Development of Reversible Solid Oxide Fuel Cells (RSOFCs)and Stacks

Abstract

A reversible solid oxide fuel cell (RSOFC) is a SOFC that can function efficiently under both power generation mode for electricity production and electrolysis mode for hydrogen/chemical production. The RSOFC thus can be used as a fuel cell or an electrolysis cell or both depending on the application. Multi-cell RSOFC stacks have been built and reversible operation has been demonstrated. Experiments on RSOFCs (yttria-stabilized zirconia or YSZ electrolytes, Ni/YSZ hydrogen electrodes, and perovskite oxygen electrodes) showed certain performance irreversibility of the perovskite electrode. Significant performance degradation was observed under electrolysis mode for predominantly electronic-conducting oxygen electrodes such as Sr-doped lanthanum manganite (LSM). Mixed-conducting oxygen electrodes such as lanthanum strontium cobalt iron oxides (LSCF) showed better performance and performance stability. Long-term operation of RSOFC stacks using stainless steel interconnects at 800oC showed elemental (Sr and Cr) migration and interactions at oxygen electrode/interconnect interfaces.