Single Chamber Solid Oxide Fuel Cell Under Low Concentration Of Fuel

Single-chamber solid oxide fuel cell （SC-SOFC） is a novel type of Solidoxide fuel cell （SOFC）, and the anode and cathode of the battery are completelyexposed to the atmosphere of a mixture of fuel and oxidant. It relies on theselectively catalytic properties of the two electrodes against the differentcomponents of the mixture. It possesses the advantages of no sealing and can useporous electrolyte, so that it’s easy to build a cell stack. Currently, the incompletecombustion process of fossil fuels, such as coal and oil, will cause waste ofresources and environmental pollution. The SC-SOFC can work in the mixture offuel and oxygen so that the incompletely burned fuel may be transformed.Purpose of this thesis is to explore the SC-SOFC electrode material which is ableto run in medium temperature region and gas mixtures of low fuel concentrationwhich may be biased in an oxidizing atmosphere. Focused on testing SC-SOFCelectrochemical performance at600℃⁸00℃and in a mixed atmosphere ofdifferent fuel concentration and the electrodes of the SC-SOFC is three kinds ofconventional cathode materials. Evaluated the catalytic properties of theelectrode material through mass spectrometry analysis and analyzed the workingmechanism. The introduction of Pt catalyst on the electrodes and the performanceof the impregnated cell were also studied in this paper. Mainly include:The open circuit voltage （OCV）, discharge curves and impedancespectroscopy of an anode supported SC-SOFC with three different conventionalcathode materials were tested at a condition of lower temperature and fuelconcentration. The results show that the OCV of the cell tested at a relatively lowtemperature shocks smaller and become more stable. When the fuel concentrationis lower, fuel efficiency of the cell becomes higher, and the battery output powerbecomes lower.To accommodate the lower exhaust gas concentration requirements for thework under an oxidizing atmosphere, try to make the conventional cathodematerials combination of two or make one cathode material and Ag in pairsrespectively, as two electrodes （cathode and anode） of the SC-SOFC. Measuredthe OCV of the cell in the mixed atmosphere of CH₄and O₂under the lower temperature, found that the traditional cathode material under certain conditionsalso have catalytic to the partial oxidation reaction of CH₄. If one has strongcatalytic activity and the electrode potential is significantly lower, it can act asthe anode. As the result, the electrolyte-supported SC-SOFC with LSCF andBSCF has the lowest electric potential difference and the SC-SOFC with LSMand BSCF has the highest electric potential difference （140.7mV）.The pretreatment was carried out on the conventional cathode powders toanalog the manufacturing operation and the working environment of theSC-SOFC. And the catalytic activity to the CH₄-O₂-Ar mixture of differentcathode materials was studied through mass spectrometry under relatively lowtemperature. Then we discussed the impact of the cathode in the whole cell andanalyzed the cell reaction mechanism. We found that all of the three cathodematerials can catalyze the partial oxidation of CH₄, but the catalytic capacityvaries—LSM strongest, BSCF weakest.H₂PtCl₆（aq） was impregnated to introduce Pt into LSM of LSM|YSZ|BSCF.The performance of the cell degenerated obviously only through one temperaturecycle. According to the result of the MS, the patial oxidation of CH₄is moredrastic because of Pt. LSM was resolved under the impact of H₂which comesfrom the partial oxidation of CH₄and this reduced the catalyse activity of LSM.