BSCF계 혼합전도성 공기극의 두께에 따른 고체산화물 연료전지의 전기화학적 특성

Abstract

In order to reduce the costs and to improve the durability of solid oxide fuel cell (SOFC), the operating temperature should be decreased while the power density is maintained as much as possible. However, lowering the operating temperature increases the cathode interfacial polarization resistances dramatically, limiting the performance of low-temperature SOFC at especially purely electronic conducting cathode. To improve cathode performance at low temperature, the number of reaction sites for the oxygen reduction should be increased by using a mixed ionic and electronic conducting (MIEC) material. In this study, anode-supported fuel cells with two different thicknesses of the MIEC cathode were fabricated and tested at various operating temperatures. The anode supported cell with <TEX>$32.5{\mu}m$</TEX>-thick BSCFZn-LSCF cathode layer showed much lower polarization resistance than that with <TEX>$3.2{\mu}m$</TEX> thick cahtode and higher power density especially at low temperature. The effects of cathode layer thickness on the electrochemical performance are discussed with analysis of impedance spectra.