The Effect of Fabrication Conditions for GDC Buffer Layer on Electrochemical Performance of Solid Oxide Fuel Cells

Abstract

Abstract:A Gd-doped ceria (GDC) buffer layer is required between a conventional yttria-stabilized zirconia (YSZ) electrolyte and a La-Sr-Co-Fe-O3 (LSCF) cathode to prevent their chemical reaction. In this study, the effect of varying the conditions for fabricating the GDC buffer layer, such as sintering temperature and amount of sintering aid, on the solid oxide fuel cell (SOFC) performance was investigated. A finer GDC powder (i.e., ultra-high surface area), a higher sintering temperature (∼1290℃), and a larger amount of sintering aid (∼12%) resulted in improved densification of the buffer layer; however, the electrochemical performance of an anode-supported cell containing this GDC buffer layer was poor. These conflicting results are attributed to the formation of (Zr, Ce)O2 and/or excess cobalt grain boundaries (GBs) at higher sintering temperatures with a large amount of sintering aid (i.e., cobalt oxide). A cell comprising of a cobalt-free GDC buffer layer, which was fabricated using a low-temperature process, had lower cell resistance and higher stability. The results indicate that electrochemical performance and stability of SOFCs strongly depend on fabrication conditions for the GDC buffer layer.

Gd0.2Ce0.8O2 Diffusion Barrier Layer between (La0.58Sr0.4)(Co0.2Fe0.8)O3−δ Cathode and Y0.16Zr0.84O2 Electrolyte for Solid Oxide Fuel Cells: Effect of Barrier Layer Sintering Temperature on Microstructure

“…Based on SEM imaging, previous work suggests that sintering at higher temperature decreases the porosity of screen-printed GDC layers. 47 However, our FIB/SEM tomography work demonstrates that the volume fraction of open porosity in GDC layers does not decrease with increasing sintering temperature between 1100 and 1400 °C. 17 To our knowledge, there is no other quantitative investigation on the temperature dependence of porosity in screen-printed GDC layers on YDZ.…”

Gadolinium doped ceria interlayers for Solid Oxide Fuel Cells cathodes: Enhanced reactivity with sintering aids (Li, Cu, Zn), and improved densification by infiltration

“…Using a Gd-doped ceria (GDC) interlayer between the LSCF cathode and the YSZ electrolyte is a widespread approach to limit such an issue [2,3]. To be fully efficient, the GDC interlayer should be dense, as reported by several authors [4][5][6][7][8][9][10][11], because Sr species can easily diffuse on the surface of GDC grains and still react with zirconia if the interlayer is porous [12]. The most common way to prepare GDC interlayers is the screen-printing of a GDC ink followed by a sintering step at high temperature.…”

Development of a processing map for safe flash sintering of gadolinium‐doped ceria

“…All rights reserved powder is difficult handle with respect to agglomeration and may not be cost effective for large scale production. The sintering aids may deteriorate the electrochemical properties 26 , and using reducing atmosphere requires re-oxidation at a high temperature to reliably avoid the microcracking 25,27 .…”