2O3-
δ and used it as an air electrode in reversible solid oxide cells. In the SOFCs mode, the peak power density is up to 1.056 W cm-2 at 850 ºC using hydrogen as the fuel and air as the oxidant. It can achieve 1.43 A cm-2 at 850 ºC under an operating voltage of 1.3 V in the SOECs mode with water content of 50%. Moreover, the cell can run stably in both SOFCs and SOECs modes with showing excellent reversibility. During a short-time reversible term, it remains both electrochemical performance and structure stable. These results demonstrate that the perovskite Pr0.8Ca0.2Fe0.8Co0.2O3-
δ is promising air electrode for applications in RSOCs.

References

[1] Choi S, Davenport T C, Haile S M. Protonic ceramic electrochemical cells for hydrogen production and electricity generation: exceptional reversibility, stability, and demonstrated faradaic efficiency. Energy & Environmental Science, 2019, 12(1): 206-215.

[2] Y. Luo, Y. Shi, Y. Zheng, N. Cai, Reversible solid oxide fuel cell for natural gas/renewable hybrid power generation systems, J Power Sources, 340 (2017), pp. 60-70.

[3] Meng X., Liu Y., Yang N., Tan X., Liu J., J.C. Diniz da Costa, Liu S. Appl. Energy, 205 (2017), pp. 741-748
Simulation of a Flat-Tube Solid Oxide Fuel Cell with Symmetric Double-Sided Cathode Considering Different Fuel Compositions
Authors: Zhang Xiaoqiang , Espinoza Andaluz Mayken , Wang Lei , Li Tingshuai , Andersson Martin
Published: July 2021

Due to its high operating temperature, solid oxide fuel cells (SOFCs) can use a variant of hydrocarbon fuels. Then the methane steam reforming (MSR) and water gas shift (WGS) reactions are active within the anode during the energy conversion process. On one hand, the air velocity controls the heat within a SOFC, e.g., through control of heat convection, on the other hand, the internal endothermal reactions also have an impact on the heat balance through different fuel composition. It should be noted that the carbon deposition greatly reduces the catalytic property of the anode material.

The reforming process can be synthetized by the following electrochemical reactions:

2CO ↔ C(s)+ CO2 (1)

CO+H2 ↔ C(s)+H2O (2)

C
n
H2n+2 ↔ nC(s)+(n+1)H2 (3)

Thus, it is important to investigate the effect of internal reforming reactions of different fuel composition on cell performance.

Numerical simulations can reduce the cost of experimental design and achieve desirable accuracy. A flat-tube SOFC with a symmetric double-sided cathode is built using the commercial software COMSOL Multiphysics®. Our model includes the simulation of the ion, electron, momentum, heat, and mass transport phenomena. Also, MSR and WGS reactions are considered in the model. The geometric representation of the flat-tube SOFC anode is shown in Figure 1.

Figure 1
Performance Evolution of Ni-YSZ Anode-Supported SOFCs During Initial-Stage Operation
Authors: Lyu Zewei , Han Minfang
Published: July 2021

Solid oxide fuel cell (SOFC) is a clean and efficient power generation device, which has been widely used in recent years. However, its operation lifetime still needs to be improved to meet the requirements of further commercialization. The performance degradation of SOFCs is affected by many factors. It is meaningful to distinguish these factors and determine the dominant factor(s) for extending the operation lifetime. In this work, the initial operation stage (<100 h) of Ni-YSZ anode-supported SOFCs is mainly focused, since it has been found that the electrochemical performance changes most significantly in this stage. The electrochemical impedance spectroscopy (EIS) is continuously monitored during the operation of cells. Different electrode processes are distinguished through coupled distribution of relaxation time (DRT) and equivalent circuit model (ECM) analysis. Accordingly, the changes of different electrode processes in the initial-stage operation are obtained by detailed comparative analysis of EIS. It’s found that SOFCs go through activation stage and aging stage in turn: i) In the activation stage, the residual NiO in the anode is further reduced, so the porosity of the anode increases and the gas phase diffusion is enhanced, resulting in the performance improvement of the cell. ii) In the aging stage, the Ni particles in the anode agglomerate, so the effective three phase boundary (TPB) density decreases, which leads to the degradation of anode interface reactions and the drop of cell performance. Besides, we speculate that the dominant degradation mechanism in long-term operation (>100 h) is the continuous increase of the anode interface reaction-related resistance, which is mainly caused by gradual agglomeration of Ni particles. This evolution mechanism of electrochemical performance is then confirmed by detailed microstructure characterization.

Figure 1
Electrochemical Reaction Mechanism of LSM-YSZ Composite Cathode Based on 3D Simulation of Oxygen Diffusion and Oxygen Labeling Experiment
Authors: Shimura Takaaki , Nagasawa Tsuyoshi , Shikazono Naoki , Hanamura Katsunori
Published: July 2021

Electrochemical reaction mechanism of an LSM-YSZ composite cathode is investigated using a combined measurement of oxygen labeling experiment and 3D microstructural reconstruction. First, oxygen isotope gas 18O2 was exposed to the LSM-YSZ cathode at 750 °C and a current density of 0.052 A/cm2. After 2 minutes of 18O2 supply, the gas was switched to water-cooled He to quench the cell and fix the incorporated isotope at the operating condition. After the oxygen labeling experiment, the cell piece was filled with an epoxy resin and polished to prepare the sample. Three-dimensional microstructure was obtained using a focused ion beam-scanning electron microscopy (FIB-SEM). Furthermore, between the measurement of the FIB-SEM, secondary ion mass spectroscopy (SIMS) analysis was conducted at the middle plane of the observed volume to correlate 18O distribution with the 3D microstructure. Based on percolation analysis of the microstructure, several isolated LSMs showed quite low 18O concentration, whereas some isolated LSMs showed 18O incorporation. For a further understanding of the correlation between the 18O distribution and microstructure, 3D numerical simulation using the reconstructed microstructure was carried out. First, potential distribution was obtained by solving gas diffusion and charge transportations which are coupled with the reaction at the reaction sites using the lattice Boltzmann method. Then, 18O distribution was predicted by solving oxygen diffusion along the calculated potential field. The electrochemical reaction mechanism was discussed by comparing the results of numerical simulation and experiment.
Recent Achievement of Degradation Analyses in Japanese National Project: High Efficiency and Dynamic Operation Effects on the Durability of SOFC Stacks
Authors: Horita Teruhisa
Published: July 2021

To achieve high efficiency of 65% LHV in the solid oxide fuel cells (SOFCs), the fuel utilization should increase to the level of over 80%, which is 10-15% higher fuel utilization (Uf) than the standard condition, and severe degradation can occur at the component materials. When the current density is controlled in the stack level, there might be the distribution of fuel utilization in the cells due to the distribution of fuel gas, water vapor pressures, and temperatures. So far, many studies were examined on the clarification of degradation mechanism under fuel cell operation.

In this report, recent achievements of the Japanese national projects (NEDO projects) are presented, especially on the rapid evaluation methods for degradation (2018-2019) and most recent “Development of advanced evaluation and analysis technologies for the durability of Solid Oxide Fuel Cells stacks (2020-)”. Especially, the anode durability was discussed with different kinds of cell-stack geometry at high fuel utilization. The degradation mechanism and fuel utilizations are compared at the planer and flat tubular type cell-stacks. We discussed the microstructure change and stability of the Ni-YSZ cermet anode at high Uf and current density conditions.
(ECS High-Temperature Energy, Materials, & Processes Division Subhash Singhal Award Address) Solid Oxide Fuel Cell Technology - Perspectives on the Future
Authors: Minh Nguyen Q.
Published: July 2021

Solid oxide fuel cells (SOFCs) have several attractive features that distinguish the technology from other types of fuel cell and many energy systems. The key differentiating attributes of the SOFC are capability (i.e., multi-functional, capable of functioning in several operating modes - power generation, energy storage and chemical production), adaptability (i.e., appropriate for diverse applications and versatile in practical system sizes), and flexibility (i.e, fuel flexible, suitable for efficient operation on a variety of fuels). Having these characteristics along with the property of compatibility (i.e., environment compatible) and the potential for affordability (i.e., cost effective and cost competitive), the SOFC has the prospect to serve as a base technology for many energy systems in the future. This presentation discusses selected examples of advances and innovations in design and engineering, materials and manufacture that could help to move the SOFC toward this future expectation.
Electro-Chemo-Mechanical Failure in a High-Performance Solid Oxide Cell
Authors: Lenser Christian , Zhang Jun , Russner Niklas , Weber Andre , Guillon Olivier , Menzler Norbert
Published: July 2021

Fuel electrode-supported solid oxide cells (FE-SOC) offer the possibility of low operation temperatures and / or high power density through the incorporation of a thin, supported electrolyte between two highly active electrodes. However, integrating fuel electrodes with an ionic conductor that is different from that of the electrolyte into FE-SOC remains a challenge due to the interdiffusion phenomena during co-sintering of the half-cell. As a result, most FE-SOC use cermet fuel electrodes made from Ni and stabilized zirconia.

Here, we present a FE-SOC based on a Ni-Gd0.1Ce0.9O2-
d (GDC) fuel electrode, a three-layer GDC / zirconia / GDC electrolyte and an La0.58Sr0.4CoO3-
d (LSC) air electrode. The electrolyte is fabricated by co-sintering a thin, screen-printed layer of GDC with the fuel electrode and support. Subsequent electrolyte layers are deposited via physical vapor deposition (PVD), and the air electrode is fabricated via screen printing. The total electrolyte thickness is less than 5 µm, enabling an area-specific ohmic resistance < 10 mΩ cm² at 700 °C. A current density of 1.6 Acm-² is achieved at a cell voltage of 800 mV and a temperature of 700 °C, using 10% H2O/H2 as fuel and air as oxidant. This performance is about twice as high as that of a conventional Jülich cell using Ni-YSZ and LSCF electrodes and a 10 µm YSZ electrolyte under similar conditions. An electrolysis current of 2 A cm-² was achieved at a cell voltage of 1.11 V, at a temperature of 800 °C and using 50% H2O/H2 and air. The conventional Jülich cell requires a cell voltage above 1.25 V under similar conditions. Under these conditions, the new cell achieves a cell efficiency of 84 %, compared to 73 % for the conventional cell.

However, running high electrolysis currents at temperatures below 750 °C resulted in catastrophic cell failure, visible as large voltage jumps in the I-V curve. In addition, a decreasing OCV value with decreasing temperature indicated damage to the cell before the catastrophic failure. Post-test analysis found a large number of cracks in the electrolyte, nucleating at the fuel electrode / electrolyte interface and running toward the air electrode. We show that the likely cause for this failure is the electrochemical reduction and subsequent chemical expansion of the doped ceria electrolyte layer, necessitating a detailed study of the local mechanical stresses in the cell during operation.
N-Doped Biochar as H2s Adsorbent for the Biogas-Fueled SOFC
Authors: Setiawan Hendrik , Sakamoto Mio , Shiratori Yusuke , Fujisaki Takaya
Published: July 2021

Reliability of biogas-fueled SOFC is tied directly to the purity of biogas used as fuel. Even miniscule amount of H2S can poison the anode material and drastically shorten the operation time of biogas-fueled SOFC. In order to prevent the performance degradation caused by H2S poisoning, the aim of this study is to develop an attractive process to obtain a nitrogen (N)-doped carbon derived from biomass feedstock using the digested liquid as a source of N, which can act as an excellent adsorbent material to reduce the H2S concentration in biogas below sub ppm level.

Rice husk (RH) was pyrolyzed at 500oC for 2 h under O2-free atmosphere to produce biochar (BC). Rice husk biochar (RH-BC) was then treated with ammonia gas (25% NH3) at 500 or 900°C for 2 h (Intense N-doping) to have N-doped RH-BC (RH-BC(N500-120) and RH-BC(N900-120)). 10% NH3 solution was prepared to simulate the concentrated ammonia solution obtained from the digested liquid discharged from the methane fermentation reactor. The 10% NH3 solution was heated at 30oC through which 100 mL min-1 N2 was passed to obtain the vaporized NH3. RH-BC was treated with the NH3 vapor at 850°C for 90 or 270 min (Mild N-doping) to have N-doped RH-BC (RH-BC(EN850-90) and RH-BC(EN850-270)). Aiming at increasing the total H2S adsorption capacity (ACPH2S
), prior to the mild N-doping, pre-treatment of RH-BC with 15 vol% steam was performed at 850°C for 90 min (RH-BC(S850-90 + EN850-90)).

Specific surface area (SSA) of the porous RH-BC was 146 m2 g-1. By the NH3 treatment of the RH-BC, pyridinic-like N can be doped on the surface contributing to the formation of the oxygen radicals to consume H2S, leading to the enhancement of the ACPH2S
. RH-BC(N900-120) exhibited the highest breakthrough capacity (APCH2S(0)
) of 8.02 mg H2S g-BC-1 and ACPH2S
of 9.58 mg H2S g-BC-1. However, the highest ACPH2S
, 25.6 mg H2S g-BC-1, was obtained for RH-BC(S850-90 + EN850-90), while its APCH2S(0)
was 3.64 mg H2S g-BC-1.

XPS analysis revealed that, during the H2S adsorption, intense N-doping (RH-BC(N900-120)) resulted in the larger amount of sulfate formation on the surface compared to the mild N-doping (RH-BC(S850-90 + EN850-90)). Abundance of oxygen radicals on the surface is preferable for the sulfate formation. This explains the high ACPH2S(0)
of the intensely N-doped sample, RH-BC(N900-120). On the other hand, for the mildly N-doped sample, RH-BC(S850-90 + EN850-90), interaction of the surface with H2S was moderately weakened to avoid the blocking of the micropore openings with sulfate, which enables the H2S molecules to adsorb into the micropores, resulting in the higher ACPH2S
.
Improvement in Power Density of Protonic Ceramic Fuel Cells with Yb Doped BaZrO3 Electrolyte
Authors: Shimada Hiroyuki , Yamaguchi Yuki , Sumi Hirofumi , Nomura Katsuhiro , Shin Woosuck , Mizutani Yasunobu
Published: July 2021

Protonic ceramic fuel cells (PCFCs) have attracted much attention due to potential to achieve ultra-high energy-conversion efficiency. Besides high efficiency, high power density even at lower temperatures is needed to widespread application. We selected Yb doped BaZrO3 as the electrolyte material of our PCFCs and then developed anode-supported PCFCs. The resulting power density of the PCFCs at 600°C reached 0.4 W cm－2.
Defect and Structural Properties of Pr-Doped Strontium Cerate as a Mixed Conductor
Authors: Ostrovskiy Yevgeniy , Huang Yilin , Pellegrinelli Christopher , Hussain Mohammaned , Sakhbodin Mann , Wachsman Eric
Published: July 2021

Proton conducting membranes that are designed for mixed ionic and electronic conductivity are often limited by their low electronic conductivity. Improving the electronic conductivity of these membranes would increase their hydrogen permeation flux. One of the most promising classes of materials for ceramic proton conductors, perovskites, have highly-tunable compositions that allow for the optimization of both ionic and electronic conductivity. Many of these perovskites that act as mixed conductors, such as SrCeO3, are primarily limited by their electronic conductivity, which becomes a bottleneck for overall hydrogen permeation. In this work Pr-doped SrCeO3 was studied over a wide range of oxygen partial pressures (pO2’s) and temperatures to determine its defect properties and conductivity. Under reducing conditions Pr-doped SrCeO3 was found to be chemically and structurally stable, with the optimal doping level being 10%. This composition also shows greater conductivity compared to previous reported Eu-doped SrCeO3. In the low pO2 region, Pr-doped SrCeO3 exhibited primarily n-type behavior as its conductivity dramatically increased in reducing atmosphere, suggesting that the electronic conductivity of SrCeO3 is significantly enhanced by Pr doping. Under high pO2 conditions, Pr-doped SrCeO3 showed a considerable improvement in conductivity in the presence of water, affirming its high protonic conductivity. This validates the use of Pr as a means of enhancing electronic conductivity in perovskites.

Figure 1
Loss of the mitochondrial phosphate carrier SLC25A3 induces remodeling of the cardiac mitochondrial protein acylome
Authors: Peoples Jessica N. , Ghazal Nasab , Duong Duc M. , Hardin Katherine R. , Manning Janet R. , Seyfried Nicholas T. , Faundez Victor , Kwong Jennifer Q.
Published: July 2021

Mitochondria are recognized as signaling organelles, because under stress, mitochondria can trigger various signaling pathways to coordinate the cell’s response. The specific pathway(s) engaged by mitochondria in response to mitochondrial energy defects in vivo and in high-energy tissues like the heart are not fully understood. Here, we investigated cardiac pathways activated in response to mitochondrial energy dysfunction by studying mice with cardiomyocyte-specific loss of the mitochondrial phosphate carrier (SLC25A3), an established model that develops cardiomyopathy as a result of defective mitochondrial ATP synthesis. Mitochondrial energy dysfunction induced a striking pattern of acylome remodeling, with significantly increased posttranslational acetylation and malonylation. Mass spectrometry-based proteomics further revealed that energy dysfunction-induced remodeling of the acetylome and malonylome preferentially impacts mitochondrial proteins. Acetylation and malonylation modified a highly interconnected interactome of mitochondrial proteins, and both modifications were present on the enzyme isocitrate dehydrogenase 2 (IDH2). Intriguingly, IDH2 activity was enhanced in SLC25A3-deleted mitochondria, and further study of IDH2 sites targeted by both acetylation and malonylation revealed that these modifications can have site-specific and distinct functional effects. Finally, we uncovered a novel cross talk between the two modifications, whereby mitochondrial energy dysfunction-induced acetylation of sirtuin 5 (SIRT5), inhibited its function. Because SIRT5 is a mitochondrial deacylase with demalonylase activity, this finding suggests that acetylation can modulate the malonylome. Together, our results position acylations as an arm of the mitochondrial response to energy dysfunction and suggest a mechanism by which focal disruption to the energy production machinery can have an expanded impact on global mitochondrial function.
Evidence for reprogramming of monocytes into reparative alveolar macrophages in vivo by targeting PDE4b
Authors: Rochford Ian , Joshi Jagdish Chandra , Rayees Sheikh , Anwar Mumtaz , Akhter Md Zahid , Yalagala Lakshmi , Banerjee Somenath , Mehta Dolly
Published: July 2021

Increased lung vascular permeability and neutrophilic inflammation are hallmarks of acute lung injury. Alveolar macrophages (AMϕ), the predominant sentinel cell type in the airspace, die in massive numbers while fending off pathogens. Recent studies indicate that the AMϕ pool is replenished by airspace-recruited monocytes, but the mechanisms instructing the conversion of recruited monocytes into reparative AMϕ remain elusive. Cyclic AMP (cAMP) is a vascular barrier protective and immunosuppressive second messenger in the lung. Here, we subjected mice expressing GFP under the control of the Lysozyme-M promoter (LysM-GFP mice) to the LPS model of rapidly resolving lung injury to address the impact of mechanisms determining cAMP levels in AMϕ and regulation of mobilization of the reparative AMϕ-pool. RNA-seq analysis of flow-sorted Mϕ identified phosphodiesterase 4b (PDE4b) as the top LPS-responsive cAMP-regulating gene. We observed that PDE4b expression markedly increased at the time of peak injury (4 h) and then decreased to below the basal level during the resolution phase (24 h). Activation of transcription factor NFATc2 was required for the transcription of PDE4b in Mϕ. Inhibition of PDE4 activity at the time of peak injury, using intratracheal rolipram, increased cAMP levels, augmented the reparative AMϕ pool, and resolved lung injury. This response was not seen following conditional depletion of monocytes, thus establishing airspace-recruited PDE4b-sensitive monocytes as the source of reparative AMϕ. Interestingly, adoptive transfer of rolipram-educated AMϕ into injured mice resolved lung edema. We propose suppression of PDE4b as an effective approach to promote reparative AMϕ generation from monocytes for lung repair.
Deep Learning-Based CT Image Characteristics and Postoperative Anal Function Restoration for Patients with Complex Anal Fistula
Authors: Han Lingling , Chen Yue , Cheng Weidong , Bai He , Wang Jian , Yu Miaozhi
Published: July 2021

Objective. This study aimed to optimize the CT images of anal fistula patients using a convolutional neural network (CNN) algorithm to investigate the anal function recovery. Methods. 57 patients with complex anal fistulas admitted to our hospital from January 2020 to February 2021 were selected as research subjects. Of them, CT images of 34 cases were processed using the deep learning neural network, defined as the experimental group, and the remaining unprocessed 23 cases were in the control group. Whether to process CT images depended on the patient’s own wish. The imaging results were compared with the results observed during the surgery. Results. It was found that, in the experimental group, the images were clearer, with DSC = 0.89, precision = 0.98, and recall = 0.87, indicating that the processing effects were good; that the CT imaging results in the experimental group were more consistent with those observed during the surgery, and the difference was notable (

P
<
0.05

). Furthermore, the experimental group had lower RP (mmHg), AMCP (mmHg) scores, and postoperative recurrence rate, with notable differences noted (

P
<
0.05

). Conclusion. CT images processed by deep learning are clearer, leading to higher accuracy of preoperative diagnosis, which is suggested in clinics.