Structural Stability of the GDC Electrolyte for Low Temperature SOFCs Depending on Fuels

Abstract

It has been considered to apply Od 0.1 Ce 0.9 0 1―x (GDC) to low temperature solid oxide fuel cell (SOFC) electrolytes at a low temperature. However, ceria cannot be efficiently used with hydrogen and wet hydrocarbon fuels because its structure change Ce4 + → Ce 3+ ) causes a decline of mechanical strength under a reducing atmosphere. In this work, the structural stability test of the GDC electrolyte was investigated under H 2 and dry CH 4 atmospheres depending on the fuels at 650°C. This study clearly confirmed from the scanning electron microscopy, X-ray photoelectron spectroscopy, and mechanical strength data that many more Ce 4+ ions transform into Ce 3+ ions under the reducing (H 2 ) atmosphere [J. Alloys Compd., 408―412, 628 (2006); Solid State Sci., 7, 539 (2005)].