Effect of strontium doping on structural and electrical conductivity of BaTi0.8Zr0.2O3-δ cathode materials for solid oxide fuel cell

Abstract

Cathode materials are crucial for the efficient operation of solid oxide fuel cell (SOFC), serving as a key component for the oxygen reduction reaction (ORR). Cobalt-containing cathode materials have shown good performance in terms of electronic conductivity and ORR kinetics. However, they suffer from significant drawbacks, including high cost, and instability at the high operating temperatures of SOFC. Thus, there is an increasing need to investigate cobalt-free alternatives that can overcome these limitations and enhance the overall performance and durability of SOFC. In this study, cobalt-free Ba_1-xSr_xTi_0.8Zr_0.2O_3-δ (BSTZ0, BSTZ25, and BSTZ50; x = 0, 0.25, 0.5) cathode materials were synthesized via traditional solid-state reaction techniques. The synthesized samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), to analyse their structural properties, and surface morphology. Electrical conductivity of the synthesised materials measured in air revealed promising results, with BSTZ0, BSTZ25, and BSTZ50 exhibiting conductivities of 18.2 S/cm, 19.5 S/cm, and 22.6 S/cm, respectively. X-ray diffraction analysis confirmed that all compositions crystallize in the tetragonal P4/mmm space group. Findings from this investigation indicate that the synthesized Sr-doped BaTi_0.8Zr_0.2O_3-δ materials exhibit excellent thermal stability and are promising candidates for SOFC cathodes.