Theoretical Analysis of Solid Oxide Fuel Cells: The Effect of Electrode Characteristics

Abstract

Theoretical analysis which assesses the effect of electrode thickness, electrode porosity, and electrolyte thickness on the performance of a solid oxide fuel cell (SOFC) is presented. The analysis assumes efficient electrocatalysis or zero charge transfer resistance. Transport of H{sub 2}, O{sub 2}, and H{sub 2}O, through the electrodes is assumed to occur by diffusion. The analysis essentially yields the effect of concentration polarization on cell performance. All calculations, which are for operation at 800 C, show that for electrode thicknesses as high as 1 mm, concentration polarization is small for electrode porosity > 10%. By contrast, as expected, the effect of electrolyte thickness is significant. The analysis suggests that a prospective SOFC should consist of a thin electrolyte and relatively thick electrodes. That is, either the anode or the cathode, rather than the electrolyte should be the supporting member of an SOFC.