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TY  - THES
AU  - Zhang, Jun
TI  - Electrolyte development for a SOFC operating at low temperature
VL  - 492
PB  - RWTH Aachen University
VL  - Dissertation
CY  - Jülich
M1  - RWTH-2020-07776
T2  - Schriften des Forschungszentrums Jülich. Reihe Energie & Umwelt = Energy & environment
SP  - 1 Online-Ressource (vi, 121 Seiten) : Illustrationen, Diagramme
PY  - 2020
N1  - Druckausgabe: 2020. - Onlineausgabe: 2020. - Auch veröffentlicht auf dem Publikationsserver der RWTH Aachen University
N1  - Dissertation, RWTH Aachen University, 2020
AB  - Solid oxide fuel cells (SOFCs) operating at low temperature ( 500 °C) enable applications, such as auxiliary power units (APUs) or portable devices. However, the state-of-the-art electrolyte material (yttria-stabilized zirconia (YSZ)) used in intermediate-temperature SOFCs does not provide a sufficiently high ionic conductivity. Two approaches can therefore be taken to deal with that. First, an alternative electrolyte material to YSZ with a higher conductivity. However, when looking for alternatives, the conductivity values for each material found in widely-cited literature can be confusing, as the reported values are sometimes in conflict with each other. Second, an electrolyte film with thinner thickness. While spin coating is reported to be able to fabricate a YSZ electrolyte with thickness as thin as 1 μm, further thickness decrease by spin coating is a big challenge. Moreover, spin coating is very time consuming, needing multiple steps of coating, drying and heat-treatment, which could take several days. Therefore, in this study we present a systematic comparison of the conductivity of the three most popular electrolyte materials, i.e., YSZ, scandium-stabilized zirconia (ScSZ), and gadolinium-doped ceria (GDC). Using electrochemical impedance spectroscopy (EIS) to characterize the ionic conductivity, we find that at 500 °C, GDC has a higher ionic conductivity (5.8e-3 S cm-1) than ScSZ (2.5e-3 S cm-1) and YSZ (1.1e-3 S cm-1). The properties of the starting powders, powder processing and the microstructure after sintering are all taken into account. Following up on this, a GDC electrolyte is developed on an industrial scale anode, with a dimension of 5 cmx5 cm, by screen printing. After sintering at 1400 °C for 5 h, a thin and dense GDC electrolyte, with thickness of 3.5 μm and air leakage rate of 3.54e-6 hPa dm2 s-1 cm-2, is achieved. The single cell test shows the cell has a high cell performance, a measured voltage of 0.84 V at a current density of 2Acm-2 and 750 °C (air,H2 with 10
LB  - PUB:(DE-HGF)11 ; PUB:(DE-HGF)3
DO  - DOI:10.18154/RWTH-2020-07776
UR  - https://publications.rwth-aachen.de/record/794614
ER  -