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Composite (La, Sr)MnO3–YSZ cathode for SOFC
Solid State Ionics 177 (2006) 2071 – 2074 www.elsevier.com/locate/ssi
Composite (La, Sr)MnO3 –YSZ cathode for SOFC Toshio Suzuki a,*, Masanobu Awano a, Piotr Jasinski b, Vladimir Petrovsky c, Harlan U. Anderson c a
Advanced Manufacturing Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora Shimo-Shidami, Moriyama-ku Nagoya 463-8560, Japan b Department of Biomedical Engineering, Gdansk University of Technology, Gdansk, Poland c Electronic Materials Applied Research Center, University of Missouri-Rolla., Missouri, U.S.A. Received 30 June 2005; received in revised form 12 December 2005; accepted 14 December 2005
Abstract (La, Sr)MnO3 (LSM) – Y doped ZrO2 (YSZ) composite was prepared using YSZ colloidal suspension (initial YSZ particle size ¨100 nm), YSZ and LSM polymer precursors on dense substrates at 800 -C annealing temperature. The results of a symmetrical LSM – YSZ composite cell test showed the area specific resistance for overpotential of 0.14 V cm2 at 800 -C, which indicated that the LSM – YSZ composite could be a potential candidate for cathode in SOFCs. The performance of the cell with the LSM – YSZ composite cathode and Ni-YSZ anode was investigated and the power density of about 0.26 W cm 2 was obtained at 850 -C using hydrogen fuel. D 2005 Elsevier B.V. All rights reserved. Keywords: Cathode; SOFC; YSZ; LSM; Low temperature processing
1. Introduction Solid oxide fuel cells (SOFCs) have been paid a lot of attention as a new energy source for the next generation due to their high fuel utilization [1 – 3]. Recent studies have proposed new materials and cell configurations to reduce operating temperatures, which open opportunities of SOFCs in variety of application use [4,5]. Several successful results have been shown for cells with Ni-cermet anode support to reduce the thickness of an electrolyte (anode supported SOFC) for intermediate temperature (IT)-SOFCs [6,7]. One of approaches for the development of IT-SOFCs is to reduce a cell processing temperature because it could (i) avoid interfacial reactions between an electrode and an electrolyte, which may cause degradation of cell performance, (ii) avoid sample damages due to thermal expansion mismatch at high processing temperature and (iii) provide variety of material selection (iv) reduce processing cost. Several low temperature * Corresponding author. Tel.: +81 52 736 7299; fax: +81 52 736 7405. E-mail addresses: [email protected] (T. Suzuki), [email protected] (M. Awano), [email protected] (P. Jasinski), [email protected] (V. Petrovsky), [email protected] (H.U. Anderson). 0167-2738/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.ssi.2005.12.016
ceramic processing techniques have been proposed such as chemical vapour phase deposition, polymeric precursor spin coating and radio frequency sputtering. Among these techniques, the polymer precursor technique has been proven to be one of the suitable methods for the preparation of oxide in low temperature under 800 -C [8]. Our group previously showed that a dense YSZ electrolyte could be prepared on porous substrates with 400 -C annealing temperature to receive as same conductivity as bulk YSZ has by using the YSZ polymer precursor and YSZ colloidal suspension (YSZ particle size ¨100 nm) [9]. The process of this technique is as follows; first, a YSZ skeleton layer is prepared by the colloidal suspension, then, densified the layer by filling the YSZ polymer precursor. This technique can be applied for the process of not only an electrolyte but also electrodes by choosing suitable polymer precursors and controlling concentration of materials in the polymer precursor. In this study, a new type of composite cathode has been prepared using (La, Sr)MnO3 (LSM) polymer precursor, Y doped ZrO2 (YSZ) polymer precursor and YSZ colloidal suspension at 800 -C processing temperature. The composite LSM – YSZ was examined for performance as a cathode for SOFCs in different conditions including overpotential
2072
T. Suzuki et al. / Solid State Ionics 177 (2006) 2071 – 2074 103
Gain Phase Analyzer with 4-probe configuration, which were typically used for planar SOFC measurement. The fuel cell performance was evaluated in the double chamber configuration using a forming gas (10 vol.% H2 in N2) at an anode side and air at a cathode side. A mixture of Ag paste and YSZ powder was used as a current collector, which was applied to the area of electrodes, 0.28 cm2. Analysis of the impedance spectra was made using a software, Zview (Scribner Associates, Inc.). All data were fitted to an equivalent circuit to determine the electrolyte and overpotential resistances.
La0.8Sr0.2MnO3-δ
Conductivity, Scm-1
102 101
Composite LSM-YSZ
100 10-1 YSZ
10-2 10-3 0.9
1.0
1.1 3
1.2
1.3
3. Results and discussion
-1
10 /T, K
measurement using a symmetrical composite LSM – YSZ cell and a fuel cell measurement. 2. Experimental Composite (La0.8Sr0.2)0.9MnO3 – Y doped ZrO2 (LSM – YSZ) was prepared by coating YSZ colloidal suspension (initial YSZ particle size ¨100 nm) and LSM polymer precursor on dense YSZ substrate (0.4 mm thick). Commercially available YSZ powder (8 mol% Y2O3 doped ZrO2, Daiichiki Genso Co, Japan) was used for processing colloidal suspension. For the preparation of polymer precursors, the details were discussed elsewhere [10]. Preparation process is as follows; (i) Preparation of YSZ colloidal suspension. (ii) Preparation of polymer precursors (YSZ and target cathode materials). (iii) Coating the colloidal suspension on the substrate to prepare YSZ porous layer. (iv) Application of YSZ polymer precursor to a porous layer to connect particles. (v) Impregnation process — impregnate LSM polymer precursor to a porous layer by spin coating for 15 times. Every coating, the polymer coatings are converted to the oxide by heating to 380 -C to remove the hydrocarbons. (vi) Annealing at 800 -C. For the preparation of a symmetrical cell, the composite LSM – YSZ was prepared for both sides of a 0.4 mm thick YSZ substrate, which was used as an electrolyte. For a fuel cell preparation, Ni-YSZ powder ink (Ni 45 wt.%) was screen printed on the YSZ substrate and sintered at 1400 -C for 1 h. Then, the composite LSM – YSZ was prepared on the other side. The microstructures of the resulting cells were analyzed using a scanning electron microscope (Hitachi S4700). Impedance spectroscopy techniques were utilized to investigate the performance of the composite LSM – YSZ symmetrical cell using Solartron 1470 Battery Tester and 1255B Impedance
3.1. Electrical conductivity of the composite LSM – YSZ Fig. 1 shows the electrical conductivity of the composite LSM –YSZ as a function of reciprocal temperature along with the conductivity of YSZ [11] and LSM [12]. Compared to the literature for the LSM, composite LSM – YSZ showed lower conductivity simply due to lower concentration of LSM in the composite. However, it was observed to have a sufficient value of conductivity, which made the composite LSM – YSZ attractive to use as a cathode. 3.2. Symmetrical cell test (composite cathode – electrolyte– composite cathode cell) Fig. 2 shows the impedance spectra of the symmetrical cell obtained in air at 700– 800 -C. Two semi-circles were observed in the impedance spectra, which are typically interpreted as the charge transfer and gas diffusion process [13], namely R 2 and R 3, respectively, as shown in Fig. 2. High frequency resistance, R 1, is corresponding to the resistance of the YSZ substrate. Fig. 3 shows the area specific resistance for the composite LSM –YSZ symmetrical cell determined from the impedance spectra using a equivalent circuit shown in Fig. 2. The fitting errors estimated by the program were within 10%. Overpotential resistances, R 2 and R 3, are low compared to the electrolyte resistance, which are corresponding to the charge transfer and the gas diffusion processes, respectively. Relatively large overpotential from the gas diffusion process was
-1.0 -0.8
Z'', Ωcm2
Fig. 1. Electrical conductivity of the composite LSM – YSZ along with the conductivity of bulk YSZ and La0.8Sr0.2MnO3 d .
R1
R2
R3
CPE
CPE
-0.6 -0.4 R3
o
o
800 C
-0.2 0.0 0.0
0.5
750 C
o
700 C
R2
1.5
1.0
Z', Ωcm2
2.0
R1
Fig. 2. Impedance spectra of the composite LSM – YSZ symmetrical cell (symmetrical double sided cell, electrode area = 0.28 cm2).
T. Suzuki et al. / Solid State Ionics 177 (2006) 2071 – 2074 -1.5
102
Z'', Ωcm2
ASR, Ωcm2
R1 R3
R3
R2
R1 101
2073
R1= electrolyte R2+ R2 = overpotential
-1.0
CPE
CPE
-0.5
R2
100
o
700 C
o
o
800 C
o
850 C
0.0 0.0
750 C
1.5
1.0
0.5
10-1
2.0
2.5
Z', Ωcm2 Fig. 5. Impedance spectra for the composite LSM – YSZ/YSZ/Ni-YSZ cell.
-2
10
0.9
1.0
1.1
1.2
1.3
1.4
1.5
-1
1000/T, K
Fig. 3. Area specific resistance of the composite LSM – YSZ symmetrical cell.
observed probably due to dense structure of the composite LSM – YSZ. Total overpotential resistance for the composite LSM – YSZ cathode can be estimated as 0.14 V cm2 at 800 -C and 0.3 V cm2 at 700 -C for single electrode.
mined from the symmetrical cell test was estimated as 0.14 V cm2 at 800 -C. The performance of the cell was mainly limited by the electrolyte resistance, which can be easily improved by reducing the thickness of an electrolyte. Further investigation is undergoing to improve microstructure of the composite to decrease the overpotential from gas diffusion process, as well as searching for new materials for a composite cathode. 4. Conclusions
3.3. Fuel cell test (anode/electrolyte/composite cathode cell) Fuel cell performance of the composite LSM – YSZ (cathode)/YSZ/Ni-YSZ (anode) cell was investigated using a forming gas (10 vol.% H2 in N2). Fig. 4 shows the discharge profile of the cell at the temperature range from 650 to 850 -C. The results showed that a maximum power density of about 0.26 W cm 2 was obtained at a temperature of 850 -C with a current density of 0.65 A cm 2. The impedance spectra for this cell were shown in Fig. 5. The spectra showed distorted semicircles with relatively higher high frequency resistance corresponding to thick YSZ electrolyte. The area specific resistances of the cell were shown in Fig. 6. The overpotential ASR of the cell was estimated as 0.3 V cm2 at 800 -C, which is the total of anode and cathode overpotential. It appeared that about a half of ASR was originated from anode overpotential, since the overpotential ASR of the composite cathode deter-
Composite LSM – YSZ was prepared by combining YSZ colloidal suspension (initial YSZ particle size ¨100 nm) and YSZ and LSM polymer precursor coatings. This composite technique allows preparing fuel cell components under 800 -C, which makes it possible to use a variety of materials and cell configurations. The composite LSM – YSZ prepared at 800 -C showed high conductivity enough to be used as a electrode. The results of the symmetrical cell test showed that the area specific resistances (ASR) for overpotential were 0.14 and 0.3 V cm2 at 800 and 700 -C, respectively, mainly due to the gas diffusion process. The performance of the composite LSM –YSZ as a cathode for SOFC was investigated. A maximum power density of about 0.26 W cm 2 at 850 -C was obtained using 0.4 mm thick YSZ electrolyte and Ni-YSZ as an anode, with the ASR for total overpotential about 0.17 V cm2 at 850 -C.
0.5
1.2
101 0.4
0.3 0.6 0.2 0.4
850 oC
Electrolyte ASR
ASR, Ωcm2
0.8
Power Density, Wcm-2
Terminal Voltage, V
1.0
0
10
Overpotential ASR
0.1
0.2
650 oC
0.0 0.0
0.2
700 oC 0.4
750oC
0.6
0.8
800 oC 1.0
1.2
0.0 1.4
Current Density, Acm-2
10-1 - R1 from symmetrical cell test 0.85
0.90
0.95
1.00
1.05
1.10
1000/T, K-1 Fig. 4. I – V discharge profile and I – P characterization for the composite LSM – YSZ/YSZ/Ni-YSZ cell.
Fig. 6. Area specific resistance of the composite LSM – YSZ/YSZ/Ni-YSZ cell.
2074
T. Suzuki et al. / Solid State Ionics 177 (2006) 2071 – 2074
References [1] N.Q. Minh, T. Takahashi, Science and Technology of Ceramic Fuel Cell, Elsevier, The Netherlands, 1995. [2] B.C.H. Steele, J. Mater. Sci. 36 (2001) 1053. [3] S.C. Singhal, MRS Bulletin, March 2000, p. 16. [4] B.C.H. Steele, Solid State Ionics 86 – 88 (1996) 1223. [5] S. Park, R.J. Gorte, J.M. Vohs, J. Electrochem. Soc. 148 (5) (2001) A443 (direct hydrocarbon). [6] B.C.H. Steele, Solid State Ionics 94 (1997) 239.
[7] R.E. Williford, L.A. Chick, G.D. Maupin, S.P. Simner, J.W. Stevenson, J. Electrochem. Soc. 150 (8) (2003) A1067. [8] T. Suzuki, I. Kosacki, H.U. Anderson, J. Am. Ceram. Soc. 85 (6) (2002) 1492. [9] V. Petrovsky, T. Suzuki, P. Jasinski, T. Petrovsky, H.U. Anderson, Electrochem. Solid-State Lett. 7 (6) (2004) A138. [10] H.U. Anderson, M.M. Nasrallah, C.C. Chen, U.S. Patent, 5494700 (1996). [11] T.H. Etsell, S.N. Flengas, Chem. Rev. 70 (1970) 339. [12] J.H. Kuo, H.U. Anderson, D.M. Sparlin, J. Solid State Chem. 87 (1990) 55. [13] S.B. Adler, Solid State Ionics 111 (1998) 125.
Composite (La, Sr)MnO3 –YSZ cathode for SOFC Toshio Suzuki a,*, Masanobu Awano a, Piotr Jasinski b, Vladimir Petrovsky c, Harlan U. Anderson c a
Advanced Manufacturing Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora Shimo-Shidami, Moriyama-ku Nagoya 463-8560, Japan b Department of Biomedical Engineering, Gdansk University of Technology, Gdansk, Poland c Electronic Materials Applied Research Center, University of Missouri-Rolla., Missouri, U.S.A. Received 30 June 2005; received in revised form 12 December 2005; accepted 14 December 2005
Abstract (La, Sr)MnO3 (LSM) – Y doped ZrO2 (YSZ) composite was prepared using YSZ colloidal suspension (initial YSZ particle size ¨100 nm), YSZ and LSM polymer precursors on dense substrates at 800 -C annealing temperature. The results of a symmetrical LSM – YSZ composite cell test showed the area specific resistance for overpotential of 0.14 V cm2 at 800 -C, which indicated that the LSM – YSZ composite could be a potential candidate for cathode in SOFCs. The performance of the cell with the LSM – YSZ composite cathode and Ni-YSZ anode was investigated and the power density of about 0.26 W cm 2 was obtained at 850 -C using hydrogen fuel. D 2005 Elsevier B.V. All rights reserved. Keywords: Cathode; SOFC; YSZ; LSM; Low temperature processing
1. Introduction Solid oxide fuel cells (SOFCs) have been paid a lot of attention as a new energy source for the next generation due to their high fuel utilization [1 – 3]. Recent studies have proposed new materials and cell configurations to reduce operating temperatures, which open opportunities of SOFCs in variety of application use [4,5]. Several successful results have been shown for cells with Ni-cermet anode support to reduce the thickness of an electrolyte (anode supported SOFC) for intermediate temperature (IT)-SOFCs [6,7]. One of approaches for the development of IT-SOFCs is to reduce a cell processing temperature because it could (i) avoid interfacial reactions between an electrode and an electrolyte, which may cause degradation of cell performance, (ii) avoid sample damages due to thermal expansion mismatch at high processing temperature and (iii) provide variety of material selection (iv) reduce processing cost. Several low temperature * Corresponding author. Tel.: +81 52 736 7299; fax: +81 52 736 7405. E-mail addresses: [email protected] (T. Suzuki), [email protected] (M. Awano), [email protected] (P. Jasinski), [email protected] (V. Petrovsky), [email protected] (H.U. Anderson). 0167-2738/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.ssi.2005.12.016
ceramic processing techniques have been proposed such as chemical vapour phase deposition, polymeric precursor spin coating and radio frequency sputtering. Among these techniques, the polymer precursor technique has been proven to be one of the suitable methods for the preparation of oxide in low temperature under 800 -C [8]. Our group previously showed that a dense YSZ electrolyte could be prepared on porous substrates with 400 -C annealing temperature to receive as same conductivity as bulk YSZ has by using the YSZ polymer precursor and YSZ colloidal suspension (YSZ particle size ¨100 nm) [9]. The process of this technique is as follows; first, a YSZ skeleton layer is prepared by the colloidal suspension, then, densified the layer by filling the YSZ polymer precursor. This technique can be applied for the process of not only an electrolyte but also electrodes by choosing suitable polymer precursors and controlling concentration of materials in the polymer precursor. In this study, a new type of composite cathode has been prepared using (La, Sr)MnO3 (LSM) polymer precursor, Y doped ZrO2 (YSZ) polymer precursor and YSZ colloidal suspension at 800 -C processing temperature. The composite LSM – YSZ was examined for performance as a cathode for SOFCs in different conditions including overpotential
2072
T. Suzuki et al. / Solid State Ionics 177 (2006) 2071 – 2074 103
Gain Phase Analyzer with 4-probe configuration, which were typically used for planar SOFC measurement. The fuel cell performance was evaluated in the double chamber configuration using a forming gas (10 vol.% H2 in N2) at an anode side and air at a cathode side. A mixture of Ag paste and YSZ powder was used as a current collector, which was applied to the area of electrodes, 0.28 cm2. Analysis of the impedance spectra was made using a software, Zview (Scribner Associates, Inc.). All data were fitted to an equivalent circuit to determine the electrolyte and overpotential resistances.
La0.8Sr0.2MnO3-δ
Conductivity, Scm-1
102 101
Composite LSM-YSZ
100 10-1 YSZ
10-2 10-3 0.9
1.0
1.1 3
1.2
1.3
3. Results and discussion
-1
10 /T, K
measurement using a symmetrical composite LSM – YSZ cell and a fuel cell measurement. 2. Experimental Composite (La0.8Sr0.2)0.9MnO3 – Y doped ZrO2 (LSM – YSZ) was prepared by coating YSZ colloidal suspension (initial YSZ particle size ¨100 nm) and LSM polymer precursor on dense YSZ substrate (0.4 mm thick). Commercially available YSZ powder (8 mol% Y2O3 doped ZrO2, Daiichiki Genso Co, Japan) was used for processing colloidal suspension. For the preparation of polymer precursors, the details were discussed elsewhere [10]. Preparation process is as follows; (i) Preparation of YSZ colloidal suspension. (ii) Preparation of polymer precursors (YSZ and target cathode materials). (iii) Coating the colloidal suspension on the substrate to prepare YSZ porous layer. (iv) Application of YSZ polymer precursor to a porous layer to connect particles. (v) Impregnation process — impregnate LSM polymer precursor to a porous layer by spin coating for 15 times. Every coating, the polymer coatings are converted to the oxide by heating to 380 -C to remove the hydrocarbons. (vi) Annealing at 800 -C. For the preparation of a symmetrical cell, the composite LSM – YSZ was prepared for both sides of a 0.4 mm thick YSZ substrate, which was used as an electrolyte. For a fuel cell preparation, Ni-YSZ powder ink (Ni 45 wt.%) was screen printed on the YSZ substrate and sintered at 1400 -C for 1 h. Then, the composite LSM – YSZ was prepared on the other side. The microstructures of the resulting cells were analyzed using a scanning electron microscope (Hitachi S4700). Impedance spectroscopy techniques were utilized to investigate the performance of the composite LSM – YSZ symmetrical cell using Solartron 1470 Battery Tester and 1255B Impedance
3.1. Electrical conductivity of the composite LSM – YSZ Fig. 1 shows the electrical conductivity of the composite LSM –YSZ as a function of reciprocal temperature along with the conductivity of YSZ [11] and LSM [12]. Compared to the literature for the LSM, composite LSM – YSZ showed lower conductivity simply due to lower concentration of LSM in the composite. However, it was observed to have a sufficient value of conductivity, which made the composite LSM – YSZ attractive to use as a cathode. 3.2. Symmetrical cell test (composite cathode – electrolyte– composite cathode cell) Fig. 2 shows the impedance spectra of the symmetrical cell obtained in air at 700– 800 -C. Two semi-circles were observed in the impedance spectra, which are typically interpreted as the charge transfer and gas diffusion process [13], namely R 2 and R 3, respectively, as shown in Fig. 2. High frequency resistance, R 1, is corresponding to the resistance of the YSZ substrate. Fig. 3 shows the area specific resistance for the composite LSM –YSZ symmetrical cell determined from the impedance spectra using a equivalent circuit shown in Fig. 2. The fitting errors estimated by the program were within 10%. Overpotential resistances, R 2 and R 3, are low compared to the electrolyte resistance, which are corresponding to the charge transfer and the gas diffusion processes, respectively. Relatively large overpotential from the gas diffusion process was
-1.0 -0.8
Z'', Ωcm2
Fig. 1. Electrical conductivity of the composite LSM – YSZ along with the conductivity of bulk YSZ and La0.8Sr0.2MnO3 d .
R1
R2
R3
CPE
CPE
-0.6 -0.4 R3
o
o
800 C
-0.2 0.0 0.0
0.5
750 C
o
700 C
R2
1.5
1.0
Z', Ωcm2
2.0
R1
Fig. 2. Impedance spectra of the composite LSM – YSZ symmetrical cell (symmetrical double sided cell, electrode area = 0.28 cm2).
T. Suzuki et al. / Solid State Ionics 177 (2006) 2071 – 2074 -1.5
102
Z'', Ωcm2
ASR, Ωcm2
R1 R3
R3
R2
R1 101
2073
R1= electrolyte R2+ R2 = overpotential
-1.0
CPE
CPE
-0.5
R2
100
o
700 C
o
o
800 C
o
850 C
0.0 0.0
750 C
1.5
1.0
0.5
10-1
2.0
2.5
Z', Ωcm2 Fig. 5. Impedance spectra for the composite LSM – YSZ/YSZ/Ni-YSZ cell.
-2
10
0.9
1.0
1.1
1.2
1.3
1.4
1.5
-1
1000/T, K
Fig. 3. Area specific resistance of the composite LSM – YSZ symmetrical cell.
observed probably due to dense structure of the composite LSM – YSZ. Total overpotential resistance for the composite LSM – YSZ cathode can be estimated as 0.14 V cm2 at 800 -C and 0.3 V cm2 at 700 -C for single electrode.
mined from the symmetrical cell test was estimated as 0.14 V cm2 at 800 -C. The performance of the cell was mainly limited by the electrolyte resistance, which can be easily improved by reducing the thickness of an electrolyte. Further investigation is undergoing to improve microstructure of the composite to decrease the overpotential from gas diffusion process, as well as searching for new materials for a composite cathode. 4. Conclusions
3.3. Fuel cell test (anode/electrolyte/composite cathode cell) Fuel cell performance of the composite LSM – YSZ (cathode)/YSZ/Ni-YSZ (anode) cell was investigated using a forming gas (10 vol.% H2 in N2). Fig. 4 shows the discharge profile of the cell at the temperature range from 650 to 850 -C. The results showed that a maximum power density of about 0.26 W cm 2 was obtained at a temperature of 850 -C with a current density of 0.65 A cm 2. The impedance spectra for this cell were shown in Fig. 5. The spectra showed distorted semicircles with relatively higher high frequency resistance corresponding to thick YSZ electrolyte. The area specific resistances of the cell were shown in Fig. 6. The overpotential ASR of the cell was estimated as 0.3 V cm2 at 800 -C, which is the total of anode and cathode overpotential. It appeared that about a half of ASR was originated from anode overpotential, since the overpotential ASR of the composite cathode deter-
Composite LSM – YSZ was prepared by combining YSZ colloidal suspension (initial YSZ particle size ¨100 nm) and YSZ and LSM polymer precursor coatings. This composite technique allows preparing fuel cell components under 800 -C, which makes it possible to use a variety of materials and cell configurations. The composite LSM – YSZ prepared at 800 -C showed high conductivity enough to be used as a electrode. The results of the symmetrical cell test showed that the area specific resistances (ASR) for overpotential were 0.14 and 0.3 V cm2 at 800 and 700 -C, respectively, mainly due to the gas diffusion process. The performance of the composite LSM –YSZ as a cathode for SOFC was investigated. A maximum power density of about 0.26 W cm 2 at 850 -C was obtained using 0.4 mm thick YSZ electrolyte and Ni-YSZ as an anode, with the ASR for total overpotential about 0.17 V cm2 at 850 -C.
0.5
1.2
101 0.4
0.3 0.6 0.2 0.4
850 oC
Electrolyte ASR
ASR, Ωcm2
0.8
Power Density, Wcm-2
Terminal Voltage, V
1.0
0
10
Overpotential ASR
0.1
0.2
650 oC
0.0 0.0
0.2
700 oC 0.4
750oC
0.6
0.8
800 oC 1.0
1.2
0.0 1.4
Current Density, Acm-2
10-1 - R1 from symmetrical cell test 0.85
0.90
0.95
1.00
1.05
1.10
1000/T, K-1 Fig. 4. I – V discharge profile and I – P characterization for the composite LSM – YSZ/YSZ/Ni-YSZ cell.
Fig. 6. Area specific resistance of the composite LSM – YSZ/YSZ/Ni-YSZ cell.
2074
T. Suzuki et al. / Solid State Ionics 177 (2006) 2071 – 2074
References [1] N.Q. Minh, T. Takahashi, Science and Technology of Ceramic Fuel Cell, Elsevier, The Netherlands, 1995. [2] B.C.H. Steele, J. Mater. Sci. 36 (2001) 1053. [3] S.C. Singhal, MRS Bulletin, March 2000, p. 16. [4] B.C.H. Steele, Solid State Ionics 86 – 88 (1996) 1223. [5] S. Park, R.J. Gorte, J.M. Vohs, J. Electrochem. Soc. 148 (5) (2001) A443 (direct hydrocarbon). [6] B.C.H. Steele, Solid State Ionics 94 (1997) 239.
[7] R.E. Williford, L.A. Chick, G.D. Maupin, S.P. Simner, J.W. Stevenson, J. Electrochem. Soc. 150 (8) (2003) A1067. [8] T. Suzuki, I. Kosacki, H.U. Anderson, J. Am. Ceram. Soc. 85 (6) (2002) 1492. [9] V. Petrovsky, T. Suzuki, P. Jasinski, T. Petrovsky, H.U. Anderson, Electrochem. Solid-State Lett. 7 (6) (2004) A138. [10] H.U. Anderson, M.M. Nasrallah, C.C. Chen, U.S. Patent, 5494700 (1996). [11] T.H. Etsell, S.N. Flengas, Chem. Rev. 70 (1970) 339. [12] J.H. Kuo, H.U. Anderson, D.M. Sparlin, J. Solid State Chem. 87 (1990) 55. [13] S.B. Adler, Solid State Ionics 111 (1998) 125.