Enhanced ORR Activity of A-Site-Deficient SrCo<sub>0.8</sub>Nb<sub>0.1</sub>Ti<sub>0.1</sub>O<sub>3−δ</sub> as a Bifunctional Air Electrode for Low-Temperature Solid Oxide Fuel Cells
Qi Zhang, Hao Qiu, Shanshan Jiang, Yang Liu, Jiahuan Xu, Wei Wang, Daifen Chen, Chao Su
Abstract
Solid oxide fuel cells (SOFCs) working at intermediate and low temperatures (≤650 °C) demonstrate tremendous potential benefits including their ease of manipulation, improvement in durability, and utilization of metallic interconnects. However, the sluggish oxygen reduction reaction (ORR) of air electrodes at lower temperatures is the main reason for constraining their supply of power. In this work, an A-site-deficient perovskite Sr 0.95 Co 0.8 Nb 0.1 Ti 0.1 O 3−δ (S 0.95 CNT) has been developed as a bifunctional air electrode for both oxygen-ion-conducting SOFCs (O-SOFCs) and proton-conducting SOFCs (H-SOFCs). The generation of 5% A-site deficiency in SrCo 0.8 Nb 0.1 Ti 0.1 O 3−δ (S 1 CNT) could increase the concentration of oxygen vacancies, thus facilitating the ORR kinetics for intermediate and low-temperature solid oxide fuel cells (ILT-SOFCs). The S 0.95 CNT air electrode delivers excellent area specific resistances (ASRs) at 500 °C, with values of only 0.13 and 1.08 Ω cm 2 for S 0.95 CNT on the Sm 0.2 Ce 0.8 O 1.9 (SDC) and BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3−δ (BZCYYb) electrolytes, respectively, and remarkable peak power densities (PPDs) at 600 °C for O-SOFCs and H-SOFCs of 1369 and 569 mW cm –2, respectively, both about 18% higher than that of S 1 CNT with no deficiency. Overall, this work supplies a simple and effective way to improve the ORR kinetics of S 1 CNT as the bifunctional air electrode for ILT-SOFCs.