scholarly journals Complexions at the Electrolyte/Electrode Interface in Solid Oxide Cells

2021 ◽  
Author(s):  
Hanna Türk ◽  
Franz-Philipp Schmidt ◽  
Thomas Götsch ◽  
Frank Girgsdies ◽  
Adnan Hammud ◽  
...  
Keyword(s):  
Solid Oxide ◽  
Atomic Scale ◽  
Lanthanum Strontium Manganite ◽  
Compositional Gradient ◽  
Transmission Electron ◽  
Electrode Interface ◽  
Multi Method Approach ◽  
New Perspective ◽  
Ysz Electrolyte ◽  
Method Approach

Rapid deactivation presently limits a wide spread use of high-temperature solid oxide cells (SOCs) as otherwise highly efficient chemical energy converters. With deactivation triggered by the ongoing conversion reactions, an atomic-scale understanding of the active triple-phase boundary (TPB) between electrolyte, electrode and gas phase is essential to increase cell performance. Here we use a multi-method approach comprising transmission electron microscopy and first-principles calculations and molecular simulations to untangle the atomic arrangement of the prototypical SOC interface between a lanthanum strontium manganite (LSM) anode and an yttria-stabilized zirconia (YSZ) electrolyte. We identify an interlayer of self-limited width with partial amorphization and strong compositional gradient, thus exhibiting the characteristics of a complexion that is stabilized by the confinement between two bulk phases. This offers a new perspective to understand the function of SOCs at the atomic scale. Moreover, it opens up a hitherto unrealized design space to tune the conversion efficiency.

scholarly journals Complexions at the Electrolyte/Electrode Interface in Solid Oxide Cells

2021 ◽  
Author(s):  
Hanna Türk ◽  
Franz-Philipp Schmidt ◽  
Thomas Götsch ◽  
Frank Girgsdies ◽  
Adnan Hammud ◽  
...  
Keyword(s):  
Solid Oxide ◽  
Atomic Scale ◽  
Lanthanum Strontium Manganite ◽  
Compositional Gradient ◽  
Transmission Electron ◽  
Electrode Interface ◽  
Multi Method Approach ◽  
New Perspective ◽  
Ysz Electrolyte ◽  
Method Approach

Rapid deactivation presently limits a wide spread use of high-temperature solid oxide cells (SOCs) as otherwise highly efficient chemical energy converters. With deactivation triggered by the ongoing conversion reactions, an atomic-scale understanding of the active triple-phase boundary (TPB) between electrolyte, electrode and gas phase is essential to increase cell performance. Here we use a multi-method approach comprising transmission electron microscopy and first-principles calculations and molecular simulations to untangle the atomic arrangement of the prototypical SOC interface between a lanthanum strontium manganite (LSM) anode and an yttria-stabilized zirconia (YSZ) electrolyte. We identify an interlayer of self-limited width with partial amorphization and strong compositional gradient, thus exhibiting the characteristics of a complexion that is stabilized by the confinement between two bulk phases. This offers a new perspective to understand the function of SOCs at the atomic scale. Moreover, it opens up a hitherto unrealized design space to tune the conversion efficiency.

Fabrication of Anode-Supported Micro-Tubular Solid Oxide Fuel Cell Using an Extrusion and Vacuum Infiltration Technique

2008 ◽  
Author(s):  
Jung-Hoon Song ◽  
Nigel M. Sammes ◽  
Xiaoyu Zhang
Keyword(s):  
Open Circuit ◽  
Vacuum Infiltration ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Lanthanum Strontium Manganite ◽  
Infiltration Process ◽  
Electrochemical Tests ◽  
Thin Electrolyte Layer ◽  
Infiltration Technique ◽  
Ysz Electrolyte

A simple and mass productive extrusion technique was applied to fabricate anode-supported micro-tubular solid oxide fuel cells (SOFCs). A standard NiO/8YSZ (Nickel oxide/8 mol % yttria stabilized zirconia) cermets anode, 8 YSZ electrolyte, and LSM (Lanthanum strontium manganite) cathode were used as the materials components. SEM (secondary electron microscopy) images indicated vacuum infiltration method successfully generated the thin electrolyte layer (10∼15 μm) with a structurally effective three phase boundaries. Fabricated unit cell showed the open circuit voltage of 1.12 V without any fuel leaking problems. Electrochemical tests showed a maximum power density up to 0.30 W/cm2 at 800 °C, implying the excellent performance as micro-tubular SOFCs. This study verified that the extrusion aided by vacuum infiltration process could be a promising technique for mass production of microtubualr SOFCs.

Fabrication and Performance of Anode-Supported Micro-Tubular Solid Oxide Fuel Cells

2006 ◽  
Vol 3 (4) ◽  
pp. 482-486 ◽  
Author(s):  
Jakub Pusz ◽  
Alidad Mohammadi ◽  
Nigel M. Sammes
Keyword(s):  
Solid Oxide Fuel Cells ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Lanthanum Strontium Manganite ◽  
Scanning Electron Microscopy Micrographs ◽  
Stabilized Zirconia ◽  
Excellent Performance ◽  
Lanthanum Strontium ◽  
And Performance ◽  
Ysz Electrolyte

A solid oxide fuel cell was fabricated using standard NiO/8YSZ cermet anode, 8mol% yttria stabilized zirconia (YSZ) electrolyte, and lanthanum strontium manganite cathode. The anodes were extruded using an hydraulic ram extruder. An electrolyte was deposited using a novel technique allowing obtaining a 3-5μm thin and dense YSZ layer. The cathode was deposited by brush painting. The cells were operated under different temperature and fuel conditions, and showed excellent performance of up approximately 0.6Wcm−2 at 890°C. Performance data as well as scanning electron microscopy micrographs of the cells are presented.

Brittle Fracture Studies of Solid Oxide Fuel Cells

2009 ◽  
Vol 409 ◽  
pp. 81-93
Author(s):  
Jürgen Malzbender ◽  
Rolf W. Steinbrech ◽  
Egbert Wessel
Keyword(s):  
Fuel Cells ◽  
Solid Oxide Fuel Cells ◽  
Glass Ceramics ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Lanthanum Strontium Manganite ◽  
Decentralized Energy ◽  
Ysz Electrolyte ◽  
Power Densities

Solid Oxide Fuel Cells (SOFCs) with electrical efficiencies above 50 % are considered as very promising option for future decentralized energy conversion. At the Forschungszentrum Juelich (FZJ) planar SOFC stacks are currently being developed and tested at 800°C and up to 10000 h using H2 and methane as fuel. Stacks in the kW class routinely reach power densities of 700 W/cm². Typically the layered material composite of the FZJ-stack consists of cells with yttria stabilized zirconia (YSZ) electrolyte, Ni-YSZ anode and a cathode of lanthanum strontium manganite. The cells are mounted between ferritic steel interconnects. The fuel and air compartment are sealed by glass-ceramics and more recently also by metal brazes. Significant progress in reliable stack operation has been achieved over the past decade. However, problems with thermo-chemical and thermo-mechanical compatibility still remain a major challenge. To illustrate the complexity of material interactions in SOFCs, selected problems related to mechanical failure processes are presented. The role of residual stresses is addressed and fracture phenomena of cell and sealant are described in greater detail.

Electron Microscopy Studies of The Chemistry And Microstructure of BaF2 / YBa2Cu3O7-x Thin Films

1994 ◽  
Vol 52 ◽  
pp. 796-797
Author(s):  
J. L. Lee ◽  
C. A. Weiss ◽  
R. A. Buhrman ◽  
J. Silcox
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Thin Films ◽  
Scanning Transmission Electron Microscope ◽  
Atomic Scale ◽  
Island Growth ◽  
Multilayer Systems ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Mgo Substrate

BaF2 thin films are being investigated as candidates for use in YBa2Cu3O7-x (YBCO) / BaF2 thin film multilayer systems, given the favorable dielectric properties of BaF2. In this study, the microstructural and chemical compatibility of BaF2 thin films with YBCO thin films is examined using transmission electron microscopy and microanalysis. The specimen was prepared by using laser ablation to first deposit an approximately 2500 Å thick (0 0 1) YBCO thin film onto a (0 0 1) MgO substrate. An approximately 7500 Å thick (0 0 1) BaF2 thin film was subsequendy thermally evaporated onto the YBCO film.Images from a VG HB501A UHV scanning transmission electron microscope (STEM) operating at 100 kV show that the thickness of the BaF2 film is rather uniform, with the BaF2/YBCO interface being quite flat. Relatively few intrinsic defects, such as hillocks and depressions, were evident in the BaF2 film. Moreover, the hillocks and depressions appear to be faceted along {111} planes, suggesting that the surface is smooth and well-ordered on an atomic scale and that an island growth mechanism is involved in the evolution of the BaF2 film.

Images and Applications of Ion Explosion Spike Pits

1990 ◽  
Vol 48 (1) ◽  
pp. 584-585
Author(s):  
P. Fraundorf ◽  
J. Tentschert
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Bulk Material ◽  
Coulomb Repulsion ◽  
The Body ◽  
Atomic Scale ◽  
Early Solar System ◽  
Transmission Electron ◽  
Nuclear Particle ◽  
Particle Tracks

Since the discovery of their etchability in the early 1960‘s, nuclear particle tracks in insulators have had a diverse and exciting history of application to problems ranging from the selective filtration of cancer cells from blood to the detection of 244Pu in the early solar system. Their usefulness stems from the fact that they are comprised of a very thin (e.g. 20-40Å) damage core which etches more rapidly than does the bulk material. In fact, because in many insulators tracks are subject to radiolysis damage (beam annealing) in the transmission electron microscope, the body of knowledge concerning etched tracks far outweighs that associated with latent (unetched) tracks in the transmission electron microscope.With the development of scanned probe microscopies with lateral resolutions on the near atomic scale, a closer look at the structure of unetched nuclear particle tracks, particularly at their point of interface with solid surfaces, is now warranted and we think possible. The ion explosion spike model of track formation, described loosely, suggests that a burst of ionization along the path of a charged particle in an insulator creates an electrostatically unstable array of adjacent ions which eject one another by Coulomb repulsion from substitutional into interstitial sites. Regardless of the mechanism, the ejection process which acts to displace atoms along the track core seems likely to operate at track entry and exit surfaces, with the added feature of mass loss at those surfaces as well. In other words, we predict pits whose size is comparable to the track core width.

High-Temperature Synthesis of CdSe-Based Core/Shell, Core/Shell/Shell, and Core/Graded-Shell Nanoplatelets for Stable and Efficient Narrowband Emitters

2019 ◽  
Author(s):  
Aurelio A. Rossinelli ◽  
Henar Rojo ◽  
Aniket S. Mule ◽  
Marianne Aellen ◽  
Ario Cocina ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Temperature ◽  
Equilibrium Shape ◽  
Size Variation ◽  
Crystal Defects ◽  
Atomic Scale ◽  
Quantum Yields ◽  
Core Shell ◽  
Compositional Gradient ◽  
High Quality

<div>Colloidal semiconductor nanoplatelets exhibit exceptionally narrow photoluminescence spectra. This occurs because samples can be synthesized in which all nanoplatelets share the same atomic-scale thickness. As this dimension sets the emission wavelength, inhomogeneous linewidth broadening due to size variation, which is always present in samples of quasi-spherical nanocrystals (quantum dots), is essentially eliminated. Nanoplatelets thus offer improved, spectrally pure emitters for various applications. Unfortunately, due to their non-equilibrium shape, nanoplatelets also suffer from low photo-, chemical, and thermal stability, which limits their use. Moreover, their poor stability hampers the development of efficient synthesis protocols for adding high-quality protective inorganic shells, which are well known to improve the performance of quantum dots. <br></div><div>Herein, we report a general synthesis approach to highly emissive and stable core/shell nanoplatelets with various shell compositions, including CdSe/ZnS, CdSe/CdS/ZnS, CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S, and CdSe/ZnSe. Motivated by previous work on quantum dots, we find that slow, high-temperature growth of shells containing a compositional gradient reduces strain-induced crystal defects and minimizes the emission linewidth while maintaining good surface passivation and nanocrystal uniformity. Indeed, our best core/shell nanoplatelets (CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S) show photoluminescence quantum yields of 90% with linewidths as low as 56 meV (19.5 nm at 655 nm). To confirm the high quality of our different core/shell nanoplatelets for a specific application, we demonstrate their use as gain media in low-threshold ring lasers. More generally, the ability of our synthesis protocol to engineer high-quality shells can help further improve nanoplatelets for optoelectronic devices.</div>

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