Preparation And Study Of Electrolytes Used For Intermediate Temperature Solid Oxide Fuel Cells

Making solid oxide fuel cells work at inermediate temperature is the trend of commercialization of SOFCs. The meterial having a high oxygen ion conductivity and a low activation energy at intermediate temperature is the key of the commercialization of SOFCs. Apatite-type lanthanum silicate, oxygen ion conductor, has the characteristics of high oxygen ion conductivity and low activation energy at intermediate temperature. It is pure oxygen ion conductivity at a very wide range of oxygen partial pressure. Mg-doped apatite-type lanthanum silicate is one of the materials which have the highest oxygen ion conductivity.This paper reports on preparing the film of Mg-doped apatite-type lanthanum silicate LaioSi5.gMgo.2026.8ar>d nondoped apatite-type lanthanum silicate LaioSi6027by magnetron sputtering, and studying the effect of work pressure, negative bias, annealing tempreture on the structures of the films. The phase, surface morphology, composition and thickness of the film obtained by magnetron sputtering are detected by XRD. SEM. EPMA and so on. The experimental results indicate that the best parameters of the Mg-doped fiims are:bias voltage: OV. work pressure:0.9Pa. annealing tempreture:1100’C. The best parameters of the non-doped flims are:bias voltage:OV. work pressure:0.8Pa. annealing tempreture:1100℃This paper reports on preparing the powder of Mg-doped apatite-type lanthanum silicate LaioSi5.8Mg0.2O26.8by sol-gel method through using citric acid and glycol as the complexant. nitrate and ethyl silicate as the raw materials. The powder is pressed into plates with the diameter of6mm. and mainly studying the effect of sintering temperature on the properties of the ceramic plate. The results indicate that La10Si582Mg0.2O26.8powder calcined at900℃for8h is apatite-type lanthanum silicate. The results of ceramic plates" XRD and TEM indicate that the sintering temperature of the synthesized powder must be above155O℃. The phase of the La10Si5.8Mg0.2O26.8ceramic plates sintered at1550℃and1600"C is apatite-type lanthanum silicate and the densities are93.3%and93.5%. The densities are high. The experimental results indicate that the synthesized powder has very high sintering activity. The oxygen ion conductivity of the La10Si5.8Mg0.2O26.8ceramic plate sintered at1550℃and1600℃is8.7×10-3S/cm and9.5×10-3S/cm at800℃and the activation energy for oxygen ion conduction is0.76ev and0.87ev.