Effect of Aging on the Electrochemical Performance of LSM-YSZ Cathodes

Baqué, Laura; Jørgensen, Peter Stanley; Zhang, Wei; Søgaard, Martin

doi:10.1149/2.0181509jes

“…The C 2 cathode was extracted from a different cell from the same manufacturer. The cell from which C 2 was extracted was operated for 1500 hours; this operational time is not expected to cause significant changes to the SOFC cathode microstructure that are observable at ∼65 nm resolution, [62][63][64][65] and we simply focus on quantifying variability between regions of different cells.…”

Section: Methodsmentioning

confidence: 99%

Quantitative Analysis of Multi-Scale Heterogeneities in Complex Electrode Microstructures

Mahbub¹,

Epting²,

Hsu³

et al. 2019

J. Electrochem. Soc.

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A semi-empirical model is developed to quantitatively characterize electrode heterogeneities over the micro- and mesoscales, specifically between the relationship of the mean-squared normalized variance in the volume fraction, ( σ Φ V Φ ¯ V ) 2 , and the mean particle size normalized linear dimension, L a ¯ N . The model was developed analyzing data from five large-volume physical reconstructions – collected using Xe-plasma focused ion beam with SEM (PFIB-SEM) – of several commercial cell electrodes and from unique sets of synthetic microstructures designed to have controlled distributions in particle size and local volume fractions. When comparing physical reconstructions from distinct regions of the same electrode, millimeter length scale heterogeneities are also observed, even in microstructures with limited mesoscale variability. While the model is developed using synthetic microstructures, it is used to quantify three different types of heterogeneities in the commercial cells. The potential origins are discussed with respect to variations in particle size distributions in feedstocks and to phase distributions related to fabrication processes; the potential performance impacts are discussed with respect to two effective medium theory models. The characterization and analytical methodologies and model presented can support the design and development of improved electrodes.

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“…With this understanding, it can be inferred that a thickness of ∼14 μm appears to be closer to the optimal thickness that maximizes the available active sites for the cathode/gas interfacial reaction. [41][42][43] This proximity to the optimal thickness likely accounts for the observed reduction in LF responses (indicative of P ads ) for STF-t14.…”

Section: Resultsmentioning

confidence: 91%

“…This may be explained by the electrode being in the thin-electrode limit, 31,40 where the electrode thickness is not sufficiently large for R P to reach saturation. The hypothesis can be tested by estimating the active depth λ: 31,41…”

Section: Resultsmentioning

confidence: 99%

Enhancing Sr-deficient Sr(Ti_0.3Fe_0.7)O_3–δ Cathode Performance through Sm_0.5Sr_0.5CoO_3–δ Infiltration

Kim,

Park,

Park

2024

J. Electrochem. Soc.

1

0

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The development of cathodes with improved polarization, aimed at reducing the operating temperature of solid oxide fuel cells (SOFCs), is an important avenue of research toward more efficient SOFCs. Sr(Ti0.3Fe0.7)O3–δ recently emerged as an active and stable cathode material; although its oxygen transport capability was shown to be further improved by introducing a Sr deficiency, the accompanying increased sinterability creates challenges in optimizing cathode microstructure. One facile approach may be single-step infiltration with highly active materials, such as Sr0.5Sm0.5CoO3–δ (SSC). However, there is limited knowledge regarding the impact of SSC on the electrochemical mechanisms within Sr-deficient Sr(Ti0.3Fe0.7)O3–δ. In this study, we systematically investigate the electrochemical characteristics of SSC-infiltrated Sr0.95(Ti0.3Fe0.7)O3–δ (STF) cathodes. Transmission line model-based impedance analysis provides a mechanistic understanding of STF and the role of SSC infiltrants in polarization improvement. The results reveal that SSC effectively reduces the resistance associated with key electrode processes, including oxygen diffusion, surface exchange, and dissociative adsorption/desorption. Consequently, using SSC infiltration, the power density of a Ni–Zr0.84Y0.16O2–δ (YSZ) anode-supported full cell with thin (~2.5 μm) electrolyte increased from ~1.88 to ~2.47 W cm–2 at 800 °C.

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“…The AC impedance spectra were obtained at 380, 420, 460, 500, 540, 580, and 620 °C under an excitation of 20 mV over the frequency range from 1 mHz to 100 kHz in 5% O 2 containing dry air. The impedance spectra were fitted by Zview3.2 program by using the equivalent circuit R s (R 1 Q 1 ) (R 2 Q 2 ), where R s is the ohmic resistance and Q is the constant phase element [18,19]. The electrochemical activity was evaluated from impedance spectra by the difference between the high-frequency and low-frequency intercepts with the real axis.…”

Section: Methodsmentioning

confidence: 99%

High-Performance Limiting Current Oxygen Sensor Comprised of Highly Active La0.75Sr0.25Cr0.5Mn0.5O3 Electrode

Zou

¹

,

Lin

²

,

Cheng

³

et al. 2018

Sensors

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Zirconia-based limiting current oxygen sensor gains considerable attention, due to its high-performance in improving the combustion efficiency of fossil fuels and reducing the emission of exhaust gases. Nevertheless, the Pt electrode is frequently used in the oxygen sensor, therefore, it restrains the broader application due to the high cost. Quite recently, La0.75Sr0.25Cr0.5Mn0.5O3 (LSCM) has been reported to be highly active to catalyze oxygen reduction. Herein, with the intention of replacing the frequently used Pt, we studied the practicability of adapting the LSCM to zirconia-based limiting current oxygen sensor. Through comparing the electrocatalytic activity of LSCM and Pt, it is confirmed that LSCM gave analogous oxygen reactivity with that of the Pt. Then, limiting the current oxygen sensors comprised of LSCM or Pt are fabricated and their sensing behavior to oxygen in the range of 2–25% is evaluated. Conclusively, quick response/recovery rate (within 7s), linear relationship, and high selectivity (against 5% CO2 and H2O) in sensing oxygen are observed for the sensors, regardless of the sensing materials (LSCM or Pt) that are used in the sensor. Particularly, identical sensing characteristics are observed for the sensors consisting of LSCM or Pt, indicating the practicability of replacing the Pt electrode by adapting the LSCM electrode to future zirconia-based oxygen sensors.

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Effect of Aging on the Electrochemical Performance of LSM-YSZ Cathodes

Cited by 12 publications

References 48 publications

Quantitative Analysis of Multi-Scale Heterogeneities in Complex Electrode Microstructures

Quantitative Analysis of Multi-Scale Heterogeneities in Complex Electrode Microstructures

Enhancing Sr-deficient Sr(Ti_0.3Fe_0.7)O_3–δ Cathode Performance through Sm_0.5Sr_0.5CoO_3–δ Infiltration

High-Performance Limiting Current Oxygen Sensor Comprised of Highly Active La0.75Sr0.25Cr0.5Mn0.5O3 Electrode

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Effect of Aging on the Electrochemical Performance of LSM-YSZ Cathodes

Cited by 12 publications

References 48 publications

Quantitative Analysis of Multi-Scale Heterogeneities in Complex Electrode Microstructures

Quantitative Analysis of Multi-Scale Heterogeneities in Complex Electrode Microstructures

Enhancing Sr-deficient Sr(Ti0.3Fe0.7)O3–δ Cathode Performance through Sm0.5Sr0.5CoO3–δ Infiltration

High-Performance Limiting Current Oxygen Sensor Comprised of Highly Active La0.75Sr0.25Cr0.5Mn0.5O3 Electrode

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Product

Resources

About

Enhancing Sr-deficient Sr(Ti_0.3Fe_0.7)O_3–δ Cathode Performance through Sm_0.5Sr_0.5CoO_3–δ Infiltration