PNNL

Abstract

Over their designed lifetime, high temperature electrochemical devices, such as solid oxide fuel cells (SOFCs), can experience degradation in their electrochemical performance due to environmental conditions, operating conditions, contaminants, and other factors. Understanding the different degradation mechanisms in SOFCs and other electrochemical devices is essential to reducing performance degradation and increasing the lifetime of these devices. In this paper SOFC degradation mechanisms are discussed and a damage model is presented which describes performance degradation in SOFCs due to damage or degradation in the electrodes of the SOFC. A degradation classification scheme is presented that divides the various SOFC electrode degradation mechanisms into categories based on their physical effects on the SOFC. The application of the damage model and the classification method is applied to sulfur poisoning and antimony poisoning which occur in the anode of SOFCs. For sulfur poisoning the model is able to predict the degradation in SOFC performance based on the operating temperature and voltage of the fuel cell and the concentration of gaseous sulfur species in the anode. For antimony poisoning the effects of nickel removal from the anode matrix is investigated.