bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of La2NiO4 as Anode Material for Solid Oxide Electrolyser Cells
Authors: Egger Andreas , Schrödl Nina , Sitte Werner 
Published: February 2020

Rising capacities in renewable energy production pose major challenges resulting from the decoupling between supply and demand, which requires long-range distribution and storage of electrical power. Electrolysis of water is considered a promising method for converting, storing and distributing surplus electrical energy in chemical form. Stimulated by the large-scale installation of wind parks, interest in high temperature steam electrolysis as a highly efficient means for hydrogen production is reviving. This technology appears to be especially favourable if external heat sources from power plants or industrial facilities can be utilised to assist in sustaining operating temperatures above 600°C.
High temperature electrolysis is based on solid oxide electrolyser cells (SOEC) which adopt design concepts and materials developed for solid oxide fuel cells (SOFC). In this work the promising SOFC cathode material La2NiO4+δ is investigated with respect to its suitability as anode for SOEC application. Important material properties characterising electrical conductivity and oxygen transport kinetics are determined on densely sintered samples of La2NiO4+δ. In addition, its performance as air electrode is investigated on asymmetric cells under anodic polarisation at current densities of up to -410 mAcm-2 by means of impedance analysis and I-V measurements. Electrochemical characterisation is conducted at 800°C and 0.2 bar oxygen partial pressure and the long-term stability is studied over several thousand hours. Special emphasis is put on the effect of Cr-poisoning on the oxygen exchange kinetics and SOEC anode performance in dry and humid atmospheres. Results from post-test examination of porous electrode structures as well as dense samples of La2NiO4+δ by microstructural analysis with SEM-EDX and AFM are presented.
Effect of Ceria Content of CeScSZ Powder on the Phase Stability and Electrical Conductivity of SOFC Electrolyte
Authors: Choi Seung-Woo , Kim Kyeong-Joon , Kim Min-Young , Lim Jinsub , Yang Seung-Hoon , Kim Yu Sin , Kim Ho-Sung 
Published: February 2020

Solid oxide fuel cell (SOFC) is attracting more attention in recent years for its lower pollution emission and high energy convert efficiency. The SOFC is conventionally operated at high temperatures between 900 and 1000 °C, because of the low ionic conductivity of YSZ below 800 °C. ScSZ-based electrolyte is one of the candidate materials for IT-SOFCs because of their higher ionic conductivities compared to any other zirconia electrolytes. In general, it is reported that 1Ce10ScSZ composition is available as ScSZ-based electrolyte of SOFC [1].
In this paper, CeScSZ powders with ceria-doped content were synthesized by co-precipitation process. The crystal lattice parameter and XRD peak pattern of powders were investigated with the increase of calcination temperature and the change of ceria-doped content at a certain calcination temperature. Ionic conductivities of the CeScSZ powders were also studied at the range of 500 ~ 900 °C. In here, the XRD peaks of cubic structure were found only on the ceria-doped powders more than 1 mole% even at the calcination temperature of 1500 °C. Meanwhile, the behaviour of ionic conductivities showed little different characteristics from the XRD pattern, namely, 1 mole% ceria-doped 10ScSZ powder showed the highest conductivity. Therefore, electrolyte film was fabricated by using the synthesized 1Ce10ScSZ powder and single cell of SOFC with anode-supported electrolyte was fabricated by tape casting and co-sintering process. As a result, the SOFC cell showed power density of 1.2 W/cm2 at 2 A/cm2, 800 °C with low ohmic resistance of under 0.1 W·cm2.

References

[1] Ju Hee Kang, Young Mi Kim, Ho-Sung Kim, Moo Sung Lee, Jae Hyuk Jang, Jin-Hun Jo “Fabrication characteristics of SOFC single cell using nanocrystalline 1Ce10ScSZ electrolyte powder prepared by co-precipitation process,” J. Full Cell and Technology, 2012, Vol 9, pp. 011015.
Degradation of Electrical Conductivity in Lanthanum Silicate Oxyapatite
Authors: Ishiyama Tomohiro , Maruyama Hiraku , Kishimoto Haruo , Bagarinao Katherine Develos- , Horita Teruhisa , Yamaji Katsuhiko , Yamazaki Atsushi 
Published: February 2020

Lanthanum silicate oxyapatite (La9.33+xSi6O26+1.5x) is known to exhibit higher oxygen ionic conductivity than yttria-stabilized zirconia at temperatures below 700oC, making this material attractive for its potential use in intermediate-temperature fuel cells operated at 500~700 oC. Mineshige et. al. reported that the lanthanum content in oxyapatite phase is strongly related to its electrical conductivity, with the highest conductivity obtained when x=0.67 (La10Si6O27) [1]. It was further reported that La2SiO5 existed in addition to the oxyapatite phase even in the as-sintered sample. Another important aspect that can influence electrical conductivity is the phase stability of lanthanum apatite, which remains unclear. In this study, electrical conductivity measurements of lanthanum silicate apatite were conducted for over 100h and its phase stability was evaluated.

Lanthanum silicate apatite with nominal composition of La10Si6O27 was made by conventional solid state reaction. The pellet was sintered at 1700oC for 10h after calcining at 1400oC for 10h. Electrical conductivities were determined by impedance spectroscopy measurements conducted at 600, 800 and 1000oC for 106~201h in dry air. The phase stability was evaluated by annealing at 1500oC for 20h.

The degradation of electrical conductivity was observed at all temperatures. In particular, the conductivity decreased significantly from 5.57x10-2 Scm-1 to 3.57x10-2 Scm-1 after 201h at 1000oC. Crystallites having small facets with the size of several hundred nanometers were observed on the oxyapatite phase after conductivity measurement. On the other hand, significantly larger particles were found segregated on the surface of the sample annealed at 1500oC; these particles have a composition determined to be La2SiO5 by EDS analysis. This result suggests that the same phase segregation could have occurred at the temperature range of 600 ~ 1000oC but at a diminished degree. Moreover, the degradation of electrical conductivity could be correlated to the observed phase segregation. In this presentation, we will discuss the causes of the degradation of electrical conductivity in consideration of the phase equilibrium of lanthanum silicate.
Ref. 1: A. Mineshige, Y. Ohnishi, R. Sakamoto, Y. Daiko, M. Kobune, T. Yazawa, H. Yoshioka, T. Nakao, T. Fukutsuka, Y. Uchimoto, Solid State Ionics 192 (2011) 195.
Improvement of Protonic Ceramic Fuel Cells with Thin Film BCZY Electrolyte
Authors: Okuyama Yuji , Ebihara Noriaki , Okuyama Kenji , Mizutani Yasunobu 
Published: February 2020

Fuel cell performance of protonic ceramic fuel cells (PCFCs) using thin film BaCe0.6Zr0.2Y0.2O3-δ (BCZY622) electrolyte have been studied. First reference cell with La0.8Sr0.2MnO3-δcathode and Ni anode showed poor performance and short-term degradation. Overpotential of anode and Ohmic loss was major limiting factor, and solid solution of Ni into BCZY622 electrolyte has been observed. The electrical conductivity and the proton concentration of BCZY622 and BCZY622 doped with 5wt% NiO were measured by impedance analysis and thermogravimetric analysis. The electrical conductivity and the proton concentration of BCZY622 were decreased by introducing NiO.
To avoid short-term degradation, cell construction, manufacturing process, and firing temperatures were improved. As a result, carefully designed PCFC with thin film BCZY622 showed good power density of 200-300mW/cm2 in wide temperature range at 873 - 1073K , and performed stable generation.
Three-dimensional Modeling of Internal Reforming SOFC with a Focus on the Interconnect Size Effect
Authors: Sun Qiong , Ni Meng 
Published: February 2020

A comprehensive 3D mathematical model is developed for planar solid oxide fuel cells (SOFCs) running on hydrocarbon fuels. The model fully considers the coupled gas transport, ionic conduction, electronic conduction, electrochemical reactions, internal reforming reaction, water gas shift reaction, and heat transfer. The model is validated by comparing the simulation results with literature data. Parametric simulations are conducted to investigate how the size of interconnect rib affect the various physical and chemical processes in the SOFC. It’s found that the interconnect rib greatly influences the gas diffusion in the porous electrode thus influences the electrochemical/chemical reactions. Optimal rib size is observed for internal reforming SOFCs. The results are useful for design of SOFC stack with hydrocarbon fuels.
The Fate of Phosphine in SOFC Fuels
Authors: Finklea Harry O. , Zhang Wei , Jony Mahfuzur , Demirgok Berk 
Published: February 2020

Phosphine (PH3) is present in part-per-million levels of coal syngas, a potential fuel for SOFCs. Previous studies have shown that the SOFC loses power and ultimately fails during prolonged exposure to phosphine in wet and dry fuels. The presence of nickel phosphide phases on the anode suggests that phosphine survives the operating conditions of the SOFC fuel. In this study, a mass spectrometer was used to analyze fuel gases after passing the gases through a heated tube or after passing the fuel gases across the anode of an operating SOFC. Phosphine appears to react with residual oxygen at intermediate temperatures of 400-600ºC in dry (P(H2O) < 1 torr) hydrogen, but does not react above 600ºC and consequently reaches the anode. At higher water pressures (5-20 torr), phosphine reacts at temperatures above 400ºC. Phosphine is detected in the exhaust gas of a SOFC using dry hydrogen while at open circuit, and disappears from the exhaust gas during current flow. The inverse correlation between water content of the exhaust gas and the phosphine concentration suggests that phosphine is reacting with electrochemically generated water. No new compounds containing phosphorus were detected in the m/z range of 45-100, eliminating HPO, HPO2 and HPO3 as possible reaction products. There is evidence for the presence of nonvolatile products of phosphine in the supporting tubes after prolonged exposure to phosphine. These products can generate measurable amounts of phosphine at 800ºC in dry hydrogen initially free of phosphine.
Development of Micro Power Generator Using LPG-Fueled Microtubular Solid Oxide Fuel Cells
Authors: Sumi Hirofumi , Yamaguchi Toshiaki , Suzuki Toshio , Shimada Hiroyuki , Hamamoto Koichi , Fujishiro Yoshinobu 
Published: February 2020

Solid oxide fuel cells (SOFCs) can, in principle, directly use hydrocarbon fuels such as methane and liquefied petroleum gas (LPG). It was previously found that nickel-gadolinia doped ceria (Ni-GDC) anode has high durability under LPG utilization in SOFCs. However, the performance under direct LPG utilization was low compared to hydrogen fuel, because anode polarization resistance increased by internal reforming. Carbon was slightly deposited on the Ni-GDC anode after direct LPG utilization for 100 h at 650 oC. In this work, a catalytic partial oxidation reformer was developed for LPG utilization, and high performance was obtained using reformate gas as well as hydrogen without carbon deposition on the Ni-GDC anode for 100 h at 650 oC. Furthermore, microtubular SOFC stacks were developed using mass production technologies, and a proto-type 200 W micro power generator was demonstrated via NEDO project entitled "Technology Development for Promoting SOFC Commercialization".
Assessment of Pressure Effects on High Temperature Steam Electrolysis Based on Solid Oxide Technology
Authors: Bernadet Lucile , Gousseau Georges , Chatroux André , Laurencin Jérôme , Mauvy Fabrice , Reytier Magali 
Published: February 2020

To manage the grid with renewable electrical sources and ensure their storage, hydrogen chains have to be considered. However, hydrogen must be pressurized before being used or stored. The first levels of compression are less energetic for liquids than for the hydrogen gas, therefore the electrolysis of steam directly under pressure has to be studied. On one hand, with the solid oxide technology, the Open Circuit Voltage (OCV) presents the drawback of increasing with pressure. On the other hand, the pressure might improve the reactive species supply to the electrochemical sites and reduce the related losses. Thus, what are the electrolysis performances under pressure? And is there an energetic gain at the system level to produce pressurized hydrogen?
In this context, experimental and modelling approaches have been adopted in order to understand the basic underlying mechanisms of pressurized electrolysis operation. In this frame, SOEC performance tests were realized under pressure in the range of 1 to 10 bars on two types of single commercial cells. They were based on conventional materials and differentiated by their microstructure. Concerning the set-up, the test platform requirements were achieved by developing an innovative mechanical design associated to a specific steam management. Moreover, a previously proposed electrochemical model of solid oxide electrolysis cell was adapted to take into account the pressure effects. The model allows computing all the most important operation parameters such as local current densities, local molar fraction, overpotentials and also the cell microstructural parameters [1].
According to the complete I-V curves from 0 to -1.3 A/cm2 at 800°C with high steam conversion, it has been observed that OCVs respect the Nernst relation under pressure while the limit current appears at higher current values. This work shows that the hydrogen production can be increased thanks to a 10 bars operation at the autothermal voltage. Moreover, these trends have been analyzed with the model. The impact of pressure on the electrochemical performances is much more important in the range of 1 to 5 bars than above. In our experimental conditions, the diffusion improvement in the porous cathode alone can explain this behavior. Finally, the impact of each microstructural parameter on the cell performances with pressure is discussed.
The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) Fuel Cells and Hydrogen Joint Undertaking (FCH-JU-2013-1) under grant agreement 621173.
[1] J. Laurencin, D. Kane, G. Delette, J. Deseure, F. Lefebvre-Joud, Modelling of solid oxide steam electrolyser : impact of the operating conditions on hydrogen production, 2011, Journal of Power Sources, 196, 2080-2093.

Figure 1
Soft Sensor Design for Estimation of SOFC Stack Temperatures and Oxygen-to-Carbon Ratio
Authors: Dolenc Bostjan , Vrecko Darko , Juricic Dani , Pohjoranta Antti , Kiviaho Jari , Pianese Cesare 
Published: February 2020

The lifespan of a solid oxide fuel cell (SOFC) stack depends on several factors, such as the internal stack temperature and temperature gradients as well as the fuel gas oxygen-to-carbon (O/C) ratio within the stack. An excessively high stack operating temperature generally accelerates degradation processes while large temperature gradients over the stack increase the thermal stress within the stack which may lead to the delamination of repeating unit components. A too low O/C ratio inflicts carbon deposition which quickly leads to stack breakage. Therefore, monitoring these variables is of vital importance. Although measuring temperatures within the stack and measuring the fuel gas composition at the stack inlet is feasible, this raises the overall equipment cost. In this paper a data-driven design of soft sensors for stack minimum and maximum temperatures as well as the O/C ratio at the anode and pre-reformer inlet is presented. For temperature estimation both dynamic and static models are derived and their performance is compared. The dynamic model is identified using subspace identification, which results in a causal state-space model. The non-causal static model assumes that a combination of process variables at the stack inlet and outlet describe its internal condition. The estimation of gas composition at the inlets, which is required for O/C ratio estimation, is based solely on static relationships. The soft sensors are designed in such a way that adding extra inputs yields no further increase in estimate accuracy. The empirical data required for modelling were obtained from a complete SOFC power generation unit. The results show that estimates of all the relevant variables can be accomplished by simple linear regression models.
Keywords: SOFC, soft sensor, O/C estimation, temperature estimation

Figure 1
Ni-based Alloys as Protective Layer for a Conventional Solid Oxide Fuel Cell Fed with Biofuels
Authors: Lo Faro Massimiliano , Trocino Stefano , Campagna Zignani Sabrina , Machado Reis Rafael , Monforte Giuseppe , Ticianelli Edson A. , Aricò Antonino S. 
Published: February 2020

A possible scenario for the future is the utilization of alternative fuels especially those obtained from renewable sources including those derived from biomass. One of the main implications is regarding the consumer’s ability to use an increasingly diverse selection of energy sources. New business models could be especially important in the stationary power sector as fuel cell-based distributed energy systems become an alternative to backup for centrally generated power. Small fuel cells systems, typically less than 10kW, are under consideration for many applications that traditional electric utilities have not supplied widely. In this area, solid oxide fuel cells (SOFCs) may enable new companies to enter the power-generation business as equipment providers or heat and electricity providers. The most common type of SOFC is composed by cells based on yttrium stabilized zirconia (YSZ) as electrolyte Ni-YSZ as anode and La0.8Sr0.2MnO3 (LSM) or La0.6Sr0.4Fe0.8Co0.2 (LSFCO) as cathode operating at temperatures above 700 °C using H2 or syngas (H2+ CO) produced from a reforming process (internal or external).
Bimetallic Ni-based alloys mixed with gadolinium-doped ceria in order to obtain a composite material with mixed electronic-ionic conductivity utilized as a barrier layer in a conventional anode-supported solid oxide fuel cell may represent a practical solution to provide a mitigation of the degradation reactions occurring during the feeding of biofuels.
In this communication, we report few guidelines for the preparation of catalysts having proper behaviour for the utilization as protective layer. Complete physico-chemical characterization and electrochemical investigation of Ni0.5M0.5(M=Cu, Co, Sn, Zn, Fe) will be discussed.

Acknowledgements

The present work was in part carried out within an Agreement between the Italian Ministry of Economic Development (MSE) and National Research Council (CNR) in the framework of a Research Program for the Electric System (sub-activity: Development of materials and components, design, demonstration and optimization of FC systems for co-generative applications) and in part carried out in the framework of the Research Program promoted by the Brazialian “Conselho Nacional de Desenvolvimento Científico e Tecnológico“ entitled “Ciência sem Fronteiras” processo nº 402180/2012-7.
S. C. Zignani wants to thank CNPq for the grant n. 238319/2012-1.
R. M. Reis wants to thank FAPESP for the grant n. 2014/04100-2.
The authors also acknowledge the Italian Ministry of Research and Education for the financial support of the BIOITSOFC project within the program "PROGRAMMI DI RICERCA SCIENTIFICA DI RILEVANTE INTERESSE NAZIONALE- PRIN PROGRAMMA DI RICERCA - Anno 2010-2011 - prot. 2010KHLKFC"
Numerical Simulation of SOFC System Performance at 90% Fuel Utilization with or without Anode Off-Gas Recycle for Enhancing Efficiency
Authors: Tanaka Yohei , Terayama Takeshi , Momma Akihiko , Kato Tohru 
Published: February 2020

To investigate possibility to enhance electrical efficiency, performance of methane-fueled 10 kW SOFC systems was numerically simulated with calculated voltage-current-density curves at 750ºC of a single cell with a bipolar plate, which approximated a stack performance. Operation at 90% fuel utilization (U
f) with anode off-gas recycle (AGR) and with steam reforming (no recycle) led to 75-67%-LHV and 72-66%-LHV DC electrical efficiency at 0.05-0.40 A/cm2, respectively. System simulations considering heat loss from a cell stack clarified that 750ºC stack temperature can be maintained at 0.12-0.40 A/cm2 and 64-58% and 63-59% net AC electrical efficiency will be attainable at U
f = 90% with and without AGR, respectively. Furthermore, enhancement of net AC efficiencies was found to be 11-10 percentage points at those current densities against ones of a Ene-farm-like conventional system using steam reforming at U
f = 73%.
Influence of Ni-YSZ Electrode Thickness on the Behaviour of Commercial Solid Oxide Electrolysis Cells by Mean of Electrochemical Impedance Spectroscopy
Authors: Nechache Aziz , Cassir Michel , Ringuede Armelle 
Published: February 2020

Our world is facing energy needs always growing, the mid-term disappearance of important energy resources such as fossil fuels and global warming issues consecutive to massive greenhouse gas production. A possible answer to produce renewable and clean energy consists in combining promising technologies such as solar photovoltaic, wind turbine and fuel cell, thus making an energy mix. Hydrogen is an energy carrier which can be part of this energy mix. High temperature electrolysis (HTE) using a solid oxide electrolyte is a clean way to produce, from water and electricity, hydrogen. However, many studies showed that the electrochemical phenomena related to the Ni-YSZ electrode have a strong influence on cell performances, including the ones associated to gas transport [1-3]. Further investigations on the hydrogen side of the cell are hence needed. In the following work, two commercial cells with different Ni-YSZ thicknesses are considered. A deep analysis is performed in a two-electrode configuration by mean of electrochemical impedance spectroscopy (EIS) with the use of electrical equivalent circuits (EEC), showing that all the main phenomena governing SOEC functioning are related to the Ni-YSZ electrode for both cells, each one characterized by a specific relaxation frequency and capacitance. Indeed, the impedance diagrams measured were deconvoluted, from the highest to the lowest frequencies, into four arcs: a high frequency arc (HF arc), a first middle frequency arc (MF1 arc), a second middle frequency arc (MF2 arc) and a low frequency arc (LF arc). These arcs were respectively associated to charge transfer at the Ni-YSZ electrode, a first H2O diffusion phenomenon, gas conversion at the Ni-YSZ electrode and a second H2O diffusion phenomenon. Thus, changing Ni-YSZ electrode thickness appears to mainly influence the H2O diffusion phenomenon associated to MF1 arc and the H2O gas conversion related to MF2 arc, while phenomena associated to HF and LF arcs are poorly sensitive to this thickness change. This result suggests that the phenomena associated to MF1 and MF2 arcs occur mainly in the volume of Ni-YSZ electrode, contrary to phenomena related to HF and LF arcs. This in the same time allows distinguishing the two H2O diffusion phenomena identified.
[1] A. Nechache, M. Cassir, A. Ringuedé, J. Power Sources 258 164 (2014).
[2] P. Kim-Lohsoontorn, J. Bae, J. Power Sources, 196, 7161(2011).
[3] PK. Patro PK, T. Delahaye T, E. Bouyer E, PK Sinha, Int. J. Hydrogen Energy, 37, 3865 (2012).