The effect of Cr deposition and poisoning on BaZr_0.1Ce_0.7Y_0.2O_3-δ proton conducting electrolyte

With the development of chromium tolerant electrode materials, the evaluation of the chromium deposition and poisoning on electrolyte is critical significance for the commercial and widespread application of solid oxide fuel cell stacks (SOFCs). The Cr deposition and poisoning on BaZr_0.1Ce_0.7Y_0.2O_3-δ (BZCY) proton conducting electrolyte are initially studied, in order to understand and develop the compatibility for proton conducting SOFC (H-SOFCs). The XRD results imply that Cr₂O₃ is not chemically compatible with BZCY and BaCrO₄ is formed at high temperature above 600°C. To simulate the Cr volatilization from interconnect and poisoning on BZCY surface, the BZCY bar sample is heat-treated in the presence of Cr₂O₃ at 600°C, 700°C, and 800°C for 50 h. It is clear that Cr deposition occurs even at 600°C by SEM examination. The XPS results indicate the chemical deposition of BaCrO₄ and physical deposition of Cr₂O₃ on BZCY surface at 600°C but only chemical deposition at 700°C and 800°C. The content of Cr deposition increases with the increase of poisoning temperature. Moreover, the proton conductivity of BZCY after Cr deposition reduces after Cr deposition, indicating the Cr poisoning effect of the electrochemical performance of BZCY electrolyte.