EIS measurements for the LSC layer as a function of annealing temperature

Electrochemical impedance spectroscopy (EIS) was employed to evaluate the ohmic resistance (Rₒₕₘ) and polarization resistance (Rₚₒₗ) of the fabricated symmetrical cells (LSC|CGO|LSC). Measurements were conducted using a sinusoidal excitation signal with an amplitude of 25 mV over a frequency range spanning from 3 MHz to 50 mHz. The specimens were mounted in a compression setup, where each side of the sample was in contact with a gold mesh, which was electrically connected to platinum wires extending outside the furnace chamber. The primary objective of the EIS analysis was to investigate how the structural characteristics of the material—specifically, its partially amorphous and crystalline nature—affect its catalytic performance. All measurements were carried out under a synthetic air atmosphere at a controlled flow rate of 50 ml·min⁻¹. The temperature range for the experiments was adjusted according to the specific annealing temperature of each sample. For samples annealed at lower temperatures, measurements were taken at smaller temperature intervals to enable a more detailed assessment of the material's behavior in the low-temperature regime.