TY - JOUR
T1 - Effect of current density on poisoning rate of Co-containing fuel cell cathodes by chromium
AU - Konysheva, E. Yu
N1 - Funding Information:
ACKNOWLEDGMENTS The authors are grateful to J. Mertens, E. Wessel, K. Hilpert, L. Singheiser for their help in carrying out the experiments and also to the program of SIP Jinji Lake Double Hundred Talents for financial support of the work.
PY - 2014/6
Y1 - 2014/6
N2 - Variation of electrochemical performance of a La0.58Sr 0.4Co0.2Fe0.8O3 (LSCF) cathode due to chromium gas-phase deposition has been studied at 800°C. The highest degradation rate is observed under open circuit conditions and is related to formation of a SrCrO4 layer on the surface of an LSCF cathode. This results in an increase in both polarization and ohmic electrode resistance. The degradation rate is 3.7 and 0.5 Ohm cm2/1000 h, accordingly. When external polarization is applied, the degradation rate decreases considerably. It is found that the amount of chromium in the cathode bulk changes nonlinearly at an increase in current density. At 0.2 A/cm2, the overall amount of chromium is twice as large as under open circuit conditions, but the degradation rate is three times lower. Herewith, a considerable amount of chromium was found both on the cathode surface and in its bulk. The results of model experiments show that exposure to external electric current leads to migration of chromium cations in the bulk of the porous cathode. It is shown that the growth of a SrCrO4 layer on the surface of an LSCF cathode and penetration of chromium into the cathode bulk becomes slower at the current density of 0.5 A/cm2. Under similar conditions (temperature, current density, and time), the amount of chromium in an LSCF cathode is 2.5-7.3 times larger as compared to that in La0.65Sr0.3MnO3. However, the rate of degradation of electrochemical performance of an LSCF cathode is lower, which points to its higher tolerance towards the presence of chromium. This is due to higher oxygenionic conductivity of an LSCF cathode.
AB - Variation of electrochemical performance of a La0.58Sr 0.4Co0.2Fe0.8O3 (LSCF) cathode due to chromium gas-phase deposition has been studied at 800°C. The highest degradation rate is observed under open circuit conditions and is related to formation of a SrCrO4 layer on the surface of an LSCF cathode. This results in an increase in both polarization and ohmic electrode resistance. The degradation rate is 3.7 and 0.5 Ohm cm2/1000 h, accordingly. When external polarization is applied, the degradation rate decreases considerably. It is found that the amount of chromium in the cathode bulk changes nonlinearly at an increase in current density. At 0.2 A/cm2, the overall amount of chromium is twice as large as under open circuit conditions, but the degradation rate is three times lower. Herewith, a considerable amount of chromium was found both on the cathode surface and in its bulk. The results of model experiments show that exposure to external electric current leads to migration of chromium cations in the bulk of the porous cathode. It is shown that the growth of a SrCrO4 layer on the surface of an LSCF cathode and penetration of chromium into the cathode bulk becomes slower at the current density of 0.5 A/cm2. Under similar conditions (temperature, current density, and time), the amount of chromium in an LSCF cathode is 2.5-7.3 times larger as compared to that in La0.65Sr0.3MnO3. However, the rate of degradation of electrochemical performance of an LSCF cathode is lower, which points to its higher tolerance towards the presence of chromium. This is due to higher oxygenionic conductivity of an LSCF cathode.
KW - Co-containing cathodes with a perovskite structure
KW - cathode poisoning by chromium
KW - current density
KW - solid oxide fuel cell (SOFC)
UR - http://www.scopus.com/inward/record.url?scp=84904960007&partnerID=8YFLogxK
U2 - 10.1134/S1023193514070076
DO - 10.1134/S1023193514070076
M3 - Article
AN - SCOPUS:84904960007
SN - 1023-1935
VL - 50
SP - 630
EP - 637
JO - Russian Journal of Electrochemistry
JF - Russian Journal of Electrochemistry
IS - 7
ER -