Electrochemical Investigations of BaCe0.7-xSmxZr0.2Y0.1O3-δ Sintered at a Low Sintering Temperature as a Perovskite Electrolyte for IT-SOFCs

Abstract

Perovskite materials have gained a lot of interest in solid oxide fuel cell (SOFC) applications owing to their exceptional properties; however, ideal perovskites exhibit proton conduction due to availability of low oxygen vacancies, which limit their application as SOFC electrolytes. In the current project, Sm was doped at the B-site of a BaCe0.7-xSmxZr0.2Y0.1O3-δ perovskite electrolyte for intermediate-temperature solid oxide fuel cells (IT-SOFCs). BaCe0.7-xSmxZr0.2Y0.1O3-δ electrolytes were synthesized through a cost-effective coprecipitation method and were sintered at a low sintering temperature. The effects of samarium (Sm) doping on the electrochemical performance of BaCe0.7-xSmxZr0.2Y0.1O3-δ were investigated. X-ray diffraction (XRD) analysis confirmed that the BaCe0.7-xSmxZr0.2Y0.1O3-δ electrolyte material retained the perovskite structure. The secondary phase of Sm2O3 was observed for BaCe0.4Sm0.3Zr0.2Y0.1O3-δ. Scanning electron microscopic (SEM) imaging displayed the dense microstructure for all the compositions, while prominent crystal growth was observed for composition x = 0.3. The formation of the perovskite structure and the presence of the hydroxyl groups of metal oxides for all the compositions were confirmed by Fourier transform infrared spectroscopy (FTIR). An increased symmetrical disturbance was also observed for the increased doping ratio of the Sm. Thermogravimetric analysis (TGA) of all the compositions showed no major weight loss in the SOFC operating temperature range. It was also noted that the conductivity of BaCe0.7-xSmxZr0.2Y0.1O3-δ gradually decreased with the increased contents of the Sm metal. The maximum power density of 390 mW cm−2, and an open-circuit voltage (OCV) of 1.0 V at 600 °C, were obtained, showing that BaCe0.7-xSmxZr0.2Y0.1O3-δ, synthesized by a cost-effective method and sintered at a low temperature, can be used as a proton-conducting electrolyte for IT-SOFCs.