Fabrication of 10%Gd-doped ceria (GDC)/NiO–GDC half cell for low or intermediate temperature solid oxide fuel cells using spray pyrolysis

Abstract

Solid oxide fuel cells (SOFCs) with comparably low operating temperature play a critical role in its commercialization and reliability by allowing low-cost fabrication and a promised longer life. Recently, 10%Gd-doped ceria (GDC) has revealed its importance as solid electrolytes for intermediate temperature SOFCs. Additionally, if GDC is employed in thin film form, rather higher ionic conductivity at further lower temperatures can be obtained and thereby allowing its use in low temperature SOFC. In the present investigation, the preparative parameters of spray pyrolysis technique (SPT) were optimized to deposit dense and adherent films of GDC on ceramic substrate. NiO–GDC was used as ceramic substrate, which also acts as a precursor composite anode for GDC-based SOFCs. Prepared half cells (GDC/NiO–GDC) were characterized using XRD, SEM, and electrochemical impedance spectroscopy. The surface and fractal SEM observations of post heat-treated (at 1,000 °C) GDC/NiO–GDC structure revealed that GDC films were uniform in thickness with improved adherence to substrate. The relative density of post heat-treated films was of the order of 96%, which was attributed to the presence of nano-granules in the thin films. Maximum thickness of the GDC film prepared with optimized preparative parameters (in single run) was of the order of 13 µm. Fractal SEM of post heat-treated GDC/NiO–GDC system showed homogenous interface, which was further analyzed by electrochemical impedance spectra and found that it does not affect electrical properties of structure significantly.