Uncovering the Microstructure-Performance Interplay of Infiltrated Freeze Tape Cast Electrodes for Solid Oxide Cells by Physics-based Modelling

Abstract

Novel electrode architectures featuring hierarchical porosity and catalyst nanoparticles have been gaining increasing attention to improve the performance of the state-of-the-art solid oxide cells. In this context, a microstructure-resolved electrochemical model is here developed to unravel the properties of freeze tape cast 8YSZ scaffolds, synthetically infiltrated with Nickel nanoparticles of different size. The electrode model was built in 1D and 2D versions, including the impact of the interconnector in its 2D version. It targets the electrode design optimization by elucidating the effect of pores anisotropy on the electrochemical activity, current and gas distribution. The electrochemical properties of infiltrated microstructures are compared to those of a conventional Ni-YSZ composite to assess the potential performance gain of tailored architectures. The most promising infiltrated functional layers showed considerably lower polarization resistance (≈0.028-0.039 Ω∙cm²) than the reference Ni-8YSZ electrode (0.071 Ω∙cm²) in the investigated operating conditions. Sensitivity analyses on the morphology of the support layer are carried out in both 1D and 2D simulations. The potential detrimental impact played by low catalyst loading encourages the manufacturing of composite hierarchical microstructures. The ordered lamellar porosity of the diffusion layer was also found to question the efficacy of conventional interconnector geometries for freeze tape cast electrodes.