Last modified: 2014-10-21
Abstract
A relatively high OCV of 1.047 V at 600°C was reported recently for a cell based on a BaZr0.1Ce0.7Y0.1Yb0.1O3−δ(BZCYYb)-NiO anode-supported thin SDC electrolyte, demonstrating a peak power density of 0.50 W/cm2. In this study, an equivalent circuit model was developed for interpreting the behavior of this SDC-based SOFC. The mechanism behind the high OCV and the corresponding high peak power density were elucidated via separating the polarization processes and the corresponding characteristic frequencies, especially those for oxygen ion diffusion through the interlayer at the anode/electrolyte interface. Theoretical analysis and data fitting based on the presented circuit model indicate that the inter-diffusion layer between Ni-BZCYYb and SDC effectively suppresses electronic conduction while maintaining the catalyst activity and ionic conductivity. More importantly, careful analysis of the characteristic frequencies offers a powerful approach to assigning a specific part of the impedance data (e.g., an impedance arc or loop) to the corresponding physicochemical process. Further, any change in the characteristic frequency for a physicochemical process also reflects a change in the inherent nature of that process under the testing conditions. Once validated by more experimental results under a broader range of testing conditions, the presented equivalent circuit model, in turn, maybe used to predict fuel cell performances and optimize the operating conditions.
Presenter: Qiu-An HuangKeywords
References
[1] S.C. Singhal, K. Kendal, High Temperature Solid Oxide Fuel Cells Fundamentals, Design and Applications, Elsevier Ltd., Oxford, England, 2003.
[2] B.C.H Steel, Materials for IT-SOFC stacks 35 years R&D: the inevitability of gradualness? Solid State Ionics 134 (2000) 3-20.
[3] D.J.L. Brett, A. Atkinson, N.P. Brandon, S.J. Skinner, Intermediate temperature solid oxide fuel cells, Chem. Soc. Rev. 37(2008) 1568-1578.
[4] E.D. Wachsman, K. T. Lee, Lowering the Temperature of Solid Oxide Fuel Cells, Science 334 (2011) 935-939.
[5] A. Jaiswal, E.D. Wachsman, Fabrication of Anode Supported Thick Film Ceria Electrolytes for IT-SOFCs, Ionics 11 (2005)161-170.
[6] M. Mogensen, N.M. Sammes, G.A. Tompsett, Physical, chemical and electrochemical properties of pure and doped ceria, Solid State Ionics 129 (2000) 63-94.
[7] N. S. Choudhury, J. W. Patterson, Steady-State Chemical Potential Profiles inSolid Electrolytes, J. Electrochem. Soc.117 (1970)1384-1388.
[8] N.S. Choudhury, J.W. Patterson, Performance characteristics of solidelectrolytes under steady-state conditions, J. Electrochem. Soc.118 (1971)1398-1403.
[9] D. S. Tannhauser, The theoretical energy conversion efficiency of a high temperature fuel cell based on a mixed conductor, J. Electrochem. Soc. 125(8)(1978)1277-1282.
[10] I. Riess, Current-voltage relation and charge distribution in mixed ionic electronic solid conductors, J. Phys. Chem. Solids 47(2) (1986) 129-138.
[11] A.V. Virkar, Theoretical analysis of Solid Oxide Fuel Cells with two-layer, composite electrolytes: electrolyte stability, J. Electrochem. Soc. 138(5)(1991)1481-1487.
[12] S. Yuan, U. Pal, Analytic Solution for Charge Transport and Chemical-Potential Variation in Single-Layer and Multilayer Devices of Different Mixed-Conducting Oxides, J. Electrochem. Soc. 143(10) (1996) 3214-3222.
[13] M.L. Liu, H.X. Hu, Effect of Interfacial Resistance on Determination of Transport Properties of Mixed-Conducting Electrolytes, J.Electrochem. Soc. 143(6) (1996) L109-L112.
[14] H.X. Hu, M.L. Liu, Interfacial studies of solid-state cells based on electrolytes of mixedionic–electronic conductors, Solid State Ionics 109 (1998) 259-272.
[15] H. Näfe, Current-voltage relation and charge distribution in mixed ionic electronic solid conductors, J. Electrochem. Soc. 144(11)(1997) 3922-3929.
[16] S.W. Zha, C.R. Xia, G.Y. Meng, Calculation of the e.m.f. of solid oxide fuel cells, Journal of Applied Electrochemistry 31(2001) 93-98.
[17] H. Näfe, Solid electrolyte galvanic cell under load, Journal of the Applied Electrochemistry 31(2001) 1235-1241.
[18] I. Riess, Mixed ionic–electronic conductors—material propertiesand applications, Solid State Ionics 157 (2003) 1-17.
[19] K. L. Duncan, E. D. Wachsman, Continuum-level analytical model for solid oxide fuel cellswith mixed conducting electrolytes, J. Electrochem. Soc. 156(9)(2009) B1030-B1038.
[20] K. L. Duncan, K.T. Lee, E.D. Wachsman, Dependence of open-circuit potential and power density on electrolyte thickness in solid oxide fuel cells with mixed conducting electrolytes,J. Power Sources 196 (2011) 2445-2451.
[21] H. Näfe, Transference number of a solid electrolyte, electrode polarization and the“modified emf method”, Electrochim.Acta 56 (2011) 9004-9010.
[22] T. Matsui, M. Inaba, A. Mineshige, Z. Ogumi, Electrochemical properties of ceria-based oxides for use in intermediate-temperature SOFCs, Solid State Ionics 176 (2005) 647-654.
[23] T. Matsui, T. Kosaka, M. Inaba, A. Mineshige, Z. Ogumi, Effects of mixed conduction on the open-circuit voltage of intermediate-temperature SOFCs based on Sm-doped ceria electrolytes, Solid State Ionics 176 (2005) 663-668.
[24] J. H. Joo, G. M. Choi, Open-circuit voltage of ceria-based thin film SOFC supported on nano-porous alumina, Solid State Ionics 178 (2007) 1602-1607.
[25] X.G. Zhang, M. Robertson, C. Petit, W. Qu, O.Kesler, R.Maric, D. Ghosh, Internal Shorting and Fuel Loss of a Low Temperature Solid Oxide Fuel Cell with SDC Electrolyte, J. Power Sources 164 (2007) 668–677.
[26] A.V. Virkar, J. Wright, Transport Properties of Mixed Ionic Electronic Conductors under Thermodynamically Equilibrated Conditions: Measurements on Porous Bodies, ECS Transactions 45 (1) (2012)33-44.
[27] Q.A. Huang, B.W. Wang, W. Qu, R. Hui, Impedance Diagnosis of Metal-supported SOFCs with SDC as Electrolyte, J. Power Sources 191 (2) (2009) 297-303.
[28] W.P. Sun, Y.Z. Jiang, Y.F. Wang, S.M. Fang, Z.W. Zhu, W. Liu,A Novel Electronic Current-blocked Stable Mixed Ionic Conductorfor Solid Oxide Fuel Cells, J. Power Sources 196 (2011) 62-68.
[29] M.F. Liu, D. Ding, Y.H. Bai, T. He, M.L. Liu, An Efficient SOFC Based on Samaria-Doped Ceria (SDC)Electrolyte, J. Electrochem. Soc.159 (6) (2012)B661-B665.
[30] S.W. Zhao, C.R.Xia, G.Y. Meng, Effect of Gd (Sm) doping on properties of ceria electrolyte for solid oxide fuel cells, J. Power Sources115(1) (2003) 44-48.
[31] A. Kromp, J. Nielsen, P.Blennow, T.Klemensø, A. Weber, Break-down of Losses in High Performing Metal-Supported Solid Oxide Fuel Cells, 10th European SOFC Forum, 26 - 29 June 2012, Lucerne Switzerland, Session A09 – 84-94.
[32] J.R. Macdonald, Impedance Spectroscopy—Theory Experiment and Application, John Wiley & Sons, New York, 2005.
[33] Q.A. Huang, R. Hui, B. Wang, J. Zhang, A Review of AC Impedance Modeling and Validation in SOFC Diagnosis, Electrochim. Acta 52 (2007)8144-8164.
[34] D. D. Macdonald, Reflections on the history of electrochemical impedance spectroscopy, Electrochim. Acta 51 (2006) 1376-1388.
[35] A. Lasia in: B.E. Conway, J. Bockris, R. White(Eds.), Electrochemical Impedance Spectroscopy and its Application-Modern Aspects of Electrochemistry, Kluwer Academic/Plenum Publishers, New York, 1999, vol.32, p179.
[36] P.J. Gellings, H.J.M. Bouwmeester, The CRC Handbook of Solid State Electrochemistry,CRC Press, Boca Raton, USA, 1997.
[37] H. Yahiro, Y. Baba, K.Eguchi, H. Arai, High Temperature Fuel Cell with Ceria-Yttria Solid Electrolyte, J. Electrochem. Soc.135 (8) (1988)2077-2080.
[38] Q.A. Huang, J. Berghaus, D.F. Yang, S. Yick, Z.W. Wang, B.W. Wang, R. Hui, Polarization analysis for metal-supported SOFCs from different fabrication processes, J. Power Sources 177 (2008) 339-347.
[39] Q.A. Huang, M.F. Liu, M.L. Liu, Performance prediction and operating condition optimization for SDC-based SOFC based on an improved equivalent circuit model, in preparation.
[40] C.R. Xia, M.L. Liu, Novel cathode for low-temperature solid oxide fuel cell, Adv. Mater. 14(7)(2002)521-523.
[41] R. Barfod, M. Mogensen, T. Klemensø, A. Hagen, Y.L. Liu, P.V. Hendriksen, Detailed Characterization of Anode-Supported SOFCs by Impedance Spectroscopy, J. Electrochem. Soc. 154 (4) (2007) B371-378.