Fabrication and characterization of a YSZ/YDC composite electrolyte by a sol–gel coating method

• Published in: Journal of power sources Vol. 110; no. 1; pp. 222 - 228
• Main Authors: Kim, Seung-Goo, Yoon, Sung Pil, Nam, Suk Woo, Hyun, Sang-Hoon, Hong, Seong-Ahn
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 20.07.2002; Elsevier Sequoia
• Subjects: Applied sciences; Composite electrolyte; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Fuel cells; Low temperature SOFC; Single cell performance; Sol–gel coating; YSZ thin film; Composite electrolyte; Single cell performance; Low temperature SOFC; YSZ thin film; Sol–gel coating; Characterization; Scanning electron microscopy; Heat treatment; Manufacturing process; Sol gel process; Stabilized zirconia; Cerium oxide; X ray diffractometry; Solid oxide fuel cell
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/S0378-7753(02)00270-7

The compatibility of a composite electrolyte composed of a yttria stabilized zirconia (YSZ) film and a yttria-doped ceria (YDC) substrate in a solid oxide fuel cell (SOFC) that can be operated under 800 °C was evaluated. The YSZ film coated on a YDC substrate was derived from a polymeric YSZ sol using a sol–gel spin coating method followed by heat-treatment at 1400 °C for 2 h. The SEM and XRD analysis indicated that there were no cracks, pinholes, or byproducts. The composite electrolyte comprising a YSZ film of 2 μm thickness and a YDC substrate of 1.6 mm thickness was used in a single cell performance test. A 0.5 V higher value of open circuit voltage (OCV) was found for the composite electrolyte single cell compared with an uncoated YDC single cell between 700 and 1050 °C and confirmed that the YSZ film was an electron blocking layer. The maximum power density of the composite electrolyte single cell at 800 °C, 122 mW/cm 2 at 285 mA/cm 2, is comparable with that of a YSZ single cell with the same thickness at 1000 °C, namely 144 mW/cm 2 at 330 mA/cm 2. The hypothetical oxygen partial pressure at the interface between the YSZ film and the YDC substrate for the composite electrolyte with the same thickness ratio at 800 °C is 5.58×10 −18 atm which is two orders of magnitude higher than the equilibrium oxygen partial pressure of Ce 2O 3/CeO 2, 2.5×10 −20 atm, at the same temperature.