Journal of Power Sources (2008)

Ln_0.6Sr_0.4Co_1-yFe_yO_3-δ (Ln = La and Nd; y = 0 and 0.5) Cathodes With Thin Yttria-Stabilized Zirconia Electrolytes for Intermediate Temperature Solid Oxide Fuel Cells

Claudia Torres-Garibay, Desiderio Kovar, and Arumugam Manthiram
Electrochemical Energy Laboratory & Materials Science and Engineering Program
The University of Texas at Austin
Austin, TX 78712

ABSTRACT
The electrochemical performances of the solid oxide fuel cells (SOFC) fabricated with Ln_0.6Sr_0.4Co_1-yFe_yO_3-δ (Ln = La, Nd; y = 0, 0.5) perovskite cathodes, thin YSZ electrolytes, and YSZ-Ni anodes by tape casting, co-firing, and screen printing have been evaluated 600 – 800 ̊C. Peak power densities of ~ 550 mW/cm² were achieved at 800 °C with a La_0.6Sr_0.4CoO_3-δ (LSC) cathode that is known to have high electrical conductivity. Substitution of La by Nd (Nd_0.6Sr_0.4CoO_3-δ) to reduce the thermal expansion coefficient (TEC) results in only a slight decrease in power density despite a lower electrical conductivity. Conversely, substitution of Fe for Co (La_0.6Sr_0.4Co_0.5Fe_0.5O_3-δ or Nd_0.6Sr_0.4Co_0.5Fe_0.5O_3-δ) to reduce the TEC further reduces the cell performance greatly due to a significant decrease in electrical conductivity.  However, infiltration of the Fe-substituted cathodes with Ag to increase the electrical conductivity increases the cell performance while preserving the low TEC.