Abstract
Proton-conducting solid oxide electrolysis cells (p-SOECs) have attracted much attention due to their low operating temperature and low degradation rate compared with conventional oxygen-ion conducting solid oxide electrolysis cells (o-SOEC). However, p-SOECs suffer from relatively low Faradaic efficiency due to the electronic leakage of the electrolyte. Using an electrolyte charge carrier transport model, we quantified the dependence of Faraday efficiency on the electrolysis operation conditions. Our model describes the transport of charge carriers in the electrolyte when the polarization resistance can not be neglected during cell operations. By accounting for the overpotentials at the interface of electrode and electrolyte in the model, we found that the Faraday efficiency decreases with the increasing current densities at electrolysis mode for both BZY20 and BCZYYb. Our results provide significant insights into the development of highly efficient p-SOECs.