Electrochemical Performance of Solid Oxide Cell Oxygen Electrodes Under Pressurization

Hughes, G.; Railsback, Justin G.; Butts, Danielle M.; Barnett, Scott A.

doi:10.1149/06801.0687ecst

Cited by 11 publications

(15 citation statements)

References 22 publications

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“…5D whether the oxygen-electrode process at 600 Hz was affected by pressure, but it is assumed that the related resistance also decreases with increasing pressure, as observed in previous pressurized electrode experiments. [23,29] The difference spectrum in Fig. 5B for the shift in the H2O composition has a peak around 6 kHz in agreement with previous observations on Ni-YSZ-electrodes.…”

Section: Impedance Vs Pressuresupporting

confidence: 90%

“…It has previously been observed that charge transfer limited reactions involving dissociative adsorbed oxygen at low coverage on composite LSM/YSZ-electrodes exhibit a -0.25 exponent [23]. The total pressure dependency of an LSM/YSZ electrode was recently reported to exhibit a -0.17 exponent dependency [29]. A -0.27 exponent behaviour have been found for the PH2O dependence for Ni-YSZ electrodes.…”

Section: Impedance Vs Pressurementioning

confidence: 91%

“…The same trend has been observed previously on stacks, single cells and electrodes. [16,17,19,23,29] A small increase in the ASR is seen from 20 bar to 25 bar. This is most likely caused by a slightly lower stack temperature at 25 bar than at 20 bar (Fig.…”

Section: Asr Vs Pressurementioning

confidence: 93%

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Pressurized Operation of a Planar Solid Oxide Cell Stack

et al. 2016

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Abstract:Solid oxide cells (SOCs) can be operated either as fuel cells (SOFC) to convert fuels to electricity or as electrolysers (SOEC) to convert electricity to fuels such as hydrogen or methane. Pressurized operation of SOCs provide several benefits on both cell and system level. If successfully matured, pressurized SOEC based electrolysers can become more efficient both energy-and cost-wise than PEM and Alkaline systems. Pressurization of SOFCs can significantly increase the cell power density and reduce the size of auxiliary components.In the present study, a SOC stack was successfully operated at pressures up to 25 bar. The pressure dependency of the measured current-voltage (iV) curves and impedance spectra on the SOC stack are analysed and the relation between various system parameters and pressure is derived. With increasing pressure the open circuit voltage (OCV) and the reaction kinetics (electrode performance) increases for thermodynamic and kinetic reasons, respectively. Further, the summit frequency of the gas concentration impedance arc and the pressure difference across the stack and heat exchangers is seen to decrease with increasing pressure following a power-law expression. Finally a durability test was conducted at 10 bar.

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Section: Impedance Vs Pressuresupporting

confidence: 90%

Section: Impedance Vs Pressurementioning

confidence: 91%

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Pressurized Operation of a Planar Solid Oxide Cell Stack

et al. 2016

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“…The evolution of the impedance diagrams at OCP are given in Fig 7a and 7b for oxygen partial pressures ranging from 0.1 to 1 atm. It can be noticed that the electrode polarization resistance significantly decreases when increasing the oxygen content, as already experimentally observed in [49,74,75]. The reaction order m was estimated fitting the experimental data with the following relation:…”

Section: Experimental Results and Model Validation 41 Electrode 3d Reconstructions And Electrochemical Characterizationsmentioning

confidence: 75%

An Elementary Kinetic Model for the LSCF and LSCF-CGO Electrodes of Solid Oxide Cells: Impact of Operating Conditions and Degradation on the Electrode Response

Effori

Laurencin

Silva

et al. 2021

J. Electrochem. Soc.

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An elementary kinetic model was developed to predict the electrochemical response of porous LSCF and LSCF-CGO electrodes. The model was validated thanks to experiments performed on symmetrical cells using a three-electrode setup. After the model calibration on polarization curves, it has been shown that the model is able to simulate accurately the experimental impedance diagram at OCP and under polarization without additional fitting.Moreover, the evolution of the electrode polarization resistance with the oxygen partial pressure is well reproduced by the model. The electrodes reaction mechanism was thoroughly analyzed and it has been shown that the transition from the bulk path to the surface path depends on the temperature, the polarization and the oxygen partial pressure. The rate-determining steps for the LSCF electrode have been identified at OCP as function of the oxygen partial pressure.Finally, a sensitivity analysis has been performed to study the impact of LSCF demixing on the electrode performances. For a given decomposition, it has been highlighted that the surface passivation would be more impacting than the decrease of the ionic conductivity. Moreover, the impact of the LSCF decomposition would be more detrimental for the electrode performances evaluated in electrolysis mode.

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“…10 Furthermore, previous studies have shown that with increasing the pressure, the total area specific resistance (ASR total ) decreases significantly with fuel electrode supported cells. [11][12][13][14][15] During co-electrolysis operation H 2 O and CO 2 reduction occur at the fuel electrode and require energy supply due to the endothermic properties of the reactions shown in Eqs. 1…”

Section: Asr Polmentioning

confidence: 99%

Experimental Analysis of the Co-Electrolysis Operation under Pressurized Conditions with a 10 Layer SOC Stack

Riedel

Heddrich

Friedrich

2020

J. Electrochem. Soc.

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This study examines the performance of a solid oxide cell (SOC) stack during co-electrolysis of CO2 and H2O at elevated pressures up to 8 bar. Steady-state and dynamically recorded U(i)-curves were performed in order to evaluate the performance over a wide temperature range and to quantify the area specific resistance (ASR) at different pressure levels. Furthermore, the outlet gas composition at various current densities was analyzed and compared with the thermodynamic equilibrium. The open circuit voltage (OCV) was found to increase with higher pressure due to well known thermodynamic relations. An increase of the limiting current density at elevated pressure was not observed for the investigated stack with electrolyte supported cells. The ASR of the stack was found to decrease slightly with higher pressure. It revealed an increase of the cell resistance with lower H/C ratios in the feed at lower temperatures, whereas the performance of the co-electrolysis was very similar to steam electrolysis for temperatures above 820 °C. Within an impedance study for steam, co- and CO2 electrolysis operation it was shown that pure CO2 electrolysis exhibits a higher pressure sensitivity compared to pure steam or co-electrolysis due to significantly increased activation and diffusion resistances.

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Electrochemical Performance of Solid Oxide Cell Oxygen Electrodes Under Pressurization

Cited by 11 publications

References 22 publications

Pressurized Operation of a Planar Solid Oxide Cell Stack

Pressurized Operation of a Planar Solid Oxide Cell Stack

An Elementary Kinetic Model for the LSCF and LSCF-CGO Electrodes of Solid Oxide Cells: Impact of Operating Conditions and Degradation on the Electrode Response

Experimental Analysis of the Co-Electrolysis Operation under Pressurized Conditions with a 10 Layer SOC Stack

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