Preparation And Performance Of Ce_1-xRe_xO（2-δ）（Re=Sm,Gd）-BaCe_0.83Y_0.17O_3-δ Composite Electrolyte For SOFC

A fuel cell is a kind of energy conversion device which has advantages ofhigher energy conversion efficiency than traditional generator and are alsofriendly to environment. The fuel cell is composed of cathode, anode andelectrolyte. Solid oxide fuel cell （SOFC） is a fuel cell with whole solid structureand its comprehensive utilization of energy can reach80%. SOFC can use a llarge of different fuels,from H₂, CO to natural gas, liquefied gas and otherhydrocarbons. The main difficulty the SOFC faces currently is the problemcaused by high temperature and the ceramic components’ match.SOFC electrolyte is the core of the battery, whose performance has adirect impact on the overall performance of the battery. The electrolyte has tomeet the following requirements: a high oxygen ion conductivity; low electronicconductivity; resistance to reactive gas. SOFC generally employs thetraditional yttria stabilized zirconia （YSZ） as electrolyte, but this type ofelectrolyte for SOFC is required to work at1000℃. Such a high operatingtemperature of the battery has already put forward various strict requirementsfor SOFC, which will bring a series of questions. Therefore, it is extremelyimportant to reduce the operating temperature of SOFCs. On the one hand, wecan make the electrolyte of YSZ into thin films to reduce the battery’s internalresistance and finally improve the battery performance. On the other hand, wemay look for new electrolyte materials that can work in intermediate-temperaturerange, below800℃.Due to the high cost and complicated process of the filmstechnology, the former proposal is restricted. CeO2-doped electrolyte is one of themost attractive material for IT-SOFC electrolyte. But its mechanical strength is low,moreover this material has a degree of electrical conductivity, which reduces the output performance of fuel cells. Therefore, CeO₂-doped electrolyte is difficult torealize its industrial production. It is known that composite materials can not onlybe designed and produced according to the needed requirements, but also showa comprehensive advantage of all raw materials. In this paper, we did adetailed research on the Re-doped CeO₂（Re=Sm, Gd）. And we synthesizedCe_1-xRe_xO（2-δ）（Re=Sm, Gd） and BCY composite electrolyte materials. Wemade a full advantage of the two kinds of electrolyte materials, and overcomethe shortcomings of a single electrolyte.The electrolyte material Ce0.85Sm0.15O1.925（SDC） were synthesized bymeans of glycine-nitrate process（GNP） and then the BaCe_0.83Y_0.17O_3-δ（BCY）were prepared by sol gel process。Afterwards，composite SDC with a smallamount of BCY，the prepare different proportion of composite electrolytematerials，just as SB95,SB90, SB85, SB80. We studyed the structure andproperties of composite electrolytes in the present work. SOFC werefabricated with Ni_0.9Cu_0.1-SDC as anode and BaCo_0.7Fe_0.22Nb_0.08O_3-δascathode,then measure the power density of cells. The results showed that therelative density of every composite electrolytes is higher than SDC.Theconductivity tests also showed GB95is the highest,SB80is a little lower thanSDC，so we can know a small amount of BCY is beneficial effect，but excessis harmful effect to conductivity composited.Single-cell tests showed that theoutput performance of the cells which employed the composite electrolytes ofSB95,SB90，SB85are better than cell with pure SDC.Among the SDC-BCYcomposite electrolyte, the one with ratio of90:10showed the maximum poweroutput density0.159W/cm²at600℃. The curve of OCV shows OCV withcomposite electrolytes is better than pure SDC.The electrolyte material Ce_0.9Gd_0.1O_1.95（GDC） were synthesized bymeans of glycine-nitrate process（GNP） and then the BaCe_0.83Y_0.17O_3-δ（BCY）were prepared by sol gel process。Afterwards，composite GDC with a smallamount of BCY，the prepare different proportion of composite electrolyte materials，just as GB99,GB98, GB97, GB95.We studyed the structure andproperties of composite electrolytes in the present work. SOFC werefabricated with Ni0.9Cu0.1-SDC as anode and BaCo_0.7Fe_0.22Nb_0.08O_3-δascathode,then measure the power density of cells. The results showed that therelative density of every composite electrolytes is higher than GDC.Theconductivity tests also showed GB98is the highest，so we can know a smallamount of BCY is beneficial effect.Single-cell tests showed that the outputperformance of the cells which employed the composite electrolytes ofGB99,GB98，GB97are better than cell with pure GDC.Among the GDC-BCYcomposite electrolyte, the one with ratio of99:01showed the maximum poweroutput density0.204W/cm²at600℃. The curve of OCV shows OCV withcomposite electrolytes is better than pure GDC.