8YCSZ/rGO composites for components in SOFC: Microstructure and electrical conductivity
POYATO R. 1, COTO F. 1,2, DE LA CRUZ-BLANCO A. 1,2, MORICHE R. 2, LÓPEZ-PERNÍA C. 2, MORALES-RODRÍGUEZ A. 2, GALLARDO-LÓPEZ Á. 2
1 Instituto de Ciencia de Materiales de Sevilla (ICMS) CSIC – Universidad de Sevilla, Avda. Américo Vespucio 49, 41092 Sevilla, Spain, Seville, Spain; 2 Dpto. Física de la Materia Condensada, Universidad de Sevilla. Avd. Reina Mercedes s/n, 41080 Sevilla, Spain, Seville, Spain
Very recently, ceramic composites with graphene as filler have been proposed as promising materials for components in solid-state electrochemical applications as oxygen transport membranes or solid-oxide fuel cells (SOFC), thanks to their mixed ionic and electronic conductivity. Specifically, these composites have been proposed for their use as electrolyte, anode, or ceramic interconnect in SOFC.
In this work, 8 mol% yttria cubic stabilized zirconia (8YCSZ) with 1, 2.5, 5 and 10 vol% reduced graphene oxide (rGO) composites were consolidated by Spark Plasma Sintering (SPS) at two different temperatures. The in-situ reduction of GO during SPS, the crystallographic phases and the distribution of rGO throughout the ceramic matrix were characterized by Raman spectroscopy, X ray diffraction and scanning electron microscopy, respectively. The effect of rGO on the electrical performance of the composites was analyzed by impedance spectroscopy as a function of temperature. The percolation threshold was established and the electrical behavior modifications from ionic- to electronic-dominated electrical conduction were revealed.