Performance and stability of large planar solid oxide fuel cells using phosphine contaminated hydrogen fuel

• Published in: Journal of power sources 2018-08, Vol.395 (C), p.185-194
• Main Authors: Ross, T.B.A., Zondlo, J.W., Sabolsky, E.M., Ciftyurek, E., Koneru, A., Thomas, T., Celik, I., Liu, X., Sezer, H., Damo, U.M.
• Format: Article
• Language: English
• Subjects: Anodes; Chemistry; Coal syngas; Contaminants; Electrochemistry; Energy & Fuels; Gasification; Materials Science; Solid Oxide Fuel Cells (SOFC); Thermodynamic analysis
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2018.04.105

Coal syngas, a potential fuel for SOFCs, contains impurities like PH3, which rapidly degrade Ni-based SOFC anodes. Past research showed significant reconstruction of Ni anodes in button cells with degradation rates of ∼0.5 mV∙h−1. It is not evident that these rates correspond to actual stack applications due to major differences in fuel utilization and delivery. Herein, a single planar repeat unit with an active area of 32.64 cm2 is constructed using a Haynes® 242 manifold. The cell operates at 800 °C using dry H2 with and without 10 ppm PH3. The cell employs a co-flow configuration with a fuel utilization of 12.5%. The performance of the cell is evaluated over 440 h by voltage-current measurements and electrochemical impedance spectroscopy. The post-run analysis of the contaminated cell is conducted via XRD, XPS and SEM. The degradation rate for the cell is found to be 3×10−3 mV∙h−1, which is far lower than that reported previously. The cell shows low evidence of significant PH3 poisoning and there is no reconstruction of the Ni-anode microstructure, as seen in button cell testing. Some basic electrochemical and thermodynamic modeling, and microstructural/chemical characterization are presented and related to the cell's relatively stable performance observed in this work. •Planar SOFC stack repeat unit tested using Haynes 242 interconnect.•SOFC stack repeat unit operated at 800 °C with 10 ppm PH3 in dry H2 fuel.•Degradation rate due to PH3 was 3 × 10−3 mV·h−1 at 800 °C after 440 h of testing.•Lower degradation than previous reported levels for small-scale testing.