O2‐reduction at high temperatures:SOFC

Abstract

AbstractIn this chapter the general requirements for solid oxide fuel cell (SOFC) cathodes and several ways of implementing them are described. The transport properties of cathode structures based on different perovskite type metal oxides are the main focus. Various possible reaction pathways for the two classes of cathode material, i.e., electronic conducting and mixed ionic/electronic conducting cathodes, are discussed. The importance of the microstructural properties of the cathode/electrolyte interface is illustrated. The dependence of cathode performance on the interaction between cathode composition and interface structure is demonstrated by i/v‐characteristics of different cathode/electrolyte configurations. A literature review of models for the high temperature oxygen reduction is given. The elementary reaction steps used in the different models are classified into three categories: surface reaction, surface and bulk diffusion, and incorporatied into the electrolyte. A general approach for modeling and simulation of the electrical response of the oxygen reduction process is presented by using a two‐step model accounting for surface adsorption of oxygen and charge transfer of oxygen into the electrolyte in the vicinity of the three phase boundary.