Influence of Microstructure on Electrochemical Performance of Plasma Sprayed Ni‐YSZ Anodes for SOFCs

The influence of anode microstructural parameters on the electrochemical performance of plasma sprayed solid oxide fuel cells with metal supports has been investigated. Electrochemical impedance spectroscopy (EIS) was used to correlate the measured polarization resistances associated with both the three‐phase boundary length density and gas diffusivity of porous nickel/yttria‐stabilized zirconia (YSZ) anodes. Each anode was deposited in atmospheric conditions using solution precursor plasma spraying (SPPS), dry‐powder plasma spraying (DPPS), or suspension plasma spraying (SPS). The high‐frequency (> 1 kHz) part of the impedance spectrum was found to correlate with the three‐phase boundary length per unit volume of each anode. The low‐frequency part of the impedance spectrum was found to correlate with diffusive transport of gases through the porous anode. Gas transport measurements in the context of the dusty gas model were used to extract microstructure‐dependent parameters that provided a quantitative comparison among the distinct microstructures obtained using the three plasma spray methods. These results were compared to measurements using Darcy's law, which yielded similar trends and provided an efficient method to more rapidly compare gas transport rates in porous electrodes having different structures.