Gd-Doped Ceria with Extraordinary Oxygen-Ion Conductivity for Low Temperature Solid Oxide Fuel Cells

Abstract

Abstract Doped ceria has been extensively explored as an efficient electrolyte material for intermediate to low temperature solid oxide fuel cell. Among other ceria electrolytes, gadolinia doped ceria (GDC) is one of the most extensively studied electrolyte materials for low temperature SOFC applications. Here, co-precipitation method is employed to synthesize GDC composites with stoichiometric ratio of GdxCe1−xO2−δ (with 0\(\le\)x \(\le 0.\)20). In this process, the molecular water of the precursors has been utilized during the co-precipitation to avoid possible agglomeration caused by hydrogen bonding. The cubic phase formation was examined using X-ray diffraction (XRD) and Raman profile ascribing absence of other phases. The granularity of the sample was observed using field emission scanning electron microscopy (FESEM) with elemental mapping by EDS. The electrochemical behavior was investigated using electrochemical impedance spectroscopy (EIS), which was taken between the temperature ranges of 350–700°C. It is observed from the EIS study that ceria doped with 15 mol % Gd3+ (Gd0.15Ce0.85O2−δ) is having highest grain boundary ionic conductivity of about 0.104 S cm−1 at 700°C with an activation energy of 0.81 eV. This work demonstrates the correlation between oxygen vacancy generation and the enhancement of ionic conductivity with Gd3+ doping in ceria.