To design durable and reliable solid oxide fuel cells (SOFCs) for commercialization, we investigate the degradation behavior of yttria-stabilized zirconia-based anode-supported cells under two electrical load conditions -load trip (0.2-0 A • cm −2 ) and load cycle (0.20-0.12 A • cm −2 ) modes for 60 times (about 1,450 h). During the load trip condition, the operating voltage of the cell decreases by 86 mV through the 1,443 h operation (60 load trips) with the degradation ratio of 9.1% (59.5 μV • h −1 at 0.2 A • cm −2 ), while the cell voltage decreases with the different degradation ratios of 7.1% and 4.2% at 0.2 and 0.12 A • cm −2 , respectively, during the 60 load cycles (49.4 μV • h −1 at 0.2 A • cm −2 ). A combination of electrochemical impedance spectroscopy and distribution function of relaxation times, thermochemical (Gibbs equilibrium calculations), and post-mortem analysis (field emission-scanning electron microscopy and electron probe micro-analysis with an energy dispersive X-ray spectroscopy) demonstrates the main degradation mechanism of SOFCs under dynamic electrical load conditions. Furthermore, an operation strategy to mitigate the performance degradation under dynamic electrical loads is proposed through the identification of weak points of SOFC components.

In order to investigate a high-performance and durable cathode material for protonic ceramic fuel cells (PCFCs), we prepare BaCo0.4Fe0.4Zr0.2O3-δ (BCFZ) materials and analyze systematically using X-ray diffraction and scanning electron microscopy to obtain a single-phase perovskite material. Chemical compatibility of BCFZ with BaCe0.7Zr0.1Y0.2-xYbxO3-δ (BCZYYb) at high temperature (1000 °C for 8 h) exhibited no secondary-phase formation, indicating that they have good chemical compatibility with each other. We use electrochemical impedance spectroscopy to evaluate the electrochemical performance using a BCZYYb symmetrical cell configuration. BCFZ at 600 °C in humidified (3% H2O) air shows 1.62 Ω·cm2 polarization resistance, comparable to Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF), which showed 1.77 Ω·cm2. This result demonstrates that BCFZ has an excellent oxygen-reduction reaction for PCFCs, especially at intermediate temperatures. The desired electrochemical activity for BCFZ has inspired us to explore new dopants that could further improve electrocatalytic activity for ORR at low temperatures.

Fuel cells are happened to be one of the best solutions for future energy requirement. Solid oxide fuel cell (SOFC) has many advantages including fuel flexibility, long time stability, high efficiency, low emissions and relatively low cost. One of the major disadvantages of SOFC is related to its high operating temperature (800-950 °C). Proton conducting electrolytes show good performance at the intermediate temperature range (400-700 °C). This leads to the study of a novel proton conducting electrolyte, Ba0.9Sr0.1Ce0.5Zr0.35Y0.1Sm0.05O3- d (BSCZYSm), based SOFC to observe the electrochemical performance and microstructure changes. Electrochemical impedance measurements of electrolyte material show the protonic conduction. A fuel cell of NiO/NiO-BSCZYSm|BSCZYSm|Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) was prepared and tested in H2 as fuel in the anode side and air as oxidant in the cathode side. The cell shows a peak power density of 272 mW/cm2 with an open circuit voltage of 0.9282 V at 700 °C. This cell performance might be increased through microstructural improvements of the constituting materials.