Simulating transport of charged defects in BaZr0.8Y0.2O3‐δ|BaZr0.1Ce0.7Y0.1Yb0.1O3−δ bilayer electrolytes using a Nernst–Planck–Poisson model

Bilayer electrolytes can enhance the performance of protonic ceramic fuel cells (PCFCs). In this work, the transport of charged defects through ${\text{BaZr}}_{0.8}{Y}_{0.2}{O}_{3-\delta }$|${\text{BaZr}}_{0.1}{\mathrm{Ce}}_{0.7}{Y}_{0.1}{\mathrm{Yb}}_{0.1}{O}_{3-\delta }$ bilayer electrolytes is modeled using a Nernst–Planck–Poisson formulation. New parameter sets were fitted to accurately represent the conductivity data and predict the i – V curve. The concentration and electrostatic potential profiles were calculated, along with the defect fluxes. The results show that the bilayer electrolyte exhibits lower hole conduction compared to the corresponding single-layer electrolytes. Additionally, a positive proton concentration gradient towards the cathode side is observed in the bilayer electrolyte, which is not present in single-layer electrolytes. The slope of the concentration profile increases as the $L_{\mathrm{BZY}}/L_{\mathrm{tot}}$ ratio decreases, corresponding with improved cell performance. This observed increase in proton concentration towards the cathode side suggests favorable conditions for proton supply to the cathode, thereby enhancing overall cell performance.