Electrochemical Characterization of Mixed Ionic- Electronic Ceria Doped LSM Conductors for Solid Oxide Fuel Cells

Abstract

In this study, composite cathode materials were fabricated for solid oxide fuel cells (SOFCs). Ceria based electrolyte (NDC, GDC, SDC, and CDC) doped in LSM and (LSM-NDC, LSM-GDC, LSM-SDC and LSM-CDC) cathode composites for solid oxide fuel cell were prepared successfully. All these Composites were prepared by Solid State reaction method. These materials give better results and produce more oxygen ions vacancies which enhance the oxidation reduction reaction. The synthesized material is characterized by using Raman Spectroscopy, UV-Vis spectroscopy, and Electrochemical Impedance Spectroscopy. Raman spectra show vibration modes and the structure of materials particles. Raman spectroscopy showed well defined CeO2 vibrational modes at 455 cm⁻ ¹ and 461 cm⁻ ¹, suggesting increased crystallinity and weak intense peak representing oxygen ion vacancies. It tells about which type of shifting occurring in prepared material. In all prepared materials, there is red shifting and wavelength is increasing which shows that particles size is increasing. In UV-Vis’s spectroscopy result demonstrated the band gap values which ranges from 2.5 eV to 3.5 eV. EIS tells about charge transfer and mass transfer in material. EIS tells about the ionic and electronic behavior of materials. in (La0.2Sr0.8 MnO3-δ)0.6 –(Nb0.2Ce0.8O2-δ)0.4 cathode showed the lowest resistances, 0.38 Ω series resistance, 0.68 Ω charge transfer resistance, and 0.30 Ω polarization resistance, in electrochemical impedance spectroscopy at 700°C. These findings were confirmed by fuel cell testing, which showed that (La0.2Sr0.8 MnO3- δ)0.6/(Nb0.2Ce0.8O2-δ)0.4cathode showed highest open circuit voltage of 1.07 V at 700 °C. The conductivity of materials can be calculated with the help of EIS, which is found to be 0.801 Scm -1 at 700 °C