Characteristics of La0.6Sr0.4Co0.2Fe0.8O3-Cu2O mixture as a contact material in SOFC stacks

La0.6Sr0.4Co0.2Fe0.8O3 (LSCF), a cathode material for solid oxide fuel cells, is mixed with six weight percentages (2.46-21.74 wt%) of more conductive Cu2O powder for use as a cathode contact material. Electrical conductivity change is measured at 800 °C for 600 h. Conductivity first increases with the Cu2O weight percentage to reach a peak value 30.67 S/cm at 7.18 wt%, then decreases with further more Cu2O content. Microstructural examination reveals that Cu2O oxidizes as CuO in the high temperature environment with a loose matrix, which can raise the electrical resistance. LSCF-Cu2O paste with three weight percentages of Cu2O is also applied in steel/paste/steel assemblies. The area specific resistance is measured at 800 °C for 200-300 h. It is found that LSCF-7.18 wt% Cu2O exhibits the lowest resistance. Additionally, stack performance is compared between two single-cell stacks with Ag mesh and LSCF-4.9 wt% CuO as the contact layer respectively. It shows that the LSCF-4.9 wt% CuO stack yields comparable power output with a lower degradation rate. Experimental results indicate that LSCF with 7.18 wt% Cu2O addition can serve as a potential contact material.