From Ideal to Stack-like Contacting of an SOC

The cell performance of a solid oxide cell strongly depends on the testing environment and conditions. In case of an inert testing set-up with ceramic (Al 2 O 3 ) flow fields and gold (cathode) and nickel (anode) contact grids the losses inside the cell determine the performance [1]. For an electrolyte-supported cell with a nickel / gadolinium-doped ceria (Ni/CGO) fuel electrode and LSCF air electrode, the ideal cell behavior has been characterized by electrochemical impedance spectroscopy (EIS) and the subsequent analysis of the distribution of relaxation times (DRT) considering technically meaningful operating conditions. Furthermore, the deconvolution and quantification of the gas diffusion polarization has been shown with the help of ternary fuel gas mixtures with different gas diffusion coefficients. [2-4] In this contribution, the electrochemical characterization is now extended to a stack-like contacting of the solid oxide cell with different metallic interconnectors, protective coatings and contact layers. The resulting contact loss is quantified with a method by Kornely et al. [5] using potential probes at the interconnector and the air electrode in order to enable voltage loss measurements. The stack-like contacting leads to gas transport conditions different from the ideal case which is investigated at the fuel and air side with modified gas diffusion coefficients by using gas mixtures containing nitrogen and helium as well [2]. The positive effect of the protective coating towards the cell performance is evaluated by current-voltage characteristics and EIS measurements. Further, the electrode electrochemistry influenced by effects like chromium-poisoning will be shown and compared to the ideal contact set-up [2]. References: [1] D. Klotz et al., Electrochim. Acta , 227 , 110 (2017). [2] C. Grosselindemann et al., J. Electrochem. Soc. , 168 , 124506 (2021). [3] C. Grosselindemann et al., Proceedings of the 15 th EFCF , July 5 th -8 th (2022). [4] M. Riegraf et al., J. Electrochem. Soc. , 166 , F865 (2019). [5] M. Kornely et al., J. Power Sources , 196 , 7209-7216 (2011).