P. H. Liao, C. Zhang, P. C. Coddet, University of Technology Belfort-Montbeliard, Belfort Cedex, France; C. J. Li, C. -. J. Li, C. -. X. Li, School of Materials Science and Engineering, Xi'an Jiaotong University, Xi'an, China
Yttria stabilized zirconia and lanthanum strontium manganate (YSZ/LSM) have been employed to fabricate the composite cathode functional layer for solid oxide fuel cells (SOFCs). In the present study, the YSZ/LSM composite coating was deposited by atmospheric plasma spray (APS). The electrical conductivity of the composite coating was measured by the means of Direct Current (DC) measurement in a temperature range of 500-900 oC. The electrical conductivity of YSZ-50%LSM coating changed from 2.17 S/cm to 3.60 S/cm along the direction parallel to the coating surface at the temperature range. For the same specimen, the electrical conductivity in the perpendicular direction is less than one-tenth of that in the parallel direction. The anisotropy of the electrical conductivity is attributed to the phases of different properties in the composite coating and the APS coating structure characteristics. The activation energy of the composite coating at both directions was calculated. The results showed that the electrical conduction of the composite was strongly influenced by the YSZ content.
Summary: However, for the lamellar structure features of plasma spraying coating with limited lamellar interface bonding and vertical cracks, the obtained electrolyte is not gas-tight and has a relatively low ionic conductivity compared with that of bulk materials, consequently led to a low energy efficiency of the cell. In such a context, microwave (MW) sintering was introduced as a post-spray process to modify the microstructure of plasma spraying YSZ electrolyte.
