Dependence of power density on anode functional layer thickness in anode-supported solid oxide fuel cells

To improve the power densities of anode-supported multilayer solid oxide fuel cells (SOFCs) based on an anode functional layer (AFL) and an anode support of Ni–YSZ (8 mol%Y2O3–ZrO2), we systematically investigated how the AFL thickness influenced power density and impedance spectra, preparing the AFL using 65 wt% NiO–35 wt% YSZ with the anode support using 60 wt% NiO–40 wt% YSZ. Among the prepared SOFCs with AFL thicknesses from 0 to 100 μm, the ∼10-μm-AFL SOFC (AFL10) showed the highest power density. Impedance spectroscopy of the prepared SOFCs was composed of an ohmic resistance as well as three constant phase elements (CPEs) resulting from activation- and concentration-polarizations. The impedance spectroscopy showed that AFL10 effectively decreased both the contact- and activation polarization-resistances. In addition, a part of the concentration polarization resistances for AFL10 was lower among the prepared SOFC samples. As such, AFL10 exhibited the highest power density among the prepared SOFC samples.