Performance Of Electrolyte And Cathode Materials For Proton-conducting Solid Oxide Fuel Cells

The fuel cell is one of the effective ways to solve the current energy and environmental crisis.It convert chemical energy of fuel and oxidizer directly into electrical energy with many potential advantages,such as high efficiency,low pollutant emissions etc.Traditional SOFC using yttrium-stabilized zirconia（YSZ）as electrolyte requires high operating temperatures（800–1000°C）,which leads to high costs,materials degradation or corrosion or thermal expansion mismatch between adjacent SOFC components,thus hindering its practical commercial applications.Aiming to avoid these problems for traditional SOFCs.Recently,proton-conducting SOFCs（H⁺-SOFCs）are attracting increasing attention due to their potential advantages with respect to the proton conducting one for reduced temperature application.It is critical to develop proper cathodes and electrolyte for the development of H⁺-SOFCs.Based on the above considerations,the electrolyte and cathode materials for proton-conducting solid oxide fuel cells were studied,and their feasibility as H⁺-SOFCs was discussed in this work.BaCe_0.7Zr_0.1Y_0.2-xZn_xO_3-δ（x=0.05,0.10）were synthesized by the typical solid state reaction method for protonic solid oxide fuel cell.The influence of ZnO content on the crystal structure,conductivity,thermal expansion coefficient,and relative density were studied.The addition of an appropriate amount of BaCe_0.7Zr_0.1Y_0.1Zn_0.1O_3-δ(BZCYZn_0.1)into NdBaCo_2/3Fe_2/3Cu_2/3（NBCFC）to form composite cathodes to improves cathode performance.NBCFC-10BZCYZn_0.1composite cathodes display better performance.The polarization resistance（R_p）of the NBCFC-10BZCYZn_0.1.1 is 0.42Ωcm² at 750°C in air.The peak power density of single cell(NiO-BZCYZn_0.1/BZCYZn_0.1/NBCFC-10BZCYZn_0.1)with a 300μm-thick BZCYZn_0.1.1 electrolyte achieved 238.5 mWcm^-22 in H₂ fuel at 750°C higher than that of NiO-BZCYZn_0.1/BZCYZn_0.1/NBCFC.Perovskite Sr_1.75.75 K_0.25Fe_1.5Mo_0.5O_6-δ（SKFMO）powders were prepared via a combined ethylene diamine tetraacetic acid（EDTA）-citric acid（CA）sol-gel methodd as a cathode material for intermediate-temperature proton-conducting SOFCs（H⁺-SOFCs）,determine the method of synthesis of the cathode material.A larger and more symmetric lattice by doping K⁺into the Sr-site of the Sr₂Fe_1.5Mo_0.5O_6-δ（SFM）perovskite oxide,and also bring a higher concentration of oxygen vacancies.which are benefit to the improvement of proton conduction efficiency.The SKFMO shows a good chemical compatibility with BaZr_0.4Ce_0.4Y_0.2O_3-δ（BZCY4）at 950°C for 10 h.The SKFMO exhibits low Rp values under both air and humid air due to the attribute of triple-conducting.The anode-supported single cell with the structure NiO-BZCY4/BZCY4/SKFMO are manufactured and tested under the intermediate temperature range（550–750°C）using the H₂（3%H₂O）as fuel gas exhibits maximum power densities of 361.24 mWcm^-22 at 750°C.The cell performance without any observable degradation over 100 h in the atmospheres of the dry air and wet H₂（3%H₂O）.