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@PHDTHESIS{Ramler:1052712,
      author       = {Ramler, Denise},
      title        = {{D}evelopment of an oxygen ion conducting solid oxide
                      electrolysis cell based on gadolinium-doped cerium oxide as
                      fuel electrode and electrolyte material},
      volume       = {689},
      school       = {RWTH Aachen University},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2026-01069},
      isbn         = {978-3-95806-879-7},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {ix, 162},
      year         = {2026},
      note         = {Dissertation, RWTH Aachen University, 2025},
      abstract     = {The global transition toward CO2-neutral energy systems
                      requires a significant expansion of hydrogen technologies,
                      with solid oxide electrolysis cells (SOECs) offering a
                      highly efficient route for hydrogen production via
                      high-temperature electrolysis. However, despite their
                      superior efficiency, SOECs remain technologically less
                      mature than low-temperature alternatives such as alkaline or
                      proton exchange membrane electrolyzers. Advancing SOEC
                      development therefore demands innovation in both cell design
                      and manufacturing strategies to achieve high performance,
                      mechanical stability, and costefficiency. This dissertation
                      focuses on the development and investigation of fully
                      screen-printed, fuel electrodesupported solid oxide cells
                      featuring a co-sintered tri-layer electrolyte architecture.
                      The work was conducted within the framework of the ElChFest
                      project, which aims to model the electro-chemomechanical
                      behavior of gadolinium-doped ceria based solid oxide cells
                      and understand crack formation phenomena in the electrolyte
                      during operation. A key objective was to fabricate
                      mechanically robust and electrochemically efficient cells by
                      optimizing the interplay between powder properties, paste
                      formulation, sintering behavior, and final microstructure.
                      Particular attention was paid to residual stresses induced
                      during manufacturing. The fabrication strategy centered
                      around screen printing as a scalable and cost-effective
                      deposition method. The project included the transition of
                      previously sputtered barrier layers to screen-printed
                      alternatives. A comprehensive study of powder processing
                      (encompassing pre-calcination and milling) was carried out
                      to tailor the sintering behavior and enable co-sintering of
                      the multi-layer cell. Rheological characterization of
                      screen-printing pastes revealed strong correlations between
                      print quality and parameters such as damping factor, yield
                      point, and particle distribution asymmetry. These findings
                      highlighted the critical role of paste rheology in achieving
                      defect-free and reproducible ceramic layers. The sintering
                      behavior of gadolinium-doped ceria (GDC) and
                      yttria-stabilized zirconia (YSZ) powders was evaluated using
                      both bulk pellets and screen-printed layers.
                      Gadolinium-doped ceria exhibited an earlier onset of
                      sintering and higher shrinkage than yttria-stabilized
                      zirconia. While co-doping and precalcination effectively
                      modified sintering kinetics, translating these findings to
                      printed layers required further adaptation due to the
                      mechanical constraints induced by the support. Co-sintering
                      trials showed that substrate shrinkage behavior had a
                      significant influence on electrolyte densification.
                      Pre-calcined NiO-8YSZ substrates often inhibited proper
                      densification, leading to increased porosity and cell
                      warping. The development of the tri-layer electrolyte
                      revealed additional microstructural challenges. Interfacial
                      porosity driven by interdiffusion and Kirkendall effects was
                      observed at the GDC/YSZ interfaces, when screen printing was
                      used. This porosity was not present in cells with sputtered
                      barrier layers. Consequently, optimizing the sintering
                      temperature became a balancing act between achieving
                      sufficient densification and suppressing
                      interdiffusion-related degradation. Electrochemical
                      characterization confirmed that cells with Ni-GDC fuel
                      electrodes outperformed conventional Ni-YSZ cells in terms
                      of stability, validating the choice of doped ceria. While
                      the best electrochemical performance was achieved in cells
                      with sputtered barrier layers, the fully screen-printed
                      cells showed competitive initial current densities and
                      area-specific resistances comparable to the stateof- the-art
                      Jülich Type III reference design. These results underscore
                      the viability of screen printing for fabricating
                      high-performance SOECs, provided that careful attention is
                      paid to interfacial engineering and sintering conditions. In
                      summary, this work demonstrates that fully screen-printed,
                      fuel electrode-supported SOECs with trilayer electrolytes
                      can be fabricated with high quality and performance but
                      require tightly controlled processing conditions. The
                      findings emphasize the need for compatible sintering
                      behaviors, advanced paste rheology control, and substrate
                      design tailored for co-sintering. Future work should focus
                      on developing novel, shrinkage-matched substrates to reduce
                      sintering temperatures without compromising densification.
                      Additional research into long-term stability under realistic
                      electrolysis conditions, reversible operation, and varying
                      steam concentrations is also essential to enable the broader
                      deployment of this technology in hydrogen production and
                      energy conversion.},
      cin          = {IMD-2},
      cid          = {I:(DE-Juel1)IMD-2-20101013},
      pnm          = {1231 - Electrochemistry for Hydrogen (POF4-123)},
      pid          = {G:(DE-HGF)POF4-1231},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      doi          = {10.34734/FZJ-2026-01069},
      url          = {https://juser.fz-juelich.de/record/1052712},
}