Mathematical modeling of a proton-conducting solid oxide fuel cell with current leakage

Abstract

In this work, a framework of charge transports in proton-conducting solid oxide fuel cells (H-SOFCs) with considering current leakage is developed by assuming four electrode reactions. Current leakage occurs when electron holes pass through the electrolyte and combine with electrons at the anode side. An analytical solution of leakage currents is proposed depending on the Nernst-Planck equation. On the basis of the analysis expression, a mathematical model of H-SOFCs is proposed, which can provide the information about current-voltage characteristics, leakage current density, Faraday and energy efficiencies. Furthermore, H-SOFCs with the BaZr0.8Y0.2O3 electrolyte are fabricated and tested, and the proposed model well reproduces the experimental data. The simulation results indicate that current leakage primarily affects the H-SOFC performance when the output voltage is close to the OCV. Both Faraday efficiencies and energy efficiencies decrease with increasing operating temperatures due to the existence of current leakage.