Preparation And Electrical Property Of Y Doped Barium Zirconate Based Composite Solid Electrolyte

Y doped BaZrO₃（BZY）-based proton conductors show good chemical stability,mechanical property and high grain conductivity, but its low sinterability and high grainboundary resistance greatly degrade its applications in solid oxide fuel cells. In this paper,BZY as matrix, Y and Zn doped BaCeO₃（BCYZn） or Sm doped CeO₂（SDC） were introducedto improve the sintering performance and conductivity of BZY, and obtained compositeelectrolyte of high density, high conductivity and stability at lower sintering temperature. Theinfluence of the conductivity and microscopic structure of the composite electrolyte wereresearched on the complex composition and content of components by XRD, SEM and EISanalysis methods.Composite electrolyte of10wt%BaZr_0.9Y_0.1O_2.95-90wt%BaCe0.86Y0.1Zn0.04O2.91（10BZY-90BCYZn） was synthesized via the mechanical mixing and polymerization gelcoating, and the effects of preparation methods on the microstructure and electrical propertiesof BZY-BCYZn electrolyte have been studied. The results showed that dense10BZY-90BCYZn composite electrolytes were obtained by polymerization gel coating andsintering at1350oC for5h, the total conductivity of10BZY-90BCYZn composite electrolytereached7.3mS/cm at600oC under wet Ar atmosphere, and the conductivity of10BZY-90BCYZn synthesized by mechanical mixing was only2.3mS/cm under the samecondition.Composite electrolyte of10BZY-90BCYZn and10BZY-90BCY+ZnO were prepared byintroducting4%mol ZnO as dopant and sintering additives respectively, the effects ofintroduction methods on the microstructure and electrical properties of two compositeelectrolyte have been studied. The results showed that dense10BZY-90BCYZn compositeelectrolytes were obtained after sintering at1350oC for5h, and the total conductivity of 10BZY-90BCYZn composite electrolyte reached2.3mS/cm at500oC under wet Aratmosphere, while the conductivity of10BZY-90BCY+ZnO composite electrolyte was only0.9mS/cm under the same condition.A series of （100－x） wt%BaZr_0.9Y_0.1O_2.95-x wt%BaCe0.86Y0.1Zn0.04O2.91（BZY-BCYZn）（x=70、80、90） composite electrolytes were synthesized via polymerization gel coating, theeffects of different content of BCYZn on the microstructure and electrical properties of BZY-BCYZn electrolytes have been studied. The results showed that the sintering density andconductivity of BZY-BCYZn composite electrolytes increased gradually with the increasity ofBCYZn content, which had the highest desity and electrical conductivity in the matrix phaseBZY and second phase BCYZn in quality ratio of10:90. The total conductivity of10BZY-90BCYZn composite electrolyte reached10mS/cm and7.3mS/cm at600oC underwet5H2/Ar and Ar respectively.A series of （100－x） wt%BaZr_0.9Y_0.1O_2.95-x wt%Ce0.8Sm0.2O1.9（BZY-SDC）（x=70、80、90） composite electrolytes were synthesized via mechanical mixing, the effects of differentcontent of SDC on the microstructure and electrical properties of BZY-SDC electrolyte havebeen studied. The results showed that the sintering density and conductivity of the BZY-SDCcomposite electrolytes increased gradually with the increasity of SDC content, which had thehighest desity and electrical conductivity in the matrix phase BZY and second phase SDC inquality ratio of10:90. The total conductivity of10BZY-90SDC composite electrolyte reached26mS/cm and20mS/cm at600oC under wet5H2/Ar and Air respectively.Composite electrolytes of BZY-BCYZn and BZY-SDC have been studied on themicrostructure and electrical properties. The results indicate that both two compositeelectrolytes are good candidate materials for intermediate-low temperature solid oxide fuelcells and have good application and development prospect.