Numerical Simulation of the SrZrO3 Formation in Solid Oxide Fuel Cells

The Ce1-xGdxO2-delta (CGO) interlayer is a common reaction barrier layer employed in solid oxide fuel cells (SOFCs), to prevent chemical reactions between the (La1-xSrx)(Co1-yFey)O3-delta (LSCF) cathode and the Y2O3-stabilized ZrO2 (YSZ) electrolyte. However, even with the existence of the CGO layer, formation of SrZrO3 (SZO) insulating phase can still take place, causing cell degradation. Considering there have already been a large amount of experimental investigations conducted on the above degradation phenomenon, the current work is attempting to numerically model the process. A simplified numerical model of SZO formation at the YSZ-CGO interface is constructed. Based on the thermodynamic information and diffusion kinetics of the YSZ-CGO-LSCF system from the literature, the interdiffusion between YSZ and CGO, the Sr diffusion through the CGO layer, and the formation of SZO at the YSZ-CGO interface are modelled, reproducing the experimental data well. Limitations of the current modeling work are further discussed.