Abstract
This paper presents a mathematical model of mass and charge transport and electrochemical reaction in porous composite cathodes for application in solid oxide fuel cells. The model describes a porous composite cathode as a continuum, and characterises charge and mass transfer and electrochemical kinetics using effective parameters (i.e. conductivity, diffusivity, exchange current) related to morphology and material properties by percolation theory. The model accounts for the distribution of morphological properties (i.e. porosity, tortuosity, density of contacts among particles) along cathode thickness, as experimentally observed on scanning electron microscope images of LSM/YSZ cathodes of varying thickness. This feature allows the model to reproduce the dependence of polarisation resistance on thickness, as determined by impedance spectroscopy on LSM/YSZ cathodes of varying thickness. Polarisation resistance in these cathodes is almost constant for thin cathodes (up to 10 µm thickness), it sharply decreases for intermediate thickness, to reach a minimum value for about 50 µm thickness, then it slightly increases in thicker cathodes.
Similar content being viewed by others
Abbreviations
- a :
-
Contact surface area (m2)
- F :
-
Faraday constant (C mol−1)
- i :
-
Current density (A cm−2)
- j :
-
Current density (A (contact point)−1)
- i 0 :
-
Exchange current (A cm−2)
- j 0 :
-
Exchange current (A (contact point)−1)
- k :
-
Compression factor
- n V :
-
Density of contact points (contact point m−3)
- R :
-
Resistance (Ω cm2)
- R g :
-
Gas constant (J mol−1 K−1)
- T :
-
Temperature (K)
- V :
-
Potential (V)
- X :
-
Volume fraction
- z :
-
Axial coordinate (m)
- α:
-
Transfer coefficient
- δ:
-
Cathode thickness (m)
- γ:
-
Relative grey level
- η:
-
Overpotential (V)
- ρ:
-
Resistivity (Ω m)
- τ:
-
Tortuosity
- el:
-
Electronic
- io:
-
Ionic
- p:
-
Polarisation
- tot:
-
Total
- tr:
-
Transfer
- 0:
-
Single-component material
- cr:
-
Percolation threshold
- eq:
-
Equilibrium
- r :
-
Relative
References
Kenjo T, Osawa S, Fujikawa K (1991) J Electrocem Soc 138(349):355
Adler SB (2004) Chem Rev 104(4791):4843
Bouvard D, Lange FF (1991) Acta Metall Mater 39(3083):3091
Radhakrishnan R, Virkar AV, Singhal SC (2005) J Electrochem Soc 152:A210–A218
Fleig J (2003) Annu Rev Mater Res 33(361):382
Costamagna P, Costa P, Antonucci V (1998) Electrochimica Acta 43(375):394
Kenney B, Karan K (2007) Solid State Ion 178(297):306
Schneider LCR, Martin CL, Bultel Y, Dessemond L, Bouvard D (2007) Electrochim Acta 52(3190):3198
Mizusaki J, Tagawa H, Tsuneyoshi K, Sawata A (1991) J Electrochem Soc 138(1867):1873
Brichzin V, Fleig J, Habermeier H-U, Cristiani G, Maier J (2002) Solid State Ion 152–153(499):507
Juhl M, Primdahl S, Manon C, Mogensen M (1996) J Power Sources 61(173):181
Barbucci A, Carpanese P, Reverberi AP, Cerisola G, Blanes M, Cabot ML, Viviani M, Bertei A, Nicolella C (2008) J Appl Electrochem 38(939):945
Virkar AV, Chen JC, Tanner CW, Kim J-W (2000) Solid State Ion 131(189):198
Barbucci A, Carpanese P, Viviani M, Nicolella C (2008) J Appl Electroch (submitted)
Bard AJ, Faulker RL (2002) Electrochemical methods: fundamentals and applications. Wiley, New York
Carpanese P (2008) Electrochemical investigations of composite cathodes for SOFCs: experimental and theoretical study. PhD Thesis, University of Genoa
Yi JY, Choi GM (2002) Solid State Ion 148(557):565
Sotta P, Long D (2003) Eur Phys J 11(375):388
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Nicolella, C., Bertei, A., Viviani, M. et al. Morphology and electrochemical activity of SOFC composite cathodes: II. Mathematical modelling. J Appl Electrochem 39, 503–511 (2009). https://doi.org/10.1007/s10800-008-9691-3
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10800-008-9691-3