Sol-gel synthesis of gadolinia-doped ceria diffusion barriers for intermediate temperature solid oxide cells

2^nd International Conference and Exhibition on Materials Science and Chemistry

July 13-14, 2017 Berlin, Germany

Sun-Dong Kim

Korea Institute of Energy Research, South Korea

Posters & Accepted Abstracts: J Material Sci Eng

Abstract :

Bi-layers of a gadolinia-doped ceria (GDC)/yttria-stabilized zirconia (YSZ) have been suggested as an alternative electrolyte for the reduced-temperature operation of solid oxide cells (SOCs). One problem arises from the formation of a barrier layer on YSZ electrolytes is that it becomes difficult to achieve a dense GDC layer below 1400�ºC. In this study, a technology for manufacturing dense diffusion barriers below 1000�ºC by the sol-gel process using metal (i.e., Gd and Ce) alkoxide precursors was developed. Gadoliniadoped ceria (GDC) sols were synthesized by the controlled hydrolysis and condensation of cerium(IV) isopropoxide with each gadolinia doping agent. The crystallinity of a GDC sol using gadolinium(III) isopropoxide as the doping agent was five to six times stronger than that when using gadolinium(III) nitrate hydrate as the doping agent. The GDC diffusion barrier was fully densified by infiltration of a GDC sol into a porous GDC structure under heat treatment at 1000�ºC. The performance of a cell was highly improved from 0.60 W/cm2 to 0.92 W/cm2 at 750�ºC by densification of the diffusion barrier. EIS results suggest that the improved performance is mainly due to the reduced Ohmic resistance through the composite electrolyte (i.e., YSZ/GDC). Finally, the degradation of a single cell with a dense GDC was maintained below 1.72%/1000 h, which was lower than that of a cell with a porous GDC (7.69%/1000 h). Based on these results, it can be concluded that the enhancement of the performance and durability of a single cell with a dense GDC was the result of reduced Ohmic resistance through the composite electrolyte.

Biography :

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