Modeling the Polarization-Dependent Microstructure-Resolved Distribution of Oxygen Chemical Potential in Ceria-Based Electrolysis Cells

ECS Meeting Abstracts, vol. MA2025-03, pp. 186

Abstract

Incorporation of tri-layer ceria-based electrolyte structures with submicron thin yttria-stabilized zirconia layer (YSZ) sandwiched between the Gd-doped ceria (GDC) was reported to enhance the fuel cell performance, which was superior to that of conventional YSZ-based solid oxide fuel cells (SOFC) at intermediate temperatures [1]. Yet the trade-off between performance and durability of ceria-based cells becomes challenging, especially, if operated in electrolysis mode. The multi-layer solid oxide electrolyzer cells (SOEC) based on doped-ceria electrolyte are vulnerable to strong interfacial mechanical stresses that result from chemical expansion of reduced ceria under low-oxygen fuel conditions and inhomogeneous distribution of oxygen chemical potential within the cell microstructure. The phenomenon is believed to induce cracking of the electrolyte layer and associated drastic drop of cell performance under high electrolysis currents at high temperatures [2]. Previously, a virtual assembly of the hypothetical cell with no reference to its actual microstructure was used to create a one-dimensional model and analyse the electro-chemo-mechanical relationships in ceria-based SOEC under typical operational conditions [2]. In this contribution, we report on developing of three-dimensional finite elements method-based model for simulation of spatial distribution of oxygen chemical potential within the real microstructure of high-temperature solid oxide electrolyzer cells operated at typical ranges of polarization currents and hydrogen-steam ratios in the fuel. The microstructure of the cells was reconstructed using the focused ion beam scanning electron miscroscope tomography (FIB-SEM), in which the structure of porous Ni-GDC cathode and tri-layer GDC/YSZ/GDC electrolyte were explicitly resolved [3]. This tentative model solves for oxygen chemical potential in a GDC phase and accounts for its mixed ion-electron conductor nature and p O2 -dependence of electrical conductivity within the framework of secondary current distribution physics for electrochemical cells. The simulated spatial distribution of oxygen chemical potential in porous Ni-GDC cathode and tri-layer electrolyte provides the basis to estimate local chemical expansion and related mechanical stresses in the doped-ceria-based electrolysis cells under typical operating conditions. Additionally, the cell performance curves are simulated and compared to those obtained experimentally for the electrolyzer cells of the same design. In perspective, the developed model should enable the identification of possible sources and the mechanisms of cells' electro-chemo-mechanical failure on a microstructural level, hence, providing hints for determination of feasible operating conditions and optimization of the designs of ceria-based high-performance solid oxide electrolysis cells. References: J. Zhang, C. Lenser, N. Russner, A. Weber, N.H. Menzler, O. Guillon, J.Am.Ceram. Soc. 106, 93–99 (2023) C. Lenser, J. Zhang, N. Russner, A. Weber, O. Guillon and N. H. Menzler, J. Power Sources 541, 231505 (2022) L. Wehner, C. Lenser, K. Dzieciol, E. Wessel, J. Malzbender, R. Schwaiger, ECS Trans. 111 , 231–239 (2023)

Authors 8

1. Iurii Kogut

   Karlsruhe Institute of Technology

   Affiliation as printed

   IAM-ET, Karlsruhe Institute of Technology (KIT)

2. Christian Lenser

   Forschungszentrum Jülich

   Affiliation as printed

   IMD-2, Forschungszentrum Jülich GmbH

3. Denise Ramler Aachen

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   IMD-2, Forschungszentrum Jülich GmbH

   RWTH Aachen University, GHI

4. Stefan Kucharski

   Forschungszentrum Jülich

   Affiliation as printed

   IMD-2, Forschungszentrum Jülich GmbH

5. Luzie Wehner

   Forschungszentrum Jülich

   Affiliation as printed

   IMD-1, Forschungszentrum Jülich GmbH

6. E. Wessel

   Forschungszentrum Jülich

   Affiliation as printed

   IMD-1, Forschungszentrum Jülich GmbH

7. Norbert Heribert Menzler Aachen

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Forschungszentrum Jülich GmbH

   RWTH Aachen University, GHI

8. André Weber

   Karlsruhe Institute of Technology

   Affiliation as printed

   IAM-ET, Karlsruhe Institute of Technology (KIT)