Modified Butler-Volmer Type Model Which Accounts for Triple and Double Phase Boundary Reaction Pathways

Abstract

In recent years, detailed reduced order reaction models have been presented which consider more detailed physics than the widely-used Butler-Volmer (BV) equations. A reduced order oxygen reduction reaction (ORR) model previously developed specifically for yttria stabilized zirconia (YSZ)/lanthanum strontium manganite (LSM) cathodes is studied here. This model requires separate species transport equations to be solved for numerous species and surface coverages resulting in a stiff system of non-linear equations. However, models that apply the traditional BV type equations, while much less computationally intensive, are not able to distinguish between the reactions at the triple phase boundaries (TPBs) and the double phase boundaries (DPBs). In the study, the relationship between over potential and current density at TPBs and DPBs is explored based on the aforementioned ORR model and a new BV type model is proposed for modeling the exchange current density considering both TPB and DPB pathways.