Comparison of Ceramic Electrolyte Materials in Solid Oxide Fuel Cells for Emission Reduction

Abstract Fuel cells are a renewable energy technology that directly convert chemical energy into electrical energy. Solid oxide fuel cells (SOFCs) are a type of fuel cell that are composed of ceramic materials and consist of two dissimilar electrodes separated by an electrolyte layer. The components of the positive electrode on a SOFC allow for the reduction of oxygen in a typical reaction. However, this mechanism also allows for nitric oxide (NO) to be separated at the positive electrode surface. NO is a toxic pollutant released by internal combustion engines due to incomplete combustion. Although exhaust cleaning technologies are implemented into internal combustion engines, current methods of removing NO from exhaust are insufficient. Catalytic converters can break down NO, however in lean conditions the catalytic converters fail to clean exhaust. A lean nitrogen oxide trap can be implemented in lean conditions, however once the storage capacity is reached it is no longer useful in removing NO from exhaust. SOFCs are a more efficient catalyst for cleaning exhaust, as operation for breaking down NO does not depend on equivalence ratio and the fuel cell separates nitrogen and oxygen rather than capturing NO, so there is no storage capacity. Previous work has shown the SOFC’s ability to break down NO using lanthanum strontium cobalt ferrite-gadolinium doped ceria (LSCF-GDC) for the positive electrode material. This work will investigate other types of ceramics to use for the positive electrode material. This will help to find the ideal material for the catalyst to clean exhaust and will lead to a deeper understanding of the reaction occurring at the positive electrode.