scholarly journals Ba0.5Gd0.8La0.7Co2O6−δ Infiltrated BaZr0.8Y0.2O3-δ Composite Oxygen Electrodes for Protonic Ceramic Cells

2022 ◽  
Author(s):  
qingjie wang ◽  
Sandrine Ricote ◽  
Yu Wang ◽  
Peter Vang Hendriksen ◽  
Jian-Qiang Wang ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Electrode Reaction ◽  
Oxygen Electrode ◽  
Operating Conditions ◽  
Partial Pressures ◽  
Oxygen Electrodes ◽  
Symmetrical Cell ◽  
Proton Migration ◽  
Reaction Processes

Abstract In this study, a composite oxygen electrode is prepared by infiltrating a protonic-electronic conducting material, Ba0.5Gd0.8La0.7Co2O6−δ (BGLC) into a proton-conducting BaZr0.8Y0.2O3-δ (BZY20) backbone. The composite oxygen electrode is studied in a symmetrical cell configuration (BGLC-BZY20//BZY20//BGLC-BZY20). The electrode and cell performance are characterized via electrochemical impedance spectroscopy (EIS) with varying the operating conditions, including temperatures, oxygen, and steam partial pressures, with the purpose to identify and characterize the different electrochemical processes taking place in the oxygen electrode. Three electrode reaction processes are observed in the impedance spectra, which are tentatively assigned to i) diffusion of adsorbed oxygen/proton migration/hydroxyl formation, ii) oxygen reduction, and iii) charge transfer, going from the low- to high-frequency range. The BGLC-BZY20 electrode developed in this work shows a low polarization resistance of 0.22, 0.58, and 1.43 Ω cm2 per single electrode in 3 % humidified synthetic air (21% O2/79% N2) at 600, 550, and 500 °C, respectively. During long-term measurement, the cell shows no degradation in the first 350 hours but degrades afterward possibly due to insufficient material stability.

scholarly journals Chromium deposition and poisoning of La0.8Sr0.2MnO3 oxygen electrodes of solid oxide electrolysis cells

2015 ◽  
Vol 182 ◽  
pp. 457-476 ◽  
Author(s):  
Kongfa Chen ◽  
Junji Hyodo ◽  
Aaron Dodd ◽  
Na Ai ◽  
Tatsumi Ishihara ◽  
...  
Keyword(s):  
Surface Segregation ◽  
Oxygen Electrode ◽  
Operating Conditions ◽  
Solid Oxide ◽  
Electrolysis Cell ◽  
Electrolyte Interface ◽  
Oxygen Electrodes ◽  
Inner Surface ◽  
Solid Oxide Electrolysis ◽  
Electrolyte Surface

The effect of the presence of an Fe–Cr alloy metallic interconnect on the performance and stability of La0.8Sr0.2MnO3 (LSM) oxygen electrodes is studied for the first time under solid oxide electrolysis cell (SOEC) operating conditions at 800 °C. The presence of the Fe–Cr interconnect accelerates the degradation and delamination processes of the LSM oxygen electrodes. The disintegration of LSM particles and the formation of nanoparticles at the electrode/electrolyte interface are much faster as compared to that in the absence of the interconnect. Cr deposition occurs in the bulk of the LSM oxygen electrode with a high intensity on the YSZ electrolyte surface and on the LSM electrode inner surface close to the electrode/electrolyte interface. SIMS, GI-XRD, EDS and XPS analyses clearly identify the deposition and formation of chromium oxides and strontium chromate on both the electrolyte surface and electrode inner surface. The anodic polarization promotes the surface segregation of SrO and depresses the generation of manganese species such as Mn2+. This is evidently supported by the observation of the deposition of SrCrO4, rather than (Cr,Mn)3O4 spinels as in the case under the operating conditions of solid oxide fuel cells. The present results demonstrate that the Cr deposition is essentially a chemical process, initiated by the nucleation and grain growth reaction between the gaseous Cr species and segregated SrO on LSM oxygen electrodes under SOEC operating conditions.

Electrochemical stability of Sm0.5Sr0.5CoO3−δ-infiltrated YSZ for solid oxide fuel cells/electrolysis cells

2015 ◽  
Vol 182 ◽  
pp. 477-491 ◽  
Author(s):  
Hui Fan ◽  
Minfang Han
Keyword(s):  
Electrochemical Impedance ◽  
Xrd Analysis ◽  
Oxygen Electrode ◽  
Composite Electrodes ◽  
Constant Voltage ◽  
Infiltration Process ◽  
X Ray ◽  
Sem Micrograph ◽  
Electrolysis Mode

Composite SSC (Sm0.5Sr0.5CoO3−δ)–YSZ (yttria stabilized zirconia) oxygen electrodes were prepared by an infiltration process. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) of the composite electrodes showed the formation of SSC perovskite and a well-connected network of SSC particles in the porous YSZ backbone, respectively. The electrochemical performance of the cell was investigated under both fuel cell and steam electrolysis modes using polarization curves and electrochemical impedance spectroscopy (EIS). The cell experienced a large degradation rate at 700 °C with a constant voltage of 0.7 V for over 100 h under power generation operation. The subsequent post-cell SEM micrograph revealed that agglomeration of the infiltrated SSC particles was possibly the cause for the performance deterioration. Furthermore, the long-term stability of the cell was examined at 700 °C with a constant voltage of 1.3 V under steam electrolysis mode. SEM associated with energy dispersive X-ray spectroscopy (EDS) was employed to characterize the post-test cell after the long-term electrolysis operation and it indicated that besides the agglomeration of SSC particles, the delamination of the SSC–YSZ oxygen electrode from the YSZ electrolyte, as well as segregation of cobalt-enriched particles (particularly cobalt oxides) at the interface, was probably responsible for the cell degradation under the steam electrolysis mode.

scholarly journals Analysis of Performance Losses and Degradation Mechanism in Porous La2−X NiTiO6−δ:YSZ Electrodes

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2819
Author(s):  
Juan Carlos Pérez-Flores ◽  
Miguel Castro-García ◽  
Vidal Crespo-Muñoz ◽  
José Fernando Valera-Jiménez ◽  
Flaviano García-Alvarado ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Degradation Mechanism ◽  
Ambient Air ◽  
Secondary Phases ◽  
Peak Broadening ◽  
Symmetrical Cell ◽  
Xrd Patterns ◽  
Crystalline Domains ◽  
Analysis Of Performance

The electrode performance and degradation of 1:1 La2−xNiTiO6−δ:YSZ composites (x = 0, 0.2) has been investigated to evaluate their potential use as SOFC cathode materials by combining electrochemical impedance spectroscopy in symmetrical cell configuration under ambient air at 1173 K, XRD, electron microscopy and image processing studies. The polarisation resistance values increase notably, i.e., 0.035 and 0.058 Ωcm2 h−1 for x = 0 and 0.2 samples, respectively, after 300 h under these demanding conditions. Comparing the XRD patterns of the initial samples and after long-term exposure to high temperature, the perovskite structure is retained, although La2Zr2O7 and NiO appear as secondary phases accompanied by peak broadening, suggesting amorphization or reduction of the crystalline domains. SEM and TEM studies confirm the ex-solution of NiO with time in both phases and also prove these phases are prone to disorder. From these results, degradation in La2−xNiTiO6−δ:YSZ electrodes is due to the formation of La2Zr2O7 at the electrode–electrolyte interface and the ex-solution of NiO, which in turn results in the progressive structural amorphization of La18NiTiO6−δ phases. Both secondary phases constitute a non-conductive physical barrier that would hinder the ionic diffusion at the La2−xNiTiO6−δ:YSZ interface and oxygen access to surface active area.

Amperometric assay of vitamin C using an ascorbate oxidase enzyme electrode

1979 ◽  
Vol 44 (11) ◽  
pp. 3395-3404 ◽  
Author(s):  
Pavel Posádka ◽  
Lumír Macholán
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Oxygen Electrode ◽  
Ascorbate Oxidase ◽  
Current Response ◽  
Reaction Conditions ◽  
Long Term Storage ◽  
Oxidase Enzyme ◽  
Optimal Reaction

An oxygen electrode of the Clark type, coated by a thin, active layer of chemically insolubilized ascorbate oxidase from squash peelings specifically detects by measuring oxygen uptake 10 to 400 μg of ascorbic acid in 3 ml of phosphate buffer. The record of current response to substrate addition lasts 1-2 min. The ascorbic acid values determined in various samples of fruit juices are in good agreement with the data obtained by titration and polarography. The suitable composition of the membrane and its lifetime and stability during long-term storage are described; optimal reaction conditions of vitamin C determination and the possibilities of interference of other compounds are also examined. Of the 35 phenols, aromatic amines and acids tested chlorogenic acid only can cause a positive error provided that the enzyme membrane has been prepared from ascorbate oxidase of high purity.

scholarly journals Computational engineering of the oxygen electrode-electrolyte interface in solid oxide fuel cells

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Kaiming Cheng ◽  
Huixia Xu ◽  
Lijun Zhang ◽  
Jixue Zhou ◽  
Xitao Wang ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Solid Oxide Fuel Cells ◽  
Microstructure Evolution ◽  
Oxygen Electrode ◽  
Solid Oxide ◽  
Ohmic Loss ◽  
Oxide Fuel ◽  
Computational Engineering ◽  
Electrolyte Interface

AbstractThe Ce0.8Gd0.2O2−δ (CGO) interlayer is commonly applied in solid oxide fuel cells (SOFCs) to prevent chemical reactions between the (La1−xSrx)(Co1−yFey)O3−δ (LSCF) oxygen electrode and the Y2O3-stabilized ZrO2 (YSZ) electrolyte. However, formation of the YSZ–CGO solid solution with low ionic conductivity and the SrZrO3 (SZO) insulating phase still happens during cell production and long-term operation, causing poor performance and degradation. Unlike many experimental investigations exploring these phenomena, consistent and quantitative computational modeling of the microstructure evolution at the oxygen electrode–electrolyte interface is scarce. We combine thermodynamic, 1D kinetic, and 3D phase-field modeling to computationally reproduce the element redistribution, microstructure evolution, and corresponding ohmic loss of this interface. The influences of different ceramic processing techniques for the CGO interlayer, i.e., screen printing and physical laser deposition (PLD), and of different processing and long-term operating parameters are explored, representing a successful case of quantitative computational engineering of the oxygen electrode–electrolyte interface in SOFCs.

scholarly journals Intelligent long-term performance analysis in power electronics systems

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Saeed Peyghami ◽  
Tomislav Dragicevic ◽  
Frede Blaabjerg
Keyword(s):  
Performance Indicator ◽  
Thermal Characteristics ◽  
Operating Conditions ◽  
System Level ◽  
Power Electronic ◽  
Reliability Modeling ◽  
Artificial Neural Network Ann ◽  
Long Term Performance ◽  
Term Performance

AbstractThis paper proposes a long-term performance indicator for power electronic converters based on their reliability. The converter reliability is represented by the proposed constant lifetime curves, which have been developed using Artificial Neural Network (ANN) under different operating conditions. Unlike the state-of-the-art theoretical reliability modeling approaches, which employ detailed electro-thermal characteristics and lifetime models of converter components, the proposed method provides a nonparametric surrogate model of the converter based on limited non-linear data from theoretical reliability analysis. The proposed approach can quickly predict the converter lifetime under given operating conditions without a further need for extended, time-consuming electro-thermal analysis. Moreover, the proposed lifetime curves can present the long-term performance of converters facilitating optimal system-level design for reliability, reliable operation and maintenance planning in power electronic systems. Numerical case studies evaluate the effectiveness of the proposed reliability modeling approach.

Ni-based bimetallic nano-catalysts anchored on BaZr0.4Ce0.4Y0.1Yb0.1O3−δ for internal steam reforming of methane in a low-temperature proton-conducting ceramic fuel cell

2021 ◽  
Author(s):  
Kyungpyo Hong ◽  
Stephanie Nadya Sutanto ◽  
Jeong A. Lee ◽  
Jongsup Hong
Keyword(s):  
Steam Reforming ◽  
Low Temperatures ◽  
Operating Conditions ◽  
Hydrogen Yield ◽  
Carbon Formation ◽  
Long Term Stability ◽  
Ceramic Fuel Cell ◽  
Ceramic Fuel ◽  
Nano Catalysts

Ni–Rh and Ni–Co nano-scale alloys exhibit high methane conversion, hydrogen yield, resistance to carbon formation, and long-term stability at low temperatures, allowing them to cope with the various operating conditions of direct methane-fueled PCFCs.

Effect of CO2 on Anti-Corrosion Property of a Polyurea Coating Modified with Organosilicone

2014 ◽  
Vol 789 ◽  
pp. 466-470
Author(s):  
Qing Hao Shi ◽  
Bing Ying Wang ◽  
Bin Zhao
Keyword(s):  
High Temperature ◽  
Partial Pressure ◽  
Composite Coating ◽  
Corrosion Test ◽  
Electrochemical Impedance ◽  
Failure Process ◽  
Corrosion Property ◽  
Corrosion Mechanism ◽  
Partial Pressures ◽  
High Temperature High Pressure

The corrosion mechanism of organic silicon modified polyurea composite coating under different CO2 partial pressures was studied using high-temperature autoclave, combined with scanning electron microscopy (SEM), adhesion tests and electrochemical impedance spectroscopy (EIS) technology. The experimental results showed that: there was no corrosion product formed on the surface of coating sample after high-temperature high-pressure corrosion test, and with the increasing of CO2 partial pressure, the coating adhesion and impedance values decline increases. Moreover CO2 partial pressure increases accelerated the failure process of polyurea composite coating system.

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