Detailed Characterization of Anode-Supported SOFCs by Impedance Spectroscopy

Anode-supported thin electrolyte cells are studied by electrochemical impedance spectroscopy (EIS). The aim is to describe how the losses of this type of cells are distributed at low current density (around open-circuit voltage) as a function of temperature. An equivalent circuit consisting of an inductance, a serial resistance (R s ), and five arcs to describe the polarization resistance is suggested. This equivalent circuit is based on previous studies of single electrodes in three-electrode and two-electrode symmetric cell setups. The equivalent circuit components have been assigned to the electrode processes, and the assignments were verified by extensive full cell studies in which the partial pressure of reactant gases on both the electrodes as well as temperature was systematically varied with the aim to identify frequency regions which are dominated by an electrode specific process. Furthermore, the model is applied on a good performing cell with area specific resistance (ASR) = 0.15 Ω cm 2 at 850°C and a poor performing cell with ASR = 0.29 Ω cm 2 at the same temperature. Both cells were fabricated using nominally the same procedure. The EIS analysis indicated that the difference in performance originates from microstructural differences on the cathode. This is further supported by the observation of large differences in the cathode microstructure by scanning electron microscope.

[1]  D. Jeon,et al.  A comprehensive micro-scale model for transport and reaction in intermediate temperature solid oxide fuel cells , 2006 .

[2]  A. Hagen,et al.  Properties and Performance of SOFCs Produced on a Pre‐Pilot Plant Scale , 2006 .

[3]  Yann Bultel,et al.  Theoretical optimisation of a SOFC composite cathode , 2005 .

[4]  Volker Krebs,et al.  Macroscale modeling of cathode formation in SOFC , 2004 .

[5]  S. Adler.  Factors governing oxygen reduction in solid oxide fuel cell cathodes. , 2004, Chemical reviews.

[6]  J. Vohs,et al.  Effect of Polarization on and Implications for Characterization of LSM-YSZ Composite Cathodes , 2004 .

[7]  S. Jiang,et al.  Issues on development of (La,Sr)MnO3 cathode for solid oxide fuel cells , 2003 .

[8]  S. Chan,et al.  Identification of O2 reduction processes at yttria stabilized zirconia|doped lanthanum manganite interface , 2003 .

[9]  Mogens Bjerg Mogensen,et al.  Progress in understanding SOFC electrodes , 2002 .

[10]  Stuart B. Adler,et al.  Reference Electrode Placement in Thin Solid Electrolytes , 2002 .

[11]  Mogens Bjerg Mogensen,et al.  Impedance of Solid Oxide Fuel Cell LSM/YSZ Composite Cathodes , 2001 .

[12]  Mogens Bjerg Mogensen,et al.  Gas Diffusion Impedance in Characterization of Solid Oxide Fuel Cell Anodes , 1999 .

[13]  S. Jiang,et al.  An electrode kinetics study of H2 oxidation on Ni/Y2O3–ZrO2 cermet electrode of the solid oxide fuel cell , 1999 .

[14]  I. Vinke,et al.  Reaction of hydrogen/water mixtures on nickel-zirconia cermet electrodes. II. AC polarization characteristics , 1999 .

[15]  Ludwig J. Gauckler,et al.  La2Zr2O7 formation and oxygen reduction kinetics of the La0.85Sr0.15MnyO3, O2(g)|YSZ system , 1998 .

[16]  S. Barnett,et al.  Oxygen transfer processes in (La,Sr)MnO3/Y2O3-stabilized ZrO2 cathodes: an impedance spectroscopy study , 1998 .

[17]  Mogens Bjerg Mogensen,et al.  Gas Conversion Impedance: A Test Geometry Effect in Characterization of Solid Oxide Fuel Cell Anodes , 1998 .

[18]  Z. Ogumi,et al.  Preparation of Perovskite‐Type La1 − x Sr x MnO3 Films by Vapor‐Phase Processes and Their Electrochemical Properties II. Effects of Doping Strontium to on the Electrode Properties , 1998 .

[19]  Mogens Bjerg Mogensen,et al.  Oxidation of hydrogen on Ni/yttria-stabilized zirconia cermet anodes , 1997 .

[20]  Z. Ogumi,et al.  Preparation of Perovskite‐Type La1 − x Sr x MnO3 Films by Vapor‐Phase Processes and Their Electrochemical Properties , 1997 .

[21]  M. Mogensen,et al.  Kinetic and geometric aspects of solid oxide fuel cell electrodes , 1996 .

[22]  A. Hammouche,et al.  Impedance spectroscopy analysis of La1 − xSritxMnO3-yttria-stabilized zirconia electrode kinetics , 1995 .

[23]  Sukhvinder P.S. Badwal,et al.  Zirconia-based solid electrolytes: microstructure, stability and ionic conductivity , 1992 .

[24]  B. Boukamp.  A Nonlinear Least Squares Fit procedure for analysis of immittance data of electrochemical systems , 1986 .

[25]  H. Brongersma,et al.  The limiting factor for oxygen exchange at the surface of fuel cell electrolytes , 2003 .

[26]  Mogens Bjerg Mogensen,et al.  Chapter 10 – Testing of Electrodes, Cells and Short Stacks , 2003 .

[27]  P. Hendriksen,et al.  Breakdown of losses in thin electrolyte SOFCs , 2003 .

[28]  J. Bentzen,et al.  Improvement of LSM cathode for high power density SOFCs , 2003 .

[29]  Henricus J.M. Bouwmeester,et al.  Electrode Properties of Sr‐Doped LaMnO3 on Yttria‐Stabilized Zirconia II. Electrode Kinetics , 1997 .

[30]  H. Bouwmeester,et al.  Electrode Properties of Sr‐Doped LaMnO3 on Yttria‐Stabilized Zirconia I. Three‐Phase Boundary Area , 1997 .

[31]  H. Iwahara,et al.  Dependence of observed overvoltages on the positioning of the reference electrode on the solid electrolyte , 1994 .