bluuebunny/crossref_metadata_2025_split huggingface dataset:
Research and Development of Ammonia-Fueled SOFC Systems
Authors: Muroyama Hiroki , Srifa Atthapon , Okanishi Takeou , Matsui Toshiaki , Kishimoto Masashi , Saito Motohiro , Iwai Hiroshi , Yoshida Hideo , Eguchi Koichi , Saito Masaki , Koide Takeshi , Iwai Hiroyuki , Suzuki Shinsuke , Takahashi Yosuke , Horiuchi Toshitaka , Yamasaki Hayahide , Matsumoto Shohei , Yumoto Shuji , Kubo Hidehito , Kawahara Jun , Okabe Akihiro , Kikkawa Yuki , Isomura Takenori 
Published: February 2020

Hydrogen is the primary fuel source for fuel cells. However, the low volumetric energy density and difficulty in storage and transportation are major obstacles for the practical utilization. Thus, the on-site generation of hydrogen from its carrier is an effective method for the fuel supply. Among various hydrogen carriers, ammonia is one of the promising candidates because of its high hydrogen density, low production cost, and ease in liquefaction and transport.
Ammonia decomposes into nitrogen and hydrogen through a mildly endothermic process. The ammonia decomposition temperature is close to the operating conditions of solid oxide fuel cells (SOFCs). Therefore, the integration of these two devices is beneficial in terms of efficient heat and energy managements and will lead to the development of simplified generation systems. Furthermore, hydrogen and nitrogen produced from ammonia fuel are expected to have little negative effect on fuel cell performance, while hydrocarbon fuels draws some severe problems at electrodes, such as CO poisoning and carbon deposition in low- and high-temperature fuel cells, respectively.
We have investigated three types of ammonia-fueled SOFC systems. In one system, ammonia is directly supplied to the anode chamber. Ammonia decomposes into nitrogen and hydrogen over Ni-based cermet anode, and subsequently the generated hydrogen is electrochemically oxidized to produce steam and electron. The second system consists of ammonia cracker and SOFC. In this case, ammonia is catalytically decomposed through the ammonia cracker, and hydrogen produced is electrochemically oxidized on the anode. Ruthenium catalysts are well-known to promote the decomposition of ammonia, but the limited availability of ruthenium requires the development of new catalyst systems. Then, we have developed nickel-based catalysts and applied them for the ammonia cracker due to their relatively high activity for ammonia decomposition among base metals. The last one is the system combined with auto-thermal ammonia cracker, which will be suitable for the rapid start-up.
In this study, we introduce the development of ammonia-fueled SOFC systems. 200 W-class stacks as well as button-type cells were applied as SOFCs. The performance of the three systems were evaluated and compared with each other.
This work was supported by Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), “energy carrier” (Funding agency: JST).
Surface Segregation in Strontium Doped Lanthanum Cobalt Ferrite: Effect of Composition and Strain
Authors: Yu Yang , Ludwig Karl F , Gopalan Srikanth , Pal Uday Bhanu , Woicik Joseph C , Kaspar Tiffany C , Basu Soumendra Nath 
Published: February 2020

The oxygen reduction reaction (ORR) at the cathode is often the rate-controlling step in the electrochemical reactions occurring in the solid oxide fuel cells (SOFCs). Strontium doped lanthanum cobalt ferrite (LSCF) is a widely used cathode material due to its high electronic and ionic conductivity, and reasonable oxygen surface exchange coefficient. However, LSCF can have long-term stability issues such as surface segregation of Sr during SOFC operation, which can adversely affect the electrochemical performance. Thus, understanding the nature of the Sr surface segregation phenomenon, and how it is affected by the composition of LSCF and strain are critical.
In this research, heteroepitaxial thin films of La1-x
Sr
x
Co0.2Fe0.8O3-δ
with various Sr contents (x = 0.4, 0.3, 0.2) were deposited by Pulsed Laser Deposition (PLD) on single crystal NdGaO3, SrTiO3 and GdScO3 substrates, leading to different strains in the films. The LSCF thin films were annealed at 800 °C for 10 hours in air. The extent of Sr segregation at the post-annealed film surface was quantified using synchrotron-based total reflection X-ray fluorescence (TXRF) technique. The formation of secondary phases were found and their surface area coverage was quantified by Atomic Force Microscope (AFM). Transmission electron microscope (TEM) and related spectroscopy techniques were used for microstructural and quantitative elemental analyses of the secondary phases on surface which were found to be Sr-rich phases. The bonding environment of the Sr-rich phases formed on the surface were investigated by synchrotron-based hard X-ray photoelectron spectroscopy (HAXPES).
The extent of Sr segregation was found to be a function of the Sr content in bulk. Lowering the Sr content from 40% to 30% reduced the surface segregation, but further lowering the Sr content to 20% increased the segregation. The strains of LSCF thin films on various substrates were measured using high-resolution X-ray diffraction (HRXRD) and the Sr surface segregation was found to be reduced with compressive strain and enhanced with tensile strain present within the thin films. A model was developed correlating the Sr surface segregation with Sr content and strain effects to explain the experimental results.
Semi-Solid Typed Ionic Conductor for Solid-State Electrochromic Approaches
Authors: Kim Joo Yeon , Oh Ji Young , Jeon Sanghoon , Ryu Hojun , Cho Seong M. , Ah Chil-Sung , Kim Yong-Hae , Hwang Chi-Sun 
Published: February 2020

Electrochromic (EC) phenomena are that their optical transmittance and/or reflectance change because of chemical reduction/oxidation processes occurred by the ions insertion and extraction when a potential is externally applied. In order to increase the ratio and speed of chemical reduction/oxidation processes, which are essential required property, there are many efforts to prepare the ionic conductors based on such as organic-solvents/liquids, ionic liquids, and polymer/gel.
Although organic-solvent/liquid based ion conductors show better physical properties likely lower viscosity, density, and melting point helps easier ion mobility in medium, they exhibit low stability, high flammability, and low safety which limit the promising wide range application of EC devices (ECDs). Therefore instead of using organic-solvent/liquid based ion conductors, ionic liquids (ILs) are considered because of non-volatility, possibly makes choice and/or certainly increasing ion concentration, etc. In spite of these advantages, polymer and/or gel-typed ion conductors are only suitable in terms of the flexibility and scalability of ECDs.
As their visco-elastic properties, polymer/gel-based ion conductors afford guaranteed good contact with the electrodes, and they also have simple processablity resulted in low production cost and better mechanical properties along with improved stability, reliability, and safety.
Therefore, in the present work, polymer-based ion conductor is prepared and is optimized in order to obtain the efficient contrast ratio and switching speed for ECDs. In order to see the feasibility, the operation of polymer-based ion conductor introduced ECD fabricated on flexible substrate will be also presented.
Acknowledgement
This work was supported by Institute for Information & communications Technology Promotion (IITP) grant funded by the Korea government (MSIP) (B0101-16-0133, The core technology development of light and space adaptable energy-saving I/O platform for future advertising service).
Ion Conduction of BaPrO3-δ Thin Film with Mixed Valence State for SOFC Anode Electrode
Authors: Furuichi Shoto , Tsuchiya Takashi , Minohara Makoto , Kobayashi Masaki , Horiba Koji , Kumigashira Hiroshi , Higuchi Tohru 
Published: February 2020

The BaPrO3 (BPO) is expected as a candidate for anode materials in solid oxide fuel cell (SOFC) using oxide protonics material as a solid electrolyte, due to a possible presence of mixed conductivity or holes (electrons)and protons. BPO ceramics has the possibility of electron-ion mixed conduction because of auto-ionization of Pr+4/Pr+3. Therefore, the electrode of fuel cell should be used as thin film form. However, details of high mixed conduction of BPO thin film have not been clarified thus far.
In this study, we have deposited the BPO thin films on Al2O3 (0001) single crystal and Nb-doped SrTiO3 substrates by radio frequency (RF) magnetron sputtering. The deposition pressure and substrate temperature were set at 4.0×10-3 Torr and 500 °C, respectively. In order to obtain the high mixed conduction of the thin film, the influence of film thickness was probed between 60 and 170 nm. The BPO thin film was characterized by XRD, AC impedance method, X-ray photoemission spectroscopy (XPS), and X-ray absorption spectroscopy (XAS). The AC impedance was measured by means of a frequency response analyzer in the frequency range of 0.1 Hz – 32 MHz. Impedance spectra were collected at temperatures between 200 °C and 600 °C with a step of 25 °C. The measurement atmosphere used dry Air (the mix gas of O2 and Ar) and wet Air (the mix gas of O2 and Ar and H2O). The electrode made a Pt comb type electrode by RF magnetron sputtering. In order to probe conducting carriers, the conductivity was measured by changing by gas partial pressure.
The prepared thin films exhibit highly a-axis orientation. The lattice constant of a-axis decreases with increasing film thickness. We conformed the electron structure by XPS and RPES in order to prove the mixed valent states of Pr4+ and Pr3+. This originates the changes of lattice constant with film thickness. The electrical conductivity increases and the activation energy decreases with increasing film thickness. The activation energy does not match with the energy separation between the Fermi level and the top of valence band. However, the conductivity at 300 °C depends on the oxygen partial pressure, indicating the existence of electron-oxygen ion mixed conduction. The thin films below 100 nm have proton conductivity in wet atmosphere. The above results indicates that the thin film has proton conduction in addition to electron-oxygen ion mixed conduction.
Characterization of Reliability of Solid Oxide Fuel Cell Sealants and Anodes
Authors: Wei Jianping , Pećanac Goran , Malzbender Jürgen 
Published: February 2020

Typically brittle sealant and anode materials are critical for the reliability of solid oxide fuel cells (SOFCs). Hence, characterization of these failure-relevant materials is crucial for the long term operation. In particular, the mechanical behaviour and elevated temperature stability which is strongly affected by creep has to be thoroughly understood and in terms of property – microstructure correlation, related to the materials’ compositions, crystallization, porosity and phase stability.
Since sealant leakage can lead to malfunction of the whole system, the structural integrity of the sealant is a key issue for the operation of SOFC stacks and systems. Fracture properties and elevated temperature deformation need to be assessed, particularly for partially crystallized glass-ceramic sealants that might suffer from instability issues at operation relevant temperatures due to viscoelastic deformation of the residual glass phase. In this work, a modified sealant, which consists of a composition from the BaO-CaO-SiO2 ternary system with Ag particles reinforcement, was characterized. Bending tests were carried out at room temperature and typical stack operation temperatures on a head-to-head specimen geometry in an as-sintered and annealed state, yielding average fracture stresses and apparent creep data. Since the sealants are exposed to a complex loading state in the stack environment, complementary torsion tests were used to investigate the shear strength. Advanced microstructural characterization was carried out to gain insight into the annealing and reinforcement filler effects. The results are compared and discussed with respect to literature data and their relevance for the application in SOFCs operating at different temperatures in the range of 600°C to 800°C.
Typical anode substrate materials (NiO-3YSZ and NiO-8YSZ) along with their reduced and re-oxidized state were analysed by means of fracture toughness at room temperature and 800 °C. Effects related to porosity and transformation toughening could be verified. Furthermore, creep of porous Ni-YSZ composite has been investigated under H2/Ar atmosphere at typical operating temperatures. Ni-YSZ materials with different porosities and Ni/YSZ ratios were tested in order to investigate material´s composition and porosity effects. Different loading configurations such as compression, four-point bending and ring-on-ring bending have been used to assess the differences in creep response of these materials. Interpretation and analysis of the data were based on analytical and finite element simulation. The systematic comparison and discussion of the results was aided by microstructural investigations.
Research and Development on Oxygen Transport Membranes at the Technical University of Denmark from Materials to Modules
Authors: Kiebach Ragnar , Pirou Steven , Ovtar Simona , Haugen Astri Bjørnetun , Hendriksen Peter Vang 
Published: February 2020

Oxygen transport membranes (OTMs) are inorganic, high temperature devices that have the potential to efficiently supply oxygen to combustion processes, for example for oxy-fired (biomass) gasification or in the cement and steel industry.
This work reviews aspects of material selection, design, characterization and testing of single phase and composite based OTMs that are taking place at the Technical University of Denmark (DTU). The focus will be on high performance asymmetric OTMs, in which a dense thin film oxygen separation membrane is deposited on a porous mechanically supporting layer.
An OTM material should ideally have high ionic and electronic conductivity as well as good chemical stability under both oxidizing and reducing conditions. Strategies for increasing the performance by using composite dual phase membranes consisting of an ionic conductor and a electronic conductor will be discussed. Particularly membranes based on i) La0.6Sr0.4FeO3 (LSF) and CGO and ii) 10Sc1YSZ ((Y2O3)0.01(Sc2O3)0.10(ZrO2)0.89) and MnCo2O4 seem to be promising combinations and results on manufacturing and testing, including long-term results for >1500 h, of these membranes will be presented.
The second part of the presentation will focus on module design and application oriented testing. Here first results from integration of OTMs into the slip stream of a biomass gasifier will be shown. Also highlights from the “Highly Efficient Tubular Membranes for Oxy-Combustion (HETMOC)” European FP7 project are included. In this project a proof-of-concept module with 25 one-end closed BCSF (BaxSr1-xCo0.8Fe0.2O3) tubes was designed and tested in a high pressure test stand designed at DTU. To maximize the partial pressure difference across the membrane, high pressure up to 5 bar was applied on the feed side and a vacuum pump was used to lower the pressure on the permeate side. Results on performance and long-term stability as well as problems encountered during the project will be presented.
Synthesis and H- Conductivity of Ba2LiH3-2x
O1+X
Authors: Kobayashi Genki , Watanabe Akihiro , Suzuki Kota , Hirayama Masaaki , Yonemura Masao , Kanno Ryoji 
Published: February 2020

Hydride ions are attractive as charge carriers because these have an ionic radius appropriate for fast ionic conduction and also show strong reducing properties with a standard redox potential of H–/H2 (–2.25 V vs. SHE), which is close to that of Mg/Mg2+ (–2.38 V vs. SHE). Therefore, H– conductors may be applied in energy storage and conversion devices with high energy densities. Recently, we have found La2-x-y
Sr
x

+y
LiH1-x+y
O3-y
(LSLHO) oxyhydride system possessing pure H– conductivity, and have confirmed the capability of the oxyhydride to act as an H– solid electrolyte by demonstrating the battery reaction of an all-solid-state Ti/LSLHO/TiH2 cell [1]. The LSLHO system shows H– conductivity of 10-4 S·cm–1 at 300 ºC. However, a higher H– conductivity will be required to make novel electrochemical devices using H– conduction phenomenon. In this study, we attempted to synthesize a new H– conductive oxyhydride, Ba2LiH3-2x
O1+x
(BLHO), in order to achieve a higher H– conductivity than that of LSLHO [2].
BLHO was designed on the basis of LSLHO with the K2NiF4-type structure. La/Sr in LSLHO was substituted by Ba to expand the bottleneck size for H– diffusion in the crystal lattice. Furthermore, H– vacancies were introduced into the structure by controlling H/O ratio in the composition of BLHO. Crystal structure of BLHO was determined by X-ray and neutron diffraction. The X-ray diffraction peak of the sample could be indexed as the K2NiF4-type structure. The crystal structure of Ba2LiH3O (BLHO: x = 0) and Sr2LiH3O (LSLHO: x = 0, y = 2) determined by the Rietveld analysis are compared in Figure 1. The anion arrangement of Ba2LiH3O is basically same with Sr2LiH3O. The two apical anion sites in Li-octahedra are preferentially occupied by oxide ions. Oxide and hydride ions randomly occupy the apical site. In contrast, the four axial anion sites of the Li-anion octahedra prefer to be occupied by only hydride ions. As a result, square-planar LiH4 is formed in the Li-octahedra. When the A-site cation in the composition of A
2LiH3O changed from Sr to Ba, the lattice volume expand depending on the difference of ionic radii between Sr2+ (1.58 Å) and Ba2+ (1.75 Å). In particular, influences of the volume expansion mainly appeared to ab plane in the crystal lattice. The details of H– conduction properties for BLHO will be discussed in our presentation.

References:

[1] Genki Kobayashi et al., Science, 351, 1314-1317 (2016).
[2] Akihiro Watanabe, Genki Kobayashi et al., to be submitted.

Figure 1
Structural and Transport Properties of the Blc-Pbco System; Effects of Cation Ordering
Authors: Druce John , Wang Tianqi , Téllez Helena , Kilner John A. , Ishihara Tatsumi 
Published: February 2020

The drive to reduce the operating temperatures of solid oxide fuel cells (SOFCs) and electrolysers (SOECs) requires the discovery of new materials showing enhanced oxygen transport and electrocatalytic properties. As well as modifying the composition of materials with the simple perovskite structure, lately there has also been interest in materials with other, often, layered structures including the Ruddlesden-Popper type materials, such as La2NiO4, and double perovskites such as GdBaCo2O5 (GBCO) and PrBaCo2O5 (PBCO) [1].

Whilst Sr-substituted lanthanum cobaltite (La0.6Sr0.4CoO3-d, LSC64) is widely used, the Ba-substituted analogue La1-xBaxCoO3-d (BLC) is attracting recent interest showing competitive electrode performances [2,3]. On the other hand, the double perovskite PrBaCo2O5+d (PBCO) has high diffusivity and surface exchange activity, which is often attributed to the anisotropic diffusion of oxygen due to the ordering of Pr and Ba cations on the A-site. However, experimental measurements suggest that the degree of anisotropy between diffusion in along the c axis and in the ab plane is only around half an order of magnitude [4]. Therefore, the family of compositions between single perovskite BLC and double perovskite PBCO offers an interesting system to study the effects of cation ordering on transport behaviour.

In this work, we have studied the structural and oxygen transport properties of materials in the La0.5-x/2Prx/2Ba0.5CoO3-d compositional space. The materials were synthesised by a conventional solid state reaction route, and X-ray diffraction revealed that Pr-rich compositions (0.7 < x < 1) retain the same double perovskite structure as PBCO, with cation ordering on the A-site, and hence more properly written as La1-xPrxBaCo2O5+d. The La-rich compositions (0 < x <0.7) showed a cubic symmetry, similar to the Sr-analogue LSC64.

Oxygen isotope exchange studies on the Ba0.5La0.5CoO3 end member show that the oxygen tracer diffusion (D*) and exchange (k*) coefficients are similar to those of PBCO, and of Sm0.5Sr0.5CoO3, which are some of the highest reported [5], explaining the high electrochemical performance of the single perovskite material [2,3]. Preliminary results indicate these values change only slightly across the composition field, with no significant increase as the structure changes from single to double perovskite. These findings seem to suggest that it is not the A-cation ordering in the crystal structure of PBCO that provides per se its high performance, but the defect chemistry, namely the high concentration of oxygen vacancies in the material.

References
[1] A. Tarancon et al., J. Mater. Chem. 20, pp 3799 – 3813 (2010)
[2] T. Ishihara et al., Solid State Ionics 152-153, pp 609 - 613 (2002)
[3] G.M. Rupp et al., J. Electrochem. Soc. 163(6), pp F564-F573, (2016)
[4] M. Burriel et al., Chem. Mater. 24, pp 613 – 621 (2012)
[5] I. Fullarton et al., Ionics 1, pp 51 – 58 (1995)
Electrolyte Systems for High Energy Cells
Authors: Abraham Daniel P 
Published: February 2020

High energy – high voltage lithium-ion cells are being developed at Argonne as part of the U.S. DOE’s Advanced Battery Research program. These cells typically contain transition-metal bearing layered oxide positive electrodes, graphite-bearing negative electrodes and LiPF6-bearing carbonate solvent electrolytes. Although these cells deliver high energy densities initially, they display significant capacity loss and impedance rise during calendar or cycle-life aging. Extensive diagnostic studies indicate that cell impedance rise mainly arises at the positive electrode, and cell capacity fade mainly results from lithium trapping in the solid electrolyte interphase (SEI) at the negative electrode. During electrochemical aging, both electrodes undergo a cycle of surface film formation, decomposition, dissolution, and redeposition; this process results in continuous consumption of lithium ions, thereby reducing cell capacity and often increasing cell impedance.
Electrolyte additives are an economic means of improving cell performance and calendar life. In the past two decades, many organic and inorganic compounds have been identified as effective electrolyte additives: examples include vinylene carbonate, ethylene sulfite, vinyl ethylene carbonate, and fluoroethylene carbonate. However, these additives are mostly used in lithium ion cells that are cycled at relative low voltages (<4.3 V vs Li+/Li). Initial studies indicate that these common electrolyte additives are not effective at enhancing long-term cycling performance of high voltage cells, i.e. stable electrode passivation is not achieved with these traditional additives.
Several promising electrolyte additives for high voltage and high capacity lithium-ion cells are being developed at Argonne; these include LiF2BC2O4 (LiDFOB) and various polyfluoroalkyl (PFA) compounds. The PFA additives have two components: (i) a reactive head-group for attachment onto electrode surfaces via either reductive or oxidative decomposition, so that it becomes an integral part of the surface layer; (ii) a polyfluoroalkyl chain that self-assembles on the electrode surface into a solvophobic passivating layer that reduces both surface degradation and electrolyte decomposition. Various additive combinations are also being studied to minimize the performance degradation observed at high voltages. The rationale for electrolyte additive selection and the performance of the resulting electrolyte systems will be highlighted during this presentation.