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@INPROCEEDINGS{Thankappakurup:1054009,
      author       = {Thankappakurup, Saranya and Vibhu, Vaibhav and Wolf,
                      Stephanie and Frömling, Till and Eichel, Rüdiger-A.},
      title        = {{E}lectrochemical impedance analysis and degradation
                      behavior of a commercial {N}i-{YSZ}/{YSZ}/{GDC}/{LSC} single
                      cell in direct {CO}2 electrolysis},
      reportid     = {FZJ-2026-01663},
      year         = {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},
      month         = {Jul},
      date          = {2025-07-13},
      organization  = {19th International Symposium on Solid
                       Oxide Fuel Cells (SOFC-XIX), Stockholm
                       (Sweden), 13 Jul 2025 - 18 Jul 2025},
      subtyp        = {After Call},
      cin          = {IET-1},
      cid          = {I:(DE-Juel1)IET-1-20110218},
      pnm          = {1232 - Power-based Fuels and Chemicals (POF4-123)},
      pid          = {G:(DE-HGF)POF4-1232},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/1054009},
}