Effectiveness of anode in a solid oxide fuel cell with hydrogen/oxygen mixed gases Isaiah D. Kellogg a,b, *, Umit O. Koylu a , Vladimir Petrovsky b , Fatih Dogan b a Department of Mechanical and Aerospace Engineering, Missouri University of Science & Technology, Rolla, MO, USA b Department of Materials Science and Engineering, Missouri University of Science & Technology, Rolla, MO, USA article info Article history: Received 5 September 2008 Received in revised form 6 February 2009 Accepted 14 February 2009 Available online 7 May 2009 Keywords: Hydrogen Fuel cell SOFC Single chamber Anode NiO Voltage oscillation Redox abstract A porous Ni/YSZ cermet in mixed hydrogen and oxygen was investigated for its ability to decrease oxygen activity as the anode of a single chamber SOFC. A cell with a dense 300 mm YSZ electrolyte was operated in a double chamber configuration. The Ni–YSZ anode was exposed to a mixture of hydrogen and oxygen of varying compositions while the cathode was exposed to oxygen. Double chamber tests with mixed gas on the anode revealed voltage oscillations linked to lowered power generation and increased resistance. Resis- tance measurements of the anode during operation revealed a Ni/NiO redox cycle causing the voltage oscillations. The results of these tests, and future tests of similar format, could be useful in the development of single chamber SOFC using hydrogen as fuel. ª 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved. 1. Introduction Single chamber solid oxide fuel cells (SC-SOFC) are immersed in a flow of mixed fuel and oxygen, relying on the selectivity of the respective electrode catalysts to create a difference in oxygen ion activity across the thickness of the electrolyte [1,2]. In order to increase the effectiveness of SC-SOFC, previous research has explored various possibilities including quantification of elec- trode catalytic activity [3,4] and detailed studies of oxygen reduction in the cathode [5] as well as enhancing electrode performance by adding new dopants [6]. Other studies investi- gated improved electrolyte fabrication [7–9] and use of electro- lyte supported cells [10–12], alternative electrolyte materials [13,14] or improving existing electrolyte materials with added oxide layers [15], and increasing the conductivity and chemical stability of potential proton-conducting perovskite electrolytes [16]. Efficiency could be significantly improved with a thermally self-sustaining cell heated only by the exothermic reaction at the anode [17]. In a traditional double chamber SOFC, the fuel and oxygen are separated by the electrolyte. The oxygen ions (O 2 ) diffuse through the electrolyte due to the high O 2 activity on the cathode side and low O 2 activity on the anode side. The fuel simply prevents a buildup of O 2 on the anode side by consuming the O 2 . In a single chamber SOFC, the same mixed gas is flowing over both electrodes, so the anode must * Corresponding author. 111 Toomey Hall, 400 West 13th St, Missouri University of Science and Technology, Rolla, MO 65409-0050, USA. Tel.: þ1 573 465 1803; fax: þ1 573 341 6934. E-mail address: ikellogg@mst.edu (I.D. Kellogg). Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he 0360-3199/$ – see front matter ª 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2009.02.086 international journal of hydrogen energy 34 (2009) 5138–5143