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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]

In this work, anode-supported solid oxide fuel cells (SOFCs) has been successfully prepared by tape casting and co-sintering technique. The structure contains the thin and dense 10% Sc 2 O 3 -stabilized-ZrO 2 (SSZ) electrolyte layer and the anode layers with continuous porosity gradient. The decomposition of organic additives and the shrinkage of green tape were analyzed by thermo-gravimetric and differential thermal analyses (TG-DSC) and thermal dilatometry. The microstructure morphologies and the porosity of anodes were examined by SEM and Archimedes method. The obtained anodes with continuous porosity gradient facilitate diffusion of the fuel gas and enlarge electrochemical active three phase boundaries. The open circuit voltage (OCV) was close to 1.1 V. The maximum power densities of single cell with graded Ni-SSZ anode were higher than non-gradient Ni-SSZ anode at 600, 650, 700, 750 and 800 °C and were 0.15, 0.30, 0.51, 0.70 and 1.00 W cm −2 , respectively. R p of cell with graded Ni-SSZ anode was lower than that of non-gradient Ni-SSZ anode. [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]

The extensive explorations of potential cathode materials are prominently critical for the rapid development of high performance solid oxide fuel cells (SOFCs). Herein, we develop a novel Nb and Cu co-doped SrCoO 3-δ (SCNC) cathode base on solid state reaction, which exhibits decent compatibility with gadolinium doped cerium oxide (GDC) electrolyte. The SCNC is successfully stabilized with cubic structure at room temperature when incorporating of small amount of high valence Nb5+. Meanwhile, the oxygen vacancy concentration of SCNC is efficiently improved with the addition of Cu. The Nb and Cu co-doping also substantially promotes the electronic conductivity, achieving 550 S cm−1 for the optical doped SrCo 0.85 Nb 0.05 Cu 0.10 O 3-δ (SCNC10) at 400 °C. In addition, the polarization of SCNC is remarkably reduced, reaching as low as 0.021 Ω cm2 for SCNC10 at 700 °C. The activation energy for reaction is also significantly lowered to 0.78 eV. The reaction order m is deduced to be about 0.30, implying that the rate determination step for SCNC10 is the charge transfer reaction. The peak power density of the single cell reaches 780 mW cm−2 at 800 °C. All these outstanding performances demonstrate that SCNC is a promising cathode for SOFCs when operating at intermediate temperature (IT). (a)The EIS of SCNC10 at different oxygen pressure at 700 °C; (b)the relationship of lnRp to ln (Po 2) for SCNC10 measured at 700 °C. The reaction order m is about 0.30, suggesting that the RDS for SCNC10 is probably to be the charge transfer reaction. Image 1 • A novel Nb and Cu co-doped SrCoO 3-δ improved its oxygen vacancy concentration. • The ASR for SCNC10 was only 0.021 Ω cm−2 at 700 °C, with the activation for reaction is only 0.78 eV. • The reaction orders suggest that the rate determine step is probably to be the charge transfer reaction. [ABSTRACT FROM AUTHOR]