Search

Cobalt-free composite cathodes consisting of Pr 0.6 Sr 0.4 FeO 3−δ – x Ce 0.9 Pr 0.1 O 2−δ (PSFO- x CPO, x = 0–50 wt%) have been synthesized using a one-pot method. X-ray diffraction, scanning electron microscopy, thermal expansion coefficient, conductivity, and polarization resistance ( R P ) have been used to characterize the PSFO- x CPO cathodes. Furthermore the discharge performance of the Ni-SSZ/SSZ/GDC/PSFO- x CPO cells has been measured. The experimental results indicate that the PSFO- x CPO composite materials fully consist of PSFO and CPO phases and posses a porous microstructure. The conductivity of PSFO- x CPO decreases with the increase of CPO content, but R P of PSFO-40CPO shows the smallest value amongst all the samples. The power density of single cells with a PSFO-40CPO composite cathode is significantly improved compared with that of the PSFO cathode, exhibiting 0.43, 0.75, 1.08 and 1.30 W cm −2 at 650, 700, 750 and 800 °C, respectively. In addition, single cells with the PSFO-40CPO composite cathode show a stable performance with no obvious degradation over 100 h when operating at 750 °C. [ABSTRACT FROM AUTHOR]

Abstract: Understanding the sintering processes extensively is critical in fabricating a flat cell for solid oxide fuel cell stacks, but few have reported the sintering process and stress development during the constrained sintering of the electrolyte layer on anode substrate. In this study, we show that the green tape of half cell fabricated by co-tape casting cracks into several pieces when it is heated directly to 1400 °C of profile I, while it remains flat and complete when the green tape is sintered with additional pre-sintered profile at 1300 °C of profile II. The strain rate characteristics indicate that the difference of 2.43 × 10−6 s−1 between the electrolyte and the anode layer leads to the stress development in the directly sintered cell, while it reduces to 6.7 × 10−8 s−1 for the pre-sintered cell, which is only 3% of that without pre-sintering. The stress based on continuum model calculated results in the sintered cell demonstrates that the stress increases from 0 at about 1000 °C to 2.60 MPa at 1300 °C, and increased from 2.60 MPa to 6.54 MPa in temperature range of 1300–1400 °C. But it was lower than half of the stress for the pre-sintered cell according to profile II. The SEM images, together with a circuit voltage of 2.22 V for two cell stack, indicate that the electrolyte of the unit cell is dense. The power is 41.7 W, with a power density of 0.26 W cm−2 at 1.4 V and 750 °C for a two tells stacks sintered according to profile II. The ASR of the two cells stack is 2.50 Ω cm2. [Copyright &y& Elsevier]