Characterization of Atmospheric Plasma-Sprayed Strontium Doped Lanthanum Chromite Interconnector for Tubular Solid Oxide Fuel Cells

For tubular SOFCs, individual cells are connected in series by the interconncector to obtain desired voltage and power output. In consideration of the relative low electrical conductivity and poor sinterability of conventional LaCrO₃-based materials, a novel bilayered ceramic interconnector consisting of Mn_1.5Co_1.5O₄ (MCO) spinel exposed to cathodic gas and La_0.3Sr_0.7TiO_3-δ (LST) perovskite exposed to anodic gas is fabricated by atmospheric plasma spraying (APS). In this study, dense deposits with enhanced lamellar interface bonding are achieved at elevated deposition temperatures over the critical bonding temperatures. Besides, the chemical composition of LST is particularly controlled by suppressing the preferential evaporation of SrO during plasma spraying. The thermal and chemical compatibility of the bilayered interconncector, as well as the stability under both reducing and oxidizing conditions are studied at an operating temperature of 850 °C. The electrical conductivities along the perpendicular and parallel directions are measured for bilayered interconncectors with different thickness ratios. An electron transport model involving the oxygen partial pressure gradient across the interconnnector is proposed. The results show that the bilayered MCO/LST is a promising design for high performance SOFC interconnector application.