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| Home > Publications database > Electrochemical impedance analysis and degradation behavior of a commercial Ni-YSZ/YSZ/GDC/LSC single cell in direct CO2 electrolysis |
| Home > Publications database > Electrochemical impedance analysis and degradation behavior of a commercial Ni-YSZ/YSZ/GDC/LSC single cell in direct CO2 electrolysis |
| Conference Presentation (After Call) | FZJ-2026-01663 |
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2025
Abstract: This study investigated the performance and electrochemical behavior of a commercial Ni-YSZ/YSZ/GDC/LSC single cell using AC- and DC- techniques under high temperature CO2 electrolysis conditions. The effects of the operating temperature, CO2 content in the fuel gas, and the oxygen partial pressure on the oxygen electrode side were evaluated. The maximum current density observed was 1.36 A‧cm-2 at 1.5 V and 900 °C. Furthermore, the maximum current densities of -1.2, -0.99, and -0.77 A·cm-2 were observed at 850, 800, and 750 °C, respectively, at 1.5 V under a fuel gas composition of 80% CO2 and 20% CO. The corresponding observed Area Specific Resistance (ASR) values are 0.29, 0.33, 0.38, and 0.49 Ω·cm2 at 900, 850, 800, 800, and 750 °C, respectively. A direct correlation was observed between temperature and ASR values: as the temperature increases, the current density increases, while the ASR values decrease. Furthermore, to analyze the ohmic resistance (RΩ), polarization resistance (Rp), and electrode processes, electrochemical impedance spectroscopy (EIS) was used. The recorded impedance spectrum was analyzed using the Distribution of Relaxation Times (DRT) method and an equivalent circuit model (ECM). The ECM consisting of four-time constants (LR–RC1–RC2–RQ–Ws) gives the best fit of the impedance data compared to other models. The activation energies for RΩ and Rp were calculated from the slopes of the Arrhenius plots. The obtained activation energies were 44 ± 8 kJ mol⁻¹ and 32 ± 3 kJ mol⁻¹ for RΩ and Rp, respectively. The electrode processes were then compared with the literature and found that the low-frequency Warburg short element (Ws) was attributed to gas diffusion at the fuel electrode, while the mid-frequency processes (R₃ and R₄) were associated with the combined contributions of the fuel and oxygen electrodes. Activation energies for the resistances R1, R2, R3, R4 and Ws were calculated using the Arrhenius plot.Finally, the short-term stability tests were conducted at 700, 750, and 800 °C for over 650 hours under a constant current load of -0.5 A‧cm⁻² under 80% CO2 and 20% CO gas composition. The degradation rates of 38, 36, and 34 mV‧kh-1 were found at 700, 750, and 800 °C, respectively. These are lower than the values reported in the literature under CO2 electrolysis conditions
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