Pr- and Sm-Substituted Layered Perovskite Oxide Systems for IT-SOFC Cathodes

Sung Hun Woo,Hyunil Kang,Tae Ho Shin,Seung-Wook Baek,Wonseok Choi,Kyeong Eun Song,Jun-Young Park,Jung Hyun Kim

doi:10.3390/en14206739

Abstract

In this study, the phase synthesis and electrochemical properties of A/A//A///B2O5+d (A/: Lanthanide, A//: Ba, and A//: Sr) layered perovskites in which Pr and Sm were substituted at the A/-site were investigated for cathode materials of Intermediate Temperature-Operating Solid Oxide Fuel cells (IT-SOFC). In the PrxSm1−xBa0.5Sr0.5Co2O5+d (x = 0.1–0.9) systems, tetragonal (x < 0.4) and orthorhombic (x ≥ 0.5) crystalline structures were confirmed according to the substitution amount of Pr, which has a relatively large ionic radius, and Sm, which has a small ionic radius. All of the layered perovskite oxide systems utilized in this study presented typical metallic conductivity behavior, with decreasing electrical conductivity as temperature increased. In addition, Pr0.5Sm0.5Ba0.5Sr0.5Co2O5+d (PSBSCO55), showing a tetragonal crystalline structure, had the lowest conductivity values. However, the Area-Specific Resistance (ASR) of PSBSCO55 was found to be 0.10 Ω cm2 at 700 °C, which is lower than those of the other compositions.

Highlights

Solid Oxide Fuel Cells (SOFCs) are energy converters that directly convert the chemical energy of oxygen and hydrogen into electrical energy at high temperatures
A/ A// A/// B2 O5+d (A/ : Lanthanide, A// : Ba and A/// : Sr), a layered perovskite oxide system, an orthorhombic crystalline structure was found when the A/-site was substituted by Sm, which had a relatively small ionic radius, while a tetragonal crystalline structure was formed when Nd, which had a relatively large ionic radius, was substituted
Upon comparison of the previous results described above and the results summarized in Figure 1, it can be seen that all the X-ray diffraction (XRD) peaks were split in the case of

Summary

Introduction

Solid Oxide Fuel Cells (SOFCs) are energy converters that directly convert the chemical energy of oxygen and hydrogen into electrical energy at high temperatures. There is a problem, in their long-term performance, such as in the chemical reaction of the electrode and the poisoning of Cr when devices are operating at high temperatures [1,2,3,4]. To solve these problems, many domestic and overseas research institutes are focusing on research and development toward Intermediate Temperature-Operating Solid Oxide. Oxygen vacancy in the [LnOd ] layer was acknowledged to prevent spin glass behavior, resulting in excellent oxygen mobility and surface properties [5,6]

Methods

Results

Conclusion