Journal of Power Sources, Vol.353, 115-122, 2017
Prediction of overpotential and effective thickness of Ni/YSZ anode for solid oxide fuel cell by improved species territory adsorption model
The reliability of analytical model for hydrogen oxidation at Ni/YSZ anode in solid oxide fuel cell named as species territory adsorption model has been improved by introducing referenced thermodynamic and kinetic parameters predicted by density function theory calculations. The model can explicitly predict anode overpotential using unknown values of quantities of state for oxygen migration process in YSZ near a triple phase boundary (TPB), frequency factor for hydrogen oxidation, and effective anode thickness. The former two are determined through careful fitting process between the predicted and experimental results of Ni/YSZ cermet and Ni-patterned anodes. This makes it possible to estimate effective anode thickness, which tends to increase with temperature in six kinds of Ni/YSZ anodes in references. In addition, the comparison between the proposed model and a published numerical simulation indicates that the model can predict more precise dependence of anode overpotential on steam partial pressure than that by Butler-Volmer equation with empirical exchange current density. The introduction of present model into numerical simulation instead of Butler-Volmer equation can give more accurate prediction of anode polarization. (C) 2017 Elsevier B.V. All rights reserved.
Keywords:Solid oxide fuel cells;Ni/YSZ anode;Hydrogen oxidation;Analytical model;Anode overpotential;Effective anode thickness