Performance of protonic ceramic fuel cells with Ba(Zr,Yb,Co)O3-δ cathodes and the impact of Co contained in cathode on durability

To investigate the effect of Co in cathodes on the durability of protonic ceramic fuel cells (PCFC) using a BaZr0.8Yb0.2O3-δ electrolyte, new cathode materials, specifically Ba(Zr0.875-xYb0.125Cox)O3-δ (x = 0.125, 0.25, 0.375, 0.625, and 0.75), were employed. We examined several material properties of the cathodes and evaluated cell performance, showing that Ba(Zr0.375Yb0.125Co0.5)O3-δ exhibits high performance and a matching thermal expansion coefficient with the electrolyte. During the 1000 h power generation test, the segregation of Co and anode-derived Ni in the cathode progressed. Segregation of Co and Ni was also observed at the grain boundaries in the electrolyte, indicating a decrease in the mechanical strength of the electrolyte caused by the diffusion of Co from the cathode and Ni from the anode. From these results, it became clear that the suppression of Co diffusion into the electrolyte is an important issue for the practical application of PCFCs with a BaZr0.8Yb0.2O3-δ electrolyte and Co-containing cathodes. [Display omitted] •Evaluation of material properties and cell performance using novel cathode materials, Ba(Zr,Yb,Co)O3-δ.•Analysis of transition metal diffusion and segregation in the cathode and electrolyte before and after 1000 h of power generation.•Analysis of degradation using the distribution of relaxation time and H/D isotope method.