TY - JOUR
T1 - Determination of relevant factors affecting the surface oxygen exchange coefficient of solid oxide fuel cell cathode with ionic conducting oxide coating
AU - Budiman, R. A.
AU - Hong, H. J.
AU - Hashimoto, S.
AU - Yashiro, K.
AU - Bagarinao, K. D.
AU - Kishimoto, H.
AU - Yamaji, K.
AU - Kawada, T.
N1 - Funding Information:
This work was supported by JST, Japan, as part of “Phase Interface Science for Highly Efficient Energy Utilization” project in strategic basic research program, CREST .
Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2020/10/1
Y1 - 2020/10/1
N2 - In order to investigate the relevant factors affecting the transport properties of solid oxide fuel cell cathodes upon coating with Ce0.9Gd0.1O1.95 (GDC), the surface oxygen exchange coefficient, k*, and oxide ion diffusivity, D*, of La0.6Sr0.4CoO3-δ (LSC) and La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) were measured by a combination of isotope exchange technique and secondary ion mass spectrometry (SIMS). The k* of LSCF/GDC enhanced compared to a bare LSCF for all measured temperatures. In contrast, the k* of LSC/GDC only showed an enhancement compared to the bare LSC at relatively low temperatures (below 873 K) but not at higher temperatures. From these results, GDC has a less significant effect on the k* of LSC compared to LSCF. This suggests that the enhancement of k* is possibly induced only when the oxygen vacancy concentration, δ, of the cathode is lower than that of GDC, although another factor may affect the enhancement. The enhancement of k* is attributed to the formation of triple-phase boundary where a spill-over mechanism controlled the oxygen reduction reaction. The change of rate-determining step of LSCF due to the GDC coating suggests that the enhancement of the k* is not only with respect to the incorporation process, but it is possibly enhancing the reaction steps that involve δ as well.
AB - In order to investigate the relevant factors affecting the transport properties of solid oxide fuel cell cathodes upon coating with Ce0.9Gd0.1O1.95 (GDC), the surface oxygen exchange coefficient, k*, and oxide ion diffusivity, D*, of La0.6Sr0.4CoO3-δ (LSC) and La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) were measured by a combination of isotope exchange technique and secondary ion mass spectrometry (SIMS). The k* of LSCF/GDC enhanced compared to a bare LSCF for all measured temperatures. In contrast, the k* of LSC/GDC only showed an enhancement compared to the bare LSC at relatively low temperatures (below 873 K) but not at higher temperatures. From these results, GDC has a less significant effect on the k* of LSC compared to LSCF. This suggests that the enhancement of k* is possibly induced only when the oxygen vacancy concentration, δ, of the cathode is lower than that of GDC, although another factor may affect the enhancement. The enhancement of k* is attributed to the formation of triple-phase boundary where a spill-over mechanism controlled the oxygen reduction reaction. The change of rate-determining step of LSCF due to the GDC coating suggests that the enhancement of the k* is not only with respect to the incorporation process, but it is possibly enhancing the reaction steps that involve δ as well.
KW - Isotope exchange technique
KW - Oxide ion diffusivity
KW - Oxygen vacancy concentration
KW - Spill-over mechanism
KW - Surface oxygen exchange
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U2 - 10.1016/j.ssi.2020.115372
DO - 10.1016/j.ssi.2020.115372
M3 - Article
AN - SCOPUS:85086453857
SN - 0167-2738
VL - 353
JO - Solid State Ionics
JF - Solid State Ionics
M1 - 115372
ER -