A complete polarization model of a solid oxide fuel cell and its sensitivity to the change of cell component thickness

This paper presents a complete polarization model of a solid oxide fuel cel l (SOFC) that eliminates the ambiguity of the suitability of such model whe n used under different design and operating conditions. The Butler-Volmer e quation is used in the model to describe the activation overpotential inste ad of using simplified expressions such as the Tafel equation and the linea r current-potential equation. In the concentration overpotential, both ordi nary and Knudsen diffusions are considered to cater for different porous el ectrode designs. Sensitivity tests are then conducted to show the effect of the thickness of the respective fuel cell components on the drop in cell v oltage. Results show that the performance of an anode-supported fuel cell i s superior to that using cathode as the support under elevated operating pr essure in the cathode compartment. The former can achieve an improved opera ting range of current density under normal atmospheric conditions. (C) 2001 Elsevier Science B.V. All rights reserved.