Comparison of chromium poisoning between lanthanum strontium manganite and lanthanum strontium ferrite composite cathodes in solid oxide fuel cells

JOURNAL OF POWER SOURCES

卷:476

Article

Wang, Ruofan¹  Sun, Zhihao¹  Lu, Yanchen¹  Gopalan, Srikanth^1,2  Basu, Soumendra N.^1,2  Pal, Uday B.^1,2 

[1] Boston Univ, Div Mat Sci & Engn, 15 St Marys St, Brookline, MA 02446 USA

[2] Boston Univ, Dept Mech Engn, 110 Cummington Mall, Boston, MA 02215 USA

关键词: Solid oxide fuel cells;    Chromium poisoning;    Degradation;    Lanthanum strontium manganite;    Lanthanum strontium ferrite;    Mixed ion-electron conductor;   

DOI  :  10.1016/j.jpowsour.2020.228743

来源: Elsevier

【 摘 要 】

Degradation mechanisms of chromium poisoning have been extensively investigated for last two decades on various cathode materials for solid oxide fuel cells. While most researchers used half-cell experiments to investigate the effects of chromium impurities, this paper compares the degradation phenomena of LSM-YSZ and LSF-GDC cathodes in full cells under different operating conditions, namely polarized current density and humidity over the cathode. Under cathodic load, performance degradation of LSF-GDC cathode is significantly less than that of LSM-YSZ cathode. Most interestingly, under humidified air condition, LSF-based cell hardly experiences performance degradation while LSM-based cell shows a catastrophic degradation. Cr deposition in LSM-based cells occurs mainly near the electrolyte under both dry and humidified air conditions. In contrast, Cr deposition in LSF-based cell concentrates at the cathode surface under dry air condition, but concentrates both at cathode surface and near electrolyte under humidified air condition. Microstructure analysis reveals Mn-associated Cr deposits in LSM-based cathode, and Sr- and Fe-associated Cr deposits in LSF-based cathode. With the help of distribution of relaxation time analysis, the different electrochemical behaviors of LSM- and LSF-based cells are carefully interpreted. The effects of electrochemical deposition, Sr surface segregation, and humidity on LSM- and LSF-based cathodes are discussed.

【 授权许可】

Free