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Solid oxide fuel cells (SOFCs) have strong potential for next-generation energy conversion systems. However, their high processing temperature due to multi-layer ceramic components has been a major challenge for commercialization. In particular, the constrained sintering effect due to the rigid substrate in the fabrication process is a main reason to increase the sintering temperature of ceramic electrolyte. Herein, we develop a bi-layer sintering method composed of a Bi 2 O 3 sintering sacrificial layer and YSZ main electrolyte layer to effectively lower the sintering temperature of the YSZ electrolyte even under the constrained sintering conditions. The Bi 2 O 3 sintering functional layer applied on the YSZ electrolyte is designed to facilitate the densification of YSZ electrolyte at the significantly lowered sintering temperature and is removed after the sintering process to prevent the detrimental effects of residual sintering aids. Subsequent sublimation of Bi 2 O 3 was confirmed after the sintering process and a dense YSZ monolayer was formed as a result of the sintering functional layer-assisted sintering process. The sintering behavior of the Bi 2 O 3 /YSZ bi-layer system was systematically analyzed, and material properties including the microstructure, crystallinity, and ionic conductivity were analyzed. The developed bi-layer sintered YSZ electrolyte was employed to fabricate anode-supported SOFCs, and a cell performance comparable to a conventional high temperature sintered (1400 °C) YSZ electrolyte was successfully demonstrated with significantly reduced sintering temperature (<1200 °C). [ABSTRACT FROM AUTHOR]

We report a 3.5-fold improvement in the performance of solid oxide fuel cells (SOFCs) operating at 450 °C with the introduction of electrospun yttria-stabilized zirconia (YSZ) nanofiber interlayers between the electrolyte and cathode. YSZ nanofibers with diameters of 150–200 nm were uniformly deposited with various thicknesses on a single-crystal YSZ substrate. Electrochemical impedance spectroscopy analyses revealed a drastically reduced polarization resistance, which was mainly attributed to the high specific surface area and high porosity of the YSZ nanofiber interlayers. Our results demonstrate the possibility of using YSZ nanofibers for the development of high-performance SOFCs at low temperature. [ABSTRACT FROM AUTHOR]

Yttria-stabilized zirconia thin films were deposited with a controlled argon flow rate via DC reactive magnetron sputtering processes. Typically, thin film electrolytes fabricated by physical vapor deposition onto nano-porous substrates generate pinholes due to their columnar grain structure. The grain boundaries between these columnar grains can be considered as structural defects and can cause voltage drops due to electrical shorting when used as thin film electrolytes in energy conversion systems. By controlling the argon flow rate of the reactive sputtering method, YSZ thin films with dense and restrained columnar grains were fabricated. Scanning electron microscopy inspection was conducted to analyze the surface morphologies, grain structures, and nano-defects in the interior of YSZ thin films. X-ray photoelectron spectroscopy revealed that the composition of the YSZ electrolyte is determined by the flow rate of the oxygen-reactive gas. In addition, X-ray diffractometry was conducted to verify the crystalline phase of the YSZ films; it was determined that a lower argon flow rate produces a better crystalline phase. The films also showed high ionic conductivity compared to the reference data, and the restrained columnar structure had higher conductivity due to a reduction in the ion transport blockage. Furthermore, the fuel cell with the YSZ electrolyte fabricated under a low argon flow rate, which had restrained columnar grains, showed a higher peak power density and superior open circuit voltage performance compared to the fuel cell with a higher argon flow rate. [ABSTRACT FROM AUTHOR]