Work

Processing Nano-YSZ in Solid Oxide Fuel Cells: The Effect of Sintering Atmosphere on Thermochemical Stability

Year: 2019

Type: article

Abstract: The thermochemical stability of nanoscale yttria-stabilized-zirconia (nYSZ), processed via in situ carbon templating, was studied between 850°C–1350°C in four sintering atmospheres: Ar, N 2 , H 2 , and humidified H 2 . The in situ carbon templating method generates nanoscale ceramic particles surrounded by an amorphous carbon template upon sintering. The carbon template is subsequently removed by low temperature oxidation, leaving behind nanoscale ceramic particles. In Ar and H 2 , a ZrC impurity formed at temperatures ≥1150°C. In humidified H 2 , either a ZrC impurity formed or the carbon template oxidized. In N 2 , ZrC was not observed over the temperature range studied and the carbon template was preserved. After carbon template removal, the nYSZ surface areas were high for Ar, H 2 , and N 2 : 55–99 m 2 ·g −1 . For humidified H 2 , nYSZ surface area decreased as the carbon template was lost. Finally, nYSZ, processed in N 2 at 850°C and 1250°C, was integrated into symmetric YSZ-Lanthanum Strontium Ferrite (YSZ-LSF) cathode cells. The addition of nYSZ decreased cathode non-ohmic resistance, at 550°C in air, by 40% and 27% for nYSZ processed at 850°C and 1250°C, respectively. This work demonstrates that N 2 is a thermochemically stable atmosphere for in situ carbon templating and that the resulting nYSZ considerably improves electrode performance.

Source: Journal of The Electrochemical Society

DOI: 10.1149/2.0261902jes