Electrochemical performance of La 0.6 Sr 0.4 CoO 3– δ –Ce 0.9 Gd 0.1 O 1.95 composite cathode for IT‐SOFCs

Abstract In this work, the performance of solid oxide fuel cells is improved by physically mixing Ce 0.9 Gd 0.1 O 1.95 (GDC) in La 0.6 Sr 0.4 CoO 3– δ (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 × 10 −5 K −1 at 650°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 Ω cm 2 at 650°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°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.