Effect of anode thickness on impedance response of anode-supported solid oxide fuel cells

This study examines effects of the anode functional layer thickness on the performance of anode-supported solid oxide fuel cells (SOFCs). The SOFCs with different AFL thicknesses (8 μm, 19 μm, and 24 μm) exhibit similar power densities at the measured current density range (0–2 A cm−2), but show different impedance responses. Further investigation on the spectra using the CNLS fitting method based on DRT-based equivalent circuit model helps us pinpoint two electrochemical processes directly affected by the AFL thickness changes, the charge transfer reaction in the AFL as well as the diffusion-coupled charge transfer reaction in the AFL. The combined effects of these two electrochemical processes probably forged a minimal impact on the overall fuel cell performance by offsetting each other, which offers a reasonable explanation of the seemingly little influence of the AFL thickness on the SOFC performance. ► Anode-supported SOFCs are prepared with an anode functional layer thickness (8, 19, and 24 μm). ► SOFCs with different AFL thicknesses exhibit similar performances at the 0–2 A cm−2 of current. ► However, SOFCs with different AFL thicknesses show different impedance responses. ► Two elements in the equivalent circuit respond to the AFL thickness by the fitting model.