Investigation into the effect of molybdenum-site substitution on the performance of Sr sub(2)Fe sub(1.5)Mo sub( 0.5)O sub(6- delta ) for intermediate temperature solid oxide fuel cells

• Published in: Journal of power sources Vol. 272; pp. 759 - 765
• Main Authors: Hou, Mingyue, Sun, Wang, Li, Pengfa, Feng, Jie, Yang, Guoquan, Qiao, Jinshuo, Wang, Zhenhua, Rooney, David, Feng, Jinsheng, Sun, Kening
• Format: Journal Article
• Language: English
• Published: 25-12-2014
• Subjects: Cathodes; Doping; Niobium; Oxidants; Performance degradation; Perovskite structure; Resistivity; Solid oxide fuel cells
• ISSN: 0378-7753
• DOI: 10.1016/j.jpowsour.2014.09.043

In this paper, niobium doping is evaluated as a means of enhancing the electrochemical performance of a Sr sub(2)Fe sub(1.5)Mo sub( 0.5)O sub(6- delta ) (SFM) perovskite structure cathode material for intermediate temperature solid oxide fuel cells (IT-SOFCs) applications. As the radius of Nb approximates that of Mo and exhibits +4/+5 mixed valences, its substitution is expected to improve material performance. A series of Sr sub(2)Fe sub(1.5)Mo sub( 0.5-x)Nb sub(x)O sub(6- delta ) (x = 0.05, 0.10, 0.15, 0.20) cathode materials are prepared and the phase structure, chemical compatibility, microstructure, electrical conductivity, polarization resistance and power generation are systematically characterized. Among the series of samples, Sr sub(2)Fe sub(1.5)Mo sub( 0.4)Nb sub(0.10)O sub(6- delta ) (SFMNb sub(0.10)) exhibits the highest conductivity value of 30 S cm super(-1) at 550 [degrees]C, and the lowest area specific resistance of 0.068 ohm cm super(2) at 800 [degrees]C. Furthermore, an anode-supported single cell incorporating a SFMNb sub(0.10) cathode presents a maximum power density of 1102 mW cm super(-2) at 800 [degrees]C. Furthermore no obvious performance degradation is observed over 15 h at 750 [degrees]C with wet H sub(2) (3% H sub(2)O) as fuel and ambient air as the oxidant. These results demonstrate that SFMNb shows great promise as a novel cathode material for IT-SOFCs.