Electrochemical performance of La0_.6Sr0_.4CoO_3--Ce0< sub>.9Gd0_.1O_1.95 composite cathode for IT-SOFCs

In this work, the performance of solid oxide fuel cells is improved by physically mixing Ce0(.9)Gd0(.1)O(1.95) (GDC) in La0(.6)Sr0(.4)CoO(3-)(& delta;) (LSC) cathode. The grain size and chemical compatibility of the powder were analyzed using X-ray diffraction. Scanning electron microscopy was used to observe the microstructure of powder and cells. The thermal expansion coefficients (TECs) of LSC-GDC powder with different mass ratios were tested (LSC:GDC = 10:0, 9:1, 8:2, 7:3, 6:4, and 5:5) and LSC-GDC (5:5) showed the minimal TEC (1.34 x 10(-5) K-1 at 650 & DEG;C). The cathodes with different mass ratios are prepared by screen printing. The symmetrical cell with LSC-GDC (5:5) had the smallest cathode polarization resistance (0.0801 & omega; cm(2) at 650 & DEG;C) and the lowest activation energy (1.12 eV). The button cell with LSC-GDC (5:5) exhibited the maximum power density (513 mW cm(-2) at 650 & DEG;C) and could be discharged for 550 h without significant degradation. The LSC-GDC (5:5) cathode was applied to a flat-tube solid oxide fuel cell and achieved a high power density of 552 mW cm(-2) at 0.8 V. The results show that the LSC-GDC (5:5) has a bright future in commercialization.