Fabrication Of Ceria-based Electrolytes Of Solid Oxide Fuel Cell

The deVloPrnen and crt situation of sOlid okide fue ceIl, ceriabaSedelectrolyte, gel-casting technology and pwhcle coating of codc powder werereviewed, and the crystal to, mpnies and processing of the ceriabasedelectrOlyte were emPhallcally described.The ceria-based electrolyte has attraCed researchers' muh intereSt for itS highoxygen-ion conducivity and low activation energy for ionic conduCon, Whichmakes it usable at teInPeratUr below 800C. The decrease in operation teInperatUreal1ows for flexibility in electrode selechon, and reduction in mainteance coSt andheat-insulatin parts.But the ceria-based electro1ytes haVe been lboted in aPPlication for itS easycation reduction in low oxygen pAnai pressure, Which resuIts in the decrease inelectrolyte condutivity and effechveness of ceIls.In ode to produce ceria-based electrOlytes with high density high oxygen ioncondutivity and high stability in oPeration condition, it was proposed for the thethme to combine ptricle coating Processing with gel-casting technologyA1umina was selected as coating materials for its low electrOnic conductivityand high oxygen ion conduhvityAlfor coated ceria poWders were prePared by heterogeneousamcleationprocess.It is showed by the result of SEM, XPS and Zds potential tha the coating ofalumina prtcles on ceria powders was successfuI. In the XPS speCtrUIn of coatedpowders, the Peaks of energy absorption of Ce and Gd are very loW bUt tha of Alvery high. The Zeta potential of coated powders moved toWar that of kl,O,.The size of coated poWders is about l. l u m, which is sbolar tO that of uncoatedpowders. W pattems show tha thch Inain crystal PliaSes are cubic fluOrite ceria.for both coated and uncoated POwders.It is the bo tiIn to Ptoduce Ceriahased electrOlytes by gel-casting teclmologyTo oM slwhes with high solid volume and low viscosity the effect of diMcontent, PH value and solid voluIne on the hability and rheology of slwhes werestudied systffeaticaIly It is shown that whe dispersant cnd is 8vol%, pH 8.5,and solid voltnne 50vol%, the slwhes are OPtimal to gel-casting.The Wence of Propedes of ceriathased eleCtrlytes on fonning methds,sintering curves, doping and pwhcle coating was investigated in detall.The result showed tha the H and conduCvity of eleCtrDlytes ~ed bygel-casting Process were 98.5% and 0.l8S.cm-', respectively They wer higherthan those by isostatic Pressing. The comPlex ~dane SPebe indicated tbathe ~ bountw resistivity ofelchlytes by gel-casting Process was fower thantha by isondc pressing.During low tW zone, the ceriabased electrolytes produced by gel-casting process couldn't be treated with high heating rate, or cracks ndgh occurand density decreased. In thes stud the desbole rate of heating is considered to be50oCth. The oPtimum silltering temPeratUre thelding tirne) is l650C(4h). So thebest sintering curve is:R.T. 50c/h 600'C l00c/h l650'C (4h)-- eql650'C (4h )The lattice constans and conduCvity of ceriabased electrolytes increased witbdoping gadolinia, samaria and gadolnda/Samaria in ceria.Particle coating made the grain bountw resistivity of electrOlytes increase, and. the conduCivity decrease someWha. But tbat mad the Stability of eleebolyteSincrase undr operation conditions, esPecially at high wodrig temPeratUre for along time.