Performance of single cells and short stacks for intermediate temperature solid oxide fuel cell using thin electrolyte of YSZ and ScSZ

We have launched a project to develop a 1-kW-class SOFC system for residential power generation (RPG). Using cost-effective interconnects such as ferritic stainless steel, we developed an anode-supported, planar-type 1.2-kW-class SOFC stack that can be operated at intermediate temperatures (650° or 700°C). To achieve better cell performance at reduced temperatures, we improved cathode performance by replacing LSM with LSCF, a mixed conducting material. Then we introduced the functional layered structural concept at the anode substrate. Finally, we used ScSZ (scandia stabilized zirconia) instead of YSZ (yttria stabilized zirconia) for a thin electrolyte, about 20 μm thick. Anode-supported single cells were manufactured by press molding, screen printing technology, and a cofiring process, then formed into 5 x 5 and 10 x 10 cm cells about 1.8 mm thick. We evaluated the I-V and AC impedance characteristics of improved single cells and long-term performance of small stacks at intermediate temperatures using hydrogen gas as fuel.