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The development of suitable sealants for high-temperature solid oxide fuel cells (SOFC) is a major challenge, as such sealants must withstand harsh conditions. They must be inert at the high temperatures used in SOFC operation (i.e., resistant to environments composed of oxidative and reducing gases), as well as thermo-chemically and thermo-mechanically compatible with the materials with which they are in contact. This paper presents a post-experimental analysis of variously sealants—mica paper, flexible mica paper, and thermiculite 866—used in high-temperature SOFC operation. The sealants are exposed to air or hydrogen at 600 °C–1000 °C for 100 h. The goal of this work is to investigate the thermal expansion properties (thickness expansion, coefficients of thermal expansion CTE and porosity), mechanical stability, and leakage during midterm operation. After the sealants fired at 1000 °C, their relative thicknesses increased to around 0.98, 1.01, and 0.568 mm, respectively. The coefficients of thermal expansion CTEs (600–1000 °C) for mica paper and flexible mica paper were calculated to be from 8.0 × 10−4 K−1 to 10.0 × 10−4 K−1, the CTEs of thermiculite 866 were around 1.0 × 10−4 K−1. The relative porosity of thermiculite 866, as determined through the density method, changed from 15.4% to 28.7% for temperatures from 600 °C to 1000 °C, respectively. Scanning electron microscopy is used to investigate the structure of thermiculite 866. It is tested for leakage using hydrogen from 500 to 3000 cc min−1 at 25 °C and 800 °C. The leakage rates at 3000 cc min−1 are 4.06% and 8.4% at 25 °C and 800 °C, respectively, showing that thermiculite 866 is a suitable sealant for SOFC applications.

This study reports the manufacturing of its core device–hydrogen electrode supported cell of reversible solid oxide fuel cell (RSOFC) with use of different oxygen electrode (La 0.8 Sr 0.2 MnO 3−δ = LSM, La 0.8 Sr 0.2 MnO 3 /yttria stabilized zirconia = LSM/YSZ) and its operation under solid oxide fuel cell (SOFC) and solid oxide electrolyzer cell (SOEC) mode. In order to lower difficulties during cell assembly, acceptable curvature of hydrogen electrode supported cell is accomplished with improvement of manufacturing process. Also reported are the resulting performances, both in SOEC and SOFC modes, as a function of its operating parameters such as temperature. We found that the RSOFC performance improved with increasing temperature for all oxygen electrodes–LSM, LSM + YSZ. SOFC performance with oxygen electrode–LSM is a better option while SOFC/SOEC recycling with oxygen electrode-LSM/YSZ is more durable. Identical material composition and no obvious weak connection between oxygen electrode-LSM/YSZ and electrolyte after SOFC/SOEC cycling tests are the main reasons leading to minor performance drops compared to that with electrode – LSM.

Previous study demonstrates that the strength of yttria-stabilized zirconia (YSZ) can be enhanced through the addition of alumina (Al 2 O 3 ). In the present study, the toughness of YSZ/Al 2 O 3 composite is further enhanced by 100% through the addition of a small amount of two aliovalent additives, NiO and Nb 2 O 5 . Though the addition of these two additives affects little on oxygen vacancy concentration, the electrical conductivity and thermal conductivity of YSZ/Al 2 O 3 composites are reduced. It suggests that other defects and/or structural distortion are formed due to the addition of NiO and Nb 2 O 5 . The amount of monoclinic phase increases with increasing additive content; the toughness enhancement shows strong dependence on the amount of monoclinic phase.

Anode-supported cells are prepared by a sequence of hot pressing and co-sintering processes for solid oxide fuel cell (SOFC) applications. Commercially available porous anode tape (NiO/YSZ = 50 wt %/50 wt %), anode tape (NiO/YSZ = 30 wt %/70 wt %), and YSZ are used as the anode substrate, anode functional layer, and electrolyte layer, respectively. After hot pressing, the stacked layers are then sintered at different temperatures (1250 °C, 1350 °C, 1400 °C and 1450 °C) for 5 h in air. Different compressive loads are applied during the sintering process. An (La,Sr)MnO3 (LSM) paste is coated on the post-sintered anode-supported electrolyte surface as the cathode, and sintered at different temperatures (1100 °C, 1150 °C, 1200 °C and 1250 °C) for 2 h in air to generate anode-supported cells with dimensions of 60 × 60 mm2 (active reaction area of 50 × 50 mm2). SEM is used to investigate the anode structure of the anode-supported cells. In addition, confocal laser scanning microscopy is used to investigate the roughness of the cathode surfaces. At sintering temperatures of 1400 °C and 1450 °C, there is significant grain growth in the anode. Furthermore, the surface of the cathode is smoother at a firing temperature of 1200 °C. It is also found that the optimal compressive load of 1742 Pa led to a flatness of 168 µm/6 cm and a deformation of 0.72%. The open circuit voltage and power density of the anode-supported cell at 750 °C were 1.0 V and 178 mW·cm−2, respectively.