Electrical conductivities and microstructures of LSM, LSM-YSZ and LSM-YSZ/LSM cathodes fabricated on YSZ electrolyte hollow fibres by dip-coating

Abstract

Lanthanum strontium manganite – La0.80Sr0.20MnO3 (LSM), LSM-Yttria stabilised zirconia (LSM-YSZ) composite and LSM-YSZ/LSM double-layer cathodes were separately fabricated on Yttria stabilised zirconia (YSZ) electrolyte hollow fibres by dip coating; their electrical conductivities and microstructures were then determined by the direct current four-probe method and scanning electron microscopy (SEM), respectively. Excellent cathode-electrolyte and cathode-cathode adhesion without delamination were achieved by the dip-coating fabrication method. The apparent electrical conductivities of porous LSM, LSM-YSZ and LSM-YSZ/LSM cathodes manufactured on YSZ hollow fibre by dip-coating and sintered at various temperatures in the range 1273–1473 K for 3 h, were 1.8 × 103–5.5 × 103 S/m, 0.32–209 S/m and 1.3 × 103–5.5 × 103 S/m, respectively, at measurement temperatures of 673–1073 K. The operating temperature dependence of the apparent electrical conductivity of the LSM, LSM-YSZ and LSM-YSZ/LSM cathodes was defined by the Arrhenius equation for electrical conductivity. The activation energies for electrical conductivity were derived as 0.106–0.147 eV, 0.83–0.94 eV, and 0.104–0.146 eV for the LSM, LSM-YSZ and LSM-YSZ/LSM cathodes, respectively. The LSM-YSZ and LSM-YSZ/LSM cathodes were strongly influenced by the YSZ and LSM phases, respectively.