Electrochemical Performance of SmBaCo2/3Fe2/3Cu2/3O5+d-Ce1.9Gd0.1O1.9 composite cathodes for IT-SOFC

Abstract

Intermediate-temperature solid oxide fuel cells (ITSOFCs) with high working efficiency at 500-750 oC have attracted much attention in the area of power fabrication. Recent studies on new types of mixed ionic-electronic conducting (MIEC) oxides, such as cation ordered LnBaCo2O5+δ (Ln = Gd, Sm, Pr and La) with two dimensional ion-diffusion channels have shown them to be attractive potential cathode materials for IT-SOFCs [1,2]. Jo et al., have reported that a unique composition of GdBaCo2O5+δ (GBCO) co-doped with Fe and Cu ions in the Co sites exhibited reduced thermal-expansion coefficient (TEC) and enhancement of electrochemical performance, and good chemical compatibility with Ce0.9Gd0.1O1.95 (CGO) [3]. However, much attention of the research was mainly focused on the structure, conductivity and electrochemical properties of the single-phase LnBaCo2O5+δ cathode. The polarization resistance and TEC of MIEC cathodes can be often reduced by adoption of composite cathode, i.e., adding a second phase with high oxygen ion conductivity. In this study, a systematic investigation of LnBaCo2O5+δ + (1–x) Ce1.9Gd0.1O1.95 composite cathodes will be discussed.