Combined Cr and S poisoning of La0.8Sr0.2MnO3-δ (LSM) cathode of solid oxide fuel cells
Not Available
Wang, Cheng Cheng↗
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Preparation and Characterization of (La 0.8 Sr 0.2 ) 0.95 MnO 3-δ (LSM) Thin Films and LSM/LSCF Interface for Solid Oxide Fuel Cells
Uniform, dense, and conformal coatings of (La,Sr)MnO 3-δ (LSM) have been successfully deposited on a silicon wafer and a dense (La,Sr)(Co,Fe)O 3-δ (LSCF) substrate using a stable LSM sol consisting of metal acetate and nitrate precursors dissolved in a mixed organic solvent of 2-methoxyethanol and acetic acid with enhanced wettability. The processing conditions are optimized for precise control of composition, morphology, microstructure, and thickness of the LSM films to examine the microstructure and chemical stability of an LSM film as a catalytic coating for an LSCF cathode. The thicknesses of the LSM films are controlled within the range of 5–60 nm by spin-coating of LSM sol with different concentrations. The LSM films grow epitaxially on the LSCF substrate grains after annealing at 800°C for 1 h due to their structural similarity. The LSM coatings show good stability on LSCF substrates and may suppress strontium oxide segregation on LSCF surface during annealing at 850°C for 900 h, implying that LSM-coated LSCF surfaces have better structural and chemical stability under typical fuel cell operating conditions.
36 MATERIALS SCIENCE↗
Characterization of Interaction between Fe‐Infiltrates and LSM Backbone in Solid Oxide Fuel Cells
In this paper, detailed materials characterization analyses on the interaction between FeO x nanoparticles infiltrated onto a La 0.8 Sr 0.2 MnO 3 (LSM) backbone cathode in a solid oxide fuel cell (SOFC) are reported. The infiltration process leads to an increase of 3.4% in cell performance. X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) as well as energy dispersive X‐ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS) are utilized to perform a comprehensive examination of the microstructure and chemical properties at the interface of the infiltrate and backbone materials. Mn from the LSM backbone diffuses into the FeO x infiltrate and forms a Fe‐Mn‐O spinel. A small amount of Fe also diffuses into the LSM backbone, which could partially be responsible for the enhanced performance of the cell. The valence state of Mn increases from the surface of the Fe‐Mn‐O particle into bulk LSM, with the highest value being at the interface of the Fe‐Mn‐O/LSM backbone. Possible mechanisms are discussed for the change in Mn valence state within the LSM phase. Trace amounts of Mn and La are found in the YSZ phase, as a result of interdiffusion between LSM and YSZ.
Yu, Yang↗
Operating Stresses and Their Effects on Degradation of LSM-Based SOFC Cathodes
The performance of solid oxides fuel cells (SOFCs) with four different Mn excess of lanthanum strontium manganite (LSM) -based cathodes were examined under different temperatures (1,000 °C, 900 °C), current densities (0, 380, and 760 mA cm -2 ), and cathode atmospheres (p O 2 )=0.1,0.15,0.21) for durations ranging from 58 to 1,008 h. Each yttria-stabilized zirconia (YSZ) electrolyte-supported “button” cell had a porous Ni/YSZ composite anode and a porous LSM/YSZ composite cathode. The cells’ output voltage versus time were recorded and electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) measurements were performed every 24 hours. The total area specific resistance (ASR) was calculated from these measurements. The values of ASR from both EIS and LSV were comparable between each other but lower than that from durability test. Distribution of relaxation times (DRT) analysis was performed to investigate the electrochemical processes and their corresponding relaxation frequencies as well as their attributions to the total ASR. The series resistance and parallel resistance that obtained from the equivalent circuit fit of the Nyquist plot were higher at low temperature and low p O 2 regardless of LSM compositions. The area of the peaks derived from DRT analysis increased with time during individual tests. The microstructures of the tested cells were examined using scanning electron microscopy and energy-dispersive x-ray spectroscopy (SEM/EDS). Manganese oxide particles were observed near the cathode-electrolyte interface after prolonged (1,008 h) testing in air of a cell with LSM of 11% manganese excess, and after a short test (58 h) under low oxygen (p O 2 = 0.10) in a cell with LSM of 5% manganese excess. However, the role of MnOx in cell degradation is still unknown.
08 HYDROGEN↗
(SPT-)LSM theorems from projective non-invertible symmetries
Projective symmetries are ubiquitous in quantum lattice models and can be leveraged to constrain their phase diagram and entanglement structure. In this paper, we investigate the consequences of projective algebras formed by non-invertible symmetries and lattice translations in a generalized 1+1 1 + 1 D quantum XY model based on group-valued qudits. This model is specified by a finite group G G and enjoys a projective \mathsf{Rep}(G)× Z(G) 𝖱 𝖾 𝗉 ( G ) × Z ( G ) and translation symmetry, where symmetry operators obey a projective algebra in the presence of symmetry defects. For invertible symmetries, such projective algebras imply Lieb-Schultz-Mattis (LSM) anomalies. However, this is not generally true for non-invertible symmetries, and we derive a condition on G G for the existence of an LSM anomaly. When this condition is not met, we prove an SPT-LSM theorem: any unique and gapped ground state is necessarily a non-invertible weak symmetry protected topological (SPT) state with non-trivial entanglement, for which we construct an example fixed-point Hamiltonian. The projectivity also affects the dual symmetries after gauging \mathsf{Rep}(G)× Z(G) 𝖱 𝖾 𝗉 ( G ) × Z ( G ) sub-symmetries, giving rise to non-Abelian and non-invertible dipole symmetries, as well as non-invertible translations. We complement our analysis with the SymTFT, where the projectivity causes it to be a topological order non-trivially enriched by translations. Throughout the paper, we develop techniques for gauging \mathsf{Rep}(G) 𝖱 𝖾 𝗉 ( G ) symmetry and inserting its symmetry defects on the lattice, which are applicable to other non-invertible symmetries.
Pace, Salvatore D. (ORCID:0000000306093335)↗
Long Term Degradation of LSM Based SOFC Cathodes: Use of a Proven Accelerated Test Regimen
The overall goals of the program were: • To understand the microstructural basis of long-term performance loss in solid oxide fuel cells (SOFCs) with cathodes based on lanthanum strontium manganite (LSM, (La 1–x Sr x ) 1–yM nO 3±z ); • To develop strategies for optimizing LSM–based cathodes that achieve improved long-term performance, while exhibiting microstructural and chemical stability, for commercial fuel cell systems. The research project carried out accelerated testing of SOFCs with LSM-based cathodes of selected compositions. After intervals of accelerated testing (and control tests using non-accelerated conditions), the cells underwent extensive microstructural characterization to determine the physical and chemical changes in the cells. By analysis of a) the results of the testing, b) the observed microstructural changes, and c) the differences in these correlations between different cathode compositions and test durations, the research: • Identified a correlation between microstructural change and performance loss: specifically, between decrease of three-phase boundary (TPB) density and increase of area specific re-sistance (ASR) during operation; • Identified a cathode composition parameter — Mn excess, defined as 1/(1–y) in (La 1–x Sr x ) 1–y MnO 3±z ) — and how it affects TPB density, ASR and change of cell performance over time.
08 HYDROGEN↗
Modeling of the oxygen reduction reaction for dense LSM thin films
In this study, the oxygen reduction reaction mechanism is investigated using numerical methods on a dense thin (La 1-x Sr x ) y MnO 3±δ film deposited on a YSZ substrate. This 1-D continuum model consists of defect chemistry and elementary oxygen reduction reaction steps coupled via reaction rates. The defect chemistry model contains eight species including cation vacancies on the A- and B-sites. The oxygen vacancy is calculated by solving species transportation equations in multiphysics simulations. Due to the simple geometry of a dense thin film, the oxygen reduction reaction was reduced to three elementary steps: surface adsorption and dissociation, incorporation on the surface, and charge transfer across the LSM/YSZ interface. The numerical simulations allow for calculation of the temperature- and oxygen partial pressure-dependent properties of LSM. The parameters of the model are calibrated with experimental impedance data for various oxygen partial pressures at different temperatures. The results indicate that surface adsorption and dissociation is the rate-determining step in the ORR of LSM thin films. With the fine-tuned parameters, further quantitative analysis is performed. The activation energy of the oxygen exchange reaction and the dependence of oxygen non-stoichiometry on oxygen partial pressure are also calculated and verified using the literature results.
36 MATERIALS SCIENCE↗
Measurement and modeling of muon-induced neutrons in LSM in application for direct dark matter searches
Due to a very low event rate expected in direct dark matter search experiments, a good understanding of every background component is crucial. Muon-induced neutrons constitute a prominent background, since neutrons lead to nuclear recoils and thus can mimic a potential dark matter signal. EDELWEISS is a Ge-bolometer experiment searching for WIMP dark matter. It is located in the Laboratoire Souterrain de Modane (LSM, France). We have measured muon-induced neutrons by means of a neutron counter based on Gd-loaded liquid scintillator. Studies of muon-induced neutrons are presented and include development of the appropriate MC model based on Geant4 and analysis of a 1000-days measurement campaign in LSM. We find a good agreement between measured rates of muon-induced neutrons and those predicted by the developed model with full event topology. The impact of the neutron background on current EDELWEISS data-taking as well as for next generation experiments such as EURECA is briefly discussed.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Experimental validation of solid oxide fuel cell polarization modeling: An LSM-YSZ/YSZ/Ni-YSZ case study
Polarization modeling based on the measured I-V curves is a useful tool for analyzing SOFC performance and diagnosing performance limitations. Using the polarization model, the overpotential of a cell is usually separated into different polarization contributions, including area specific ohmic polarization, activation polarization, and anodic and cathodic concentration polarizations. In this study, we aim to experimentally validate the accuracy of the polarization model. As a case study, anode-supported cells with LSM-YSZ/YSZ/Ni-YSZ configuration are used. By curve-fitting the I-V curves of a cell tested under different cathode oxygen partial pressures into the polarization model, the contributions of different polarization losses are quantified. To validate the polarization model, independent experiments/studies including electrochemical impedance spectroscopy, cathode kinetics study, ex-situ diffusivity measurement, and tortuosity measurement using 3D reconstructed anode are conducted. The results from polarization modeling and from validation studies are in good agreement, thereby validating the polarization model for SOFC performance analysis.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
A Micro-Scale Model for Oxygen Reduction on LSM-YSZ Cathode
In this study, a micro-scale model is developed to simulate the oxygen reduction on LSM-YSZ composite cathode. The model incorporates the effects of cathode microstructural properties on the local transport phenomena and electrochemistry inside the cathode. A detailed reaction mechanism is used in the model which has two parallel routes for oxygen conversion into oxide ions, namely two-phase boundary and three-phase boundary pathways. The model predicts field distributions of local thermodynamic values, over-potential, Faradaic current and other parameters relevant to cathode performance. Electrochemical impedance simulations are performed using the current model to analyze the contribution of various processes to the overall impedance.
30 DIRECT ENERGY CONVERSION↗
Operating Stresses and their Effects on Degradation of LSM-Based SOFC Cathodes
The overall goals of the program were: To understand how selected operational parameters affect the performance of solid oxide fuel cells (SOFCs), with a focus on parameters affecting cathodes (air electrodes) comprised of lanthanum strontium manganite (LSM, (La 1-x Sr x ) 1-y MnO 3±δ ) and yttria-stabilized zirconia (YSZ, (Zr 1–z Y z )O 2±δ ). To relate the observed relationships between operational parameters and cell performance to the microstructural changes that can be observed in the cells after operation.
01 COAL, LIGNITE, AND PEAT↗
LSM and CPT
We study a number of 1+1d lattice models with anti-unitary symmetries that simultaneously reflect space and reverse time. Some of these symmetries are anomalous, leading to Lieb-Schultz-Mattis-type constraints, thus excluding a trivially gapped phase. Examples include a mod 8 anomaly in the Majorana chain and various mod 2 anomalies in the spin chain. In some cases, there is an exact, non-anomalous lattice symmetry that flows in the continuum to CPT. In some other cases, the CPT symmetry of the continuum theory is emergent or absent. Depending on the model, the anomaly of the lattice model is matched in the continuum in different ways. In particular, it can be mapped to an emergent anomaly of an emanant symmetry.
Anomalies in Field and String Theories↗
Crystal Structure of Lsm3 Octamer from Saccharomyces cerevisiae: Implications for Lsm Ring Organisation and Recruitment
Abstract not provided
Naidoo, Nishen↗
Interface and grain boundary degradation in LSM-YSZ composite Solid Oxide Fuel Cell cathodes operated in humidified air
Not Available
Chen, Yun (ORCID:0000000264716636)↗
Multiple cycle chromium poisoning and in-situ electrochemical cleaning of LSM-based solid oxide fuel cell cathodes
Not Available
30 DIRECT ENERGY CONVERSION↗
Solar Thermochemical Redox Cycling Using Ga- and Al-Doped LSM Perovskites for Renewable Hydrogen Production
Solar thermochemical hydrogen production using redox-active metal oxides is a promising pathway for the production of green hydrogen and synthetic fuel precursors. Herein, the perovskite material (La 0.6 Sr 0.4 ) 0.95 Mn 0.8 Ga 0.2 O 3–δ (LSMG6482) is identified as a promising metal oxide for thermochemical water splitting. LSMG6482, along with more-established water splitters ceria and (La 0.6 Sr 0.4 ) 0.95 Mn x Al 1–x O 3–δ (LSMA) perovskites, is experimentally characterized via thermogravimetric (TGA) analysis and high-temperature water splitting in a reactor simulating solar concentrating conditions. TGA analysis demonstrated that LSMG6482 has high and stable oxygen exchange capacity under controlled pO 2 redox cycling, demonstrated by large changes in oxygen nonstoichiometry (δ) relative to ceria. Water splitting experiments using laser heating (T red = 1400 °C, T ox = 1200 °C) resulted in H 2 yields of 165.1 μmol g –1 for the candidate LSMG6482 composition, exceeding that of all benchmark materials tested. Under high conversion oxidation conditions, where H 2 is cointroduced with H 2 O (150 ≤ nH 2 O/nH 2 ≤ 500), H 2 yields were greatest for LSMG6482 and LSMA6482, up to four times that of ceria at the highest nH 2 O/nH 2 conditions. Crystallographic analysis showed that over the course of experimentation, there is some secondary phase growth for all perovskite compositions, except for LSMA6482, but there was no observable degradation in H 2 yields.
08 HYDROGEN↗
Thermodynamic properties, defect equilibria, and water splitting behavior of Ga- doped LSM perovskite
Thermodynamic properties of a Ga-doped La–Sr–Mn perovskite are experimentally extracted and used to compare its water splitting behavior to ceria.
McCord, Dylan C. [Department of Mechanical and Aer↗