Evaluation of LaxSr1−xZnyFe1−yO3−δ (x = 0.54, 0.8, y = 0.2, 0.4) as a promising cobalt free composite cathode for SOFCs

Abstract

Nowadays, cobalt containing cathodes are widely used in solid oxide fuel cells (SOFCs) due to their high performance. There are many disadvantages of cobalt based cathodes such as reduction, high cost and evaporation of cobalt. In order to reduce these detrimental effects, cobalt free composites such as La_0.54Sr_0.46Zn_0.20Fe_0.80O_3−δ (LaSrZnFeO1) La_0.80Sr_0.20Zn_0.20Fe_0.80O_3−δ (LaSrZnFeO2), and La_0.80Sr_0.20Zn_0.40Fe_0.60O_3−δ (LaSrZnFeO3) have been prepared by the sol–gel technique. The electrical properties and microstructure of the proposed cathode materials were investigated in this study. The characterization of the prepared materials was carried out by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The thermal stability of the synthesized materials was observed with thermogravimetric analysis (TGA). The highest DC conductivity of LaSrZnFeO1, LaSrZnFeO2 and LaSrZnFeO3 cathodes achieved was 8.12, 7.12 and 6.62 S cm⁻¹ at 600 °C, respectively. The single cell achieved maximum power densities of 436, 370 and 296 mW cm⁻² with LaSrZnFeO1, LaSrZnFeO2, and LaSrZnFeO3 cathodes at 600 °C, respectively. The better current densities of 1472, 1422 and 1397 mA cm⁻² for LaSrZnFeO1, LaSrZnFeO2 and LaSrZnFeO3 were attained at 600 °C, respectively. The SEM images disclosed that the prepared nanocomposite cathodes were porous and homogeneous. The purity of the prepared samples was confirmed by XRD. The proposed LaSrZnFeO1, LaSrZnFeO2 and LaSrZnFeO3 cathodes achieved a maximum OCV of 0.90, 0.83 and 0.76 volts at 600 °C, respectively.