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Cobalt-based layered perovskite oxides have been recognized as pioneering cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs) due to their fast oxygen diffusion, surface exchange kinetics, and high electrical conductivity. Herein, we study novel Fe doped layered perovskites, YBa0.5Sr0.5Co2-xFexO5+δ (x=0, 0.25, 0.5, and 0.75) in terms of their structural properties, thermal expansion behavior, electrical properties, and electrochemical performances for potential usage as a cathode. Among them, YBa0.5Sr0.5Co2-xFexO5+δ (YBSCF25, x = 0.25) not only shows enhanced structural stability but also meets the essential required properties, including an appropriate thermal expansion coefficient (TEC), chemical compatibility with the electrolyte, and suitable electrical conductivity. Moreover, power density as high as 1.5 W cm-2 at 600°C is achieved for the YBSCF25-GDC composite cathode with a full cell with a dense thin gadolinium doped ceria (GDC) electrolyte and a Ni-GDC composite anode in humidified H2. These favorable features highlight the potential of YBSCF25 as a promising cathode material for IT-SOFCs. [ABSTRACT FROM AUTHOR]

Interconnects present major technical challenges in the commercialization of solid oxide fuel cells (SOFCs) with high performance and durability. To mitigate surface oxidation (chromia growth) and chromium evaporation under high-temperature oxidizing conditions, metallic interconnects should be coated with conductive metal oxides. In this study, we report a protective coating based on perovskite-type LaNi0.6Fe0.4O3 (LNF) fabricated by a facile electrophoretic deposition (EPD) process. LNF powders with a narrow size distribution are synthesized by using the Pechini method. EPD parameters, including solid content in a suspension, deposition time, and applied voltage, are adjusted to control the microstructure, morphology, and thickness of the LNF coating. An LNF coating of ~7.7 μm thickness is fabricated on an SOFC interconnect via EPD under optimized conditions. The electrophoretically deposited LNF layer serves as an effective protective coating for SOFC interconnects, showing a low resistance (~4.2 mΩ cm2) as well as high stability during long-term operation at 800°C. [ABSTRACT FROM AUTHOR]

A carbon gasified carbon-based fuel cell (CFC) short stack was fabricated and investigated for generating effective carbon fuel cell reactions. Anode-supported tubular CFC cells with a 45 cm2 active electrode area were used to manufacture the CFC short stack, which was coupled with a dry gasifier induced by a reverse Boudouard reaction. Activated carbon (BET area 1800 m2/g) powder was mixed with K2CO3 powder (5 wt.%) and used to fill a dry gasifier as a solid carbon fuel, and pure CO2 gas was supplied to the gasifier. The CO fuel generated by the reverse Boudouard reaction in the dry gasifier increased the performance of the CFC short stack. The tubular CFC short stack showed a maximum power of 29.4 W at 800 °C. It was operated under a range of operating conditions by changing the operating temperature, flow rate of the pure CO2 and the thermal cycle operation. The results indicate that the fabricated tubular CFC is a promising power generation system candidate for many practical applications, such as residential power generation (RPG) and stationary power systems. [ABSTRACT FROM AUTHOR]

Layered perovskites have attracted abundant interest as advanced cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs) due to their high electrical conductivity and excellent catalytic properties for the oxygen reduction reaction (ORR). However, cobalt related layer perovskite oxides generally suffer from larger thermal expansion co-efficiency (TEC) than that of electrolyte materials. In this study, we have prepared a thin interlayer, SmBa0.5Sr0.5Co2O5+δ (SBSCO) layered perovskite, via pulsed laser deposition (PLD) on a Sr- andMg- doped LaGaO3 (LSGM) thin film electrolyte to prevent the formation of a micro-gap arising from the thermal mismatch between the SBSCO cathode and LSGM electrolyte. A Samaria-doped ceria (SDC) buffer layer was prepared between the cathodic interlayer and LSGM electrolyte in order to prevent interdiffusion of cations. The cathodic interlayer of SBSCO is helpful for overcoming the thermal mismatch between the SBSCO powder cathode and the LSGM electrolyte, and also shows high power generating properties and small area specific resistance under typical fuel cell operating conditions. [ABSTRACT FROM AUTHOR]

In this study, sulfur tolerance of a conventional Ni-yttria stabilized zirconia (Ni-YSZ) anode for solid oxide fuel cells is significantly improved by surface modification. The Ni-YSZ anode modified by the infiltration of BaZr0.1 Ce0.7 Y0.1 Yb0.1 C3-δ (BZCYYb) demonstrates stable performance in a sulfur-containing H2 fuel over 500 hours. In contrast, the bare Ni-YSZ anode without surface modification degrades drastically when exposed to the sulfur-containing H2 fuel. This implies that the BZCYYb coating is an excellent catalyst for surface modification of the conventional Ni-YSZ anode. A single step infiltration of BZCYYb into the Ni-YSZ anode was sufficient to provide good sulfur tolerance. [ABSTRACT FROM AUTHOR]

A unit bundle of a flat tubular segmented-in-series (SIS)-solid oxide fuel cell (SOFC) for intermediate temperature (650-800 °C) operation was fabricated and operated in this study. We fabricated flat tubular ceramic supports through an extrusion process and analyzed the basic properties of the flat tubular ceramic support: the visible microstructure, porosity, mechanical strength, and pore size distribution. After that, we manufactured a flat tubular SIS-SOFC single cell using screen printing and a vacuum slurry dip-coating method for the electrode/interconnect and electrolyte. In addition, to make a unit bundle for a flat tubular SIS-SOFC, five SIS-SOFC single cells with an effective electrode area of 0.8 cm² were coated onto the surface of the prepared ceramic support and were connected in series using an Ag + glass interconnect between each single SIS-SOFC cell. The performance of the 5-cell unit bundle for a flat tubular SIS-SOFC in 3% humidified H2 and air at 800 °C had a maximum power of 2.5 W. [ABSTRACT FROM AUTHOR]

Direct carbon fuel cells (DCFCs) have recently attracted great interest because they could provide a considerably more efficient means of power generation in comparison with conventional coal-fired power plants. Among various types of DCFCs under development, a hybrid system offers the combined advantages of solid oxide and molten carbonate electrolytes; however, there is a significant technical challenge in terms of power capability. Here, we report an experimental study demonstrating how anode microstructure influences the power-generating characteristics of hybrid DCFCs. The anode microstructure (pore volume and surface area) is modified by using poly(methyl methacrylate) (PMMA) pore-formers. Polarization studies indicate that cell performance is strongly dependent on the anode surface area rather than on the pore volume. The incorporation of PMMA-derived pores into the anode leads to improved power capability at typical operating temperatures, which is attributed to an enlarged active zone for electrochemical CO oxidation. [ABSTRACT FROM AUTHOR]