Reliable Lab-Scale Evaluation for Enhanced SOFCs Electrode Performance - Influence of Electronic Transport

Abstract

Understanding and optimizing electrochemically active zone for oxygen reduction reaction (ORR) in solid oxide fuel cells (SOFCs) cathodes are indispensable to maximize device’s performance. For a mixed ionic and electronic conducting electrode, the range of this zone depends on the oxygen surface exchange and solid-state oxygen/electron transport properties of electrode materials and the oxygen gas transport through porous electrode. This implies that electrode microstructure, including surface area, porosity, and tortuosity, needs to be carefully designed and controlled to maximize electrochemically active electrode volume. This aspect is also critical to realize valid characterization of the electrode’s electrochemical activities. For instance, when a material’s electronic conductivity is low or the electrical contact points are spaced beyond a critical distance, the electrode polarization resistance measured by electrochemical impedance spectroscopy will be controlled by the sheet resistance not the oxygen exchange resistance. In this presentation, we will discuss our synthesis approach of lanthanum strontium cobalt ferrite (LSCF) and spinel powders by using co-precipitation with a continuous stirred-tank reactor, in order to precisely control powder’s chemistry and morphology (ultimately, electrode microstructure). And, we will discuss the influence of electrode microstructure and current collecting method on electronic conduction in porous electrode and, eventually, on electrochemical performance and its reliable evaluation in a lab-scale button cell configuration.This work was supported by the US Department of Energy (DOE), Office of Fossil Energy, (Office of Fossil Energy & Carbon Management), “Solid Oxide Fuel Cell Manufacturing in Support of Office of Fossil Energy” program through Argonne National Laboratory under FWP No. 27327.1.