Synthesis and ionic conductivity of calcium-doped ceria relevant to solid oxide fuel cell applications

Abstract

Towards the development of green energy devices, it is necessary to focus on commercial electrolyte materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). Ca-doped ceria (CDC) samples having a composition of Ce(1−x)CaxO2−δ (0.03 ≤ x ≤ 0.1) were synthesized by a facile solid-state route and sintered at a lower temperature (1473 K). X-ray diffraction, Raman, X-ray photoelectron, Fourier-transform infrared, UV-VIS diffuse reflectance, field emission scanning electron microscopy - energy dispersive X-ray with elemental mapping, and electrochemical impedance spectroscopy techniques were used for the characterization of these CDC samples. The 0.10 CDC showed high oxide ion conductivity of 8.01 × 10−3 S cm−1 at 973 K with a lower activation energy of 0.78 eV. The 0.03 CDC, 0.05 CDC, and 0.07 CDC samples exhibited ionic conductivities of 1.66 × 10−4, 4.42 × 10−3, and 5.76 × 10−3 S cm−1 at 973 K with activation energies of 1.65, 1.01, and 0.92 eV, respectively. The present work aims to develop Ca-doped ceria as economically viable electrolytes for IT-SOFCs.