Implications of Cation Interdiffusion between Double Perovskite Cathode and Proton-Conducting Electrolyte for Performance of Solid Oxide Fuel Cells

Chemical compatibility and cation interdiffusion between the double perovskite cobaltites RBaCo2O6-delta (R = Gd, Pr) and proton-conducting electrolyte BaZr0.8Y0.2O3-delta were studied. Chemical interaction was found to occur already at 1100 degrees C as a result of the partial dissolution of RBaCo2O6-delta (R = Gd, Pr) in BaZr0.8Y0.2O3-delta. Analysis of the element distribution along the cross sections of diffusion couples RBaCo2O6-delta(R = Gd, Pr)|BaZr0.8Y0.2O3-delta showed strong interdiffusion of cations, with cobalt being the most mobile one. Its diffusion depth in the electrolyte reaches up to several hundreds of micrometers. The addition of NiO as a sintering aid to BaZr0.8Y0.2O3-delta promotes cation diffusion especially through the grain boundary mechanism, increasing the diffusion depth of Co. The possible implications of cation interdiffusion on the performance of proton-conducting SOFCs are discussed based on the results obtained.