Design of efficient and durable symmetrical protonic ceramic fuel cells at intermediate temperatures via B-site doping of Ni in BaCe0.56Zr0.2Ni0.04Y0.2O3–δ

BaCe0.5Zr0.3Y0.2O3–δ (BCZY), regarded as one of the most promising proton–conducting electrolytes, often experiences difficulty because of its high sintering temperature. Here, a B–site doped BaCe0.56Zr0.2Ni0.04Y0.2O3–δ (BCZNY) electrolytes were fabricated to address this drawback. The impact of Ni addition on sintering and electrical properties was examined. By adding Ni to the B–site of BCZY, a substantial decrease in the sintering temperature was achieved, i.e., from 1600 °C (for BCZY) to 1300 °C (for BCZNY). A conductivity of 0.05 S cm−1 at 700 °C was observed for BCZNY electrolyte in a moist nitrogen environment. In addition, SrFe0.8Mo0.2O3–δ (SFM) is utilized as a symmetrical electrode material due to its high ionic and electronic conductivity. SFM electrode was synthesized via combustion process and exhibited suitable chemical and thermal compatibility with BCZY and BCZNY electrolytes up to 1100 °C. A single–phase cubic structure along with the surface morphology of electrolyte–supported symmetrical cells was confirmed by X–ray diffraction and scanning electron microscopy. Electrochemical impedance spectroscopy was conducted to identify the area–specific polarization resistance (ASR). The lowest ASR values of 0.037, 0.081, and 0.327 Ω cm2 at 800, 700, and 600 °C in humidified hydrogen were obtained in SFM-BCZNY composite electrode. The symmetrical cell achieved a peak power density of 254 m W cm−2 (cell configuration; SFM-BCZNY | BCZNY | SFM-BCZNY) at 800 °C. The fuel cell devices showed long–term stability of the fuel cell device for 100 h at 700 °C under a current of 120 mA cm−2. Considering the presented results, the as-prepared BCZNY is a promising protonic electrolyte for IT-SOFCs.