Linear discharge model, power losses and overall efficiency of the solid oxide fuel cell with thin film samarium doped ceria electrolyte. Part II: Power losses and overall efficiency

Abstract

Samarium doped ceria (SDC) shows obvious electronic conduction in a reducing atmosphere, which results in internal short-circuiting of the SOFC. In this work, we initiatively combine the Gorelov modified electromotive force (EMF) method and the Liu modified EMF method to determine the internal electronic resistance of the SOFC with 60 μm SDC film electrolyte. The internal electronic resistance determined with the Gorelov modified EMF method is a little larger than that determined with the Liu modified EMF method. The power loss of the SOFC is mainly resulted from the internal short-circuiting, oxygen ionic resistance and electrode polarization resistance. At low external current density, the internal short-circuiting power loss is predominant, while at high current density the oxygen ionic resistance power loss is predominant. Temperature has little effect on the maximum efficiency of the SOFC. When the SOFC works at the maximum power output, the efficiency of the cell is about 30%, but if the electronic conduction of the SDC electrolyte could be eliminated, the efficiency could be improved by 2.5 times.