Study Of Intermediate-temperature Flat CeO₂-based SOFC

Solid Oxide Fuel Cell(SOFC)is expected to become one of the most potential energy sources in 21 century.It is an electrochemical device that converts the energy of a chemical reaction into electrical energy directly.In recent years,reseaches focus on reducing the working-temperature of SOFC,and to find proper materials which can work well under temperature lower than 800℃is hot.In this paper Ce_0.8Sm_0.2O_1.9(SDC)power was synthesized by spay pyrogenation, with cerium acetate and samarium carbonate as raw materials.The diameter of primary particles of SDC is 10-20 nm and many hollow sphere shells are formed by primary particles.The diameter of the shells is 0.5-5μm and the thickness of the shell is 30-40 nm.After sintered at 1500℃for 2 h in air,the SDC sample acquired 96.4%of relative density,which can satisfy the need of SOFC,with little pollution,easy and continuous operation,the preparation method is promising used in commercial production.La_0.6Sr_0.4Co_0.2Fe_0.803(LSCF)powder was synthesized by solid phase synthesis, then LSCF-50 wt.%SDC and composite anode material NiO-45 wt.%SDC powders were prepared by ball milling,using LSCF powder,commercial NiO powder and SDC powder as the raw materials.The pore-creating performance of black carbon was compared with that of ammonium carbonate.Results show that the proper porosity were obtained when cathode material contained 54 wt%ammonium carbonate and anode material contained 34 wt.%ammonium carbonate.Cathode layer,anode layer and anode interlayer on electrolyte were prepared by spin coating method.A single electrolyte-support cell which has a anode inter-layer of Ni-SDC||YSZ||SDC||LSCF-SDC and another electrolyte-support cell of Ni-SDC||SDC|| LSCF-SDC which has not an anode inter-layer were assembled.The characteristics of electrical performances were tested with H₂ as the fuel and air as the oxidant over a temperature range of 600 to 800℃.The testing results of the cells showed that the open-circuit voltages(OCVs)of electrolyte-support SOFC with inter-layer were 0.828 V,0.821 V and 0.791 V while the working temperature wsa 800℃,700℃and 600℃respectively.At the same time the OVCs of the one without inter-layer were 0.798 V,0.793 V and 0.732 V. YSZ layer decreases the reducing effect of H₂ to electrolyte and blocks the electron's moving,so the function of electron conductivity can be reduced.When the working temperature was 800℃,the cell with inter-layer had the max power density of 30.84 mW·cm^-2and the cell without the inter-layer had 27.84 mW·cm^-2.The main reason that the power density isn't high is that the ohmic loss was too much which caoused by the resistance of electrolyte,interface resistance between electrolyte and electric pole,contact resistance of collecting wire and electric pole.The hard-working study is needed to reduce the resistances.