Durability and thermal cycling of Ni/YSZ cermet anodes for solid oxide fuel cells

The long-term properties of Ni/yttria stabilized zirconia (YSZ) cermet anodes for solid oxide fuel cells were evaluated experimentally. A total of 13 anodes of three types based on two commercial NiO powders were examined. The durability was evaluated at temperatures of 850 ∘C, 1000 ∘C and 1050 ∘C over 1300 to 2000 h at an anodic d.c. load of 300 mA cm−2 in hydrogen with 1 to 3% water. The anode-related polarization resistance, RP, was measured by impedance spectroscopy and found to be in the range of 0.05 to 0.7 Ω  cm2. After an initial stabilization period of up to 300 h, RP varied linearly with time within the experimental uncertainty. At 1050 ∘C no degradation was observed. At 1000 ∘C a degradation rate of 10 mΩ cm2 per 1000 h was found. The degradation rate was possibly higher at 850 ∘C. A single anode was exposed to nine thermal cycles from 1000 to below 100 ∘C at 100 ∘C h−1. An increase in RP of about 30 mΩ cm2 was observed over the first two cycles. For the following thermal cycles RP was stable within the experimental uncertainty.

[1]  H. Möbius,et al.  Potentiometrische Bestimmung des Wasserdampf‐Dissoziationsgleichgewichtes zwischen 1000 und 1300°K mit einer Festelektrolytzelle , 1968 .

[2]  B. Santo,et al.  Solid State , 2012 .

[3]  H. Sasaki,et al.  Evaluation of the cost performance of the SOFC cell in the market , 1996 .

[4]  Masamichi Ippommatsu,et al.  Preparation of Nickel Pattern Electrodes on YSZ and Their Electrochemical Properties in  H 2 ‐  H 2 O  Atmospheres , 1994 .

[5]  H. Takagi,et al.  EFFECTIVE ELECTRODE REACTION AREA OF COFIRED TYPE PLANAR SOFC , 1996 .

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

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

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

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

[10]  Tomoo Iwata,et al.  Characterization of Ni‐YSZ Anode Degradation for Substrate‐Type Solid Oxide Fuel Cells , 1996 .

[11]  J. Winkler,et al.  Geometric Requirements of Solid Electrolyte Cells with a Reference Electrode , 1998 .

[12]  Mogens Bjerg Mogensen,et al.  Characterisation of composite SOFC cathodes using electrochemical impedance spectroscopy , 1999 .

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