TY - JOUR
T1 - Effect of low temperature in-situ sintering on the impedance and the performance of intermediate temperature solid oxide fuel cell cathodes
AU - Nielsen, Jimmi
AU - Hjalmarsson, Per
AU - Hansen, Martin Hangaard
AU - Blennow Tullmar, Peter
PY - 2014
Y1 - 2014
N2 - The effect of in-situ sintering temperature and time on the electronic conductivity, impedance and performance of IT-SOFC cathodes were studied. The studied cathodes were for comparison (La0.6Sr0.4)0.99CoO3 (LSC), (La0.6Sr0.4)0.99CoO3:Ce0.9Gd0.1O1.95 (LSC:CGO), La0.58Sr0.4Co0.2Fe0.8O3 (LSCF) and La0.58Sr0.4Co0.2Fe0.8O3:Ce0.9Gd0.1O1.95 (LSCF:CGO). The LSCF-based cathodes showed poor sintering capabilities compared to the LSC-based cathodes in the studied temperature range of 650–950 °C. The poor necking between individual LSCF grains lower the electronic conductivity. Furthermore, poor cathode/electrolyte adhesion was seen as an additional high frequency impedance arc, which gradually disappeared as the LSCF cathodes were sintered at increasing temperature. Effects on the impedance shape from poor cathode grain connectivity was shown through impedance simulations to result in a possible increase in the high frequency slope of the characteristic Gerischer impedance response of porous mixed ionic and electronically conducting (MIEC) cathodes. In contrast to LSCF, the LSC-based cathodes showed excellent sintering capabilities, electronic conductivity and performance. Scanning electron microscopy investigations showed that significant interaction already takes place at 750 °C between the LSC-based cathodes and the electrolyte. The polarization resistance (Rp) of the LSC based cathodes was 0.05 Ω cm2, which to our knowledge is the best performance reported in the literature for a low temperature 800 °C in-situ sintered cathode.
AB - The effect of in-situ sintering temperature and time on the electronic conductivity, impedance and performance of IT-SOFC cathodes were studied. The studied cathodes were for comparison (La0.6Sr0.4)0.99CoO3 (LSC), (La0.6Sr0.4)0.99CoO3:Ce0.9Gd0.1O1.95 (LSC:CGO), La0.58Sr0.4Co0.2Fe0.8O3 (LSCF) and La0.58Sr0.4Co0.2Fe0.8O3:Ce0.9Gd0.1O1.95 (LSCF:CGO). The LSCF-based cathodes showed poor sintering capabilities compared to the LSC-based cathodes in the studied temperature range of 650–950 °C. The poor necking between individual LSCF grains lower the electronic conductivity. Furthermore, poor cathode/electrolyte adhesion was seen as an additional high frequency impedance arc, which gradually disappeared as the LSCF cathodes were sintered at increasing temperature. Effects on the impedance shape from poor cathode grain connectivity was shown through impedance simulations to result in a possible increase in the high frequency slope of the characteristic Gerischer impedance response of porous mixed ionic and electronically conducting (MIEC) cathodes. In contrast to LSCF, the LSC-based cathodes showed excellent sintering capabilities, electronic conductivity and performance. Scanning electron microscopy investigations showed that significant interaction already takes place at 750 °C between the LSC-based cathodes and the electrolyte. The polarization resistance (Rp) of the LSC based cathodes was 0.05 Ω cm2, which to our knowledge is the best performance reported in the literature for a low temperature 800 °C in-situ sintered cathode.
KW - Cathodes
KW - In-situ sintering
KW - IT-SOFC
KW - LSC
KW - LSCF
KW - Impedance
U2 - 10.1016/j.jpowsour.2013.06.067
DO - 10.1016/j.jpowsour.2013.06.067
M3 - Journal article
SN - 0378-7753
VL - 245
SP - 418
EP - 428
JO - Journal of Power Sources
JF - Journal of Power Sources
ER -