Break‐down of Losses in High Performing Metal‐Supported Solid Oxide Fuel Cells

A detailed electrochemical impedance study with the help of the distribution of relaxation times (DRT) method and a subsequent CNLS-fit enabled us to quantitatively analyze the different loss contributions in the cell: the ohmic resistance and the polarization processes related to the gas diffusion in the metal support, the electrochemical fuel oxidation at the anode and the oxygen reduction in the mixed ionic electronic conducting cathode. An additional process with a rather high relaxation frequency was attributed to the formation of insulating interlayers at the cathode/electrolyte-interface. Based on these results, selective measures to improve performance and stability, such as (i) PVD-deposited CGO buffer layer preventing solid state reaction between cathode and the zirconia-based electrolyte, (ii) LSC-CGO based in-situ sintered cathodes and (iii) reduced corrosion of the metal support, were adopted and validated.