Development of High Performance Ceria/Bismuth Oxide Bilayered Electrolyte SOFCs for Lower Temperature Operation

Abstract

This study examines the development of lower temperature solid oxide fuel cells (SOFCs) and the incremental improvement in performance obtained from a wide range of techniques, from pressed anodes to tape-cast anodes, from gadolinia-doped ceria (GDC) single-layer electrolytes to erbium-stabilized bismuth oxide (ESB)/GDC bilayer, and from La0.6Sr0.4Co0.2Fe0.8normalO3−δ -GDC composite cathodes to optimized Bi2Ru2normalO7 -ESB composites. GDC single-layer electrolyte-based SOFCs were prepared from four different fabrications and exhibit maximum power densities ranging from 0.338 to 1.03W/cm2 at 650°C . At each fabrication stage, an ESB layer was applied to form a bilayer electrolyte. ESB was deposited by a range of techniques including colloidal deposition and pulsed laser deposition. The result confirms that depending on a fabrication route, the bilayer electrolyte can reduce the total area specific resistance (ASR) 33–49% and increase the maximum power density 44–93%. By using a combination of the materials and fabrication routes, a maximum power density of 1.95W/cm2 and 0.079Ωcm2 total cell ASR was achieved at 650°C for a bilayer cell.

High performance ceria–bismuth bilayer electrolyte low temperature solid oxide fuel cells (LT-SOFCs) fabricated by combining co-pressing with drop-coating

“…The typical I-V and power density curves for the single cell NiO-SNDC|SNDC|ESB|ESB-LBSM at 450-650 °C is shown in Figure 3 18 and SDC|YSB (0.887 V at 500 °C) 17 . Moreover, the current relsuts show higher MPDs than many ceria-bismuth bilayer electrolytes reports, such as SDC|YSB (571 mW cm -2 at 600 °C), 17 SDC|YSB (381 mW cm -2 at 650 °C), 2 GDC|ESB (588 mW cm -2 at 650 °C), 3 GDC|ESB (667 mW cm -2 at 600 °C) 23 . Some studies show higher OCV values with lower MPDs, while some display higher MPDs accompanied with lower OCVs.…”

Interfacial modification of La0.80Sr0.20MnO3−δ–Er0.4Bi0.6O3 cathodes for high performance lower temperature solid oxide fuel cells

“…In order to overcome this, an ESB/GDC bilayered electrolyte was developed [26]. Using this bilayered electrolyte with a BRO7eESB cathode, we recently demonstrated exceptionally high power density (w2 W cm À2 at 650 C) [27,28]. These results indicate that cathode performance is promoted not only by the addition of ESB as the ion conducting phase in composite cathodes but also by using an ESB electrolyte at the cathode interface due to improved oxygen incorporation into the electrolyte lattice resulting in a reduction of the cathode polarization losses.…”

Tailoring gadolinium-doped ceria-based solid oxide fuel cells to achieve 2 W cm−2 at 550 °C

“…For that reason, studies on the fabrication of thin electrolytes have focused on yttria-stabilized zirconia, which has been widely used as an electrolyte material at high temperatures, rather than the ceria-based electrolytes [10][11][12][13] . When using the thin ceria-based electrolytes, buffer layers should be applied to protect the materials from reduction by preventing contact with the reducing gas 14,15 . The former often uses expensive deposition devices, such as pulsed laser deposition 12 that many researchers have chosen to prepare the thin film, and the latter requires complex cell fabrication processes and has the possibility of thermal expansion mismatch between the GDC and the buffer layers.…”