Low-temperature co-firing process of solid oxide fuel cells by a trace of copper

•YSZ-based SOFCs with trace of copper is fabricated by co-firing at 1250 °C.•Co-fired cell shows reasonable OCV value of 1.011 V at 850 °C.•Power density without insulating phase at cathode is 0.71 W cm−2 at 850 °C.

8 mol % yttria stabilized zirconia (8 YSZ) is widely used as an electrolyte material for solid oxide fuel cells (SOFCs) at high temperatures, but its poor sinterability causes complications of the cell fabrication processes, increasing manufacturing costs significantly. In this study, a low-temperature co-firing process for the YSZ-based SOFCs is developed by adding the small amount of Cu to each of YSZ electrolytes and anodes. The cells are successfully fabricated without any distortions or cracks. The cell is about 1.011 V at 850 °C in open circuit voltage (OCV), which is reasonable despite of the co-firing process even at 1250 °C. The maximum power density is 0.71 W cm−2 at 850 °C, which has similar performance of a conventional cell fabricated by multi-step process. Overall, the co-firing process using Cu can become promising for cost-effective fabrication process of the SOFCs except the problems related to the cathode.