bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development and Evaluation of 3-Layer Metal Supported Solid Oxide Fuel Cell Short Stack
Authors: Jang Young-hoon , Lee Sanghun , Shin Hoyong , Bae Joongmyeon 
Published: February 2020

A solid oxide fuel cell (SOFC) is promising technology because of its high electrical efficiency and environmental performance. SOFC can utilize solid ceramic electrolyte, so it can avoid the problems like corrosion, leakage and electrolyte management that often occur in liquid electrolyte. However, these ceramic based SOFC has weakness in external impacts because of its brittleness and relatively low strength. For this problem, metal-supported SOFC has been suggested. Metal supported SOFC refers to SOFC which replace its ceramic support to metal support for enhancing mechanical strength. Metal-support SOFC includes higher mechanical strength, better resistance to vibrates and impacts than conventional SOFC. So, metal-supported SOFC can be applied to movable applications like automobile, train and ship as well as stationary power generation system.
In this study, 3-layer metal-supported SOFC short stack was designed and developed for APU (Auxiliary Power Unit) application. The short stack was composed of metal-supported cells, interconnect plates, ceramic sealant, gasket and metal foams. The metal-supported SOFC cell was fabricated by sinter-joining method and dimension of metal-supported SOFC cell was 120 x 80 mm2 and active cathode area was 110 x 70 mm2. For the material of interconnect plates and metal supports, Crofer 22 APU alloy was used which has high resistance to oxidation, low rate of chrome vaporization and good electrical conductivity of its oxide layer. Also, hybrid sealing system of ceramic sealant and sealing gasket were applied for gas tightness.
Electrochemical performance of the short stack was evaluated in 800 ℃. The I-V-P characteristics was measured in 1 L/min of hydrogen and 5 L/min of air. Open circuit voltage (OCV) of the short stack was 3.0 V and it showed stable value. The maximum electrical power of the short stack was 23.1 W. In I-V curve, it seems to nearly linear shape which means ohmic resistance governs overpotential of the short stack. This ohmic resistance may originated in current collection from electrodes and it will be further analyzed. Moreover, the short stack was operated for 120 hours in galvanostatic mode with 2.16 A of discharge current. In the beginning, the operation voltage of the short stack was 2 V and there was no rapid initial degradation. Over time, voltage of the short stack was slightly decreased. After 120 hours, voltage of the short stack was 1.81 V and its degradation rate was 9.5 % per 120 hours. This seems to be due to chrome poisoning of cathode and this problem also will be further analyzed.

Figure 1
Study on the Fabrication and Performance of Very Low Pressure Plasma Sprayed Porous Metal Supported Solid Oxide Fuel Cell
Authors: Gao Jiu-Tao , Wang Yue-Peng , Li Cheng-Xin , Zhang Shan-Lin , Yang Guan-Jun , Li Chang-Jiu 
Published: February 2020

Solid oxide fuel cell (SOFC) is a high efficiency clean device that directly converts chemical energy of the fuel gas into electric energy. The long-term degradation and stability are the main problems at high temperature, so how to reduce the working temperature becomes a hotspot of research. It is an important way to reduce the thickness of electrolyte. Therefore, how to produce dense and thin electrolyte films economically becomes particularly important. It has been reported that a uniform and dense coating is hopefully prepared by using very low pressure plasma spraying (VLPPS) technology. Due to low operating pressure (~100 Pa), the plasma plume length elongates and its diameter enlarges. Under this condition, the particles can been heated for more time, and it is helpful to form dense coatings. The current study focuses on this technology for application in porous metal supported solid oxide fuel cell (MS-SOFC), especially for preparation in electrolyte. Using SEM, it was found that the densification of the electrolyte was very well, and this could be confirmed by the open-circuit voltage (OCV) of the cell. In the temperature range of 550~750 ℃, the OCV of the cell fairly stabilized between 1.05 V and 1.1 V. The cell was also analyzed by using electrochemical impedance spectroscopy (EIS). The maximum power density of the cell could be up to more than 1200 mW/cm2 at 750 ℃. The long-term stability of the cell was also preliminarily explored, and the result has shown that it is a very promising method for application in MS-SOFC.
A Comparative Study on the Densification Behavior of Yttria-Stabilized Zirconia Electrolyte Powders
Authors: Panthi Dhruba , Hedayat Nader , Du Yanhai 
Published: February 2020

Solid oxide fuel cell (SOFC) electrolytes are usually co-sintered with one of the electrodes (support component) at temperatures ≥1400 °C to get a fully densified microstructure. Lowering this temperature to 1200–1300 °C offers several advantages such as prevention of microstructure coarsening of the electrode and undesirable reactions between the electrolyte and electrode materials, lower sintering cost, and shorter production cycle time. To lower the electrolyte sintering temperature, a thorough understanding of the densification behavior of the electrolyte materials is important. In the current work, we compared the densification behavior of three different types of 8 mol% yttria-stabilized zirconia (YSZ) electrolyte powders: (i) TZ-8Y from Tosoh (Japan), (ii) MELox 8Y from MEL Chemicals (UK), and (iii) YSZ-HT from Huatsing Power (China). The YSZ powders were pressed to form disc-shaped pellets that were sintered at different temperatures ranging 1200–1400 °C. The density and linear shrinkage of the sintered pellets were measured. Among the three YSZ powders, MELox 8Y showed the best densification behavior at lower sintering temperatures with 93 and 96% of the theoretical density at 1250 and 1300 °C, respectively. Although YSZ-HT showed higher sintering rate than TZ-8Y, a sintering temperature of 1350 °C was required for both the powders to reach a theoretical density ≥95%. Our results indicate that different factors besides the particle size play a significant role in determining the sintering rate and densification behavior of the YSZ electrolyte. These factors possibly include the powder synthesis method, post-processing of the powder (such as spray drying), and so on.

Figure 1
Development and Test of a Solid Oxide Fuel Cell Subsystem with a Low Temperature Anode Off-Gas Recirculation
Authors: Peters Roland , Engelbracht Maximilian , Tiedemann Wilfried , Hoven Ingo , Deja Robert , Nguyen Van Nhu , Blum Ludger , Stolten Detlef 
Published: February 2020

Solid oxide fuel cell systems with an anode off-gas recirculation have the potential for high electrical efficiency. The anode off-gas recirculation within an SOFC system has two significant advantages. Firstly, a part of the unused fuel at the stack outlet is returned to the stack inlet, where it can again participate in the electrochemical reaction. Therefore, the amount of fresh fuel fed into the system can be reduced. This increases the system fuel utilization and leads to a significant increase in efficiency. Secondly, the recirculated electrochemically produced steam can be used for the steam reforming process. Thus, during operation an external steam supply is no longer necessary. A challenge is the high anode off-gas temperature of at least 700°C, which prohibits the use of commercially available blower units.
At Forschungszentrum Jülich GmbH an SOFC subsystem with an anode off-gas recirculation loop was developed and tested using methane as the fuel. The off-gas recirculation loop consists of two heat exchangers in combination with a low temperature blower, which operates at temperatures up to 200°C. With this setup, tests were carried out to study the influence of e.g. recirculation rate and fuel utilization on the system operation behavior and performance. During the tests the system fuel utilization was driven up to 93%. The test results indicate that changes in recirculation rate affect the cell voltage, the amount of excess air for cooling and the electrical efficiency. At constant current density high recirculation rates decrease the cell voltage, but also the amount of excess air. Therefore, high electrical efficiency could be achieved with high system fuel utilization at moderate recirculation rates.
Highly Effective Catalysts Supported on Metal Foams for Reforming Hydrocarbons for SOFCs
Authors: Snytnikov Pavel , Potemkin Dmitry , Hutton Phillip , Bosch Russell , Simonov Pavel , Sobyanin Vladimir 
Published: February 2020

The development of highly efficient modular power generation units is of great importance. Solid oxide fuel cells (SOFC) are currently considered as the most efficient devices for the conversion of hydrocarbons, (natural gas, LPG, JP or diesel) into electric power. To provide stable SOFC operation, initial fuel, before feeding to the SOFC anode, should be converted to synthesis gas with high hydrogen content. Catalytic steam, combined steam-dry, partial oxidation or autothermal reforming are the most appropriate reactions for this purpose. The optimum temperature for these reactions is 550 − 900 °C, which falls within the SOFC working temperature range. The development of a catalyst system that can act as a combined catalytic reformer and heat exchanger (to remove or supply heat at the reaction zone) is very promising for efficient power generation. The combined catalytic reformer and heat exchange catalyst should have the following characteristics:

high intrinsic activity with respect to its weight and volume (due to size limitations of the reformer);

coking resistance;

high intrinsic heat conductivity (in order to provide uniform temperature and reaction rate distribution across the reformer);

low pressure drop.
The present report summarizes the results obtained during a systematic study of several new nickel- and rhodium- based catalyst compositions supported on metal foams, their performance, and fundamental principles of the above mentioned reactions for conversion of various common hydrocarbon fuels.
A procedure for deposition of active catalyst components onto metal foams has been developed. It was systematically verified on Ni, Ni-Fe, FeCrAlY-steel foams with porosity from 10 to 70 pores per inch (ppi), obtained from various manufacturers. The catalytic performance of the coated metal foam substrates was studied in a fixed-bed continuous flow reactor. Total feed flow rate (GHSV − gas hourly space velocity) ranged from 3,000 to 30,000 hr-1. The reaction temperature varied from 500 to 800 °C. The catalysts (as-synthesized and used) were characterized by BET, XRD, XPS, TEM, EDX, SEM, TPR and TPD techniques.
Anodic Performance of La0.5Sr0.5Mn0.9Al0.1O3 Perovskite Oxide for Solid Oxide Fuel Cells Using Dry C3H8 Fuel
Authors: Ishihara Tatsumi , Bahrain Audi M. K. , Wu Kuan-Ting 
Published: February 2020

Direct utilization of hydrocarbon for Solid Oxide Fuel Cells (SOFCs) using oxide ion conductor have the advantage of cost, high energy conversion efficiency and expanding the application area of SOFC. By eliminating the initial external reforming process of hydrocarbon fuels to syngas, significant advantages in cost and simplicity of gas handling process can be expected. Theoretically, direct utilisation of hydrocarbon for fuel is possible in SOFC using oxide ion conducting electrolyte, however, this is usually not easy when the conventional Ni base metal is used for anode because the formation of carbon is significantly occurred resulting in the deactivation of anode, or in the most serious case, permanent failure of the cell is occurred. Even methane as fuel, thermodynamic calculations predict that carbon will form at 1073 K unless steam is co-fed.
In this study, Co and Al co-doping to La0.5Sr0.5MnO3 (LSM55) for anode were studied and it was found that doping Co is effective for decreasing anodic IR loss and the power density could be much increased by doping Co for Mn site of LSM doped with Al. XRD measurement suggests that Co was substituted Mn site over wide composition range and up to 40 mol%, partial substitution of Co to Mn in LaMnO3 structure was successfully performed. It was found that the maximum power density was increased by doping Co for LSM doped with 10 mol% Al for both H2 and C3H8 fuel. In particular, the smallest IR loss and anodic overpotential were achieved when 20 mol% Co was doped. The maximum power density of the cell using La0.5Sr0.5Mn0.7Al0.1Co0.2O3 was achieved 953 and 246 mW/cm2 for H2 and C3H8 fuel at 1273 and 1173 K, respectively. Increase in power density can be assigned to the increased surface activity to the electrochemical oxidation by doping Co. Although stability of LSM perovskite structure is still insufficient in dry C3H8 atmosphere, doping Al is effective for increasing stability and so co-doping Al and Co to Mn site of LaMnO3 is effective for decreasing anodic overpotential for direct C3H8 type SOFC.
Mixing oxide ion conductor to Co and Al doped LaMnO3 anode was further studied for increasing power density. Among the examined mixed conductor, it was found that mixing Sm doped CeO2 is effective for increasing power density and the MPD of 850 mW/cm2 was achieved at 1173 K on 20 wt% SDC mixed with Co and Al doped LSM anode.
Thermodynamic Stability of La0.6Sr0.4Co0.2Fe0.8O3-
δ in Carbon Dioxide Impurity: A Comprehensive Experimental and Computational Assessment
Authors: Darvish Shadi , Zhong Yu , Gopalan Srikanth 
Published: February 2020

Solid oxide fuel cells (SOFCs) operate on a variety of environments and are exposed to a variety of environmental impurities. One ubiquitous impurity in the cathode gas is carbon dioxide whose concentrations are usually upwards of 400 ppm depending on the source of the air and leaks through pinholes across the electrolyte. In this work we present a comprehensive thermodynamic assessment of the phase equilibria La0.6Sr0.4Co0.2Fe0.8O3-
δ (LSCF) – CO2 – O2 system using a molten salt method and using CALPHAD (Calculation of Phase Diagrams). Detailed thermodynamic maps of LSCF in carbon dioxide environments are provided under operando conditions and compared with available experimental data. We also examine contradictions between experimental data and computation of phase equilibria, and attempt to reconcile them by paying close attention to differences in cell operating conditions. Finally we discuss future directions where the combination of experimental and CALPHAD assessment of the thermodynamics of fuel cell component materials can be used to provide design guidance.
SOC Development at Forschungszentrum Jülich
Authors: Blum Ludger , Fang Qingping , de Haart L.G.J. , Malzbender Jürgen , Margaritis Nikolaos , Menzler Norbert H. , Peters Roland 
Published: February 2020

In order to become a substantial part of the energy supply infrastructure in the course of the German “Energiewende” (energy system transition), SOFC plants in the power range of 100 kW or larger must be realized. Scale up of units will become even more important in the field of electrolysis to balance electricity conversion and consumption. Therefore, currently one of the main goals of SOC development at the Forschungszentrum Jülich is the development of single stacks in the 15 kW power range as a basis for development of larger units. The core structural feature is a planar-type window frame stack-design, which allows the integration of standard-sized cells, e.g., 10 ×10 cm², in a 2 × 2 array. Based on this design, the 15 kW stack will consist of six sub-stacks, each having 20 planes. Initial operational results with such a sub-stack are reported. Aiming towards stationary applications, long term behaviour is of great importance. The 'world-record' short stack is now in operation under load for more than 80,000 hours, showing an average voltage degradation rate of 0.6%/kh, which decreased to less than 0.3%/kh in the last 30,000 hours. Next to long term stability, electrical net efficiency plays an important role. A net efficiency of 57% could be demonstrated with a 5 kW system operated with methane at 93% fuel utilization using low temperature anode off-gas recirculation. For stationary applications, a concept was developed and proven that allows safe system operation without additional forming gas.
In the case of mobile applications such as range extenders or APUs in trucks, the dynamic behaviour is of greater importance. Therefore, the Jülich lightweight cassette design has been advanced with the potential of improved thermomechanical properties using glass sealing instead of metal soldering to integrate the cells into the cassette frame.
Growing emphasis is placed on the development of high temperature electrolysers (SOEC). Currently, a standard two-layer short stack is in operation for more than 18,000 hours in electrolysis mode at a current density of -0.5 A.cm-², showing a voltage degradation of less than 1%/kh. Since in the field of energy storage and electricity production based on renewable energy, the reversible operation of such systems is of great interest, the concept of a 5 kW r(eversible)SOC plant has been devised and is now under construction. A 5 kW stack in a system configuration, representing the fuel cell part of the rSOC system, was operated successfully with a hydrogen utilization of 80%.
Update on Nexceris' SOFC Stack Technology
Authors: Arkenberg Gene , Swartz Scott , Sellers Chad 
Published: February 2020

Over the past several years, Nexceris has been developing solid oxide fuel cell (SOFC) stacks based on its patented FlexCell planar cell design. The FlexCell is an electrolyte-supported planar SOFC cell design based on a thin electrolyte membrane layer that is mechanically supported by a mesh of electrolyte material, this design enables high performance at targeted operating temperature range of 750 to 850°C. The dense cell periphery provides an optimum sealing surface, and thin anode layers in the FlexCell enable high single-pass fuel utilization without sacrificing performance. Nexceris has demonstrated that SOFC stacks built with this technology are capable of providing targeted power outputs with high single-pass fuel utilization (up to 80 percent), and achieving high efficiencies (45 to 50 percent, LHV basis) when operating on reformed hydrocarbon fuels. More recently Nexceris has leveraged these attributes to establish a stack design which also enables exceptionally high gravimetric power density. Another key capability of Nexceris’ stacks is unprecedented performance and stability with sulfur containing fuels, an enabling attribute for SOFC systems operating on military logistic fuels (such as JP-8). Nexceris’ stacks exhibit stable operation with reformate fuels having as much as 50 ppm H2S, with test durations of 500 hours.
Ongoing work is aimed at designing high efficiency SOFC systems based on Nexceris’ high power density and sulfur tolerant stack attributes. This work is supported by utilizing an in-house built process model which can accurately predict stack and system performance over a wide array of operating conditions (starting fuel, reforming conditions, fuel flow rate and utilization, cell area, number of cells, etc.). Nexceris currently is demonstrating its SOFC technology at 1-5 kW scale via in-furnace stack testing, ex-furnace hot box testing, and breadboard system testing. This presentation will provide a status update on Nexceris’ SOFC technology.
Microstructural and Electrochemical Characterisation of Degradation in Nickel Impregnated Scandia-Stabilised Zirconia Electrode during Isothermal Annealing
Authors: Chen Jingyi , Ruiz-Trejo Enrique , Atkinson Alan , Brandon Nigel P. 
Published: February 2020

The impregnation of nickel into porous ceramic scaffolds has been introduced as a promising alternative fabrication technique for solid oxide fuel cell (SOFC) anode as compared to conventional powder mixing [1]. Nevertheless, the stability of impregnated electrodes has not been extensively studied and understood [2]. SOFCs operate at a temperature range from 500 oC to 1000 oC and are expected to have a life time of 40,000 hours [3]. In this study, we examine the degradation of impregnated electrodes in a wet hydrogen atmosphere at a working temperature of SOFCs.
Nickel was impregnated into a porous scandia-stabilised zirconia scaffold through 12 impregnation cycles. The impregnated electrodes contained approximately 40 wt% of nickel. Continuous van der Pauw measurement was carried out when the electrode was aged at 650 oC, 800 oC and 950 oC in an atmosphere with 5 vol% hydrogen and 95 vol% nitrogen, at open circuit. A fall in sheet conductivity was found in the electrode during ageing within 1000 min. The conductivity fall was attributed to nickel microstructural evolution during ageing. Electrochemical impedance spectra were collected at a constant time intervals during isothermal annealing at 650 oC, 800 oC and 950 oC for the impregnated electrode. Four resistance contributions were decoupled by equivalent circuit fitting, i.e. the ohmic resistance, the oxygen transfer resistance and the anodic reaction resistance, and the gas diffusion resistance. The increase in both the ohmic resistance and the polarisation resistances with time revealed the isothermal degradation brought about a diminishing active anode area. A more pronounced decrease in anodic polarisation resistance suggested a reduction in triple phase boundary (TPB) density. Secondary electron images of electrodes before and after ageing showed an increase in nickel particle size and a decrease in the number of particles, providing microstructural evidence of nickel coarsening. Nickel coarsening was identified as the main mechanism of degradation for the electrode in wet hydrogen as it caused a reduction in both TPB sites and percolating nickel paths. Combining time-dependent electrochemical performance with post-mortem electrode microstructure clarifies the physical processes behind the degradation quantified by increasing area specific resistances.
[1] M. Lomberg, E. Ruiz-Trejo, G. Offer, and N. P. Brandon, “Characterization of Ni-infiltrated GDC electrodes for solid oxide cell applications,” J. Electrochem. Soc., vol. 161, no. 9, pp. F899–F905, 2014.
[2] S. P. Jiang, “Nanoscale and nano-structured electrodes of solid oxide fuel cells by infiltration: Advances and challenges,” Int. J. Hydrogen Energy, vol. 37, no. 1, pp. 449–470, Jan. 2012.
[3] H. Tu and U. Stimming, “Advances, aging mechanisms and lifetime in solid-oxide fuel cells,” J. Power Sources, vol. 127, no. 1–2, pp. 284–293, Mar. 2004.