Application of Layered Perovskites Substituted with Co and Ti as Electrodes in SOFCs

Abstract

In this study, the phase and electrochemical properties of Co and Ti substituted layered perovskites SmBaCo 2-x Ti x O 5+d (x=0.5, 0.7, 1.0, 1.1, 1.3, and 1.5) were analyzed, and their application as electrodes in solid oxide fuel cells (SOFCs) were evaluated. After calcination at 1300°C for 6 h, a single phase was observed for two compositions of the SmBaCo 2-x Ti x O 5+d oxide system, SmBaCoTiO 5+d (x=1.0) and SmBaCo 0.9 Ti 1.1 O 5+d (x=1.1). However, the phases of SmBaCoTiO 5+d (SBCTO) and SmTiO 3 coexisted for compositions with x≥1.3 (Ti content). In contrast, for compositions of x≤0.7, the SmBaCo 2 O 5+d phase was observed instead of the SmTiO 3 phase. To evaluate the applicability of these materials as SOFC electrodes, the electrical conductivities were measured under various atmospheres (air, N 2 , and H 2 ). SBCTO exhibited stable semi-conductor electrical conductivity behavior in an air and N 2 atmosphere. However, SBCTO showed insulator behavior at temperatures above 600℃ in a H 2 atmosphere. Therefore, SBCTO may only be used as cathode materials. Moreover, SBCTO had an area specific resistance (ASR) value of 0.140 Ω ･ cm 2 at 750℃. )