Doping strategies towards acceptor-doped barium zirconate compatible with nickel oxide anode substrate subjected to high temperature co-sintering

Protonic ceramic fuel cells (PCFCs) are attractive next-generation fuel cells working at in-termediate temperature (450-700 degrees C). Currently, the most common method to produce PCFCs is based on co-sintering anode-supported half cells composed of thin BaZr0.8Y0.2O3-delta (BZY20) electrolyte layers and thick NiO anode substrates. However, the BZY20 electrolyte reacts with NiO at the high temperature during co-sintering (1400-1600 degrees C), leading to significant loss of dopants in the electrolyte and thereby degradation in the conductivity. With the aim to improve the chemical compatibility between the BaZrO3-based electrolyte and NiO, in this work, we annealed the mixture of NiO and BaZrO3 doped with different dopants, and found that good compatibility was obtained between NiO and BaZr0.8Yb0.2O3-delta or BaZr0.8Tm0.2O3-delta at 1500 degrees C, and NiO and BaZr0.8Yb0.2O3-delta at 1350 degrees C. Furthermore, BaZr0.8Y0.1Yb0.1O3-delta and BaZr0.8Y0.12Yb0.08O3-delta also showed good chemical compatibility with NiO at 1350 and 1500 degrees C. Then, the half cells using the BaZrO3 electrolyte doped with Y and Yb were fabricated, and the ionic conductivities of the electrolytes implemented into the co-sintered half cells were measured directly in wet hydrogen. The results revealed that BaZr0.8YxYb0.2-xO3-delta (x 1/4 0.10, 0.12, 0.13) showed higher conductivity than that of BaZr0.8Y0.2O3-delta, and BaZr0.8Y0.1Yb0.1O3-delta exhibited the highest conductivity among the three Y and Yb co-doped samples studied in this work. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

In this study, researchers found that there was good chemical compatibility between NiO and BaZr0.8Yb0.2O3 or BaZr0.8Tm0.2O3 at 1500 degrees Celsius. Additionally, BaZr0.8Y0.1Yb0.1O3 and BaZr0.8Y0.12Yb0.08O3 showed good chemical compatibility with NiO at 1350 and 1500 degrees Celsius. The co-doped BaZrzYxYb0.2-xO3 electrolyte exhibited higher conductivity compared to BaZr0.8Y0.2O3, with BaZr0.8Y0.1Yb0.1O3 showing the highest conductivity.