Development of test protocols for solid oxide electrolysis cells operated under accelerated degradation conditions

Königshofer, Benjamin; Pongratz, Gernot; Nusev, Gjorgji; Boškoski, Pavle; Höber, Michael; Juričić, Đani; Kusnezoff, Mihails; Trofimenko, Nikolai; Schröttner, Hartmuth; Hochenauer, Christoph; Subotić, Vanja

doi:10.1016/j.jpowsour.2021.229875

Cited by 21 publications

(14 citation statements)

References 52 publications

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“…noted that the total charge transfer resistance of the hydrogen electrode increased significantly, when the feed gas water content was lowered below 40 mol% at 750 °C operating temperature and absolute current density reached higher than 0.5 A cm −2 . A similar phenomenon was also more recently discussed by Königshofer et al 33 Thus, 16 μm seems to be an optimum active layer thickness for SOC operation in electrolysis mode at 700 °C for the system used in this work. Figure 15 shows that at higher temperatures a thinner HEAL performs better as suggested and demonstrated in Fig.…”

supporting

confidence: 86%

Influence of Hydrogen Electrode Active Layer Thickness on Electrochemical Performance of Solid Oxide Cell Operating in Electrolysis Mode

Kukk,

Pylypko,

Lust

et al. 2023

J. Electrochem. Soc.

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Reversible solid oxide cell technology (RSOC) is a key technology in future hydrogen energy concepts and may play a significant role in stabilizing intermittent renewable electric power sources. Here we report an attempt to optimize the thickness of the hydrogen electrode active layer (HEAL) for solid oxide cells designed and developed initially for fuel cell application. Five cells with HEAL thickness of 0, 7, 12, 16, and 20 µm, prepared using industrial manufacturing methods, are analyzed using cyclic voltammetry and electrochemical impedance spectroscopy methods under a wide range of operating conditions. Optimal thickness of an active layer studied depends on operating conditions. Depending on the temperature and humidity applied highest performances were achieved for cells with HEAL thicknesses between 7 and 16 µm. At 800°C and 90% feed gas water content, the best cell had an active layer of 7 µm, drawing -3.5 A/cm2 current at -1.4 V.

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supporting

confidence: 86%

Influence of Hydrogen Electrode Active Layer Thickness on Electrochemical Performance of Solid Oxide Cell Operating in Electrolysis Mode

Kukk,

Pylypko,

Lust

et al. 2023

J. Electrochem. Soc.

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“…These values are in the same range or even lower compared to literature data. 17,18,[21][22][23][24][25][26][27][28] In Fig. 11 the voltage degradations of the RUs at 75% FU (SOFC) and 75% SC (SOEC) during the different mid-term operations are displayed.…”

Section: Resultsmentioning

confidence: 99%

“…[12][13][14] Moreover, the increasing need for energy storage via H 2 has fostered the research activities concerning SOC stack degradation in reversible SOFC/SOEC cycling operation mode. [15][16][17][18][19][20][21][22][23][24][25][26][27][28] However, the published stack degradation results during reversible cycling operation and the interpretations differ strongly from each other. The corresponding power degradation values in SOFC mode range from −0.5%/kh to −22%/kh and in SOEC mode from +0.1%/kh to +68%/kh.…”

Section: Challenges Of Reversible Sofc/soec Stack Operationmentioning

confidence: 99%

Analysis of Electrochemical Degradation Phenomena of SOC Stacks Operated in Reversible SOFC/SOEC Cycling Mode

Lang,

Lee,

Lee

et al. 2023

J. Electrochem. Soc.

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In recent years the degradation rates of high temperature stacks with solid oxide cells (SOC) during steady-state long-term operation in fuel cell (SOFC) and electrolysis (SOEC) mode have been steadily decreased. In contrast, the quantification and understanding of degradation mechanisms of SOC stacks during reversible SOFC/SOEC cycling operation still remains a challenging issue. Therefore, the present paper focusses on the detailed analysis and discussion of degradation phenomena of two SOC stacks during galvanostatic steady-state SOFC and reversible SOFC/SOEC cycling operation. The stacks with fuel electrode supported cells of Elcogen (Estonia) were fabricated by the industrial project partner E&KOA (Daejeon, Korea) within the Korean-German project “Solid Oxide Reversible Fuel Cell/Electrolysis Stack” (SORFES). The first 10-cell stack was tested at DLR during 1400 h and the results were used to improve the second 6-cell stack, which was operated at E&KOA during 2800 h. For electrochemical characterization jV-curves and electrochemical impedance spectroscopy were measured. The results between galvanostatic steady-state SOFC operation and reversible SOFC/SOEC cycling are compared. The degradation of the open circuit voltages, the performances and the resistances of the individual repeat units are presented and discussed. Moreover, possible degradation mechanisms are outlined.

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“…529 Although the performance of SOECs is generally improved while increasing the steam content of the cathode gas, as illustrated in section 7.2, the risk of Ni reoxidation is simultaneously increased. 501 Under a high steam content of 90 vol %, significant Ni reoxidation was observed after operating for 200 h at 835 °C, 530 and nearly 50% of the Ni on the electrode surface was similarly found to be reoxidized after merely 80 h under the condition of H 2 :H 2 O = 20:80. 531 Through converting more steam into hydrogen and reducing the propensity toward Ni reoxidation, operating at large current density offers an effective strategy to alleviate the degradation of the hydrogen electrode under high steam content, 532 whereas the degradation of the oxygen electrode is concurrently promoted, 533 and thus an optimized current density requires being selected to maximize the durability of the whole SOEC.…”

Section: Degradation Of Oxygen Electrodesmentioning

confidence: 99%

Water Electrolysis toward Elevated Temperature: Advances, Challenges and Frontiers

Zhang

Liu

et al. 2023

Chem. Rev.

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Since severe global warming and related climate issues have been caused by the extensive utilization of fossil fuels, the vigorous development of renewable resources is needed, and transformation into stable chemical energy is required to overcome the detriment of their fluctuations as energy sources. As an environmentally friendly and efficient energy carrier, hydrogen can be employed in various industries and produced directly by renewable energy (called green hydrogen). Nevertheless, large-scale green hydrogen production by water electrolysis is prohibited by its uncompetitive cost caused by a high specific energy demand and electricity expenses, which can be overcome by enhancing the corresponding thermodynamics and kinetics at elevated working temperatures. In the present review, the effects of temperature variation are primarily introduced from the perspective of electrolysis cells. Following an increasing order of working temperature, multidimensional evaluations considering materials and structures, performance, degradation mechanisms and mitigation strategies as well as electrolysis in stacks and systems are presented based on elevated temperature alkaline electrolysis cells and polymer electrolyte membrane electrolysis cells (ET-AECs and ET-PEMECs), elevated temperature ionic conductors (ET-ICs), protonic ceramic electrolysis cells (PCECs) and solid oxide electrolysis cells (SOECs).

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Development of test protocols for solid oxide electrolysis cells operated under accelerated degradation conditions

Cited by 21 publications

References 52 publications

Influence of Hydrogen Electrode Active Layer Thickness on Electrochemical Performance of Solid Oxide Cell Operating in Electrolysis Mode

Influence of Hydrogen Electrode Active Layer Thickness on Electrochemical Performance of Solid Oxide Cell Operating in Electrolysis Mode

Analysis of Electrochemical Degradation Phenomena of SOC Stacks Operated in Reversible SOFC/SOEC Cycling Mode

Water Electrolysis toward Elevated Temperature: Advances, Challenges and Frontiers

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