bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hexis and the SOFC System Galileo 1000 N: Experiences from Lab and Field Testing
Authors: Mai Andreas , Schuler J. Andreas , Fleischhauer Felix , Nerlich Volker , Schuler Alexander 
Published: February 2020

Hexis is developing and manufacturing SOFC-based micro-CHP systems for single-family or small multi-family houses. The current system Galileo 1000 N has an output of 1 kW electrical power. It furthermore covers the full heat demand of a standard single family house. More than 250 Galileo 1000 N systems have been installed up to now and are operated at customer's sites and in the lab.
The newest achievements in the field test and in the lab on durability and cyclability of SOFC stacks and complete micro-CHP systems are reported. Achievements are total system efficiencies of 95% (LHV) and electrical efficiencies of 35% (AC net, LHV). In tests with steam reforming, electrical efficiencies of more than 55 % (DC) have been shown on short-stack level. The longest system test had been running for more than 40 000 h. More recently, power degradation rates of approx. 0.5% per 1 000 h over more than 20 000 hours on short-stack level and over more than 12 000 h on full-system level have been demonstrated which were also confirmed in field tests. Cycling tests have shown a tolerance against 100 complete redox-cycles on short-stack level and 50 on-off cycles on system level. Summarized, stack lifetimes of 7 to 8 years are considered to be realistic. All-in-all, the technical market readiness has been achieved with the Galileo 1000 N. Consequently, an introduction into pilot-markets in Europe was started in autumn 2013.
Li/Na Modified Ni-SDC Anode for Methane-Fueled Solid Oxide Fuel Cells
Authors: Liu Lilu , Yang Qi , Yang Wei , Qi Xingguo , Sun Chunwen , Chen Liquan 
Published: February 2020

Solid oxide fuel cells (SOFCs) have the potential to direct use hydrocarbon fuels without pretreatment due to its high operating temperature [1]. The most common used nickel/yttria-stabilized zirconia (Ni/YSZ) anodes have showed excellent performance in H2 fuel, however, there is serious carbon deposition when hydrocarbon fuels are used. In recent years, great efforts have been devoted to develop alternative anodes to alleviate carbon deposition issue encountered in Ni-based cermets anode. However, the performance of the proposed alternative anode materials is still not satisfactory yet when hydrocarbon fuels are used. Alkali or alkaline earth oxides have been used to enhance the activity of catalysts for reforming [2] and water-gas shift reactions [3]. In this work, a facile chemically lithium/sodium insertion method has been developed to prepare Li/Na doped-NiO composites (Li/Na-NiO). The single cells were fabricated with a Li/Na doped NiO-Ce0.8Sm0.2O1.9 (SDC) composite anode screened on a 250um La0.9Sr0.1Ga0.8Mg0.2O3-
d
(LSGM) electrolyte and a composite cathode consisting of Sr0.95Ce0.05CoO3-
d and SDC (30wt%). When CH4 was used as fuel, the peak power density of the cells with the Li and Na doped NiO anode reaches about 126 mW cm-2 and 106mW cm-2 at 800oC, respectively. Compared with that of the cell with the pristine NiO-SDC anode, the cells with Li/Na doped NiO anode material shows that it gives much higher open circuit voltage (OCV) and better long-term stability at 800oC than that of the cell with the pristine Ni-based anode. The preliminary results demonstrate that the Li/Na doped NiO anode materials are promising alternative anode for hydrocarbon-fueled solid oxide fuel cells.
Micro-SOFC with High Performance and Fast Thermal-Cycling Ability
Authors: Kim Kun Joong , Park Byung Hyun , Kim Sun Jae , Bae Hongyeul , Choi Gyeong Man 
Published: February 2020

Due to a limited energy density of Li-ion batteries, miniaturized solid-oxide fuel cells (micro-SOFCs) have received growing attention for use in portable devices or vehicles. Conventional design has adopted a freestanding membrane supported by Si substate and used pure metal electrode which has shown poor thermomechanical-stability. Recently we have developed a new design of micro-SOFC consisting of robust metal support and ceramic-based electrode. Porous stainless-steel (STS) is used as a substrate to support a thin-film membrane electrode assembly (MEA) to achieve thermally-robust cell. A composite of nano-porous (La,Sr)(Ti,Ni)O3 conductor and electrolyte is applied as a contact layer between the macro-porous STS and the thin-film MEA. Excellent performance and thermal cycling ability at or below 550oC for this novel cell are shown and will be further discussed.
Prediction of SOFC Performance with or without Experiments: A Study on Minimum Requirements for Experimental Data
Authors: Yang Tao , Sezer Hayri , Celik Ismail Bektas , Finklea Harry O. , Gerdes Kirk 
Published: February 2020

A comprehensive analysis of solid oxide fuel cells (SOFCs) should consider polarization curve and impedance behavior simultaneously, as well as the cell performances at different air/fuel utilization cases and operating conditions. In the present study, a physics based protocol, combining experiments and multi-physics numerical simulations, is developed for overall analysis of SOFCs operational diagnostics and performance predictions. In this protocol, essential information for the fuel cell is extracted first by utilizing empirical polarization analysis in conjunction with experiments and refined by multi-physics numerical simulations via simultaneous analysis and calibration of polarization curve and impedance behavior. The performance at different utilization cases and operating currents is also predicted to confirm the accuracy of the proposed model. Furthermore, we also propose the requirements to determine the cell properties and model parameters with less uncertainty. It is demonstrated that, with the present electrochemical model, three air/fuel flow conditions are needed to produce a set of complete data for better understanding of the processes occurring within SOFCs. The detailed calibration procedure and performance prediction at different conditions of button cells are presented. It is also demonstrated that the methodology can be used to assess performance of planar cell without further calibration. The proposed methodology would accelerate the calibration process and improve the efficiency of design and diagnostics analysis.
Reversible Oxygen-Ion Storage for Solid Oxide Cells
Authors: Berger Cornelius M. , Hospach Andreas , Menzler Norbert H. , Guillon Olivier , Bram Martin 
Published: February 2020

In a rechargeable oxide battery (ROB) a solid oxide cell (SOC) is combined with a component that acts as storage for oxygen ions. The cell is operated at 800°C in turns as fuel cell and as electrolyser. Yet, there is no need for the delivery of fuel because of the integrated iron oxide base storage component. This material regulates the oxygen partial pressure at the fuel electrode in a range of approximately 10-21-10-18 bar, which at 800°C corresponds to water vapor to hydrogen ratios between 1:4 and 4:1.
However, repeated charging (electrolysis) and discharging (fuel cell mode) can result in coarsening of particles and external layer formation. Both effects are not desired because they decrease the overall surface and thus the reaction kinetics. Adding secondary oxides to the Fe2O3 base material can mitigate those degradation phenomena. In the present study the effect of additions of Al2O3, CeO2, Mn3O4, Cr2O3, TiO2, SiO2, and MgO to the Fe2O3 base on the degradation properties is analysed. To this end, compacted samples are repeatedly oxidised and reduced in a laboratory furnace, where the conditions present in the ROB are simulated. Using X-ray diffraction and scanning electron microscopy it was found that among the tested oxides only MgO and Al2O3 could mitigate the layer formation and the particle coarsening to some extent.
9000 Hours Operation of a 25 Solid Oxide Cells Stack in Steam Electrolysis Mode
Authors: Corre Gaël , Brisse Annabelle 
Published: February 2020

Hydrogen production through water electrolysis is one of the key processes required in the conversion of electricity to fuels. Carbon free hydrogen produced through water electrolysis can be used as a fuel for hydrogen powered applications (such as fuel cell cars) or grid injection, or as a reactant in downstream processes to produce synthetic fuels such as SNG or methanol. Among available technologies, high temperature electrolysis potentially offers significantly higher electrical to chemical conversion efficiencies compared to alkaline and PEM electrolysers, with values in excess of 100% achievable if additional thermal energy is supplied to the system. High temperature electrolysers are essentially solid oxide fuel cells operated in reverse. Hence, the development of solid oxide electrolysers (SOE) has hugely benefited from the intensive research carried out for the development of Solid Oxide Fuel Cells (SOFCs) in the past decades. A 25 cells stack manufactured by Topsoe Fuel Cells has been tested at EIFER in high temperature electrolysis mode at about 750°C and current densities of 0.57 and 0.72 A/cm2. The applied steam conversion rate was 50%, with a 90 % absolute humidity gas feed.
The total duration of the test was almost 9100 hours, split between 8300 current hours and 800 standby hours induced by incidents that occurred during the test. Incidents included losses of the steam and current supplies. After each incident, the stack performance was recovered, indicating a good robustness of the stack towards unexpected and potentially damaging conditions. The main issue during the test has been the considerable increase of the voltage drop between the positive end plate and the bottom stack repeat unit (SRU), before a sharp improvement occurred after about 2000 hours of operation, which has influenced the stack temperature distribution and in turn individual SRU degradation. The maximum observed voltage drop culminated at 2.73 V, before stabilising around 0.6V.
The stack has shown an overall voltage degradation of 2% per thousand hours, as can be seen on Figure 1. The corresponding voltage losses were 613 mV and 678 mV per thousand hours, for 0.57 and 0.72 A/cm2 current densities, respectively. This in turn corresponds to an average degradation in the range 0.24 – 0.27 mV per thousand hours per SRU.
Moreover, the stack temperature has been adjusted on a few occasion during the test, which highlighted the possibility of using the wide operating temperature range of the solid oxide technology to counter balance the stack degradation and increase the lifetime. Indeed, allowing the stack to increase at a rate of 3°C per thousand hours produced a reduced degradation rate of 1.80 % per thousand hours.

Figure 1
A Study of 8YSZ/GDC Bi-Layered Electrolyte: The Effect of 2 Mol% Fe2O3 Dopant on Sintering and Conductivity
Authors: Mehranjani Alireza Soleimany , Cumming Denis J , Call Ann V , Elder Rachael H 
Published: February 2020

The primary requirements for an electrolyte material in a Solid Oxide Cell (SOC) is the ability to provide a sufficiently high level of oxide ion conduction while preventing both the mixing of reactant gas species and leakage of current through the electrolyte. Commonly, 8 mol% Yttria-stabilised Zirconia (8YSZ) or Gd0.1Ce0.9O1.95 (GDC) are used in high performance cells. Whilst GDC has higher oxide ion conductivity than YSZ, it suffers from electronic conduction due to the partial reduction of Ce4+ to Ce3+ during operation which is detrimental to cell performance. In this work we present the use of a bi-layer 8YSZ/GDC electrolyte as an effective solution to avoid ceria reduction in a fuel (reducing) environment, thereby preventing current leakage across the electrolyte, while maintaining high oxide ion conduction. Electrolytes were produced via tape-casting, a low-cost, mass-production technique. A transition metal oxide sintering aid of 2 mol% Fe2O3 was used to reduce the sintering temperature while also mitigating the formation of a low conductivity interlayer. This study aims to determine the role of Fe2O3 during the sintering process and its subsequent influence on microstructure and the total conductivity of the bi-layer electrolyte.
Grain Size Effect on Conductivity of LSGM Thin Film Electrolyte for Solid Oxide Fuel Cell
Authors: Endo Yoichi , Dempoh Akishi , Terai Takayuki , Suzuki Akihiro 
Published: February 2020

Solid oxide fuel cell (SOFC) consisting of ion conductive ceramics has various advantages such as the high generating efficiency, the utilization of hydrocarbon-containing fuel and the non-necessity of expensive rare metal catalyst. Sr and Mg dopoed Lanthunum Gallate (La0.9Sr0.1Ga0.8Mg0.2O3-δ, LSGM) is a well-known electrolyte for solid oxide fuel cell because of the high conductivity.
It is said that thin film material can exhibit different characterization from bulk material. In our former study, we tried to reveal the mechanism of the conductivity change of LSGM thin film from the bulk. The LSGM thin films with different thickness deposited on sapphire substrate by radio frequency magnetron sputtering was studied. The grains in the thicker film were larger than those in the thinner film. The thicker the film was, the conductivity increased and the activation energy decreased. We suggested this was caused by the smaller bulk resistivity than the grain boundary resistivity. It is necessary to develop the method to separate the resistivity into the bulk resistivity and the grain boundary resistivity to confirm this hypothesis.
In this study, the radio frequency magnetron sputtering was used for obtaining LSGM films on LaSrGaO4 single crystal substrate. To crystallize and control the grain size in the LSGM film, we conducted post-annealing under various temperature. We evaluated the grain size in the LSGM film with a scanning electron microscope and measured the conductivity by electrochemical impedance spectroscopy. We try to separate the resistivity into the bulk resistivity and the grain boundary resistivity by using an equivalent circuit based on Brick-Layer model. In this paper, we report the grain size effect on the electrical conductivity in LSGM thin film.
High Ionic Conductivity in Composite Materials Under H2/Air Fuel Cell Condition
Authors: Lan Rong , Tao Shanwen 
Published: February 2020

New ionic conducting electrolyte materials for solid oxide fuel cells (SOFCs), particularly intermediate temperature fuel cells have been attracting the interests of researchers in energy materials. The typical electrolytes used for SOFCs are normally single phase oxides. Here we report a series of conductive composites with high ionic conductivity derived from an electronic conductor such as a-LiFeO2 and an insulator such as g-LiAlO2. High conductivity was observed in the composites when prepared by a solid state reaction method. These composites also exhibit O2- or/and H+ ionic conduction which was confirmed through H2/air fuel cell measurements. An exceptionally high conductivity of 0.50 S/cm at 650 °C was observed under H2/air fuel cell condition. This provides a new approach to discover novel ionic conductors in composite materials.
References:
[1] C. C. Liang, Journal of the Electrochemical Society, 120 (1973) 1289
[2] J. Maier, Nature Materials, 4 (2005) 805.
[3] S.W. Tao and J.T.S. Irvine, Advanced Materials, 18 (2006) 1581.
[4] R. Lan and S.W. Tao, Advanced Energy Materials, 4 (2014) 1301683.
Microstructural Characterization of SrZrO3 Formation and the Influence to SOFC Performance
Authors: Kanae Shu , Toyofuku Yasuhiro , Kawabata Tsutomu , Inoue Yuko , Daio Takeshi , Matsuda Junko , Chou Jyh-Tyng , Shiratori Yusuke , Taniguchi Shunsuke , Sasaki Kazunari 
Published: February 2020

One of the major phenomena to shorten SOFC durability is the formation of insulated phases, such as SrZrO3, between the cathode and the electrolyte. It is known that SrZrO3 is formed and grown during sintering processes as well as during long-term operation. A systematical study is therefore desired to clarify the SrZrO3formation mechanisms and their influence on electrochemical properties.
In this study, four parameters are considered and systematically varied: sintering temperatures of cathode, electrolyte, and buffer layer, and buffer layer thickness. The cells tested consist of yttria stabilized zirconia (YSZ) as the electrolyte, Ni- yttria stabilized zirconia (Ni-YSZ) as the anode, La(Sr)Co(Fe)O3（LSCF）as the cathode, and Ce0.9Gd0.1O2 (GDC) as the buffer layer. The GDC layer was sintered at 1300oC with 5μm in thickness, while the YSZ electrolyte was sintered at 1400oC. Cathode sintering temperature was varied from (1) 1000oC to (2) 1100oC and (3) 1200oC. The electrochemical performance of the cells was tested at 800oC, 0.2A/cm2 for 100h by feeding humidified fuel: H2 (97 cc/min) and H2O (3 cc/min). Microstructure of the three types of model cells after sintering and testing for 100h was observed in details by FE-SEM (Field Emission Scanning Electron Microscope) and STEM (Scanning Transmission Electron Microscope).
Microstructural observation has been revealed (1) no SrZrO3 formation during sintering LSCF at 1000oC, and (2) a partial formation of SrZrO3 between the cathode and the electrolyte after sintering LSCF at 1100oC. (3) After the sintering of the LSCF cathode at 1200oC, the interface was fully covered by the SrZrO3 layer, clarified by the microstructural observation with EDX elementary mapping. Such SrZrO3 formation led to a decrease in electrochemical performance. These results indicate the importance of the SrZrO3 formation controlling the SOFC performance.
A Case Study Analysis of System Efficiency, Viability and Energy Values of SOFC Based Fuel Cell Micro-CHP for Office Buildings
Authors: Tesfai Alem Teklebrhan , Mylona Anastasia , Connor Paul , Cassidy Mark , Irvine John T. S. 
Published: February 2020

A case study analysis of economical and energy values of SOFC based fuel cell micro-CHP for residential homes.

Dr Alem Tesfai, Dr Anastasia Mylona and Professor John T S Irvine
KTP Associate Chartered Institution of Building Services Engineers222 Balham High RoadLondonSW12 9BS Tel: +44 (0) 20 8772 3699 at61@st-andrews.ac.uk, ATesfai@cibse.org

Abstract

This work presents the experimental and CFD model analysis of a 1.5 kW prototype SOFC micro-CHP system. The potential application of Fuel cell micro-CHP in a typical office building is investigated experimentally. With the current fuel cell technology the use of such systems in office buildings has the potential to be more efficient and reliable than in a single family home. This study documents the economic and energy related values of the fuel cell micro-CHP. This study will also look at how to optimise the operating conditions of the system in different climate conditions i.e. during the winter, autumn and the summer. To optimise and compere the experimental data a typical single family apartment heated by radiators will be analysed using a three-dimensional CFD model. Different heat transfer coefficients for the outer wall, the window and for the doors were considered. The seasonal heat requirements were also considered and heat recovery of the fuel cell micro CHP system was optimised. Different options i.e. whether to use the hot water supplied by the fuel cell micro CHP for domestic appliances or for space heating possibly by adding a combination boiler as a booster was also considered.
Synthesis, Characterization and Performance of Calcium and Samarium Co- doped Ceria Electrolytes for Low and Intermediate Temperature Solid Oxide Fuel Cells
Authors: Pandey Dyuti , Basu Suddhasatwa 
Published: February 2020

Three different compositions of samarium and calcium co-doped ceria were synthesized by cation- complexation process. The calcium content in co-doped Ce0.8Sm0.2-xCaxO2-δ varied from x=0.5 to 0.15. The effects of variation in calcium content on phase, crystallite size and morphology of the synthesized powders were investigated by XRD, SEM and TEM analyses. All synthesized powders were fluorite-type ceria nano-solutions. The particle size of Ce0.8Sm0.15Ca0.05O2-δ was around 10-17 nm as shown in fig.1. To evaluate the electrochemical behaviour the synthesized powders were die-pressed into pellets and sintered at 1450 °C for 10 hours. At 550°C, out of the three synthesized compositions, Ce0.8Sm0.15Ca0.05O2-δ showed the highest conductivity (0.013 S/cm). Anode-supported SOFCs with LSCF/Ce0.8Sm0.2-xCaxO2- δ /NiO-Ce0.8Sm0.2-xCaxO2-δ have been fabricated and tested for the purpose of investigating their potential use in low and intermediate temperature SOFCs.

Key words: Co-doped Ceria, SOFC.

References

[1] M. Sebastian, M. Gazda, P. Jasinski, J. Rare Earths., 2009, 27(4), 655-660.
[2] M. Dudek, J. Eur. Ceram. Soc., 2008, 28, 965-971.
[3] S. Banerjee, P.S. Devi, D. Topwal, S. Mandal, K. Menon, Adv. Funct. Mater., 2007, 17, 2847-2854.

Key words: Co-doped Ceria, SOFC.

Figure 1
Assessment of Possibilities for Operation of Ni-Catalyst Partial Oxidation Reformers in SOFC Systems after Soot Formation
Authors: Baskakov Albert Pavlovich , Plotnikov Nikita , Wang W. , Peng J. , Volkova Yulia , Dong Z , Lu X , Luo Q 
Published: February 2020

Solid oxide fuel cells (SOFCs) allow us to directly convert the chemical energy of fuel into electricity. With their emissions consisting mainly of Н2О and СО2, SOFC-based power generation systems are highly efficient (with efficiency up to 70%) and environmental friendly, which makes them increasingly attractive for the use in stationary power generation systems. The mixture of CO and H2(synthesis gas) supplied to the SOFC anode can be produced from the natural gas using the dry or steam reforming or partial oxidation methods. The partial oxidation of methane, that is typically done with Ni catalysts, seems the best option for start-up systems of power plants with the anode gas recirculation or other applications where no water supply can be possibly organized. In this case, carbon deposition on the parts of reformer can be a problem, particularly, where the air-gas mixture supply system works abnormally.
The simple method of calculation of thermodynamically equilibrium composition of partial fuel oxidation products was used to calculate the degree of air consumption in a reformer which permits to avoid soot formation. The value ensuring auto thermal process in CPOX reformer was determined. Air flow rate used in reaction with synthesis gas and for cooling the reformer, was calculated also.
An experiment is carried out to simulate the abnormal operation of the CPOX reformer with further soot formation on the Ni-catalyst and its walls. The results show that even in the event of the abnormal operation and carbon deposition in it, the CPOX reformer can continue working. Specifically, the carbon gasification takes place. The CO-content of the synthesis gas in this case is twice as much, on the average; however, this is not of critical character for SOFC systems.