Synthesis and Characterization of a Spinel Type Cr-Free Ceramic Interconnect Material for Solid Oxide Fuel Cells

초록

A LaCrO3-based perovskite was widely used for a ceramic interconnect material for high temperature solid oxide fuel cells (SOFCs) because of its high electronic conductivity, high thermal conductivity and good phase stability under a reducing atmosphere as well as air. However, the LaCrO3 causes volatile Cr (VI) species, which can be segregated at triple-phase boundaries of the cathode, leading to an increase in cathodic polarization. Recently, the operating temperature of SOFCs is getting lower and thus the interconnect material is being replaced with a ferritic stainless steel and something like that. However, the LaCrO3 is still used for the interconnect material of tubular SOFCs and an oxidation protecting layer of metal-based interconnects. In this study, a Cr-free spinel type material was proposed as a flat tubular SOFC interconnect and its properties were compared with a strontium doped lanthanum chromite, La0.8Sr0.2CrO3. The powders were synthesized by glycine nitrate process (GNP) and then calcined for 5 h at 800oC and 1200oC, respectively. Sintering behavior, phase stability, physical and electrical properties of the spinel type interconnect were investigated. In addition, a bilayer, which consists of a dense interconnect thin film and porous Ni-YSZ anode support was fabricated by co-firing the gel coating film on a biscuit sintered anode support.