Preparation And Electric Properties Study On Dual Phase Electrode Materials For Solid Oxide Fuel Cell

As anode materials of solid-oxide fuel cell, dual phase materials have gainedwidely attention of the people.Thesis studiedelectrical property of NiO/La₂Mo₂O₉、NiO/YSZ and LaSr₃Fe₃O_10-δ/La₂Mo₂O₉dual phase materials.Chapter1briefly introduces principle and outlines current research status ofSOFC. Chapter2briefly introduces experimental methods used in this paper.In the chapter3, The NiO/La₂Mo₂O₉compound powder were prepare by usingchemical precipitation method and the dielectric relaxation behavior ofNiO/La₂Mo₂O₉compound powder were studied. For NiO:La₂Mo₂O₉=2:8, at848Kand within the test frequency, dielectric loss peak produced by the phase change ofαLa₂Mo₂O₉�'βLa₂Mo₂O₉. At633K dielectric relaxation peak produced by O（1） O（2）oxygen short diffusion appears in La₂Mo₂O₉. The activation energy value ofNiO:La₂Mo₂O₉=2:8sample is1.01ev. At633K dielectric loss peak was producedby NiO. For NiO:La₂Mo₂O₉=4:6, at480K and823K dielectric loss peak producedby NiO and the phase change of αLa₂Mo₂O₉�'βLa₂Mo₂O₉respectively. There arethree dielectric loss peaks at500-820K.The first peaks produced by O（1） O（2）oxygen short diffusion appears in La₂Mo₂O₉. The activation energy value ofNiO:La₂Mo₂O₉=4:6sample is1.69eV,the second and third peak does not show noobvious relaxation properties between peak temperature and test frequency.Chapter4studies LaSr₃Fe₃O_10-δ/La₂Mo₂O₉dual phase specimen （abbreviated asLSFO-LMO）, including chemical compatibility of LSFO and LMO, conductivity,dielectric relaxation behavior. XRD shows LSFO and LMO keep inert with each otherat700℃for3h,while there are few other phase in the XRD at800℃for3h. Theconductivity of dual phase material decreased with increment of LMO content. ForLSFO:LMO=2:8,at800K and within the test frequency, dielectric loss peakproduced by the phase change of αLa₂Mo₂O₉�'βLa₂Mo₂O₉. At600K dielectricrelaxation peak produced by O（1） O（2） oxygen short diffusion appears in La₂Mo₂O₉.The activation energy value of LSFO:LMO=2:8sample is1.53ev. LSFO/LMO filmswere fabricated on LMO substrates by means of Permanent voltage EPD method.Therelation between depositon weight and deposition parameters （time, voltage） werestudied. SEM observations shows that good films can be obtained when Constantvoltage（20V）functions3minute. And the thickness of the films is about30μm afterdeposited for3minutes. Films layer and LMO electrolyte were integrated and well-combined. Electrochemical performances of half cell LSFO/LMO‖LMO wereexamined by electrochemical impedance spectroscopy （EIS） methods. The results ofEIS analysis showed that ohmic resistance and polarization resistance decrease withtemperature increasing.In the chapter5, Zeta potential was used to determine the best value ofChungyang ion surface active agent of the suspension system and the NiO/YSZpowders in deionized water. The optimum composition for the suspension was:250mL deionized water+5gNiO/YSZ powders+6mL sodium dodecyl benzenesulfonate. NiO/YSZ films were fabricated onYSZ substrates by means of Permanentvoltage EPD method.The relation between deposit weight and deposition parameters（time, voltage） were studied. SEM observations show that good films can be obtainedwhen Constant voltage （20V） functions3minute. And the thickness of the films isabout20μm after deposited for3minutes. Films layer and YSZ electrolyte wereintegrated and well-combined. Electrochemical performances of half cellNiO/YSZ28‖YSZ were examined by electrochemical impedance spectroscopy （EIS）methods. The results of EIS analysis showed that ohmic resistance and polarizationresistance decrease with temperature increasing.