Construction Of Solid Oxide Fuel Cell Based On LBFZ Cathode And The Properties Of Electricity

For new application system of solid oxide fuel cell (SOFC), this paper was focused on cathode materials for SOFC. The basic properties of these materials were examined by various methods to select proper candidate for SOFC. After the material was assembled into a SOFC, the electrochemical and NO reduction properties were tested.LaxBa1-xFe0.8Zn0.2O3-δ (x=0,0.4and1) were prepared by the Sol-gel method. The phase, nitrogen oxide (NO) adsorption capacity and structural stability of them were characterized by X-ray Diffraction (XRD), Thermal Analysis (TA) and Nitrogen Oxides Temperature-programmed Desorption (NO-TPD). La0.4Ba0.6Fe0.8Zno.2O3-δ (LBFZ) was easiest to form the perovskite structure. LBFZ had a good NO adsorption capacity at the intermediate temperature. The structure of LBFZ was stable in the atmosphere of carbon dioxide and water at high temperature. After a comprehensive analysis, LBFZ was suitable for NO reduction and electricity generation based on SOFC as cathode at the intermediate temperature.LBFZs calcined at different temperatures were prepared by the Sol-gel method. The basic characterizations of cathode material were tested by XRD,TA, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM). The cubic perovskite structure appeared from about760℃. After calcined at900℃or above, the cubic perovskite formed completely. The porous structure of LBFZ calcined at1100℃was the most obvious. LBFZ had chemical compatibility with the electrolyte SDC and YSZ, which could be assembled as cathode for SOFC based on SDC and YSZ. So LBFZ calcined at1100℃was selected as cathode material of SOFC based on SDC and YSZ.Electrochemical performance of single cell was studied with configuration of SSCF/SDC/LBFZ. At the condition of550℃and5vol%NO/Ar, the maximum open circuit voltage was0.58V, the maximum current density was43.4mA/cm2and the maximum power density was5.02mW/cm2. The total impedance mainly came from cathode polarization resistance. So the cathode reaction process was the rate-determining step of the whole reaction. The LBFZ reacted with NO to product nitrate in the NO atmosphere on the surface, resulting in decreasing in the maximum power density. In all the cathode gas, CO2was the most difficult to be catalyzed. Thus CO2caused a decreasing in the maximum power density. NO and CO2caused an increasing in the total impedance.Electrochemical performance of single cell was studied with configuration of SSCF/YSZ/LBFZ. NO caused a decline in the maximum power density. The decreasing ratio decreased as the temperature incrrased. CO2caused a decline in the maximum power density. The decreasing ratio increased with the increasing temperature and had tended to remain unchanged until800℃. NO and CO2caused an increasing in the total impedance.