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The La0.5Sr0.5Fe0.9Mo0.1O3 − δ-x wt.% SDC (LSFMo-xSDC, x = 0, 20, and 30) samples were evaluated as potential cathodes for solid oxide fuel cells (SOFCs) based on both La0.9Sr0.1Ga0.8Mg0.2O3 − δ (LSGM) and Sm0.2Ce0.8O2 − δ (SDC) electrolytes. The LSFMo cathode is chemically compatible with the LSGM and SDC electrolytes with temperature up to 1000 °C. Through the comparison of the polarization resistances (Rp) of the LSFMo cathode on LSGM and SDC electrolytes, only a small difference of ~ 13-15% in the Rp was obtained. To further improve the electrochemical performance of the LSFMo cathode, 20 and 30 wt.% SDC were introduced into the LSFMo cathode. The LSGM/SDC-supported single cell with LSFMo-20SDC composite cathode was found to show the optimal performance and excellent power cycle and long-time stability. In addition, the electrical conductivity and thermal expansion coefficient (TEC) for the LSFMo-20SDC cathode were also detected and evaluated. Our results show that the LSFMo-20SDC is a very promising candidate for use in the cathode of SOFC. [ABSTRACT FROM AUTHOR]

Double perovskites Ba 2 Fe 2- x Mo x O 6- δ (BFMo x , x = 1.0–0.3) were investigated as anodes of solid oxide fuel cells (SOFCs). In H 2 , all the BFMo x samples exhibit sufficient electrical conductivities (σ > 2 S cm−1) at 600–800 °C. However, the BFMo 0.7 and BFMo 0.5 compositions exhibit relatively better redox stability than the others. Furthermore, using 250-μm-thick La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3- δ as electrolyte and Ba 0.6 Sr 0.4 Co 0.9 Nb 0.1 O 3- δ as cathode , the BFMo 0.7 and BFMo 0.5 anode cells also show higher electrochemical performances with peak power density attaining 905 and 908 mW cm−2, respectively, at 800 °C. Additi°nally, the BFMo 0.7 and BFMo 0.5 anodes show good electrochemical stability for long-term H 2 oxidation. However, the BFMo 0.7 anode exhibits an especially high thermal expansion coefficient (TEC) ∼61.9 × 10−6 K−1 at 25–886 °C in air, nearly three times larger than that of the BFMo 0.5 anode under the same condition (TEC=∼14.8 ×10−6 K−1). In view of this, the BFMo 0.5 is considered to be a preferred anode candidate for SOFC. [Display omitted] • BFMo x double perovskites were evaluated as anodes for SOFCs. • BFMo 0.5 anode shows the best redox stability. • BFMo 0.5 anode shows the lowest TEC of 14.8 × 10−6 K−1 at 25-886 °C in air. • BFMo 0.5 anode shows a P max of 908 mW cm−2 at 800 °C in H 2. • Effect of Mo level in BFMo x on anode electrochemical dynamics was investigated. [ABSTRACT FROM AUTHOR]

Pr-deficient Pr 1− x BaCo 2 O 5+ δ (P 1− x BCO) oxides are evaluated as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). Effects of Pr-deficiency on electrical conductivity, thermal expansion and electrochemical properties are investigated. Both the conductivity and thermal expansion coefficient (TEC) decrease with increasing Pr-deficiency. All of the conductivity, thermal expansion and TGA measurements demonstrate the existence of high temperature order-disorder transition. The oxygen reduction mechanism for P 1− x BCO cathodes are characterized by electrochemical impedance spectroscopy. Over the temperature range of 600−800 °C, the cathode polarization resistance is mainly contributed from electronic charge transfer over the cathode surface. Proper Pr-deficiency reduces cathode polarization resistance ( R p ), and the lowest R p (0.081 Ω cm 2 at 700 °C) is obtained for the P 0.92 BCO cathode. In addition, the effects of order-disorder transition on the properties of P 1− x BCO cathodes have also been discussed. Maximum power densities of a single-cell with P 0.92 BCO cathode on 300-μm thick Sm 0.2 Ce 0.8 O 1.9 (SDC) electrolyte achieve 446–987 mW cm −2 at 650–800 °C. These results suggest that, among various P 1− x BCO oxides, P 0.92 BCO is the most promising candidate cathode material for IT-SOFCs. [ABSTRACT FROM AUTHOR]

Ba x Sr 1− x Co 0.9 Sb 0.1 O 3− δ (BSCSbx, x = 0.0–0.8) are investigated as cathodes for intermediate temperature solid oxide fuel cells (IT-SOFCs). BSCSbx oxides are crystallized in a tetragonal structure with s.g. P4/mmm . XPS analysis shows that Ba doping reduces valence state of Co ions: Co in SrCo 0.9 Sb 0.1 O 3− δ is prone to Co 4+ , while Co in Ba doped SrCo 0.9 Sb 0.1 O 3− δ becomes more prone to Co 3+ . Oxygen deficiency δ increases with Ba doping even at high temperatures. Conductivity is found to decrease with Ba doping. Thermal expansion coefficient (TEC) decreases from 20.6 × 10 −6 K −1 for x = 0.0 to 18.4 × 10 −6 K −1 for x = 0.6 at 30–1000 °C. With increasing x from 0.0 to 0.6, polarization resistance ( R p ) decreases monotonously, and then increases with further increasing x. The lowest R p of 0.081 Ω cm 2 at 700 °C is obtained for BSCSb0.6 cathode. At 700–850 °C, the R p of BSCSb0.6 is mainly contributed from electron charge transfer; however, below 700 °C, ion charge transfer plays a more important role in R p . Maximum power densities of the cell with BSCSb0.6 cathode on 300-μm thick La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3− δ (LSGM) electrolyte attain 306–944 mW cm −2 at 700–850 °C. These results indicate that BSCSb0.6 is a promising cathode for application in IT-SOFC. [ABSTRACT FROM AUTHOR]