Solid Oxide Fuel Cell Degradation, Recovery and Control via the Electrical Terminals

2014 ◽  
Author(s):  
Peter A. Lindahl ◽  
Xuelei Hu ◽  
Joshua Wold ◽  
Matthew Cornachione ◽  
Steven R. Shaw
Keyword(s):  
Electrochemical Impedance ◽  
Open Circuit ◽  
Solid Oxide ◽  
Load Test ◽  
Electrical Performance ◽  
Oxide Fuel ◽  
Large Signal ◽  
Eis Measurements ◽  
Current Loading ◽  
And Control

This paper presents results from an investigation concerning load-induced degradation, recovery, and control of solid oxide fuel cells (SOFCs). In this study, commercially available SOFCs were subject to extended over-current conditions, followed by periods of open-circuit operation. During times of current loading, degradation was observed in the cells’ electrical performance through polarization and electrochemical impedance spectroscopy (EIS) measurements. These measurements showed an increase in the polarization curve’s ohmic region slope, i.e. large-signal resistance, as well as an increase in the cell’s small-signal low-frequency impedance. The degradation was temporary however, as the electrical performance recovered during times of open-circuit operation. These results, attributed to electrochemically-induced oxidation and reduction of nickel in the anode, suggest the degradation phenomenon is controllable via the electrical terminals. As such, an additional test was performed on an SOFC powering a pulse-width modulated load, with the load’s duty-cycle negatively proportional to the cell’s large-signal resistance. Polarization and EIS measurements taken during this test showed that despite the controlled load, degradation occurred throughout the test. However, post-test scanning electron microscope images revealed cracks in the cell’s cathode along the boundary between the active and bulk layers. This type of cracking was not observed in the original degradation and recovery tests, suggesting that the degradation observed in the controlled load test was irreversible and caused by a separate phenomenon.

Measurements of Lateral Impedance and Local Characteristics of Solid Oxide Fuel Cells

2012 ◽  
Vol 9 (4) ◽  
Author(s):  
Shih-Wei Cheng ◽  
Yaw-Hwa Shui ◽  
Yung-Neng Cheng ◽  
Ruey-Yi Lee
Keyword(s):  
Fuel Cells ◽  
Solid Oxide Fuel Cells ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Local Characteristics ◽  
Eis Measurements ◽  
Original Cell ◽  
Lower Impedance

Lateral impedance and local characteristics of anode-supported solid oxide fuel cells (SOFCs) are studied in this paper. The testing device, which combines the original cell housing with a four-point probe equipment, is set for measuring SOFC single cell. The current collectors on anode and cathode in the original cell housing are, respectively, replaced by four independent probe units. They are not only to collect current, but also become measuring probes. Therefore, the lateral impedance of anode and cathode can be measured. Furthermore, the local characteristics are examined by open circuit voltage (OCV), I-V curve, and electrochemical impedance spectroscopy (EIS) measurements. The results show that the lateral impedance is substantially varied with temperature, the OCV at the center of the cell are higher than the edge, the central location on cell have better performance and lower impedance than the marginal location.

scholarly journals Fabrication and Electrochemical Performance of Zn-Doped La0.2Sr0.25Ca0.45TiO3 Infiltrated with Nickel-CGO, Iron, and Cobalt as an Alternative Anode Material for Solid Oxide Fuel Cells

Catalysts ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 269 ◽  
Author(s):  
Nazan Muzaffar ◽  
Nasima Arshad ◽  
Daniel Drasbæk ◽  
Bhaskar Sudireddy ◽  
Peter Holtappels
Keyword(s):  
Fuel Cells ◽  
Electrochemical Performance ◽  
Solid Oxide Fuel Cells ◽  
Polarization Resistance ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Sulphur Poisoning ◽  
Operating Temperatures

In solid oxide fuel cells, doped strontium titinates have been widely studied as anode materials due to their high n-type conductivity. They are used as current conducting backbones as an alternative to nickel-cermets, which suffer degradation due to coking, sulphur poisoning, and low tolerance to redox cycling. In this work, anode backbone materials were synthesized from La0.2Sr0.25Ca0.45TiO3−δ (LSCTA-), modified with 5 wt.% Zn, and infiltrated with nickel (Ni)/ceria gadolinium-doped cerium oxide (CGO), Fe, and Co. The electrodes were further studied for their electrochemical performance using electrochemical impedance spectroscopy (EIS) at open circuit voltage (OCV) in different hydrogen to steam ratios and at various operating temperatures (850–650 °C). Infiltration of electrocatalysts significantly reduced the polarization resistance and among the studied infiltrates, at all operating temperatures, Ni-CGO showed excellent electrode performance. The polarization resistances in 3% and 50% H2O/H2 atmosphere were found to be 0.072 and 0.025 Ω cm2, respectively, at 850 °C, and 0.091 and 0.076 Ω cm2, respectively, at 750 °C, with Ni-CGO. These values are approximately three orders of magnitude smaller than the polarization resistance (25 Ω cm2) of back bone material measured at 750 °C.

scholarly journals Synthesis and Characterization of High Temperature Properties of YBa2Cu3O6+δ Superconductor as Potential Cathode for Intermediate Temperature Solid Oxide Fuel Cells

2021 ◽  
Vol 8 ◽  
pp. 82-91
Author(s):  
Joaquín Grassi ◽  
Mario A. Macías ◽  
Juan F. Basbus ◽  
Jorge Castiglioni ◽  
Gilles H. Gauthier ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Combustion Method ◽  
Catalytic Performance ◽  
Solid Oxide ◽  
Intermediate Temperature ◽  
Oxide Fuel ◽  
Space Groups ◽  
Auto Combustion ◽  
Potential Applications ◽  
Eis Measurements

YBa2Cu3O6+δ (YBC) oxygen deficient perovskite was synthesized by an auto-combustion method and was studied as potential cathode for Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC). Synchrotron X-ray thermodiffraction in air shows a phase transition from orthorhombic Pmmm to tetragonal P4/mmm space groups at ~ 425 °C. The chemical compatibility with Ce0.9Gd0.1O1.95 (GDC) electrolyte was investigated in air where certain reactivity was observed above 800 °C. However, the main phase is Ba(Ce1-xYx)O3, a good ionic conductor. The catalytic performance in air was obtained by electrochemical impedance spectroscopy (EIS) measurements on YBC/GDC/YBC symmetrical cells. The area specific resistance (ASR) values change from 13.66 to 0.14 Ω cm2 between 500 and 800 °C, with activation energy (Ea) of 0.41 eV. The results suggest potential applications of YBC as IT-SOFC cathode.

On the Identification of Impedance Spectroscopy Processes of an SOFC Under Different Hydrogen Concentrations

2012 ◽  
Vol 9 (5) ◽  
Author(s):  
Gianfranco DiGiuseppe ◽  
Li Sun
Keyword(s):  
Impedance Spectroscopy ◽  
Open Circuit Voltage ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Impedance Measurements ◽  
And Diffusion ◽  
Over Time

This paper reports a series of new electrochemical impedance measurements that were performed on an anode supported planar solid oxide fuel cell (SOFC) tested at different anode gas conditions and at different applied voltages. This study indicates that impedance spectroscopy can resolve four different processes, as long as one of those processes does not become too large. At open circuit voltage the four processes can be resolved best; however, as a voltage is applied the processes are convoluted and cannot be resolved properly. Two of the processes seem to remain almost unchanged as the fuel conditions are changed and can be attributed to the cathode. The two anode processes change with the fuel conditions and both indicate a dependence on charge transfer and diffusion. This methodology can be applied to determine the mode or modes of SOFC degradation for long term testing where one or both electrodes are deteriorating over time.

Improved electrical performance and sintering ability of the composite interconnect La0.7Ca0.3CrO3−δ/Ce0.8Nd0.2O1.9 for solid oxide fuel cells

2009 ◽  
Vol 191 (2) ◽  
pp. 377-383 ◽  
Author(s):  
Xiaoliang Zhou ◽  
Peng Wang ◽  
Limin Liu ◽  
Kening Sun ◽  
Zhiqiang Gao ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Solid Oxide Fuel Cells ◽  
Solid Oxide ◽  
Electrical Performance ◽  
Oxide Fuel

Al2O3 toughening ScSZ electrolyte fabricated by water-based tape casting technique for solid oxide fuel cells

2021 ◽  
pp. 1-17
Author(s):  
Haoran Wang ◽  
Ze Lei ◽  
Han Zhang ◽  
Yongkang Li ◽  
Junmeng Jing ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Solid Oxide Fuel Cells ◽  
Bending Strength ◽  
Tape Casting ◽  
Solid Oxide ◽  
Electrical Performance ◽  
Oxide Fuel ◽  
Casting Technique ◽  
Electrolyte Film ◽  
Water Based

Abstract A water-based tape casting slurry is reported to prepare the ceria and scandia co-doped zirconia (ScSZ) electrolyte films. The slurry is characterized and optimized through Zeta potential and rheological property measurements. Smooth and flat ScSZ electrolyte films are obtained by improving the sintering process. The microstructure, electrical performance, and mechanical property of ScSZ with adding different contents of Al2O3 are also investigated. The results show that a proper amount of Al2O3 has a beneficial effect on the densification of ScSZ. Significant decrease at the grain boundary resistance of ScSZ is observed by Al2O3 addition. The bending strength of the sample with 0.5 wt.% Al2O3 (ScSZ-0.5A) is about 400 MPa, which is 20% higher than pure ScSZ. The ScSZ-0.5A electrolyte film fabricated by water-based tape casting method shows appropriate electrical conductivity and high mechanical strength, which is promising for the practical application in solid oxide fuel cells (SOFCs).

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